.rs .\" Troff code generated by TPS Convert from ITU Original Files .\" Not Copyright ( c) 1991 .\" .\" Assumes tbl, eqn, MS macros, and lots of luck. .TA 1c 2c 3c 4c 5c 6c 7c 8c .ds CH .ds CF .EQ delim @@ .EN .nr LL 40.5P .nr ll 40.5P .nr HM 3P .nr FM 6P .nr PO 4P .nr PD 9p .po 4P .rs \v | 5i' .sp 1P .ce 1000 \v'12P' \s12FASCICLE\ VII.3 \v'4P' .RT .ce 0 .sp 1P .ce 1000 \fBRecommendations T.0\(hyT.63\fR \v'2P' .EF '% \ \ \ ^'' .OF ''' \ \ \ ^ %' .ce 0 .sp 1P .ce 1000 \fBTERMINAL\ EQUIPMENT\ AND\ PROTOCOLS\fR .ce 0 .sp 1P .ce 1000 \fBFOR\ TELEMATIC\ SERVICES\fR .ce 0 .sp 1P .LP .rs .sp 28P .ad r Blanc .EF '% \ \ \ ^'' .OF ''' \ \ \ ^ %' .ad b .RT .LP .bp .LP \fBMONTAGE:\fR \ PAGE 2 = PAGE BLANCHE .sp 1P .RT .LP .bp .ce 1000 \*QTelematic services\*U is used provisionally and includes such services as Videotex, Teletex, facsimile,\ etc. .FE \v'3P' \fBCOLLABORATION\ WITH\ OTHER\fR | \fBINTERNATIONAL\ ORGANIZATIONS\fR .ce 0 .sp 1P .ce 1000 \fBON\ CCITT\(hyDEFINED\ TELEMATIC\fR \fB\ SERVICES\fR .ce 0 .sp 1P .ce 1000 Recommendation A.21 published in Volume\ I is reproduced .sp 1P .RT .ce 0 .sp 1P .ce 1000 below for the convenience of the reader. \v'1P' .ce 0 .sp 1P .sp 2P .LP \fBRecommendation\ A.21\fR .RT .sp 2P .ce 1000 \fBCOLLABORATION\ WITH\ OTHER\ INTERNATIONAL\ ORGANIZATIONS\fR .EF '% Fascicle\ VII.3\ \(em\ Rec.\ A.21'' .OF '''Fascicle\ VII.3\ \(em\ Rec.\ A.21 %' .ce 0 .sp 1P .ce 1000 \fBON\ CCITT\(hyDEFINED\ TELEMATIC\ SERVICES\fR .ce 0 .sp 1P .ce 1000 \fI(Geneva, 1980, amended at Malaga\(hyTorremolinos, 1984)\fR .sp 9p .RT .ce 0 .sp 1P .LP The\ CCITT, .sp 1P .RT .sp 1P .LP \fIconsidering\fR .sp 9p .RT .PP (a) that, according to Article 1 of the agreement between the United Nations and the International Telecommunication Union, the United Nations recognizes the International Telecommunication Union as the specialized agency responsible for taking such action as may be appropriate under its basic instrument for the accomplishment of the purposes set forth therein; .PP (b) that Article 4 of the \fIInternational Telecommunication\fR \fIConvention\fR | (Nairobi, 1982) states that the purposes of the Union are: .LP \*Q\fIa)\fR to maintain and extend international cooperation between all Members of the Union for the improvement and rational use of telecommunications of all kinds, as well as to promote and to offer technical assistance to developing countries in the field of telecommunications; .LP \*Q \fIb)\fR to promote the development of technical facilities and their most efficient operation with a view to improving the efficiency of telecommunication services, increasing their usefulness and making them, as far as possible, generally available to the public; .LP \*Q \fIc)\fR to harmonize the actions of nations in the attainment of those ends.\*U; .PP (c) that Article 40 of the \fIConvention\fR states that \*Qin furtherance of complete international coordination on matters affecting telecommunication, the Union shall cooperate with international organizations having related interests and activities\*U; .PP (d) that this cooperation has to recognize the advisory capacity of organizations participating in the work of CCITT; .PP (e) that, in the study of terminals for new CCITT\(hydefined telematic services (e.g.\ for Teletex , Telefax , Datafax , Bureaufax , Videotex services), ISO in particular is invited to give advice to CCITT based on their work on data systems and data communications; .bp .PP (f ) that this cooperation has to be organized in a manner that will avoid duplication of work and of decisions that would be contrary to the principles set out above; .sp 1P .LP \fIrecognizes the following principles\fR .sp 9p .RT .PP (1) It is the responsibility of the CCITT alone to make the decisions regarding the operational, technical (including factors needed to ensure international interworking) and tariff principles of the CCITT\(hydefined services. .PP (2) While the CCITT will define many of the relevant factors for the CCITT\(hydefined telematic services, other international organizations will be invited to give specialist advice to CCITT on subjects that are of mutual interest, such as: .LP \(em character sets and coding; .LP \(em end\(hyto\(hyend control procedures including error protection; .LP \(em interfaces between terminals and circuit terminating equipment; .LP \(em terminal transmitter distortion and receiver margin; .LP \(em paper sizes and text formatting. .PP (3) Standardization, if required, of hardware and software implementation of terminals, such as printing systems, paper feed, character type fonts, paper characteristics,\ etc., are outside the scope of CCITT. .sp 2P .LP \fBRecommendation\ A.22\fR .RT .sp 2P .ce 1000 \fBCOLLABORATION\ WITH\ OTHER\ INTERNATIONAL\ ORGANIZATIONS\fR .EF '% Fascicle\ VII.3\ \(em\ Rec.\ A.22'' .OF '''Fascicle\ VII.3\ \(em\ Rec.\ A.22 %' .ce 0 .sp 1P .ce 1000 \fBON\ INFORMATION\ TECHNOLOGY\fR .ce 0 .sp 1P .ce 1000 \fI(Melbourne, 1988)\fR .sp 9p .RT .ce 0 .sp 1P .LP The\ CCITT, .sp 1P .RT .sp 1P .LP \fIconsidering\fR .sp 9p .RT .PP (a) that the purposes of the International Telecommunication Union and the recognition of CCITT relations with other organizations were given in 1964 and later, in CCITT Recommendation\ A.20 which concerns data transmission; .PP (b) that the principles of responsibility in regard to CCITT\(hydefined Telematic services were given in 1980 and later, in Recommendation\ A.21 which mentions some subjects of mutual interest; .PP (c) that CCITT Resolution No.\ 7 in 1984 further recognized common interests with ISO and IEC concerning Information Technology and cooperation with them by appropriate means, .sp 1P .LP \fIrecognizes the following principles\fR .sp 9p .RT .PP (1) that in accordance with CCITT Recommendations\ A.20 and A.21 and Resolution\ No.\ 7, every effort should be made in establishing respective study programmes to identify overlapping studies with a view to avoiding duplication of work; .PP (2) that where subjects are identified in which coordination seems desirable, text should be drawn up mutually and kept aligned; .PP (3) that in carrying on the respective programmes of Information Technology studies, collaborative meetings at appropriate levels should be scheduled, where necessary. In drafting aligned text, it is necessary to take into account the respective timing for approvals and publication, particularly with the ISO/IEC Joint Technical Committee\ 1 (JTC1) on Information Technology; .bp .PP (4) that commonality of text with ISO/IEC and cross\(hyreferences is considered desirable in certain areas of mutual interest, such as: .LP \(em Message Handling Systems, .LP \(em Directory Systems, .LP \(em Open Systems Interconnection (OSI) architecture \(em service definitions and protocol specifications, .LP \(em certain areas of Interworking, .LP \(em certain aspects of Telematic Services, .LP \(em Document Architecture, .LP \(em certain aspects of ISDN. .sp 2P .LP \fBRecommendation\ T.0\fR .RT .sp 2P .ce 1000 \fBCLASSIFICATION\ OF\ \fR \fBFACSIMILE\ APPARATUS\ FOR\ DOCUMENT\fR | \fBTRANSMISSION\fR .EF '% Fascicle\ VII.3\ \(em\ Rec.\ T.0'' .OF '''Fascicle\ VII.3\ \(em\ Rec.\ T.0 %' .ce 0 .sp 1P .ce 1000 \fBOVER\ THE\ PUBLIC\ NETWORKS\fR .ce 0 .sp 1P .ce 1000 \fI(Geneva, 1976; amended at Geneva, 1980;\fR .sp 9p .RT .ce 0 .sp 1P .ce 1000 \fIMalaga\(hyTorremolinos, 1984 and Melbourne, 1988)\fR .ce 0 .sp 1P .PP \fB1\fR For document facsimile transmission by international communications carried on the public networks there is a need for providing sufficient operating speeds to meet users' requirements. .sp 1P .RT .PP \fB2\fR Users' requirements may best be served at the present time by classifying the following four basic categories of document facsimile apparatus. .sp 1P .RT .sp 2P .LP 2.1 \fIApparatus for use over the\fR \fIpublic telephone network\fR .sp 1P .RT .sp 1P .LP \fIGroup\ 1\fR \ (see Note 1) .sp 9p .RT .PP Apparatus which uses double sideband modulation without any special measures to compress the bandwidth of the transmitted signal and which is suitable for the transmission of documents of ISO\ A4 size at nominally 4\ lines per\ mm in about six minutes via a telephone\(hytype circuit. .PP Apparatus in this group may be designed to operate at a lower definition suitable for the transmission of documents of ISO\ A4 size in a time between three and six minutes. .RT .sp 1P .LP \fIGroup\ 2\fR \ (see Note 2) .sp 9p .RT .PP Apparatus which exploits bandwidth compression techniques in order to achieve a transmission time of about three minutes for the transmission of an ISO\ A4 size document at nominally 4\ lines per\ mm via a telephone\(hytype circuit. Bandwidth compression in this context includes encoding and/or vestigial sideband working but excludes processing of the document signal to reduce redundancy. .RT .sp 1P .LP \fIGroup\ 3\fR \ (see Note 3) .sp 9p .RT .PP Apparatus which incorporates means for reducing the redundant information in the document signal prior to the modulation process and which can achieve a transmission time of about 1\ minute for a typical typescript document of ISO\ A4 size via a telephone\(hytype circuit. The apparatus may incorporate bandwidth compression of the line signal. .bp .RT .sp 2P .LP 2.2 \fIApparatus for use over the\fR \fIpublic data networks\fR .sp 1P .RT .sp 1P .LP \fIGroup\ 4\fR \ (see Note 4) .sp 9p .RT .PP Apparatus which incorporates means for reducing the redundant information in the document signal prior to transmission mainly via public data networks (PDNs). The apparatus will utilize procedures applicable to the PDN and will assure an essentially error\(hyfree reception of the document. The apparatus may also be used on the public telephone network where an appropriate modulation process will be utilized. .RT .PP \fB3\fR The users will choose among this apparatus, in accordance with their needs and the facilities afforded by the connection and the network. .sp 1P .RT .PP \fB4\fR Procedures for Groups\ 1, 2 and\ 3 document facsimile transmission in the public switched telephone network should be in accordance with Recommendation\ T.30. .sp 1P .RT .PP \fB5\fR Procedures for Group\ 4 document facsimile transmission should be in accordance with Recommendations\ T.62, T.62 | fIbis\fR , and\ T.70. .sp 1P .RT .PP \fINote\ 1\fR \ \(em\ This apparatus has been standardized in Recommendation\ T.2. .PP \fINote\ 2\fR \ \(em\ This apparatus has been standardized in Recommendation\ T.3. .PP \fINote\ 3\fR \ \(em\ This apparatus has been standardized in Recommendation\ T.4. .PP \fINote\ 4\fR \ \(em\ This apparatus has been standardized in Recommendations\ T.6, T.503, T.521 and T.563. .RT .PP \fB6\fR Annex\ A contains definitions for terms used in the T\(hyseries Recommendations applicable to facsimile apparatus. .sp 1P .RT .ce 1000 ANNEX\ A .ce 0 .ce 1000 (to Recommendation T.0) .sp 9p .RT .ce 0 .ce 1000 \fBDefinitions for terms used in the T\(hyseries Recommendations\fR .sp 1P .RT .ce 0 .ce 1000 \fBapplicable to fascimile apparatus\fR .ce 0 .PP The following definitions apply to Recommendations T.1, T.2, T.3 and T.4: .sp 1P .RT .sp 1P .LP A.1 \fBdead sector\fR (Recommendations T.1, T.2) .sp 9p .RT .PP In drum apparatus, that portion of the drum surface the scanning time of which cannot be used for picture signal transmission. .RT .sp 1P .LP A.2 \fBdrum factor\fR (Recommendation T.1) .sp 9p .RT .PP In drum apparatus, the ratio of the usable scanning length of the drum to its diameter. .RT .sp 1P .LP A.3 \fBfacsimile\fR (Series T) .sp 9p .RT .PP The process of scanning a document (page), converting the image scanned into electrical signals for transmission to a remote receiver and the conversion of the received signals to produce a copy of the image originally scanned. .RT .sp 1P .LP A.4 \fBfactor of cooperation\fR (Recommendation T.1) .sp 9p .RT .PP The product of the total scanning line length and the scanning density. .RT .sp 1P .LP A.5 \fBflat\(hybed transmitter\fR (Recommendation T.1) .sp 9p .RT .PP Apparatus in which the original document is placed flat and scanned line by line. .bp .RT .sp 1P .LP A.6 \fBindex of cooperation\fR (Recommendations T.1, T.2, T.3) .sp 9p .RT .PP Quotient of the factor of cooperation divided by the quantity\ \(*p. In the case of a drum apparatus, the index of cooperation is also equal to the product of the drum diameter and the scanning density. .RT .sp 1P .LP A.7 \fBjudder, longitudinal\fR (Recommendation\ T.1) .sp 9p .RT .PP Effect due to the irregular rotation of the drum or helix causing, on the reproduced picture, slight waviness or breaks in lines that are regular on the original document. .RT .sp 1P .LP A.8 \fBjudder, transverse\fR (Recommendation\ T.1) .sp 9p .RT .PP Effect due to irregularity of the scanning pitch resulting in concurrent overlapping and underlapping in the reproduced picture. .RT .sp 1P .LP A.9 \fBlost time\fR (Recommendation T.3) .sp 9p .RT .PP The portion of the scanning