.rs
.\" Troff code generated by TPS Convert from ITU Original Files
.\"                 Not Copyright ( c) 1991 
.\"
.\" Assumes tbl, eqn, MS macros, and lots of luck.
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.EN
.nr LL 40.5P
.nr ll 40.5P
.nr HM 3P
.nr FM 6P
.nr PO 4P
.nr PD 9p
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.rs
\v | 5i'
.ce 1000
APPENDIX\ I
.ce 0
.ce 1000
(to Recommendation G.722)
.sp 9p
.RT
.ce 0
.ce 1000
\fBNetworking aspects\fR 
.sp 1P
.RT
.ce 0
.PP
The purpose of this Appendix is to give a broad outline of the
interaction of 64\ kbit/s (7\ kHz) audio coding with other parts of the 
digital network. Some general guidance is also offered. 
.sp 1P
.RT
.PP
The establishment of the connection is beyond the scope of this
Recommendation.
.sp 1P
.LP
I.1
	\fINetwork characteristics\fR 
.sp 9p
.RT
.PP
This Recommendation is applicable to systems operating in networks which 
exhibit each of the following characteristics: 
.RT
.LP
	i)
	availability of network octet timing at the terminals;
.LP
	\fINote\fR \ \(em\ Octet timing may also be derived from control
signals within the frame structure defined in
Recommendation\ G.725;
.LP
	ii)
	plesiochronous networking where the reference clocks meet
the timing requirements given in Recommendation\ G.811, or
synchronous networking;
.LP
	iii)
	64 kbit/s connection types having either of the following
characteristics:
.LP
	\(em
	full 64 kbit/s transparency,
.LP
	\(em
	pulse density restriction as described in
Recommendation\ G.802.
.PP
\fINote\fR \ \(em\ 64 kbit/s (7 kHz) audio coding can also operate in
networks where there is substitution of a signalling bit for the 8th bit 
of the octet as described in Recommendation\ G.704, \(sc\ 3.1 or where 
there is 56\ kbit/s transparency only. However, a reduction of the audio 
bit rate and auxiliary 
data channel capacity occurs and only two modes of operation, denoted 1\ 
\fIbis\fR (unframed) and 3\ \fIbis\fR , are possible as follows: 
.LP
	\(em
	Mode 1 \fIbis\fR  |  56 kbit/s for audio coding and no data
channel;
.LP
	\(em
	Mode 3 \fIbis\fR  |  48 kbit/s for audio coding, a 6.4\ kbit/s data
channel and 1.6\ kbit/s for service channel framing and mode
control.
.sp 1P
.LP
I.2
	\fIIntegration into the telecommunications network\fR 
.sp 9p
.RT
.PP
It is foreseen that the 64 kbit/s (7 kHz) audio coding system will be used 
for point\(hyto\(hypoint, multipoint and broadcast applications. Examples 
of particular uses are: commentary quality channels for broadcasting purposes 
and high quality speech for audio and video conferencing applications. 
.PP
The coding system can operate over any 64 kbit/s bearer channel (see \(sc\ 
I.1), e.g.\ the public switched telephone network, leased circuits or over 
an ISDN. 
.PP
Processes such as digital speech interpolation, echo control and
digital pads must be disabled for the transmission of 64\ kbit/s (7\ kHz) 
audio coding. The disabling protocol is not the subject of this Recommendation. 
.PP
It should be noted however that signal processing may occur in a
multipoint conference unit (see \(sc\ I.7).
.RT
.sp 2P
.LP
I.3
	\fIAudio performance of the 64 kbit/s (7 kHz) audio coding\fR 
\fIsystem\fR 
.sp 1P
.RT
.sp 1P
.LP
I.3.1
	\fISpeech\fR 
.sp 9p
.RT
.PP
The speech performance of the 64 kbit/s (7 kHz) audo coding system has 
been quantified in terms of \fIQ\fR\d\fIW\fR\u\(hyvalues, where\ \fIQ\fR\d\fIW\fR\uis 
a measure of the signal\(hyto\(hycorrelated noise ratio of the wideband 
system, measured in dB. 
