9.	Proposed additions and revisions to Recommendation M.1050

LINING-UP AN INTERNATIONAL POINT-TO-POINT LEASED CIRCUIT

The first sentence of § 1 of Recommendation M.1050 should be continued:

"... in Recommendations M.1020 and M.1025) which are provided by analogue transmission systems or by a mixture of analogue and digital systems."

The following text should be inserted under the heading "2.1 National sections":

"When analogue access to the circuit is available at the terminal international centre the following tests should be performed regardless of whether the national section is provided by analogue circuit sections or a combination of analogue, mixed and digital circuit sections."

The following text should be inserted under the heading

"2.2 International section":

"When analogue access to the circuit is available at terminal international centres the following tests should be performed regardless of whether the international section is provided by analogue circuit sections or a combination of analogue, mixed and digital circuit sections."

Add the following text after the first sentence of § 3 lining up the overall circuit:

"It should be noted that satisfactory impulsive noise performance on a circuit is unlikely to be achieved if the circuit is routed via a primary digital path on which the bit error ratio exceeds 1.10-6*. It is not intended that this digital parameter be measured."

Add the following footnote to § 3:

"* This parameter is used provisionally and further study is required to assess whether other parameters (e.g. those in Recommendation G.821) would be more suitable for relating the performance of transient analogue impairments to the performance of the digital paths on which the circuits are routed."

The present § 3.8 of Recommendation M.1050 should be replaced by the following:

"3.8	Total distortion (special quality circuits only)

When the circuit includes any digital circuit sections a measurement of total distortion should be made using an instrument complying with Recommendation O.132. Such a measurement will include contributions from quantizing distortion, random noise, harmonic distortion and single tone interference. The minimum signal/total distortion ratio is given in Recommendations M.1020 and M.1025. However, if this minimum ratio is satisfied it should not be assumed that all the parameters which contribute to the measurement are satisfactory. The total distortion measurement is not a substitute for the individual measurements specified in this Recommendation."

Under the heading "4.1 National sections" insert the same text as given above for § 2.1. Similarly under the heading "4.2 International section" insert the same text as given above for § 2.2.

The same text and footnote given for § 3 of this Recommendation should be added to the end of the first paragraph under "4.1.4. Other characteristics (special quality circuits)".

The same text and footnote given for § 3 of this Recommendation should be added to the end of the second paragraph under "4.2.4 Other characteristics (special quality circuits)".

As a consequence of the above-mentioned changes the following text has to be inserted under the headings of § 2.2 and § 4.2:

"When analogue access to the circuit is available at the terminal

international centres the following tests should be performed regardless of whether the international section is provided by analogue circuit sections or a combination of analogue, mixed and digital circuit sections."

The title of § 3.11 should be changed to:

"3.11 Harmonic and intermodulation distortion (special quality circuits only)"

A new second alinea should be introduced to § 3.11 of the Recommendation as follows:

"Alternatively, by bilateral agreement between administrations, a measurement of second and third order intermodulation products using an instrument complying with Recommendation O.42 should be performed. The limit is for further study."

The following amendments should be made to the second line of § 10 of Recommendation M.1050:

"If there is a breakdown or planned interruption of a transmission system, rerouting should be carried out as far as possible at group, supergroup or digital link level. This ... distortion. When such a rerouting of transmission links cannot be effected ... should be chosen, in particular with regard to the number of FDM carrier sections and the relative number of analogue and digital circuit sections. The procedure ...".