line period which cannot be used for picture signal transmission. .PP \fINote\fR \ \(em\ In the case of drum apparatus, this is the same as the dead sector scanning time. .RT .sp 1P .LP A.10 \fBnominal black (white)\fR (Recommendation T.1) .sp 9p .RT .PP Level or frequency of the signal corresponding to a pure black (white). .RT .sp 1P .LP A.11 \fBpel\fR (Series T) .sp 9p .RT .PP A contraction of \*Qpicture element\*U. .RT .sp 1P .LP A.12 \fBphasing\fR (Recommendations T.1, T.2, T.3) .sp 9p .RT .PP At the receiver, ensuring the exact coincidence of the midpoint of the scanning field, with the corresponding point at the transmitter so as to ensure the correct positioning of the picture on the recording medium. .RT .sp 1P .LP A.13 \fBphasing signal\fR (Recommendations T.1, T.2, T.3) .sp 9p .RT .PP A signal sent by the transmitter for phasing purposes. .PP \fINote\fR \ \(em\ Phasing is known as \*Qphase white (black)\*U if the phasing signal is a black (white) signal of which a short interruption corresponding to the white (black) is sent during the lost time. .RT .sp 1P .LP A.14 \fBphototelegraphy\fR (Recommendation T.1) .sp 9p .RT .PP Method of reception of facsimile telegraphy which is chiefly intended for the reproduction of graded tonal densities and in which a photographic process is used at the receiver. .RT .sp 1P .LP A.15 \fBpicture element\fR (Recommendations T.3, T.4) .sp 9p .RT .LP a) at transmission: .PP The part of the area of the original document which coincides with the scanning spot at a given instant and which is of one intensity only, with no distinction of the details that may be included. .RT .LP b) at reception: .PP The area of the finest detail that can be effectively reproduced on the recording medium. .RT .sp 1P .LP A.16 \fBreproduction ratio\fR (Recommendation T.1) .sp 9p .RT .PP The ratio of the linear dimensions of the reproduced document to the corresponding dimensions of the original document. .RT .sp 1P .LP A.17 \fBresolution\fR (Series T) .sp 9p .RT .PP A measure of the capability for delineating picture detail. In Group\ 3 and Group\ 4 facsimile transmission resolution is expressed as picture elements or pels per\ mm (horizontal resolution) and lines per\ mm (vertical resolution). .bp .RT .sp 1P .LP A.18 \fBscanning density\fR (Recommendations T.1, T.2, T.3) .sp 9p .RT .PP Number of scanning pitches per unit length. .RT .sp 1P .LP A.19 \fBscanning line\fR (Recommendations T.1, T.2, T.3) .sp 9p .RT .PP The area explored by the scanning spot in one sweep from one side to the other of the scanning field. .RT .sp 1P .LP A.20 \fBscanning pitch\fR (Recommendation T.1) .sp 9p .RT .PP The distance between the corresponding edges of two consecutive scanning lines. .RT .sp 1P .LP A.21 \fBskew\fR (Recommendation T.3) .sp 9p .RT .PP A defect in reproduction in which lines that should be at right\(hyangles to the scanning direction are inclined to it, owing to a difference between the scanning speeds at transmission and reception. .RT .sp 1P .LP A.22 \fBsynchronization\fR (Recommendation T.1) .sp 9p .RT .PP The establishment of equal scanning line frequencies at the transmitter and receiver. .RT .sp 2P .LP \fBRecommendation\ T.1\fR .RT .sp 2P .sp 1P .ce 1000 \fBSTANDARDIZATION\ OF\ \fR \fBPHOTOTELEGRAPH\ APPARATUS\fR .EF '% Fascicle\ VII.3\ \(em\ Rec.\ T.1'' .OF '''Fascicle\ VII.3\ \(em\ Rec.\ T.1 %' .ce 0 .sp 1P .ce 1000 \fI(former CCIT Recommendation D.1; amended at\fR .sp 9p .RT .ce 0 .ce 1000 \fINew Delhi, 1960; Geneva, 1964; Mar del Plata, 1968;\fR .ce 0 .sp 1P .ce 1000 \fIMalaga\(hyTorremolinos, 1984 and Melbourne, 1988)\fR .ce 0 .sp 1P .LP The\ CCITT, .sp 1P .RT .sp 1P .LP \fIconsidering\fR .sp 9p .RT .PP that the transmission of pictures is possible only if certain characteristics of the transmitting and receiving equipments are identical, .sp 1P .LP \fIunanimously declares the view\fR .sp 9p .RT .PP that phototelegraph apparatus and the associated modulating and demodulating equipment should be constructed and employed according to the following standards: .sp 2P .LP \fB1\fR \fBScanning track\fR .sp 1P .RT .PP At the transmitting apparatus the message area should be scanned in a \*Qnegative\*U direction. The orientation of the document in relation to the scanning plane will depend upon its dimensions and is of no consequence. .PP At the receiving apparatus scanning takes place in a \*Qnegative\*U direction for \*Qpositive\*U reception and in a \*Qpositive\*U direction for \*Qnegative\*U reception. .RT .sp 2P .LP \fB2\fR \fBIndex of cooperation\fR .sp 1P .RT .PP The normal index is\ 352 (corresponds to a factor of cooperation of\ 1105). .PP The preferred alternative index, for use when less dense scanning is required, or when the characteristics of circuits (and particularly combined radio and metallic circuits) so demand, is\ 264 (a factor of cooperation of\ 829). The admissible tolerances on the above\(hymentioned values are\ \(+- | %. .bp .RT .sp 2P .LP \fB3\fR \fBDimensions of apparatus\fR .sp 1P .RT .sp 1P .LP 3.1 \fIApparatus with drum scanning\fR .sp 9p .RT .PP The most currently used drum diameters are\ 66, 70 and\ 88\ mm. .PP The drum factor of the sending apparatus shall not be more than\ 2.4. .PP The drum factor of the receiving apparatus shall not be less than\ 2.4. .PP The width of the picture\(hyretaining device (dead sector) may not exceed\ 15\ mm. An allowance of\ 3% of the total length of a scanning line is also made for phasing. Thus, since the total circumference of a drum of the diameter of 66\ mm is about 207\ mm, the usable circumference will be at least 186\ mm. .RT .sp 1P .LP 3.2 \fIApparatus with flat\(hybed scanning\fR .sp 9p .RT .PP The total lengths of the most current scanning lines are\ 207, 220 and\ 276\ mm of which 15\ mm are not used for effective transmission, because of the possibility that the receiving station may use a drum apparatus. .PP Before transmitting a picture to a receiving station using a drum apparatus, it is necessary to ensure that the value of ratio: \v'6p' .RT .sp 1P .ce 1000 @ { ength~of~document~to~be~transmitted | u1\d\u)\d } over { otal~length~of~a~scanning~line } @ \(mu \(*p .FS Measured in the direction perpendicular to the scanning line. .FE .ce 0 .sp 1P .LP .sp 1 is less or at most equal to the drum factor of the receiver used. .PP 3.3 Table\ 1/T.1 gives corresponding values of index of cooperation\ \fIM\fR , factor of cooperation\ \fIC\fR , drum diameter\ \fID\fR , total length of scanning line\ \fIL\fR , scanning pitch\ \fIP\fR and scanning density\ \fIF\fR for apparatus in most common use. .sp 9p .RT .ce \fBH.T. [T1.1]\fR .ce TABLE\ 1/T.1 .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) . \fIM\fR \fIC\fR \fID\fR (mm) \fIL\fR (mm) \fIP\fR (mm) \fIF\fR (lines/mm) _ .T& cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) . 264 \ 829 66 207 1/4\fB.77\fR \ 4\fB.77\fR .T& cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) . 264 \ 829 70 220 1/3.77 \ 3.77 .T& cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) . 264 \ 829 88 276 1/3\fB.77\fR \ 3\fB.77\fR .T& cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) . 350 1099 70 220 1/5\fB.77\fR \ 5\fB.77\fR .T& cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) . 352 1105 66 207 3/16 \fB7\fR 16/3 .T& cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(36p) | cw(48p) . 352 1105 88 276 1/4\fB.77\fR \ 4\fB.77\fR .TE .LP \fINote\fR \ \(em\ The maximum dimensions of the pictures to be transmitted result from the parameters given in the table. .nr PS 9 .RT .ad r \fBTableau 1/T.1 [T1.1], p.\fR .sp 1P .RT .ad b .RT .sp 2P .LP \fB4\fR \fBReproduction ratio\fR .sp 1P .RT .PP In the case where apparatus working with different lengths of scanning line (but with the same index of cooperation) are interconnected, there will be a slight change in size and the reproduction will bear the same proportion as the original, the ratio being that of the total lengths of the scanning lines. .bp .RT .sp 2P .LP \fB5\fR \fBDrum rotation speed\fR \fB\ \(em\ \fR \fBscanning line frequency\fR .sp 1P .RT .PP 5.1 Table\ 2/T.1 gives the normal and approved alternative combinations of drum rotation speeds or of scanning line frequencies and indices of cooperation. .sp 9p .RT .ce \fBH.T. [T2.1]\fR .ce TABLE\ 2/T.1 .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; lw(90p) | cw(54p) | cw(42p) sw(42p) , ^ | ^ | c | c. { Drum rotation speed in rpm or scanning line frequency } Index of cooperation Metallic circuits { Combined metallic and radio circuits } _ .T& lw(90p) | cw(54p) | cw(42p) | cw(42p) . Normal conditions \ 60 \ 90 352 352 264 _ .T& lw(90p) | cw(54p) | cw(42p) | cw(42p) . { Alternatives for use when the phototelegraph apparatus and metallic circuits are suitable } \ 90 120 150 { 264 and 352 264 and 352 264 } .TE .LP \fINote 1\fR \ \(em\ In the case of transmitters operating on metallic circuits, the index 264 is not intended to be used with an 88\(hymm drum. In the case of transmitters operating on combined metallic and radio circuits, the index 264 associated with a drum diameter of\ 88\(hymm is intended to be used only exceptionally. .LP \fINote 2\fR \ \(em\ The provisions given in the table are not intended to require the imposition of such standards on users who use their own equipment for the transmission of pictures over leased circuits. However, the characteristics of the apparatus used should be compatible with the characteristics of the circuits used. .nr PS 9 .RT .ad r \fBTableau 2/T.1 [T2.1], p.\fR .sp 1P .RT .ad b .RT .PP 5.2 The speed of transmitters must be maintained as nearly as possible to the nominal speed and in any case within\ \(+- | 0 parts in\ 10\u6\d of the nominal speed. The speed of receivers must be adjustable and the range of adjustment should be at least\ \(+- | 0 parts in\ 10\u6\d from the nominal speed. After regulation, the speeds of the transmitting and receiving sets should not differ by more than 10\ parts in\ 10\u6\d. .sp 9p .RT .sp 2P .LP \fB6\fR \fBJudder\fR .sp 1P .RT .PP The stability of the speed during one rotation should be such that the maximum shift of the drum surface from the average position should not exceed one quarter of the scanning pitch \ \fIP\fR at normal index\ 352, which means that the maximum angle of the oscillations should not exceed 0.08\ degree measured from the average position. .RT .sp 2P .LP \fB7\fR \fBSynchronization\fR .sp 1P .RT .PP When phototelegraph stations have available a standard of frequency which is better than\ \(+- | parts in\ 10\u6\d, verification of the synchronism between the two stations may be dispensed with. In view of the saving of time, this method should be adopted wherever possible. .PP To compare the speeds of a transmitter and a receiver, an alternating current whose frequency bears an unvarying relationship to the transmitter speed and has a nominal value of 1020\ Hz is used. .PP Where there is the possibility that the transmitter and receiver may be connected by a circuit liable to introduce frequency drifts, for example, by a carrier telephone circuit, the use of the simple 1020\(hyHz synchronizing tone is unsatisfactory. The preferred method of overcoming this difficulty is to transmit the phototelegraph carrier (of about 1900\ Hz) modulated by the 1020\(hyHz synchronizing tone. .PP At the receiving end, the 1020\(hyHz synchronizing frequency is restored by detection and can then be used in the normal manner. .bp .RT .sp 2P .LP \fB8\fR \fBPhasing\fR .sp 1P .RT .PP Phasing is performed after the speeds of the transmitter and receiver drums have been equalized. .PP For phasing purposes, the transmitter sends a series of alternating white and black signals in such a way that the black lasts\ 95% and the white\ 5% of the total scanning line period (admissible tolerance: \(+- | .5% of the total duration of a scanning line). The apparatus must be so adjusted that the pulses corresponding to the signal for white are transmitted: .RT .LP \(em during scanning of the \*Q dead sector \*U, when drum apparatus is used, .LP \(em during \*Qlost time\*U, when flat\(hybed apparatus is used, .LP and that they are placed at the middle of the dead sector (or of the interval corresponding to the lost time ). .PP (Tolerance admitted in the position of the \*Qwhite\*U pulses: \(*D\fI\fI\d\fIE\fR\u\ =\ \(+-\ 1% of a \*Qtotal scanning line length\*U.) .PP At the receiving station, phasing signals are used to start the apparatus so that short white pulses occur in the middle of the \*Qlost time\*U (tolerance admitted: \(*D\fI\fI\d\fIR\fR\u\ =\ \(+-\ 2% of a \*Qtotal scanning line length\*U). .PP \fINote\fR \ \(em\ These tolerances allow for the fact that the restitution of the original may deviate from its nominal position by\ 3% of a \*Qtotal scanning line length\*U, when the sending and receiving stations are operating with the maximum authorized drift in the same direction. .RT .sp 2P .LP \fB9\fR \fBContrast\fR .sp 1P .RT .PP The