Detailed information on \fIQ\fR \(hyvalue measurements may be found in
Recommendation\ P.81. This Recommendation, although primarily intended for
telephony bandwidth applications, has been used for the evaluation of wideband 
systems \(em\ signified by the subscript\ \fIW\fR \ \(em by use of an appropriate 
filter 
(50\(hy7000\ Hz).
.PP
For guidance purposes only, a \fIQ\fR\d\fIW\fR\uvalue of 38 dB corresponds
approximately to a 128\ kbit/s (7\ kHz) PCM system (sampling frequency 16\ kHz,
coding law as in Recommendation\ G.711), whereas a \fIQ\fR\d\fIW\fR\u\ 
value of 45\ dB is 
approximately equivalent to the audio parts of the coder interconnected
without the intermediate SB\(hyADPCM coding process.
.bp
.PP
Table I\(hy1/G.722 indicates the relative performance in \fIQ\fR\d\fIW\fR\uvalues 
for nominal input values. 
.RT
.ce
\fBH.T. [T24.722]\fR 
.ce
TABLE\ I\(hy1/G.722
.ce
\fBRelative levels of speech performance\fR 
.ce
\fB(\fR 
.ce
\fIQ\fI
.ce
 | fBvalues)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(60p) | cw(24p) sw(60p) sw(60p) , ^  | c | c | c.
Mode of  operation	Transcodings
	1	 {
4
Analogue
according to
Fig. I\(hy1/G.722
 }	 {
4
Digital
according to
Fig. I\(hy2/G.722
 }
_
.T&
cw(60p) | cw(24p) | cw(60p) | cw(60p) .
1 (64 kbit/s)	45	38	41
_
.T&
cw(60p) | cw(24p) | cw(60p) | cw(60p) .
2 (56 kbit/s)	43	36	38
_
.T&
cw(60p) | cw(24p) | cw(60p) | cw(60p) .
3 (48 kbit/s)	38	29	34
_
.TE
.nr PS 9
.RT
.ad r
\fBTable I\(hy1/G.722 [T24.722], p.\fR 
.sp 1P
.RT
.ad b
.RT
.PP
.sp 2
The performance of the 64 kbit/s (7 kHz) audio coding system has been found 
to be substantially unaffected by randomly distributed errors at BER levels 
as high as\ 1\(mu10\uD\dlF261\u4\d. High error ratios approaching\ 1\(mu10\uD\dlF261\u3\d 
produce perceptible degradation which may be considered tolerable in certain
applications.
.PP
No particular problems have been experienced in the multiple talker
condition and hence correct operation under normal conference conditions can
safely be assumed.
.PP
The performance under conditions of mode mismatch (i.e. where the
variant used in the decoder for a given octet does not correspond to the 
mode of operation) is considered in \(sc\ I.5. 
.RT
.sp 1P
.LP
I.3.2
	\fIMusic\fR 
.sp 9p
.RT
.PP
Although primarily designed for speech, no significant distortions may 
be expected when coding a wide range of music material in Mode\ 1. Further 
study on the effects on music signals is a matter of Study Group CMTT. 
.RT
.sp 2P
.LP
I.4
	 \fIAudio performance when interconnected with other coding systems on\fR 
\fIan analogue basis\fR 
.sp 1P
.RT
.sp 1P
.LP
I.4.1
	\fI64 kbit/s PCM\fR 
.sp 9p
.RT
.PP
Informal subjective tests carried out over a path consisting of an analogue 
interconnected combination of a 64\ kbit/s PCM link conforming to 
Recommendation\ G.711 and a 64\ kbit/s (7\ kHz) audio coding link has indicated
that no interworking problems will occur. However, the performance of the
combination will not be better than that of 64\ kbit/s PCM.