transmitter must transmit the original document without changing the contrast of the tone scales of the picture to be transmitted. .RT .sp 2P .LP \fB10\fR \fBModulation and demodulation equipment\fR .sp 1P .RT .sp 1P .LP 10.1 \fIAmplitude modulation\fR .sp 9p .RT .PP Phototelegraph equipment shall normally provide for transmission and reception of an amplitude modulated audio\(hyfrequency carrier, which is the normal mode of transmission for international metallic circuits. .PP The level of the output signal of the transmitter shall be greatest for white and least for black. It is desirable that the ratio of nominal white signal to nominal black signal should be approximately 30\ decibels. .PP To simplify multi\(hydestination operation and AM/FM conversion for radio operation it is desirable that the amplitude of the transmitted signal should vary linearly with the photocell voltage and that no corrections for tone scale should be made at the phototelegraph transmitting station. .PP For audio\(hyfrequency telephone circuits, the frequency of the picture carrier\(hycurrent is fixed at about 1300\ Hz. This frequency gives the least delay distortion on lightly loaded underground cables. .PP In the case of carrier telephone circuits providing a transmission band from\ 300 to\ 3400\ Hz, a carrier\(hycurrent frequency of about 1900\ Hz is recommended. .RT .sp 1P .LP 10.2 \fIFrequency modulation\fR .sp 9p .RT .PP Preferably phototelegraph apparatus should also provide for transmission and reception of a frequency\(hymodulated audio\(hyfrequency carrier for use when necessary: .RT .LP a) on combined metallic and radio circuits; .LP b) on wholly metallic circuits. .PP In such a case, the characteristics of the frequency\(hymodulated output should be: .ad r mean frequency 1900\ Hz .ad b .RT .ad r white frequency 1500\ Hz .ad b .RT .ad r black frequency 2300\ Hz .ad b .RT .LP .PP The deviation of frequency should vary linearly with photocell voltage or, in the case of conversion from amplitude modulation to frequency modulation, with the amplitude of the amplitude\(hymodulated carrier. .PP The stability of the transmission must be such that the frequency corresponding to a given tone does not vary by more than 8\ Hz in a period of 1\ second and by more than 16\ Hz in a period of 15\ minutes. .bp .PP The receiving apparatus must be capable of operating correctly when the drift of black and white frequencies received does not exceed their nominal value by more than \(+- | 2\ Hz. .PP \fINote\fR \ \(em\ It is recognized that there are difficulties operating with these frequency limits on the public switched telephone network (PSTN) where certain types of signalling equipment are used. By prior agreement between users on the PSTN, alternative frequencies of 1300\ Hz for white and 2100\ Hz for black may be used. .RT .sp 2P .LP \fB11\fR \fBPositive or negative reception\fR .sp 1P .RT .PP Selection of positive or negative reception should be made by adjustment at the receiver. The adaptation of the transmitted signals to the characteristics of the photographic materials must also be effected at the receiving end according to the type of reproduction, negative or positive. .RT .sp 2P .LP \fB12\fR \fBColour transmission\fR \fB(optional)\fR .sp 1P .RT .PP 12.1 Phototelegraphy apparatus constructed in accordance with this Recommendation can be used in colour phototelegraphy by splitting the spectrum of light reflected from the picture elements into three basic colours and transmitting the three resulting signals sequentially. Then each signal can be treated and transmitted as a phototelegraphy signal as specified in this Recommendation above. .sp 9p .RT .PP 12.2 The splitting of light reflected from picture element into three spectral components should be performed simultaneously. Thus synchro and phase coincidence and electronic colour correction can be achieved. .PP 12.3 The triad RGB (red, green, blue) shall be used as a basis of main colours. The red colour shall be in range of 575\(hy700 nm, green 485\(hy575\ nm, blue\ 400\(hy485\ nm. .PP \fINote\fR \ \(em\ For the high quality reproduction of art images by means of graphic facilities, transmission of fourth components (i.e.\ black overtone) is desirable. .PP 12.4 The order of signal transmission shall be as follows: red, green, blue. In the case of negative reproduction the order of colour separated signals transmission is reversed. .PP 12.5 The speeds of the transmitting and receiving sets should not differ by more than\ 1 part in 10\u7\d. .sp 2P .LP \fBRecommendation\ T.2\fR .RT .sp 2P .ce 1000 \fBSTANDARDIZATION\ OF\ \fR \fBGROUP\ 1\ FACSIMILE\ APPARATUS\fR .EF '% Fascicle\ VII.3\ \(em\ Rec.\ T.2'' .OF '''Fascicle\ VII.3\ \(em\ Rec.\ T.2 %' .ce 0 .sp 1P .ce 1000 \fBFOR\ DOCUMENT\ TRANSMISSION\fR .ce 0 .sp 1P .ce 1000 \fI(Mar del Plata, 1968; amended at Geneva, 1972 and 1976)\fR .sp 9p .RT .ce 0 .sp 1P .LP The\ CCITT, .sp 1P .RT .sp 1P .LP \fIconsidering\fR .sp 9p .RT .PP (a) that there is a requirement for Group\ 1 facsimile apparatus which enables an ISO\ A4 document to be transmitted over a telephone\(hytype circuit in approximately six minutes; .PP (b) that document facsimile transmission may be requested alternately with telephone conversation or when either or both stations are unattended; in both cases the facsimile operation should conform to Recommendation\ T.30, .sp 1P .LP \fIunanimously declares the view\fR .sp 9p .RT .PP that Group\ 1 facsimile apparatus for use on the general switched telephone network and international leased circuits should be designed and operated according to the following standards: .sp 2P .LP \fB1\fR \fBScanning track\fR .sp 1P .RT .PP The message area should be scanned in the same direction in the transmitter and receiver. Viewing the message area in a vertical plane, the scanning direction should be from left to right, and subsequent scans should be adjacent and below the previous scan. .bp .RT .sp 2P .LP \fB2\fR \fBIndex of cooperation\fR .sp 1P .RT .PP The nominal index of cooperation is\ 264. In cases where a lower vertical resolution is acceptable, and by agreement between the users, an optional index of cooperation of\ 176 may be used. .PP These values should be observed with a nominal tolerance of\ \(+- | % for each equipment. .RT .sp 2P .LP \fB3\fR \fBDimensions of apparatus\fR .sp 1P .RT .PP 3.1 The apparatus should accept documents up to a minimum of ISO\ A4 size (nominally 210\ mm\ \(mu\ 297\ mm). .sp 9p .RT .PP 3.2 The total scanning line length ( active sector plus dead sector) should be nominally 215\ mm. Nominally 200\ mm should be available for scanning or recording, the remainder being the dead sector . .PP 3.3 For any one document the nominal number of scans should be\ 1144 for an index of cooperation of\ 264 (762\ scans for an index of\ 176). The receiver should be capable of recording nominally 1144\ scans per document for an index of cooperation of\ 264 (or 762\ scans for an index of\ 176). .PP 3.4 Apparatus with other dimensions may be used provided that the index of cooperation is respected, that the total scanning line length lies between\ 210 and 250\ mm and the usable recording line length retains the same ratio to the total scanning line length. .sp 2P .LP \fB4\fR \fBScanning density\fR .sp 1P .RT .PP Scanning density is normally 3.85\ lines per\ mm. .RT .sp 2P .LP \fB5\fR \fBScanning line frequency\fR .sp 1P .RT .PP In the subscriber\(hyto\(hysubscriber service via the general switched telephone network, the scanning line frequency should be 180\ lines per minute (see Note). .PP For leased circuits operation the best line frequency, which may be higher or lower than 180\ lines per minute, may be chosen according to the circuit characteristics. .PP The scanning line frequency during the transmission should be kept within\ \(+- | 0 parts in\ 10\u6\d of the nominal value. .PP \fINote\fR \ \(em\ With manual control at the two ends of connection set up over the general switched telephone network, another scanning line frequency (e.g.\ 240\ per minute) may be chosen by agreement between the two operators. .RT .sp 2P .LP \fB6\fR \fBPhasing\fR .sp 1P .RT .PP The duration of the phasing signal for transmitters should be 15\ \(+-\ 1\ seconds. .PP In a preferred method of phasing (see Note\ 1), the transmitter sends a series of alternating white and black signals in such a way that the white pulse (phasing pulse) is\ 4 to\ 6% of the total scanning line length and the leading edge is\ 2 to\ 3% in advance of the middle of the dead sector. .PP Receiving apparatus should synchronize the middle of its dead sector\ 0.5 to\ 4.5% lagging the leading edge of the received phasing pulse (see Note\ 2). .PP \fINote\ 1\fR \ \(em\ In a permitted method of phasing for present generation machines, the transmitter sends a series of white and black signals in such a way that the white pulse is\ 2 to\ 12% of the total scanning line length and the leading edge is\ 2 to\ 3% in advance of the middle of the dead sector. .PP \fINote\ 2\fR \ \(em\ Maximum reduction of recorded scanning line length due to synchronizing misalignment should not exceed\ 3% of total scanning line length. Maximum reduction of recorded scanning line length due to the combined effect of deviations of the transmitter and receiver scanning line frequencies should not exceed\ 4% of total scanning line length. The effect of these reductions of recorded scanning line length may cause it to be less than the nominal 200\ mm. .bp .RT .sp 2P .LP \fB7\fR \fBModulation and demodulation equipments\fR .sp 1P .RT .sp 1P .LP 7.1 \fIAmplitude modulation\fR | (for leased circuits only) .sp 9p .RT .PP The facsimile signal level is higher for black and lower for white. .PP The carrier frequency should range between\ 1300 and\ 1900\ Hz and will depend upon the characteristics of the circuits used. .RT .sp 1P .LP 7.2 \fIFrequency modulation\fR | (for leased circuits and for switched connections) .sp 9p .RT .PP The frequency corresponding to black will normally be\ \fIf\fR\d0\u\ +\ 400\ Hz and the frequency corresponding to white will normally be\ \fIf\fR\d0\u\ \(em\ 400\ Hz (see Note). .PP For switched connections \fIf\fR\d0\u\ =\ 1700\ Hz (provisional). For leased circuits\ \fIf\fR\d0\ushould range between\ 1300\ and 1900\ Hz: the choice of the centre frequency\ \fIf\fR\d0\uwill depend upon the circuit characteristics. However, if the user, in some cases, wishes to use the apparatus on switched connections, \fIf\fR\d0\u\ =\ 1700\ Hz. .PP The stability of the transmitter must be such that the significant frequencies do not vary by more than 32\ Hz from their nominal value in a period of 15\ minutes. .PP \fINote\fR \ \(em\ Attention is drawn to the fact that there are some equipments currently in operation for which black and white elements are represented in the opposite sense, but the preferred standard for new equipment is as indicated above. .RT .sp 1P .LP 7.3 \fIPower at the transmitter output\fR .sp 9p .RT .PP When amplitude modulation is used, the power of black at the transmitter output must be able to be adjusted between \(em7\ dBm and 0\ dBm. The white level must be approximately 15\ dB below the black level. .PP In frequency\(hymodulated systems, the level at the output of the facsimile apparatus must be able to be adjusted between \(em15\ dBm and 0\ dBm. .PP The equipment should be so designed that there is no possibility of this adjustment being tampered with by an operator. .RT .sp 1P .LP 7.4 \fIPower at the receiver input\fR .sp 9p .RT .PP The facsimile receiver must be so designed that it functions correctly when the input power ranges between 0\ dBm and \(em40\ dBm, the latter value being considered provisional. In the case of amplitude modulation, this concerns the power of the black signal. No control of receiver sensitivity should be provided for operator use. .RT .sp 2P .LP \fBRecommendation\ T.3\fR .RT .sp 2P .sp 1P .ce 1000 \fBSTANDARDIZATION\ OF\ \fR \fBGROUP\ 2\ FACSIMILE\ APPARATUS | FOR\ DOCUMENT\ TRANSMISSION\fR .EF '% Fascicle\ VII.3\ \(em\ Rec.\ T.3'' .OF '''Fascicle\ VII.3\ \(em\ Rec.