.PP
Interconnection of the two coding systems on a digital basis is the
subject of \(sc\ I.8.
.RT
.sp 1P
.LP
I.4.2
	\fI32 kbit/s ADPCM\fR 
.sp 9p
.RT
.PP
An analogue interconnected combination of a 32 kbit/s ADPCM link
conforming to Recommendation\ G.721 and a 64\ kbit/s (7\ kHz) audio coding 
link is not expected to pose any interworking problems. However, the performance 
of the combination will not be better than that of 32\ kbit/s ADPCM. 
.PP
Interconnection of the two coding systems at a digital level is the
subject of further study.
.bp
.RT
.sp 1P
.LP
I.5
	\fIAudio performance under\fR 
\fImode switching\fR 
.sp 9p
.RT
.PP
It is recommended that mode switching should be performed
synchronously between the transmitter and the receiver to maximize the audio
performance. However, asynchronous mode switching may be considered since 
the condition of mode mismatch will probably be of limited duration and 
hence the corresponding performance is likely to be acceptable. Although 
not desirable, operation under permanent mode mismatch may be contemplated 
in exceptional 
circumstances. Table\ I\(hy2/G.722 indicates the relative performance under all
mode mismatch combinations for nominal input levels.
.RT
.ce
\fBH.T. [T25.722]\fR 
.ce
TABLE\ I\(hy2/G.722
.ce
\fBRelative speech performance under mode mismatch\fR 
.ce
\fB(\fR 
.ce
\fIQ\fI
.ce
 | fBvalues)\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(72p) | cw(60p) sw(60p) , ^  | c | c.
 {
Bit rate used for audio
reception
 }	 {
Bit rate used for
audio transmission
 }
	56 kbit/s	48 kbit/s
_
.T&
cw(72p) | cw(60p) | cw(60p) .
64 kbit/s	41	35
_
.T&
cw(72p) | cw(60p) | cw(60p) .
56 kbit/s	\(em	36
.TE
.LP
\fINote\fR
\ \(em\ The bits not used for audio coding have been replaced by bits of a
pseudorandom sequence.
.nr PS 9
.RT
.ad r
\fBTable I\(hy2/G.722 [T25.722], p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.sp 5
.sp 1P
.LP
I.6
	\fIAuxiliary data channel\fR \fIperformance\fR 
.sp 9p
.RT
.PP
The available combinations of audio and data channel bit rates
depends on the connection types described in \(sc\ I.1\ iii).
.PP
The data channel is unaffected by the characteristics of the audio
signal since the audio and data channels are effectively decoupled. The
transparency of the data channel is limited only by the choice of signalling
sequences which could be used to derive the terminal identification. If 
these sequences are chosen to be of a suitable format, the possibility 
of their 
simulation by audio or data bits can be made extremely low. Hence, for all
practical purposes, the data channel may be assumed to be transparent.
.PP
The control of the data channel capacity is considered in
Recommendation\ G.725.
.PP
Although the format of the data channel is not part of this
Recommendation, it may be noted that the use of two completely independent
8\ kbit/s data channels when the total data channel capacity is 16\ kbit/s 
is not prohibited by the algorithm. 
.PP
Under transmisssion error conditions the data channel is not subject to 
error multiplication due to the audio coding algorithm. 
.PP
\fINote\fR \ \(em\ It might be possible to obtain additional data channel
capacity by substituting data for the two bits normally allocated to the 
higher sub\(hyband with the consequent penalty of a reduction in the audio 
bandwidth. 
However, such an approach is likely to require a more stringent specification 
for the receive filter characteristics in order to minimize aliasing 
effects.
.bp
.RT
.sp 1P
.LP
I.7
	\fIMulti\(hypoint conference configuration\fR 
.sp 9p
.RT
.PP
The specific features of a multipoint conference arrangement
including control of the data channel, echo control, and handling of control
messages between terminals, are beyond the scope of this Recommendation.