\ T.3 %' .ce 0 .sp 1P .ce 1000 \fI(Geneva, 1976; amended at Geneva, 1980)\fR .sp 9p .RT .ce 0 .sp 1P .LP The\ CCITT, .sp 1P .RT .sp 1P .LP \fIconsidering\fR .sp 9p .RT .PP (a) that Recommendation T.2 refers to Group 1 type apparatus for ISO\ A4 document transmission in approximately six minutes; .PP (b) that there is a demand for Group 2 apparatus which enables an ISO\ A4 document to be transmitted over a telephone\(hytype circuit in approximately three minutes; .PP (c) that the Group 2 apparatus reproduces document quality similar to Group\ 1 apparatus; .bp .PP (d) that such a service may be requested either alternatively with telephone conversation, or when either or both stations are not attended; in both cases, the facsimile operation will follow Recommendation\ T.30; .PP (e) interconnection between two machines of different designs, both conforming to Recommendation\ T.3 as published in the \fIOrange\ Book\fR may give a lower guaranteed reproducible area in certain cases; .sp 1P .LP \fIunanimously declares the view\fR .sp 9p .RT .PP that Group 2 facsimile apparatus for use on the general switched telephone network and international leased circuits shall, in future, be designed and operated in accordance with this Recommendation. Apparatus conforming to Recommendation\ T.3 of the \fIOrange\ Book\fR may continue in service. .sp 2P .LP \fB1\fR \fBScanning track\fR .sp 1P .RT .PP The message area should be scanned in the same direction in the transmitter and receiver. Viewing the message area in a vertical plane, the scanning direction should be from left to right and subsequent scans should be adjacent and below the previous scan. .PP In order to avoid loss of information, users should insert documents so that the scanning direction is from the wider to the narrower margin. .RT .sp 2P .LP \fB2\fR \fBDimensions of apparatus\fR .sp 1P .RT .PP The following dimensions are recommended but apparatus with other dimensions may be used provided that the factor of cooperation is respected and that the total scanning line length lies between\ 215 and\ 222\ mm. .RT .LP Factor\ of\ cooperation\ (FOC) 829\ \(+-\ 1% .LP Total\ scanning\ line\(hylength\ (TLL) 215\ mm .LP Usable\ scanning\ line\(hylength\ (ULL) 205\ mm\ minimum .LP The end of ULL shall lie between 0 and 1\ mm within the nominal position of the right hand edge of an ISO\ A4 size document. .LP Input\ document\ size Up to a minimum of ISO\ A4 size (nominally 210 \(mu 297\ mm) .PP The foregoing dimensions give rise to the following approximate secondary dimensions. .LP Index\ of\ cooperation \ (IOC) 264 .LP Scanning density 3.85 line/mm .LP Number of scanning lines in a document 297\ mm long 1145 .sp 2P .LP \fB3\fR \fBScanning line frequency\fR .sp 1P .RT .PP 3.1 The scanning line frequency should be 360 lines per minute. .sp 9p .RT .PP \fINote\fR \ \(em\ Another scanning line frequency (e.g. 300 lines per minute) may be chosen by agreement between the two stations. .PP 3.2 The scanning line frequency during the transmission should be kept within \(+- | \ parts in 10\u6\d of the nominal value. .sp 2P .LP \fB4\fR \fBPhasing\fR .sp 1P .RT .PP For phasing prior to transmission of document information the transmitter sends a signal as shown in Figure\ 1/T.3. The start of the carrier indicates the end of the lost time . The accuracy of the adjustment at the transmitter of the end of lost time to the start of carrier should be \(+- | .5% of TLL. The receiver should phase its reference point with an accuracy of \(+- | % of TLL to this start of the carrier. The reference point should be 209\ mm before the end of ULL (see Figure\ 2/T.3). .PP \fINote\fR \ \(em\ In the case of the multiple page transmission the phasing procedure may need to be repeated between pages. .bp .RT .LP .rs .sp 16P .ad r \fBFigure 1/T.3, (M) p.\fR .sp 1P .RT .ad b .RT .LP .rs .sp 15P .ad r \fBFigure 2/T.3, (M) p.\fR .sp 1P .RT .ad b .RT .sp 2P .LP \fB5\fR \fBDocument transmission\fR .sp 1P .RT .PP 5.1 During transmission of document information the transmitter should transmit full amplitude carrier during the lost time for at least 4% of the transmission time for TLL. The phase of the carrier may be reversed at the end of this signal. .sp 9p .RT .PP Following the lost time the information transmitted to the receiver is the one contained in ULL. The value of ULL is defined in \(sc\ 2. .PP The receiver must be able to reproduce at least ULL on the reproduction media after the end of the lost time. .RT .PP 5.2 This signal may be used at the receiver as an amplitude reference independent of the document signal and also to indicate to the receiver that document transmission is still in progress. .bp .sp 2P .LP \fB6\fR \fBPaper alignment\fR .sp 1P .RT .PP All types of apparatus should be designed to ensure that paper is positioned within \(+- | .5\ mm of nominal in the horizontal direction. In the vertical direction it must be ensured that paper is positioned in such a way that scanning and recording start not more than 4\ mm down the document from the top edge. .RT .sp 2P .LP \fB7\fR \fBModulation and demodulation\fR .sp 1P .RT .PP 7.1 Equivalent modulated waveforms with vestigial sideband amplitude modulation\ \(em\ phase modulation characteristics should be used for Group\ 2 apparatus operated on leased circuits and on the general switched telephone network. The carrier frequency should be 2100\ \(+-\ 10\ Hz (see Note). A white signal should be represented by maximum carrier and a black signal by minimum (at least 26\ dB below white) or no carrier. The phase of the carrier representing white may be reversed after each transition through black. .sp 9p .RT .PP \fINote\fR \ \(em\ It should be noted that there are equipments in service using, inter alia, a carrier frequency of 2048\ Hz. .PP 7.2 The facsimile transmission could contain a limited range of half\(hytones represented by a carrier amplitude less than that sent during the lost time. .PP 7.3 A vestigial sideband filter symmetrical about the 2100\(hyHz carrier frequency should be provided at the transmitter. The response of this filter should conform to Figure\ 3/T.3. The accuracy of this filter is not critical but the relative transmittance at the carrier frequency should be 0.5 with a tolerance of \(+- | .05 and the characteristic should be sensibly symmetrical about the carrier frequency. .LP .rs .sp 21P .ad r \fBFigure 3/T.3, (M) p.\fR .sp 1P .RT .ad b .RT .PP 7.4 The receiving apparatus must be capable of operating correctly when the drift of carrier frequency does not exceed its nominal value by more than \(+- | 6\ Hz. .PP 7.5 A fixed compromise equalizer, an automatic equalizer or an adaptive equalizer may be provided in the receiver but this should be a matter for further study. .bp .sp 2P .LP \fB8\fR \fBPower at the transmitter output\fR .sp 1P .RT .PP The power of the white signal should be adjustable from \(em15\ dBm to 0\ dBm but the equipment should be so designed that there is no possibility of this adjustment being tampered with by an operator. The black level should be at least 26\ dB below the white level. .RT .sp 2P .LP \fB9\fR \fBPower at the receiver input\fR .sp 1P .RT .PP The receiving apparatus should be capable of functioning correctly when the received signal level for white is within the range\ 0\ dBm to \(em40\ dBm, the latter value being considered provisional. No control of receiver sensitivity should be provided for operator use. .RT .ce 1000 APPENDIX\ I .ce 0 .ce 1000 (to Recommendation T.3) .sp 9p .RT .ce 0 .ce 1000 \fBGuaranteed\fR \fBreproducible area for Group 2 machines\fR .sp 1P .RT .ce 0 .ce 1000 \fBconforming to Recommendation\ T.3\fR .ce 0 .LP .rs .sp 32P .ad r \fBFigure I\(hy1/T.3, (M), p.6\fR .sp 1P .RT .ad b .RT .LP .bp .sp 1P .LP I.1 \fIHorizontal loss\fR .sp 9p .RT .LP .rs .sp 21P .ad r \fBFigure I\(hy2/T.3, (M), p.7\fR .sp 1P .RT .ad b .RT .ce \fBH.T. [T1.3]\fR .ce TABLE\ I\(hy1/T/3 .ce \fBResults\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(132p) | cw(24p) sw(24p) | cw(24p) sw(24p) , ^ | c | c | c | c. Horizontal losses Left margin (mm) Right margin (mm) 205 210 205 210 _ .TE .TS center box ; lw(60p) | lw(30p) | cw(12p) | lw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) , ^ | l | c | l | c | c | c | c. Phasing Transmitter a \(+-0.5% \ 1.11 1.11 \ 1.11 \ 1.11 Receiver b \(+-1.0% \ 2.22 2.22 \ 2.22 \ 2.22 _ .T& lw(90p) | cw(12p) | lw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) . Skew c { \(+-5 \(mu 10 | uD\dlF261\u6\d } \ 2.46 2.46 \ 2.46 \ 2.46 _ .T& lw(90p) | cw(12p) | lw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) . Enlarging d \(em \(em \ 6.46 \ 6.62 _ .T& lw(90p) | cw(12p) | lw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) . Paper insertion f \ 1.50 1.50 \ 1.50 \ 1.50 _ .T& lw(60p) | lw(30p) | cw(12p) | lw(30p) | cw(24p) | cw(24p) | cw(24p) | cw(24p) , ^ | l | c | l | c | c | c | c. Lost time Min. x \(em \(em \ 1.00 \ 1.00 Max. x 5.00 \(em \(em \(em _ .TE .nr PS 9 .RT .ad r \fBTableau I\(hy1/T.3 [T1.3], p.8\fR .sp 1P .RT .ad b .RT .LP .bp .sp 1P .LP I.2 \fIVertical loss\fR .sp 9p .RT .LP .rs .sp 26P .ad r \fBFigure I\(hy3/T.3, (M), p.9\fR .sp 1P .RT .ad b .RT .LP .sp 1 .ce \fBH.T. [T2.3]\fR .ce TABLE\ I\(hy2/T.3 .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; lw(102p) | lw(24p) | cw(30p) | cw(30p) . Top (mm) Bottom (mm) _ .T& lw(102p) | cw(24p) | cw(30p) | cw(30p) . Gripping loss g 4.0 \ 4.0 _ .T& lw(102p) | cw(24p) | cw(30p) | cw(30p) . Paper insertion h _ .T& lw(102p) | cw(24p) | cw(30p) | cw(30p) . Enlarging + FOC i \(em 15.15 _ .TE .nr PS 9 .RT .ad r \fBTableau I\(hy2/T.3 [T2.3], p.10\fR .sp 1P .RT .ad b .RT .LP .sp 1 .bp .sp 2P .LP \fBRecommendation\ T.4\fR .RT .sp 2P .ce 1000 \fBSTANDARDIZATION\ OF\ \fR \fBGROUP\ 3\ FACSIMILE\ APPARATUS\fR .EF '% Fascicle\ VII.3\ \(em\ Rec.\ T.4'' .OF '''Fascicle\ VII.3\ \(em\ Rec.\ T.4 %' .ce 0 .sp 1P .ce 1000 \fBFOR\ DOCUMENT\ TRANSMISSION\fR .ce 0 .sp 1P .ce 1000 \fI(Geneva, 1980, amended at Malaga\(hyTorremolinos, 1984 and\fR \fIMelbourne, 1988)\fR .sp 9p .RT .ce 0 .sp 1P .LP The\ CCITT, .sp 1P .RT .sp 1P .LP \fIconsidering\fR .sp 9p .RT .PP (a) that Recommendation T.2 refers to Group 1 type apparatus for ISO\ A4 document transmission over a telephone\(hytype circuit in approximately six minutes; .PP (b) that Recommendation T.3 refers to Group 2 type apparatus for ISO\ A4 document transmission over a telephone\(hytype circuit in approximately three minutes; .PP (c) that there is a demand for Group 3 apparatus which enables an ISO\ A4 document to be transmitted over a telephone\(hytype circuit in approximately one minute; .PP (d) that for a large number of applications black and white reproduction is sufficient; .PP (e) that such a service may be requested either alternatively with telephone conversation, or when either or both stations are not attended; in both cases, the facsimile operation will follow Recommendation\ T.30; .sp 1P .LP \fIunanimously declares the view\fR .sp 9p .RT .PP that Group 3 facsimile apparatus for use on the general switched telephone network and international leased circuits should be designed and operated according to the following standards: .sp 2P .LP \fB1\fR \fBScanning track\fR .sp 1P .RT .PP The message area should be scanned in the same direction in the transmitter and receiver. Viewing the message area in a vertical plane, the picture elements should be processed as if the scanning direction were from left to right with subsequent scans adjacent and below the previous scan. .RT .sp 2P .LP \fB2\fR \fBDimensions of apparatus\fR .sp 1P .RT .PP \fINote\fR \ \(em\ The tolerances on the factors of cooperation are subject to further study. .RT .PP 2.1 The following dimensions should be used: .sp 9p .RT .LP a) a standard resolution and an optional higher resolution of 3.85\ line/mm\ \(+-\ 1% and 7.7\ line/mm\ \(+-\ 1% respectively in vertical direction, .LP b) 1728 black and white picture elements along the standard scan line length of 215\ mm\ \(+-\ 1%, .LP c) optionally, 2048 black and white picture elements along a scan line length of 255\ mm\ \(+-\ 1%, .LP d) optionally, 2432 black and white picture elements along a scan line length of 303\ mm\ \(+-\ 1%, .LP and, for equipment which provides A5 and/or A6 facilities: .LP e) optionally, 864 black and white picture elements along a scan line length of 107\ mm \(+- | %, .LP f ) optionally, 1216 black and white picture elements along a scan line length of 151\ mm \(+- | %, .LP g) Optionally, 1728 black and white picture elements along a scan line length of 107\ mm \(+- | %, .LP h) Optionally, 1728 black and white picture elements along a scan line length of 151\ mm \(+- | %. .bp .PP The normal method of interworking when transmitting from an A5 or A6 machine to an A4 machine not signalling such capabilities, is that the A5 or A6 content will be enlarged to fill the A4 page (see also Note\ 3). This means that if the document is then retransmitted, or if it has been stored for later retransmission, it will be received without additional reduction. .PP Where the full image contents being received from an A4 machine need to be maintained, g) or h) respectively should be used. .PP Interworking between equipments with A5/A6 and A4 facilities and between equipments with combinations of these facilities is shown in Annex\ C. .PP \fINote\ 1\fR \ \(em\ Cases e) to h) describe equipments which may be implemented singly or in any combination and would not, for A5/A6 facsimile equipments, require implementation of a) or b). These equipments may be implemented with cases different for sending and receiving. .PP \fINote\ 2\fR \ \(em\ In cases e) to h), 1728 pels will always be provided to the coder (see Annex C). .PP In cases e) and f ), the additional pels required are produced by pel processing (i.e.,\ either by picture processing or by adding white pels on each side of the central picture information) prior to coding. .PP \fINote\ 3\fR \ \(em\ It could be possible, by a setting on the A5/A6 transmitting machine, to send the document so that it is received equal size on an A4 machine not signalling such capabilities. In this case the vertical resolution will be 3.85 (or 7.7) line/mm. The user should be made aware that in this particular equal size case if the received copy is transmitted back to the A5/A6 machine the subsequent copy will be reduced. .PP \fINote\ 4\fR \ \(em\ Some Administrations may require that equipments using e) or f ) dimensions, when working with a receiver not signalling such capabilities, insert a message e.g.,\ \*QISO\ A6\*U or \*QISO\ A5\*U, as the case may be, into the picture at the transmitting side. .RT .PP 2.2 Input documents up to a minimum of ISO A4 size should be accepted. .sp 9p .RT .PP \fINote\fR \ \(em\ The size of the guaranteed reproducible area is shown in Appendix\ I. .sp 2P .LP \fB3\fR \fBTransmission time per total coded scan line\fR .sp 1P .RT .PP The total coded scan line is defined as the sum of DATA bits plus any required FILL bits plus the end\(hyof\(hyline (EOL) bits. .PP For the optional two\(hydimensional coding scheme as described in \(sc\ 4.2, the total coded scan line is defined as the sum of DATA bits plus any required FILL bits plus the EOL bits plus a tag bit. .PP To handle various printing methods, several optional minimum total coded scan line times are possible in addition to the 20\ milliseconds standard. .RT .PP 3.1 The minimum transmission times of the total coded scan line should conform to the following: .sp 9p .RT .LP 1) Alternative 1, where the minimum transmission time of the total coded scan line is the same both for the standard resolution and for the optional higher resolution: .LP a) 20 milliseconds recommended standard, .LP b) 10 milliseconds recognized option with a mandatory fall\(hyback to the 20\ milliseconds standard, .LP c) 5 milliseconds recognized option with a mandatory fall\(hyback to the 10\ milliseconds option and the 20\ milliseconds standard, .LP d) 0 millisecond recognized option with a mandatory fall\(hyback to the 5\ milliseconds option, the 10\ milliseconds option and the 20\ milliseconds standard, and an optional fall\(hyback to the 40\ milliseconds option, .LP e) 40 milliseconds recognized option. .LP 2) Alternative 2, where the minimum transmission time of the total coded scan line for the optional higher resolution is half of that for the standard resolution (see Note). These figures refer to the standard resolution: .LP a) 10 milliseconds recognized option with a mandatory fall\(hyback to the 20\ milliseconds standard, .LP b) 20 milliseconds recommended standard, .LP c) 40 milliseconds recognized option. .bp .PP The identification and choice of this minimum transmission time is to be made in the pre\(hymessage (phase\ B) portion of Recommendation\ T.30 control procedure. .PP \fINote\fR \ \(em\ Alternative 2 applies to equipment with printing mechanisms which achieve the standard vertical resolution by printing two consecutive, identical higher resolution lines. In this case, the minimum transmission time of the total coded scan line for the standard resolution is double the minimum transmission time of the total coded scan line for the higher resolution. .RT .PP 3.2 The maximum transmission time of any total coded scan line should be less than 5\ seconds. When this transmission time exceeds 5\ seconds, the receiver must proceed to disconnect the line. .sp 9p .RT .sp 1P .LP 3.3 \fIError correction mode\fR .sp 9p .RT .PP For the optional error correction mode, an HDLC frame structure is utilized to transmit the total coded scan line. This error correction mode is defined in Annex\ A. .RT .sp 2P .LP \fB4\fR \fBCoding scheme\fR .sp 1P .RT .sp 1P .LP 4.1 \fIOne\(hydimensional coding scheme\fR .sp 9p .RT .PP The one\(hydimensional run length coding scheme recommended for Group 3 apparatus is as follows: .RT .sp 1P .LP 4.1.1 \fIData\fR .sp 9p .RT .PP A line of Data is composed of a series of variable length code words. Each code word represents a run length of either all white or all black. White runs and black runs alternate. A total of 1728\ picture elements represent one horizontal scan line of 215\ mm length. .PP In order to ensure that the receiver maintains colour synchronization, all Data lines will begin with a white run length code word. If the actual scan line begins with a black run, a white run length of zero will be sent. Black or white run lengths, up to a maximum length of one scan line (1728\ picture elements or pels ) are defined by the code words in Tables\ 1/T.4 and\ 2/T.4. The code words are of two types: Terminating code words and Make\(hyup code words . Each run length is represented by either one Terminating code word or one Make\(hyup code word followed by a Terminating code word. .PP Run lengths in the range of 0 to 63 pels are encoded with their appropriate Terminating code word. Note that there is a different list of code words for black and white run lengths. .PP Run lengths in the range of 64 to 1728 pels are encoded first by the Make\(hyup code word representing the run length which is equal to or shorter than that required. This is then followed by the Terminating code word representing the difference between the required run length and the run length represented by the Make\(hyup code . .RT .sp 1P .LP 4.1.2 \fIEnd\(hyof\(hyline (EOL)\fR .sp 9p .RT .PP This code word follows each line of Data. It is a unique code word that can never be found within a valid line of Data; therefore, resynchronization after an error burst is possible. .PP In addition, this signal will occur prior to the first Data line of a page. .PP Format:\ 000000000001 .RT .sp 1P .LP 4.1.3 \fIFill\fR .sp 9p .RT .PP A pause may be placed in the message flow by transmitting Fill. Fill may be inserted between a line of Data and an EOL, but never within a line of Data. Fill must be added to ensure that the transmission time of Data, Fill and EOL is not less than the minimum transmission time of the total coded scan line established in the pre\(hymessage control procedure. .PP Format:\ variable length string of 0s. .bp .RT .ce \fBH.T. [T1.4]\fR .ce TABLE\ 1/T.4 .ce \fBTerminating codes\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(60p) | cw(54p) | cw(60p) | cw(54p) . White run length Code word Black run length Code word _ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 0 00110101 \ 0 0000110111\ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 1 000111\ \ \ 1 010\ \ \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 2 0111\ \ \ \ \ 2 11\ \ \ \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 3 1000\ \ \ \ \ 3 10\ \ \ \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 4 1011\ \ \ \ \ 4 011\ \ \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 5 1100\ \ \ \ \ 5 0011\ \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 6 1110\ \ \ \ \ 6 0010\ \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 7 1111\ \ \ \ \ 7 00011\ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 8 10011\ \ \ \ 8 000101\ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 9 10100\ \ \ \ 9 000100\ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 10 00111\ \ \ 10 0000100\ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 11 01000\ \ \ 11 0000101\ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 12 001000\ \ 12 0000111\ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 13 000011\ \ 13 00000100\ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 14 110100\ \ 14 00000111\ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 15 110101\ \ 15 000011000\ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 16 101010\ \ 16 0000010111\ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 17 101011\ \ 17 0000011000\ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 18 0100111\ 18 0000001000\ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 19 0001100\ 19 00001100111\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 20 0001000\ 20 00001101000\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 21 0010111\ 21 00001101100\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 22 0000011\ 22 00000110111\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 23 0000100\ 23 00000101000\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 24 0101000\ 24 00000010111\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 25 0101011\ 25 00000011000\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 26 0010011\ 26 000011001010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 27 0100100\ 27 000011001011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 28 0011000\ 28 000011001100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 29 00000010 29 000011001101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 30 00000011 30 000001101000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 31 00011010 31 000001101001 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 32 00011011 32 000001101010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 33 00010010 33 000001101011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 34 00010011 34 000011010010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 35 00010100 35 000011010011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 36 00010101 36 000011010100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 37 00010110 37 000011010101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 38 00010111 38 000011010110 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 39 00101000 39 000011010111 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 40 00101001 40 000001101100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 41 00101010 41 000001101101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 42 00101011 42 000011011010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 43 00101100 43 000011011011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 44 00101101 44 000001010100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 45 00000100 45 000001010101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 46 00000101 46 000001010110 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 47 00001010 47 000001010111 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 48 00001011 48 000001100100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 49 01010010 49 000001100101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 50 01010011 50 000001010010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 51 01010100 51 000001010011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 52 01010101 52 000000100100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 53 00100100 53 000000110111 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 54 00100101 54 000000111000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 55 01011000 55 000000100111 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 56 01011001 56 000000101000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 57 01011010 57 000001011000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 58 01011011 58 000001011001 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 59 01001010 59 000000101011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 60 01001011 60 000000101100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 61 00110010 61 000001011010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 62 00110011 62 000001100110 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 63 00110100 63 000001100111 _ .TE .nr PS 9 .RT .ad r \fBTableau 1/T.4 [T1.4],p.11\fR .sp 1P .RT .ad b .RT .LP .bp .ce \fBH.T. [T2.4]\fR .ce TABLE\ 2/T.4 .ce \fBMake\(hyup codes\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(60p) | cw(54p) | cw(60p) | cw(54p) . White run lengths Code word Black run lengths Code word _ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ \ 64 11011\ \ \ \ \ \ \ \ \ 64 0000001111\ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 128 10010\ \ \ \ \ \ \ \ 128 000011001000\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 192 010111\ \ \ \ \ \ \ 192 000011001001\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 256 0110111\ \ \ \ \ \ 256 000001011011\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 320 00110110\ \ \ \ \ 320 000000110011\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 384 00110111\ \ \ \ \ 384 000000110100\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 448 01100100\ \ \ \ \ 448 000000110101\ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 512 01100101\ \ \ \ \ 512 0000001101100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 576 01101000\ \ \ \ \ 576 0000001101101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 640 01100111\ \ \ \ \ 640 0000001001010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 