However, the audio coding algorithm has been chosen to maintain maximum
flexibility for multipoint conference arrangements which are likely to 
emerge. There are a number of general guidelines which should be noted: 
.RT
.LP
	\(em
	To maximize audio performance, the highest audio bit rate
possible, consistent with the transmitted data channel bit rate
requirement, should be used for transmission into and out of the
signal summing facility of the multipoint conference unit.
.LP
	\fINote\fR \ \(em\ The signal summation must be carried out on a linear
representation of the signals.
.LP
	\(em
	The transmit and receive modes of a terminal or port of a
multipoint conference unit do not necessarily have to be the
same.
.LP
	\(em
	Signal summing at the sub\(hyband uniform PCM level is preferred
for the following reasons:
.LP
	i)
	the hardware is minimized in the multipoint
conference unit (MCU) by eliminating the need for
quadrature mirror filters,
.LP
	ii)
	signal quality is maximized and additional signal
delay is eliminated by avoiding additional filtering,
.LP
	iii)
	echo control is likely to be simpler to perform
at the sub\(hyband level.
.LP
	Figure I\(hy3/G.722 indicates a possible arrangement at the
multipoint conference bridge with signal summing at the
sub\(hyband level;
.LP
	\(em
	For reasons of audio performance, the number of tandem
connected multipoint conference units interconnected with
64\ kbit/s (7\ kHz) audio coding is limited to three, see
Figure\ I\(hy4/G.722).
.LP
	\(em
	In the case where the multipoint conference unit includes
64\ kbit/s PCM ports, digital transcoding principles equivalent
to that described in \(sc\ I.8 should be used to derive the higher
and lower sub\(hyband signals.
.LP
.rs
.sp 9P
.ad r
\fBFigure I\(hy1/G.722, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 15P
.ad r
\fBFigure I\(hy2/G.722, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 22P
.ad r
\fBFigure I\(hy3/G.722, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 12P
.ad r
\fBFigure I\(hy4/G.722, p.\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
I.8
	 \fIDigital transcoding between the 64 kbit/s (7 kHz) audio coding\fR 
\fIsystem and 64 kbit/s PCM\fR 
.sp 9p
.RT
.PP
Figure I\(hy5/G.722 indicates the method recommended for the digital interconnection 
of the 64\ kbit/s (7\ kHz) audio coding system and 64\ kbit/s PCM to Recommendation\ 
G.711. 
.PP
The principle of transcoding from 64\ kbit/s PCM to 64\ kbit/s (7\ kHz) 
audio coding involves the conversion from A\(hylaw or \(*m\(hylaw PCM to 
uniform PCM and the insertion of interleaved alternate samples of zero 
amplitude to the 8\ kHz sampled uniform PCM signal to form a 16\ kHz sampled 
signal. This signal is then passed through a digital low pass filter sampled 
at 16\ kHz which does not 
significantly modify the baseband frequency response up to 3.4\ kHz and which
attenuates the frequency components above 4.6\ kHz. The resulting signal 
is then applied to the sub\(hyband ADPCM encoder as shown in Figure\ I.3/G.722. 
.PP
It should be noted that the use of the lower sub\(hyband alone to carry 
the information in a signal emanating from a 64\ kbit/s PCM link to 
Recommendation\ G.711 should be avoided.
.bp
.PP
An alternative method of deriving two sub\(hyband signals from a
64\ kbit/s PCM signal using the low pass (LP) and high pass (HP) QM filter 
designs already employed for the 64\ kbit/s (7\ kHz) audio coding scheme 
is given in Figure\ I\(hy6/G.722. The objective is to generate a higher 
sub\(hyband signal 
which will eventually cancel the aliasing distortion introduced into the 
lower sub\(hyband signal. The 64\ kbit/s PCM signal is converted to uniform 
PCM and 
upsampled to 16\ kHz by inserting alternate zero\(hyvalued samples. The 
factor\ 2 
multiplier is inserted to preserve unity gain. The lower sub\(hyband signal is
derived by two identical stages of HP QM filtering following by 2:1
subsampling. The higher sub\(hyband signal is derived by two filtering 
stages, HP followed by LP, a factor 1/2 gain reduction, sign inversion, 
followed by 2:1 
subsampling. When these two signals are input to the QM synthesis filter of
Recommendation\ G.722, an appropriate 7\ kHz form of the original PCM is
obtained.