704 011001100\ \ \ \ 704 0000001001011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 768 011001101\ \ \ \ 768 0000001001100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 832 011010010\ \ \ \ 832 0000001001101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 896 011010011\ \ \ \ 896 0000001110010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 960 011010100\ \ \ \ 960 0000001110011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1024 011010101\ \ \ 1024 0000001110100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1088 011010110\ \ \ 1088 0000001110101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1152 011010111\ \ \ 1152 0000001110110 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1216 011011000\ \ \ 1216 0000001110111 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1280 011011001\ \ \ 1280 0000001010010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1344 011011010\ \ \ 1344 0000001010011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1408\fR 011011011\ \ \ 1408 0000001010100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1472 010011000\ \ \ 1472 0000001010101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1536 010011001\ \ \ 1536 0000001011010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1600 010011010\ \ \ 1600 0000001011011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1664\fR 011000\ \ \ \ \ \ 1664 0000001100100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 1728 010011011\ \ \ 1728 0000001100101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . EOL 000000000001 EOL 000000000001\ .TE .LP \fINote\fR \ \(em\ It is recognized that machines exist which accommodate larger paper widths maintaining the standard horizontal resolution. This option has been provided for by the addition of the Make\(hyup code set defined as follows: .nr PS 9 .RT .ad r \fBTableau 2/T.4 [T2.4], p.12\fR .sp 1P .RT .ad b .RT .LP .bp .sp 1P .LP 4.1.4 \fIReturn to control (RTC)\fR .sp 9p .RT .PP The end of a document transmission is indicated by sending six consecutive EOLs. Following the RTC signal, the transmitter will send the post message commands in the framed format and the data signalling rate of the control signals defined in Recommendation\ T.30. \v'6p' .RT .ce 1000 Format:\ 000000000001 . | | | | | | | | | 000000000001 .ce 0 .sp 1P .ce 1000 (total of 6 times) .ce 0 .sp 1P .PP .sp 1 Figures 1/T.4 and 2/T.4 clarify the relationship of the signals defined herein. Figure\ 1/T.4 shows several scan lines of data starting at the beginning of a transmitted page. Figure\ 2/T.4 shows the last coded scan line of a page. .PP The identification and choice of either the standard code table or the extended code table is to be made in the pre\(hymessage (phase\ B) portion of Recommendation\ T.30 control procedures. .RT .LP .rs .sp 9P .ad r \fBFigure 1/T.4, (M), p.\fR .sp 1P .RT .ad b .RT .LP .rs .sp 6P .ad r \fBFigure 2/T.4, (M), p.\fR .sp 1P .RT .ad b .RT .sp 1P .LP 4.2 \fITwo\(hydimensional coding scheme\fR .sp 9p .RT .PP The two\(hydimensional coding scheme is an optional extension of the one\(hydimensional coding scheme specified in \(sc\ 4.1 and is as follows: .RT .sp 2P .LP 4.2.1 \fIData\fR .sp 1P .RT .sp 1P .LP 4.2.1.1 \fIParameter K\fR .sp 9p .RT .PP In order to limit the disturbed area in the event of transmission errors, after each line coded one\(hydimensionally, at most \fIK\fR \(hy1 successive lines shall be coded two\(hydimensionally. A one\(hydimensionally coded line may be transmitted more frequently than every \fIK\fR \ lines. After a one\(hydimensional line is transmitted, the next series of \fIK\fR \(hy1 two\(hydimensional lines is initiated. The maximum value of \fIK\fR shall be set as follows: .PP Standard vertical resolution:\ \fIK\fR \ =\ 2 .PP Optional higher vertical resolution:\ \fIK\fR \ =\ 4. .PP \fINote\ 1\fR \ \(em\ Some Administrations pointed out that for the optional higher vertical resolution\ \fIK\fR may optionally be set to a lower value. .bp .PP \fINote\ 2\fR \ \(em\ Some Administrations reserve the right to approve only such apparatus for use in the facsimile service in their respective countries which will be able to produce a visible sign on its received facsimile message indicating that two\(hydimensional coding has been used in the transmission process. .RT .sp 1P .LP 4.2.1.2 \fIOne\(hydimensional coding\fR .sp 9p .RT .PP This conforms with the description of Data in \(sc\ 4.1.1. .RT .sp 1P .LP 4.2.1.3 \fITwo\(hydimensional coding\fR .sp 9p .RT .PP This is a line\(hyby\(hyline coding method in which the position of each changing picture element on the current or coding line is coded with respect to the position of a corresponding reference element situated on either the coding line or the reference line which lies immediately above the coding line. After the coding line has been coded it becomes the reference line for the next coding line . .RT .sp 1P .LP 4.2.1.3.1 \fIDefinition of \fR \fIchanging picture elements\fR | (see\fR Figure 3/T.4) .sp 9p .RT .PP A changing element is defined as an element whose \*Qcolour\*U (i.e.\ black or white) is different from that of the previous element along the same scan line . .RT .LP a\d0\u The reference or starting changing element on the coding line. At the start of the coding line a\d0\uis set on an imaginary white changing element situated just before the first element on the line. During the coding of the coding line, the position of a\d0\uis defined by the previous coding mode. (See \(sc\ 4.2.1.3.2.) .LP a\d1\u The next changing element to the right of a\d0\uon the coding line. .LP a\d2\u The next changing element to the right of a\d1\uon the coding line. .LP b\d1\u The first changing element on the reference line to the right of a\d0\uand of opposite colour to a\d0\u. .LP b\d2\u The next changing element to the right of b\d1\uon the reference line. .LP .rs .sp 8P .ad r \fBFigure 3/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .sp 1P .LP 4.2.1.3.2 \fICoding modes\fR .sp 9p .RT .PP One of the three coding modes are chosen according to the coding procedure described in \(sc\ 4.2.1.3.3 to code the position of each changing element along the coding line. Examples of the three coding modes are given in Figures\ 4/T.4, 5/T.4 and\ 6/T.4. .RT .LP a) \fIPass mode\fR .LP This mode is identified when the position of b\d2\ulies to the left of a\d1\u. When this mode has been coded, a\d0\uis set on the element of the coding line below b\d2\uin preparation for the next coding (i.e.\ on a`\d0\u). .LP .rs .sp 9P .ad r \fBFigure 4/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .LP .bp .LP However, the state where b\d2\uoccurs just above a\d1\u, as shown in Figure\ 5/T.4 is not considered as a pass mode. .LP .rs .sp 9P .ad r \fBFigure 5/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .LP b) \fIVertical mode\fR .LP When this mode is identified, the position of a\d1\uis coded relative to the position of b\d1\u. The relative distance a\d1\ub\d1\ucan take on one of seven values\ V(0), V\dR\u(1), V\dR\u(2), V\dR\u(3), V\dL\u(1), V\dL\u(2) and V\dL\u(3), each of which is represented by a separate code word. The subscripts\ R and\ L indicate that a\d1\uis to the right or left respectively of b\d1\u, and the number in brackets indicates the value of the distance\ a\d1\ub\d1\u. After vertical mode coding has occurred, the position of a\d0\uis set on a\d1\u, (see Figure\ 6/T.4). .LP c) \fIHorizontal mode\fR .LP When this mode is identified, both the run\(hylengths a\d0\ua\d1\uand a\d1\ua\d2\uare coded using the code words\ H\ +\ M(a\d0\ua\d1\u)\ +\ M(a\d1\ua\d2\u). H is the flag code word 001 taken from the two\(hydimensional code table (Table\ 3/T.4). M(a\d0\ua\d1\u) and M(a\d1\ua\d2\u) are code words which represent the length and \*Qcolour\*U of the runs\ a\d0\ua\d1\uand a\d1\ua\d2\urespectively and are taken from the appropriate white or black one\(hydimensional code tables (Tables\ 1/T.4 and\ 2/T.4). After a horizontal mode coding, the position of a\d0\uis set on a\d2\u(see Figure\ 6/T.4). .sp 1P .LP 4.2.1.3.3 \fICoding procedure\fR .sp 9p .RT .PP The coding procedure identifies the coding mode that is to be used to code each changing element along the coding line. When one of the three coding modes has been identified according to Step\ 1 or Step\ 2 mentioned below, an appropriate code word is selected from the code table given in Table\ 3/T.4. The coding procedure is as shown in the flow diagram of Figure\ 7/T.4. .RT .LP .rs .sp 13P .ad r \fBFigure 6/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .PP \fINote\fR \ \(em\ It does not affect compatibility to restrict the use of pass mode in the encoder to a single pass mode. Variations of the algorithm which do not affect compatibility should be the subject of further study. .bp .sp 1P .LP \fIStep 1\fR .sp 9p .RT .LP i) If a pass mode is identified, this is coded using the word 0001 (Table\ 3/T.4). After this processing, picture element a`\d0\ujust under b\d2\uis regarded as the new starting picture element a\d0\ufor the next coding. (See Figure\ 4/T.4.) .LP ii) If a pass mode is not detected then proceed to Step 2. .sp 1P .LP \fIStep\ 2\fR .sp 9p .RT .LP i) Determine the absolute value of the relative distance a\d1\ub\d1\u. .LP ii) If | d1\ub\d1\ | \(=\ 3, as shown in Table 3/T.4, a\d1\ub\d1\uis coded by the vertical mode, after which position\ a\d1\uis regarded as the new starting picture element a\d0\ufor the next coding. .LP iii) If | d1\ub\d1\ | >\ 3, as shown in Table 3/T.4, following horizontal mode code\ 001, a\d0\ua\d1\uand a\d1\ua\d2\uare respectively coded by one\(hydimensional coding. After this processing position\ a\d2\uis regarded as the new starting picture element a\d0\ufor the next coding. .ce \fBH.T. [T3.4]\fR .ce TABLE\ 3/T.4 .ce \fBTwo\(hydimensional code table\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; lw(42p) | cw(84p) | cw(42p) | cw(60p) . Mode Elements to be coded Notation Code word _ .T& lw(42p) | cw(84p) | cw(42p) | lw(60p) . Pass b 1, b 2 P 0001\ \ \ \ \ \ _ .T& lw(42p) | cw(84p) | cw(42p) | lw(60p) . Horizontal a 0a 1, a 1a 2 H { 001 + M(a 0a 1) + M(a 1a 2) (see Note 1) } _ .T& lw(42p) | lw(54p) | cw(30p) | cw(42p) | lw(60p) , ^ | l | c | c | l ^ | ^ | c | c | l ^ | ^ | c | c | l ^ | c | c | l | c ^ | ^ | c | l | c ^ | ^ | c | l | l. Vertical a 1 just under b 1 a 1b 1 = 0 V(0) 1\ \ \ \ \ \ \ \ \ a 1 to the right of b 1 a 1b 1 = 1 V R(1) 011\ \ \ \ \ \ \ a 1b 1 = 2 V R(2) 000011\ \ \ \ a 1b 1 = 3 V R(3) { 0000011\ \ \ a 1 to the left of b 1 } a 1b 1 = 1 V L(1) 010\ \ \ \ \ \ \ a 1b 1 = 2 V L(2) 000010\ \ \ \ a 1b 1 = 3 V L(3) 0000010\ \ \ \fB _ .T& lw(42p) | cw(126p) | lw(60p) . Extension { 2\(hyD (extensions) 1\(hyD (extensions) } { 0000001xxx 000000001xxx (see Note 2) } .TE .LP \fINote\ 1\fR \ \(em\ Code M( | of the horizontal mode represents the code words in Tables\ 1/T.4 and 2/T.4. .LP \fINote\ 2\fR \ \(em\ It is suggested the uncompressed mode is recognized as an optional extension of two\(hydimensional coding scheme for Group\ 3 apparatus. The bit assignment for the xxx bits is 111 for the uncompressed mode of operation whose code table is given in Table\ 4/T.4. .LP \fINote\ 3\fR \ \(em\ Further study is needed to define other unspecified xxx bit assignments and their use for any further extensions. .LP \fINote\ 4\fR \ \(em\ If the suggested uncompressed mode is used on a line designated to be one\(hydimensinally coded, the coder must not switch into uncompressed mode following any code word ending in the sequence 000. This is because any code word ending in 000 followed by a switching code 000000001 will be mistaken for an end\(hyof\(hyline code. .nr PS 9 .RT .ad r \fBTableau 3/T.4 [T3.4], p.19\fR .sp 1P .RT .ad b .RT .LP .bp .ce \fBH.T. [T4.4]\fR .ce TABLE\ 4/T.4 .ce \fBUncompressed mode code words\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(60p) | lw(120p) . { Entrance code to uncompressed mode } { On one\(hydimensionally coded line:\ 000000001111 On two\(hydimensionally coded line:\ \ 0000001111\ \ } _ .T& lw(60p) | cw(60p) | cw(60p) . Uncompressed mode code { \fIImage pattern\fR 1\ \ \ \ 01\ \ \ 001\ \ 0001\ 00001 00000 } { \fICode word\fR 1\ \ \ \ \ \ \ \ \ \ \ 01\ \ \ \ \ \ \ \ \ \ 001\ \ \ \ \ \ \ \ \ 0001\ \ \ \ \ \ \ \ 00001\ \ \ \ \ \ \ 000001\ \ \ \ \ \ } _ .T& lw(60p) | cw(60p) | cw(60p) . { Exit from uncompressed mode code } { \ \ \ \ \ 0\ \ \ \ 00\ \ \ 000\ \ 0000\ } { 0000001T\ \ \ \ 00000001T\ \ \ 000000001T\ \ 0000000001T\ 00000000001T T\ denotes a tag bit which tells the colour of the next run (black = 1, white = 0). } _ .TE .nr PS 9 .RT .ad r \fBTableau 4/T.4 [T4.4], p.20\fR .sp 1P .RT .ad b .RT .sp 1P .LP 4.2.1.3.4 \fIProcessing the first and last picture elements in\fR \fIa line\fR .sp 9p .RT .LP a) \fIProcessing the first picture element\fR .LP The first starting picture element a\d0\uon each coding line is imaginarily set at a position just before the first picture