.PP
Note that the upsampling and subsampling process should be
synchronized so that instants of sample deletion correspond to the instants 
of zero\(hysample insertion. 
.PP
Transcoding from 64 kbit/s (7 kHz) audio coding to 64\ kbit/s PCM can be 
achieved by taking the output signal from the sub\(hyband ADPCM decoder 
and 
performing the following three processes in turn:
.RT
.LP
	\(em
	digital low pass filtering (16 kHz sampling), which does not
significantly modify the baseband frequency response up to
3.4\ kHz and which attenuates the frequency components above
4.6\ kHz;
.LP
	\(em
	the deletion of alternate samples from the resulting 16\ kHz
sampled signal;
.LP
	\(em
	conversion from the resulting 8 kHz sampled uniform PCM
signal to A\(hylaw or \(*m\(hylaw PCM.
.PP
\fINote\fR \ \(em\ The derivation of a 64 kbit/s PCM signal solely from 
the lower sub\(hyband of the 64\ kbit/s (7\ kHz) signal is subject to further 
study. 
.LP
.rs
.sp 26P
.ad r
\fBFigure I\(hy5/G.722, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 17P
.ad r
\fBFigure I\(hy6/G.722, p.\fR 
.sp 1P
.RT
.ad b
.RT
.ce 1000
APPENDIX\ II
.ce 0
.ce 1000
(to Recommendation G.722)
.sp 9p
.RT
.ce 0
.ce 1000
\fBDigital test sequences\fR 
.sp 1P
.RT
.ce 0
.PP
This Appendix gives information concerning the digital test
sequences which should be used to aid verification of implementations of the
ADPCM codec part of the wideband coding algorithm. Copies of the sequences 
are available on flexible disks (see \(sc\ II.4). 
.sp 1P
.RT
.sp 1P
.LP
II.1
	\fIInput and output signals\fR 
.sp 9p
.RT
.PP
Table II\(hy1/G.722 defines the input and output signals for the test sequences. 
It contains some signals (indicated by\ ##) peculiar to these test 
sequences in order to facilitate the interface between the test sequence
generator/receiver and the encoder/decoder. 16\(hybit word formats for 
these input and output signals are shown in Figures\ II\(hy1/G.722, II\(hy2/G.722 
and\ II\(hy3/G.722.
.RT
.sp 1P
.LP
II.2
	\fIConfiguratins for the application of test sequences\fR 
.sp 9p
.RT
.PP
Two configurations (Configuration 1 and Configuration 2) are
appropriate for use with test sequences. In both configurations, a TEST 
signal is used to make the encoder and decoder ready to be tested with 
the digital 
test sequences. When the TEST signal is provided, the QMFs are by\(hypassed and
the test sequences are applied directly to the ADPCM encoders or decoders. 
An RSS signal is extracted from the input test sequences\ X## (I## in decoder) 
and results in a reset signal RS for the encoder and decoder. The RS signal 
will be used to initialize state variables (those indicated by * in Table\ 
13/G.722 to zero or specific values. 
.RT
.sp 1P
.LP
II.2.1
	\fIConfiguration 1\fR 
.sp 9p
.RT
.PP
Configuration 1 shown in Figure II\(hy4/G.722 is a simplified version of 
Figures\ 4/G.722 and\ 5/G.722. The encoder input signals, XL and XH, are 
described in Table\ 12/G.722. These input signals are directly fed to the
respective lower and higher sub\(hyband ADPCM encoders, by\(hypassing the 
QMF. The 
encoder output signals, IL and IH, are defined in the sub\(hyblock QUANTL and
QUANTH, respectively.
.PP
This sequence is used for testing the quantizer/predictor feedback
loop in the encoder.
.bp
.RT
.ce
\fBH.T. [T26.722]\fR 
.ce
TABLE\ II\(hy1/G.722
.ce
\fBDescription of input and output signals for test sequence\fR 
.ps 9
.vs 11
.nr VS 11
.nr PS 9
.TS
center box;
cw(24p) | cw(192p) .
Name	Description
_
.T&
lw(24p) | lw(192p) .
XL	 {
15\(hybit uniformly quantized input signal to the lower sub\(hyband
encoder
 }
.T&
lw(24p) | lw(192p) .
XH	 {
15\(hybit uniformly quantized input signal to the higher sub\(hyband
encoder
 }
.T&
lw(24p) | lw(192p) .
X##	 {
Input test sequence with 16\(hybit word format as shown in
Figure\ II\(hy1/G.722
 }
.T&
lw(24p) | lw(192p) .
IL	 {
6\(hybit lower sub\(hyband ADPCM codeword
 }
.T&
lw(24p) | lw(192p) .
ILR	 {
Received 6\(hybit lower sub\(hyband ADPCM codeword
 }
.T&
lw(24p) | lw(192p) .
IH	 {
2\(hybit higher sub\(hyband ADPCM codeword
 }
.T&
lw(24p) | lw(192p) .
I##	 {
Output (in Configuration 1) and Input (en Configuration 2) test
sequence with 16\(hybit word format as shown in Figure II\(hy2/G.722
 }
.T&
lw(24p) | lw(192p) .
RL	 {
15\(hybit uniformly quantized output signal from the lower sub\(hyband
decoder
 }
.T&
lw(24p) | lw(192p) .
RH	 {
15\(hybit uniformly quantized output signal from the higher sub\(hyband
decoder
 }
.T&
lw(24p) | lw(192p) .
RL##	 {
Output test sequence with 16\(hybit word format as shown in
Figure II\(hy3/G.722
 }
.T&
lw(24p) | lw(192p) .
RH##	 {
Output test sequence with 16\(hybit word format as shown in
Figure II\(hy3/G.722
 }
.T&
lw(24p) | lw(192p) .
RSS	Reset/synchronization signal
.T&
lw(24p) | lw(192p) .
VI	Valid data indication signal
_
.TE
.nr PS 9
.RT
.ad r
\fBTableau II\(hy1/G.722 [T26.722], p. 9\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 8P
.ad r
\fBFigure II\(hy1/G.722, p. 10\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 12P
.ad r
\fBFigure II\(hy2/G.722, p. 11\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.LP
.rs
.sp 8P
.ad r
\fBFigure II\(hy3/G.722, p. 12\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.rs
.sp 13P
.ad r
\fBFIGURE II\(hy4/G.722, p. 13\fR 
.sp 1P
.RT
.ad b
.RT
.sp 1P
.LP
II.2.2
	\fIConfiguration 2\fR 
.sp 9p
.RT
.PP
Configuration 2 shown in Figure II\(hy5/G.722 is a simplified version of 
Figures\ 7/G.722 and\ 8/G.722. The test signals, ILR and IH, and the MODE 
signal are described in Table\ 12/G.722. The corresponding decoder output
signals, RL and RH, are defined in the sub\(hyblocks LIMIT in \(sc\(sc\ 6.2.1.6
and\ 6.2.2.5. For the lower sub\(hyband, the ADPCM decoder output signals are
derived for three basic modes of operation (Modes\ 1, 2 and\ 3). By\(hypassing 
the QMF, the output signals, RL and RH, are separately obtained from the 
lower and higher sub\(hyband ADPCM decoders, respectively. 