element, and is regarded as a white picture element (see \(sc\ 4.2.1.3.1). .LP The first run length on a line a\d0\ua\d1\uis replaced by a\d0\ua\d1\u\(em1. Therefore, if the first run is black and is deemed to be coded by horizontal mode coding, then the first code word M(a\d0\ua\d1\u) corresponds to a white run of zero length (see Figure\ 10/T.4, Example\ 5). .LP b) \fIProcessing the last picture element\fR .LP The coding of the coding line continues until the position of the imaginary changing element situated just after the last actual element has been coded. This may be coded as a\d1\uor \d2\u. Also, if b\d1\uand/or b\d2\uare not detected at any time during the coding of the line, they are positioned on the imaginary changing element situated just after the last actual picture element on the reference line. .sp 1P .LP 4.2.2 \fILine synchronization code word\fR .sp 9p .RT .PP To the end of every coded line is added the end\(hyof\(hyline (EOL) code word 000000000001. The EOL code word is followed by a single tag bit which indicates whether one\(hy or two\(hydimensional coding is used for the next line. .RT .PP In addition, EOL plus the tag bit 1 signal will occur prior to the first Data line of a page. .PP Format: .PP EOL\ +\ 1:\ one\(hydimensional coding of next line .PP EOL\ +\ 0:\ two\(hydimensional coding of next line .bp .RT .LP .rs .sp 47P .ad r \fBFigure 7/T.4, (MC), p.21\fR .sp 1P .RT .ad b .RT .LP .bp .sp 1P .LP 4.2.3 \fIFill\fR .sp 9p .RT .PP Fill is inserted between a line of Data and the line synchronization signal, EOL\ +\ tag bit, but is not inserted in Data. Fill must be added to ensure that the transmission time of Data, Fill and EOL plus tag bit is not less than the minimum transmission time of the total coded scan line. .PP Format:\ variable length string of 0 s. .RT .sp 1P .LP 4.2.4 \fIReturn to control (RTC)\fR .sp 9p .RT .PP The format used is six consecutive line synchronization code words, i.e.,\ 6\ \(mu\ (EOL\ +\ 1). .PP To further clarify the relationship of the signals defined herein, Figures\ 8/T.4 and\ 9/T.4 are offered in the case of K\ =\ 2. Figure\ 8/T.4 shows several scan lines of data starting at the beginning of a transmitted page. Figure\ 9/T.4 shows the last several lines of a page. .RT .LP .rs .sp 12P .ad r \fBFigure 8/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .LP .rs .sp 16P .ad r \fBFigure 9/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .sp 1P .LP 4.2.5 \fICoding examples\fR .sp 9p .RT .PP Figure 10/T.4 shows coding examples of the first part of scan lines and Figure\ 11/T.4 coding examples of the last part, while Figure\ 12/T.4 shows other coding examples. The notations\ P, H and\ V in the figures are, as shown in Table\ 3/T.4, the symbols for pass mode, horizontal mode and vertical mode respectively. The picture elements marked with black spots indicate the changing picture elements to be coded. .bp .RT .LP .rs .sp 24P .ad r \fBFigure 10/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .LP .rs .sp 24P .ad r \fBFigure 11/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .LP .bp .LP .rs .sp 20P .ad r \fBFigure 12/T.4, (M) p.\fR .sp 1P .RT .ad b .RT .sp 1P .LP 4.3 \fIError limiting mode\fR .sp 9p .RT .PP One\(hydimensional coding scheme with the division of scan line into parts. .PP The one\(hydimensional coding scheme with the division of scan line into parts is an optional extension of the one\(hydimensional coding scheme specified in Annex\ B. .RT .sp 2P .LP \fB5\fR \fBModulation and demodulation\fR .sp 1P .RT .PP Group 3 apparatus operating on the general switched telephone network shall utilize the modulation, scrambler, equalization and timing signals defined in Recommendation\ V.27 | fIter\fR , specifically \(sc\(sc\ 2, 3, 7, 8, 9, 11 and the Appendix. .RT .PP 5.1 The training signal to be used shall be the long training sequence with protection against talker echo. (See Recommendation\ V.27\ \fIter\fR , \(sc\ 2.5.1, Table\ 3/V.27 \fIter\fR ). .sp 9p .RT .PP 5.2 The data signalling rates to be used are 4800 bit/s and 2400 bit/s as defined in Recommendation\ V.27 | fIter\fR . .sp 9p .RT .PP \fINote\ 1\fR \ \(em\ Some Administrations pointed out that it would not be possible to guarantee the service at a data signalling rate higher than 2400\ bit/s. .PP \fINote\ 2\fR \ \(em\ It should be noted that there are equipments in service using, inter alia, other modulation methods. .PP \fINote\ 3\fR \ \(em\ Where quality of communication service can successfully support higher speed operation, such as may be possible on leased circuits or high\(hyquality switched circuits, Group\ 3 apparatus may optionally utilize the modulation, scrambler, equalization and timing signals defined in Recommendation\ V.29, specifically \(sc\(sc\ 1, 2, 3, 4, 7, 8, 9, 10 and 11. Under this option the data should be non\(hymultiplexed and limited to the data signalling rates of 9600\ bit/s and 7200\ bit/s. .RT .sp 2P .LP \fB6\fR \fBPower at the transmitter output\fR .sp 1P .RT .PP The average power should be adjustable from \(em15 dBm to 0 dBm but the equipment should be so designed that there is no possibility of this adjustment being tampered with by an operator. .PP \fINote\fR \ \(em\ The power levels over the international circuits will conform to Recommendation\ V.2. .bp .RT .sp 2P .LP \fB7\fR \fBPower at the receiver input\fR .sp 1P .RT .PP The receiving apparatus should be capable of functioning correctly when the received signal level is within the range of 0\ dBm to \(em43\ dBm. No control of receiver sensitivity should be provided for operator use. .RT .sp 2P .LP \fB8\fR \fBImplementation of apparatus\fR .sp 1P .RT .PP Although paper sizes are referred to, this does not always require a physical paper scanner and/or printer to be implemented. Details may be defined by Administrations. .PP If the message is not generated from a physical scanner or displayed on paper, then the signals appearing across the network interface shall be identical to those which would be generated if paper input and/or output had been implemented. .RT .ce 1000 ANNEX\ A .ce 0 .ce 1000 (to Recommendation T.4) .sp 9p .RT .ce 0 .ce 1000 \fBOptional error correction mode\fR .sp 1P .RT .ce 0 .LP A.1 \fIIntroduction\fR .sp 1P .RT .PP This annex specifies the message format required for document transmission incorporating the optional error correction capability. .RT .sp 2P .LP A.2 \fIDefinitions\fR .sp 1P .RT .PP The definitions contained in Recommendations T.4 and T.30 shall be applied unless explicitly amended. .RT .sp 2P .LP A.3 \fIMessage format\fR .sp 1P .RT .PP An HDLC frame structure is utilized for all binary coded facsimile message procedures. The basic HDLC structure consists of a number of frames each of which is subdivided into a number of fields. It provides for frame labelling and error checking. .PP Specific examples are given in Figures A\(hy1/T.4 and A\(hy2/T.4 of formats used for binary coded signalling. These examples show an initial partial page (PP) frame structure and a last PP frame structure. .PP In the following descriptions of the fields, the order in which the bits are transmitted is from the most to the least significant bit, i.e.,\ from left to right as printed. The exception to this is the frame number (see \(sc\ A.3.6.1). .PP The equivalent between binary notation symbols and the significant condition of the signalling code should be in accordance with Recommendation\ V.1. .RT .sp 1P .LP A.3.1 \fISynchronization\fR .sp 9p .RT .PP A synchronization sequence shall precede all binary coded information whenever a new transmission begins. The synchronization shall be a training sequence and a series of flag sequences for nominal 200\ ms, tolerance +100\ ms. .PP \fINote\fR \ \(em\ Continuous flags have two zeros as shown in the following diagram: \v'6p' .RT .sp 1P .ce 1000 . | | 0111 1110 0111 1110 0111 1110 . | | .ce 0 .sp 1P .LP .sp 1 .sp 1P .LP A.3.2 \fIFlag sequence (F)\fR .sp 9p .RT .PP The eight bit HDLC flag sequence is used to denote the beginning and end of the frame for the facsimile message procedure. The flag sequence is also used to establish bit and frame synchronization. To facilitate this the synchronization defined in A.3.1 should be used prior to the first frame. Subsequent frames and end of the last frame need one or more than one flag sequence. .PP Format: 0111 1110 .PP \fINote\fR \ \(em\ The leading flag of a frame may be the trailing flag of the previous frame. .bp .RT .LP .rs .sp 47P .ad r \fBFigure A\(hy1/T.4, (N), p.\fR .sp 1P .RT .ad b .RT .LP .bp .LP .rs .sp 47P .ad r \fBFigure A\(hy2/T.4, (N), p.\fR .sp 1P .RT .ad b .RT .LP .bp .sp 1P .LP A.3.3 \fIAddress field (A)\fR .sp 9p .RT .PP The eight bit HDLC address field is intended to provide identification of specific station(s) in a multi\(hypoint arrangement. In the case of transmission on the general switched telephone network, this field is limited to a single format. .PP Format: 1111 1111 .RT .sp 1P .LP A.3.4 \fIControl field (C)\fR .sp 9p .RT .PP The eight bit HDLC control field provides the capability of encoding the command unique to the facsimile message procedure. .PP Format: 1100 X000 .PP The X bit is set to 0 for the FCD frame (facsimile coded data frame) and the RCP frame (return to control for partial page frame). .RT .sp 1P .LP A.3.5 \fIFacsimile control field (FCF)\fR .sp 9p .RT .PP In order to distinguish between the FCD frame (facsimile coded data frame) and the RCP frame (return to control for partial page frame), the FCF for the in\(hymessage procedure is defined as follows: .RT .LP 1) FCF for the FCD frame .LP Format:\ 0110 0000 .LP 2) FCF for the RCP frame .LP Format:\ 0110 0001 .sp 1P .LP A.3.6 \fIFacsimile information field (FIF)\fR .sp 9p .RT .PP The facsimile information field is a length of 257 or 65 octets (see Note\ 1) and is divided into two parts, the frame number and the facsimile data field (see Note\ 2). .PP \fINote\ 1\fR \ \(em\ This does not include bit stuffing to preclude non\(hyvalid flag sequences. .PP \fINote\ 2\fR \ \(em\ There is no information field in the RCP frame. .RT .sp 1P .LP A.3.6.1\ \ \fIFrame number\fR .sp 9p .RT .PP This is an eight bit binary number. The frame number is defined to be the first eight bits of the facsimile information field. The least significant bit is transmitted first. .PP The frame number 0\(hy255 (maximum number is 255) is used to identify the facsimile data field (see\ Recommendation\ T.30, Annex\ A). .PP The frame 0 is transmitted first in each block. .RT .sp 1P .LP A.3.6.2\ \ \fIFacsimile data field\fR .sp 9p .RT .PP The coding schemes specified in\ \(sc\ 4 are valid with the following notes. .RT .LP 1) The facsimile data field is a length of 256 or 64 octets. .LP 2) The total coded scan line is defined as the sum of DATA bits plus the EOL bits. For the optional two\(hydimensional coding scheme as described in\ \(sc\ 4.2, the total coded scan line is defined as the sum of DATA bits plus the EOL bits plus a tag bit . .LP 3) At the end of facsimile data field, if necessary, Pad bits may be used to align on octet boundaries and frame boundaries (see Notes\ 1 and\ 2). The format is a variable length string of zeros. .PP \fINote\ 1\fR \ \(em\ The receiver is able to receive both Pad bits and Fill bits. .PP \fINote\ 2\fR \ \(em\ The facsimile data field length of the final frame including RTC signal may be less than 256 or 64\ octets. .bp .RT .sp 1P .LP A.3.7 \fIFrame checking sequence (FCS)\fR .sp 9p .RT .PP The FCS shall be a 16 bit sequence (see Recommendation\ T.30, \(sc\ 5.3.7). .RT .sp 1P .LP A.3.8 \fIReturn to control for partial page (RCP)\fR .sp 9p .RT .PP The end of a partial page transmission is indicated by sending three consecutive RCP frames (see Note). .PP Following these RCP frames, the transmitter will send the post message commands in the framed format and the data signalling rate of the control signals defined in Recommendation\ T.30, Annex\ A. .PP \fINote\fR \ \(em\ The flag sequence following the last RCP frame shall be less than 50\ ms. .RT .ce 1000 ANNEX\ B .ce 0 .ce 1000 (to Recommendation T.4) .sp 9p .RT .ce 0 .ce 1000 \fBOptional\fR \fBerror limiting mode\fR .sp 1P .RT .ce 0 .PP \fINote\fR \ \(em\ The text of Annex B shall be refined and studied during the next study period. .sp 1P .RT .sp 2P .LP B.1 \fIData\fR .sp 1P .RT .sp 1P .LP B.1.1 \fIThe division of a scan line into parts\fR .sp 9p .RT .PP In order to limit the disturbed area in the event of transmission error, the scan lines are divided into parts before coding. .PP The number of parts shall be used as follows: .RT .LP a) standard, 12 parts in a line composed of 1728 black and white picture elements, .LP b) optionally, 15 parts in a line composed of 2048 black and white picture elements, .LP c) optionally, 17 parts in a line composed of 2432 black and white picture elements. .PP \fINote\fR \ \(em\ For alternatives b) and c), the last part of a scan line can be shortened and then will contain 32 and 128\ pels respectively. .sp 1P .LP B.1.2 \fIScan line coding\fR .sp 9p .RT .PP All parts of a scan line are divided into whites (W) if they are composed of all white picture elements and not\(hywhite (NW) if they contain at least one black element. .PP The coding procedure is as shown in the flow diagram of Figure\ B\(hy1/T.4. .RT .sp 1P .LP B.1.2.1\ \ \fIShaping the extended\fR \fIdescription of a scan line\fR .sp 9p .RT .PP For each coded scan line the extended scan line description (ELD) is shaped. ELD represents a sequence, where the bit number is equal to the part number in a scan line, i.e.,\ each part has corresponding bit in the sequence. This bit is equal to \*Q1\*U, if the part is \*QNW\*U and it is equal to \*Q0\*U if the part is\ \*QW\*U. .RT .sp 1P .LP B.1.2.2\ \ \fIScan line part coding\fR .sp 9p .RT .PP W\(hyparts are not encoded. The coding of each NW\(hypart is independent of the coding of other parts in the given scan line. In the NW\(hypart the white and black runs alternate. The coding always begins with a white run. If the actual scan line begins with a black run then a white run length of zero will be sent. Run lengths are encoded using Tables\ 1/T.4 and\ 2/T.4 as described in \(sc\ 4.1.1. The last run of each NW\(hypart is not encoded. Resulted coded run lengths (CRL) are sent directly one after another. .RT .sp 1P .LP B.1.2.3\ \ \fICode bit number variation (CBNV)\fR .sp 9p .RT .PP It is necessary to code and send the number of coded bits for each NW\(hypart. For this purpose the code bit number of the previous NW\(hypart\ \fIq\fR\d\fIi\fR\\d\\u(em\d1\uis subtracted from the code bit number of the given NW\(hypart \fIq\fR\d\fIi\fR\u. The resulting difference \fIq\fR\d\fIi\fR\u\ \(em\ \fIq\fR\d\fIi\fR\\d\\u(em\d1\uis coded by using code words listed in Table\ B\(hy1/T.4. For the first NW\(hypart in a scan line \fIq\fR\d\fI0\fR\uis taken to be 40. In the code words given in Table\ B\(hy1/T.4 the bit\ X corresponds to the sign of the difference\ \fIq\fR\d\fIi\fR\u\ \(em\ \fIq\fR\d\fIi\fR\\d\\u(em\d1\u. When the difference is positive, bit\ X equals \*Q0\*U, but when the difference is negative bit\ X equals\ \*Q1\*U. .bp .RT .LP .rs .sp 47P .ad r \fBFigure B\(hy1/T.4, (N), p.29\fR .sp 1P .RT .ad b .RT .LP .bp .ce \fBH.T. [1T5.4]\fR .ce TABLE\ B\(hy1/T.4 .ce \fBCode table for the code bit number variation\fR .ce .ce \fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(60p) | cw(54p) | cw(60p) | cw(54p) . Absolute value of variation Code Absolute value of variation Code _ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 0 \ \ \ \ \ \ 100000 \ 51 X11111 010101 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 1 \ \ \ \ \ \ X00001 \ 52 X11111 010110 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 2 \ \ \ \ \ \ X00010 \ 53 X11111 010111 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 3 \ \ \ \ \ \ X00011 \ 54 X11111 011000 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 4 \ \ \ \ \ \ X00100 \ 55 X11111 011001 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 5 \ \ \ \ \ \ X00101 \ 56 X11111 011010 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 6 \ \ \ \ \ \ X00110 \ 57 X11111 011011 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 7 \ \ \ \ \ \ X00111 \ 58 X11111 011100 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 8 \ \ \ \ \ \ X01000 \ 59 X11111 011101 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . \ 9 \ \ \ \ \ \ X01001 \ 60 X11111 011110 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 10 \ \ \ \ \ \ X01010 \ 61 X11111 100000 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 11 \ \ \ \ \ \ X01011 \ 62 X11111 100001 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 12 \ \ \ \ \ \ X01100 \ 63 X11111 100010 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 13 \ \ \ \ \ \ X01101 \ 64 X11111 100011 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 14 \ \ \ \ \ \ X01110 \ 65 X11111 100100 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 15 \ \ \ \ \ \ X01111 \ 66 X11111 100101 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 16 \ \ \ \ \ \ X10000 \ 67 X11111 100110 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 17 \ \ \ \ \ \ X10001 \ 68 X11111 100111 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 18 \ \ \ \ \ \ X10010 \ 69 X11111 101000 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 19 \ \ \ \ \ \ X10011 \ 70 X11111 101001 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 20 \ \ \ \ \ \ X10100 \ 71 X11111 101010 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 21 \ \ \ \ \ \ X10101 \ 72 X11111 101011 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 22 \ \ \ \ \ \ X10110 \ 73 X11111 101100 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 23 \ \ \ \ \ \ X10111 \ 74 X11111 101101 \ \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 24 \ \ \ \ \ \ X11000 \ 75 X11111 101110 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 25 \ \ \ \ \ \ X11001 \ 76 X11111 101111 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 26 \ \ \ \ \ \ X11010 \ 77 X11111 110000 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 27 \ \ \ \ \ \ X11011 \ 78 X11111 110001 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 28 \ \ \ \ \ \ X11100 \ 79 X11111 110010 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 29 \ \ \ \ \ \ X11101 \ 80 X11111 110011 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 30 \ \ \ \ \ \ X11110 \ 81 \ 82 { X11111 110100 \ \ \ \ \ \ X11111 110101 \ \ \ \ \ \ } .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 31 X11111 000001 \ 83 X11111 110110 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 32 X11111 000010 \ 84 X11111 110111 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 33 X11111 000011 \ 85 X11111 111000 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 34 X11111 000100 \ 86 X11111 111001 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 35 X11111 000101 \ 87 X11111 111010 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 36 X11111 000110 \ 88 X11111 111011 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 37 X11111 000111 \ 89 X11111 111100 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 38 X11111 001000 \ 90 X11111 111101 \ \ \ \ \ \ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 39 X11111 001001 \ 91 X11111 X11110 010000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 40 X11111 001010 \ 92 X11111 X11111 000001 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 41 X11111 001011 \ 93 X11111 X11111 000010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 42 X11111 001100 \ 94 X11111 X11111 000011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 43 X11111 001101 \ 95 X11111 X11111 000100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 44 X11111 001110 \ 96 X11111 X11111 000101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 45 X11111 001111 \ 97 X11111 X11111 000110 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 46 X11111 010000 \ 98 X11111 X11111 000111 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 47 X11111 010001 \ 99 X11111 X11111 001000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 48 X11111 010010 100 X11111 X11111 001001 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 49 X11111 010011 101 X11111 X11111 001010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 50 X11111 010100 102 X11111 X11111 001011 _ .TE .nr PS 9 .RT .ad r \fBTableau B\(hy1/T.4 [1T5.4], p.\fR .sp 1P .RT .ad b .RT .LP .bp .ce \fBH.T. [2T5.4]\fR .ce TABLE\ B\(hy1/T.4 \fI(cont.)\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; cw(60p) | cw(54p) | cw(60p) | cw(54p) . Absolute value of variation Code Absolute value of variation Code _ .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 103 X11111 X11111 001100 119 X11111 X11111 011100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 104 X11111 X11111 001101 120 X11111 X11111 011101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 105 X11111 X11111 001110 121 X11111 X11111 011110 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 106 X11111 X11111 001111 122 X11111 X11111 100000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 107 X11111 X11111 010000 123 X11111 X11111 100001 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 108 X11111 X11111 010001 124 X11111 X11111 100010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 109 X11111 X11111 010010 125 X11111 X11111 100011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 110 X11111 X11111 010011 126 X11111 X11111 100100 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 111 X11111 X11111 010100 127 X11111 X11111 100101 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 112 X11111 X11111 010101 128 X11111 X11111 100110 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 113 X11111 X11111 010111 129 X11111 X11111 100111 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 114 X11111 X11111 010111 130 X11111 X11111 101000 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 115 X11111 X11111 011000 131 X11111 X11111 101001 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 116 X11111 X11111 011001 132 X11111 X11111 101010 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 117 X11111 X11111 011010 133 X11111 X11111 101011 .T& cw(60p) | cw(54p) | cw(60p) | cw(54p) . 118 X11111 X11111 011011 134 X11111 X11111 101100 .TE .LP \fINote\fR \ \(em\ Bit X corresponds to the sign of the variation. .nr PS 9 .RT .ad r \fBTableau B\(hy1/T.4 [2T5.4], p.\fR .sp 1P .RT .ad b .RT .LP .sp 2 .sp 1P .LP B.1.3 \fIData format\fR .sp 9p .RT .PP The data format for the scan line containing several NW\(hyparts is shown in Figure\ B\(hy2/T.4 and containing only one NW\(hypart is shown in Figure\ B\(hy3/T.4. The data format for the scan line containing all whites is shown in Figure\ B\(hy4/T.4. .RT .LP .rs .sp 12P .ad r \fBFigure B\(hy2/T.4, (N), p.32\fR .sp 1P .RT .ad b .RT .LP .bp .LP .rs .sp 12P .ad r \fBFigure B\(hy3/T.4, (N), p.33\fR .sp 1P .RT .ad b .RT .LP .rs .sp 13P .ad r \fBFigure B\(hy4/T.4, (N), p.34\fR .sp 1P .RT .ad b .RT .sp 1P .LP B.2 \fIEnd of line (EOL)\fR .sp 9p .RT .PP This code word follows each line of data. There is a slight probability of occurrence of the same bit combination for ELD and the code word EOL. This should be taken account in the decoding algorithm. In addition, EOL is sent prior to the format data line of the page. .PP Format: 000000000001 .RT .sp 1P .LP B.3 \fIFill\fR .sp 9p .RT .PP A pause in the message may be filled as described in \(sc\ 4.1.3. .RT .sp 1P .LP B.4 \fIReturn to control (RTC)\fR .sp 9p .RT .PP The return to control should comply with \(sc 4.1.4. .PP \fINote\fR \ \(em\ When decoding, the correction of the corrupted parts can be performed by replacing the corrupted part with the corresponding uncorrupted part from the previous line. The exceeding of the value\ 144 by the decoded part length or the absence of code word of the given part in the code table vocabulary can be shown as a sign for replacement. .bp .RT .ce 1000 ANNEX\ C .ce 0 .ce 1000 (to Recommendation T.4) .sp 9p .RT .ce 0 .ce 1000 \fBInterworking between equipments with A5/A6 and A4 facilities\fR .sp 1P .RT .ce 0 .ce 1000 \fBand between equipments with combinations of these facilities\fR .ce 0 .LP .rs .sp 47P .ad r \fBTableau C\(hy1/T.4 [T6.4] A L'ITALIENNE \ MONTAGE: A COLLER LE TITRE\ , p.35\fR .sp 1P .RT .ad b .RT .LP .bp .ce 1000 APPENDIX\ I .ce 0 .ce 1000 (to Recommendation T.4) .sp 9p .RT .ce 0 .ce 1000 \fBGuaranteed reproducible area for Group 3 apparatus\fR .sp 1P .RT .ce 0 .ce 1000 \fBconforming to Recommendation\ T.4\fR .ce 0 .LP .rs .sp 43P .ad r \fBFIGURE I\(hy1/T.4, p. + Remarques\fR .sp 1P .RT .ad b .RT .LP .bp .LP .rs .sp 18P .ad r \fBFigure I\(hy2/T.4, (M), p.37 .sp 1P .RT .ad b .RT .LP .sp 9 .ce \fBH.T. [T7.4]\fR .ce TABLE\ I\(hy1/T.4 .ce \fBHorizontal losses\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; lw(84p) | cw(42p) | cw(54p) . Printer/scanner a \(+- | .5 mm _ .T& lw(84p) | cw(42p) | cw(54p) . Enlarging b \(+- | .1 mm _ .T& lw(84p) | cw(42p) | cw(54p) . Skew c \(+- | .6 mm _ .T& lw(84p) | cw(42p) | cw(54p) . Positioning errors d \(+- | .5 mm _ .TE .nr PS 9 .RT .ad r \fBTableau I\(hy1/T.4 [T7.4], p.38\fR .sp 1P .RT .ad b .RT .LP .sp 9 .bp .LP .rs .sp 27P .ad r \fBFigure I\(hy3/T.4, (M), p.39\fR .sp 1P .RT .ad b .RT .LP .sp 4 .ce \fBH.T. [T8.4]\fR .ce TABLE\ I\(hy2/T.4 .ce \fBVertical losses\fR .ps 9 .vs 11 .nr VS 11 .nr PS 9 .TS center box; lw(84p) | cw(42p) | cw(54p) . Paper insertion f { \fB\(+-\fR | .0\fB7\fR mm } _ .T& lw(84p) | cw(42p) | cw(54p) . Skew g \(+- | .8\fB7\fR mm _ .T& lw(84p) | cw(42p) | cw(54p) . Scanning density tolerance h \(+- | .97 mm _ .T& lw(84p) | cw(42p) | cw(54p) . Gripping loss i { \fB\(+-\fR | .0\fB7\fR mm } .TE .LP \fINote\fR \ \(em\ Scanning density tolerance will reduce to 0\ mm on roll\(hyfed machines. .nr PS 9 .RT .ad r \fBTableau I\(hy2/T.4 [T8.4], p.40\fR .sp 1P .RT .ad b .RT .LP .sp 3 .bp