.PP
Configuration 2 is used for testing the inverse quantizer operation
and the predictor adaptation without a quantizer/predictor feedback loop 
in the decoder. 
.RT
.LP
.rs
.sp 16P
.ad r
\fBFigure II\(hy5/G.722, p.\fR 
.sp 1P
.RT
.ad b
.RT
.LP
.bp
.sp 1P
.LP
II.2.3
	\fIReset/synchronization signal (RSS)\fR \fI and\fR \fIvalid data\fR 
\fIindication (VI)\fR 
.sp 9p
.RT
.PP
All memory states in the two test configurations must be
initialized to the exact states specified in this Recommendation prior 
to the start of an input test sequence in order to obtain the correct output 
values 
for the test.
.PP
In Configuration 1, the input test sequence, X##, is composed of
encoder input test signals and the reset/synchronization signal (RSS) as 
shown in Figure\ II\(hy1/G.722. The RSS signal is located at the first 
LSB of the input sequence. If RSS is \*Q1\*U, the lower and higher sub\(hyband 
encoders are 
initialized, and the outputs of the encoders are set to \*Q0\*U, i.e., 
IH\ =\ \*Q0\*U and IL\ =\ \*Q0\*U. This normally forbidden output code 
is used to indicate \*Qnon\(hyvalid 
data\*U of the outputs. After the RSS signal goes to \*Q0\*U, the input 
test sequence will be valid and the ADPCM algorithm begins to operate. 
.PP
In Configuration 2, the input test sequence, I##, is composed of the first 
8\ bits of lower and higher sub\(hyband decoder input codewords, and the 
last 8\ bits consists of 7\(hybit zeroes and \*QRSS\*U in the LSB as shown 
in 
Figure\ II\(hy2/G.722. The RSS signal has the same role as in Configuration\ 
1. That is, if the RSS signal equals \*Q1\*U, the lower and higher sub\(hyband 
decoders are 
initialized. After the RSS signal goes to \*Q0\*U, the ADPCM algorithm 
will be in the operational state. The output test sequences, RL## and RH##, 
are made up of a decoder output signal of 15\ bits and a valid data indication 
signal (VI) as shown in Figure\ II\(hy3/G.722. While the RSS signal to 
the decoder is \*Q1\*U, the 
signal \*QVI\*U is set to \*Q1\*U and the decoder output set to \*Q0\*U, 
which indicates 
\*Qnon\(hyvalid data\*U of the output. When \*QVI\*U is \*Q0\*U, the output 
test sequence is valid. 
.PP
In order to establish the connection between the test sequence
generator/receiver and the encoder/decoder, four sub\(hyblocks, INFA, INFB, 
INFC, INFD in Figures\ II\(hy4/G.722 and\ II\(hy5/G.722 are provided. A 
detailed expansion 
of these sub\(hyblocks is described below using the same notations specified in
\(sc\ 6.2.
.RT
.ad r
.ad b
.RT
.sp 1P
.ce 1000
INFA
.sp 9p
.RT
.ce 0
.sp 1P
.LP
Input:
	X##
.LP
Outputs:
	XL, XH, RS
.LP
Function:
	Extract reset/synchronization signal and input signals to lower
and higher sub\(hyband ADPCM encoder.
.LP
RS = X## & 1
	|
	Extract RSS signal
.LP
	XL = S## >
> 1 
	|
	Lower sub\(hyband input signal
.LP
	XH = XL
	|
	Higher sub\(hyband input signal
.ad r
.ad b
.RT
.sp 1P
.ce 1000
INFB
.sp 9p
.RT
.ce 0
.sp 1P
.LP
Inputs:
	IL, IH, RS
.LP
Outputs:
	I##
.LP
Function:
	Create an output test sequence by combining lower and higher
sub\(hyband ADPCM encoder output signals and the reset/synchronization signal.
[Formula Deleted]
.LP