ISO-CMOS

MT8979

4-173

Table 6. Channel Associated Signalling: Data Format for CSTi1 Channels 1 to 15

Table 7. Frame Alignment Signal: Data Format for CSTi1 Channel 16

BIT

NAME

DESCRIPTION

7,

6,

5

& 4

A(N),

B(N),

C(N)

& D(N)

Transmit Signalling Bits for Channel N: These bits are transmitted on the CEPT 2048

kbit/s link in bit positions 1 to 4 of timeslot 16 in frame N, and are the A, B, C and D

signalling bits associated with telephone channel N. The value of N lies in the range 1 to

15 and refers to the channel on the CSTi1 channel from which the bits are sourced, the

telephone channel with which the bits are associated and the frame on the CEPT link on

which the bits are transmitted. For example, the bits input on the CSTi1 pin on channel 3

are associated with telephone channel 3, which is timeslot 3 of the CEPT link, and are

transmitted on bits positions 1 to 4 of timeslot 16 in frame 3 of each multiframe on the

CEPT link . If bits B, C or D are not used they should be given the values ‘1, 0‘ and ‘1‘

respectively. The combination ‘0000‘ for ABCD bits should not be used for telephone

channels 1 to 15 as this would interfere with multiframe alignment.

3,

2,

1

& 0

A(N+15),

B(N+15),

C(N+15)

& D(N+15)

Transmit Signalling Bits for Channel N+15: These bits are transmitted on the CEPT

2048 kbit/s link in bit positions 5 to 8 of timeslot 16 in frame N, and are the A, B, C and D

signalling bits associated with telephone channel N+15. The value of N lies in the range 1

to 15 and refers to both the channel on the CSTi1 stream where the bits are supplied and

the frame on the CEPT link on which the bits are transmitted, and indirectly indicates the

telephone channel with which the bits are are associated. For example, the bits input on

the CSTi1 pin on channel 3 are associated with telephone channel 18, which is timeslot 19

of the CEPT link, and are transmitted in bits positions 5 to 8 of timeslot 16 in frame 3 of

each multiframe on the CEPT link .

BIT

NAME

DESCRIPTION

7

IU0

International Use 0: When CRC is disabled, this bit is transmitted on the CEPT 2048

kbit/s link in bit position 1 of timeslot 0 of frame-alignment frames . It is reserved for

international use and should be kept at ‘1’ when not used. If CRC is enabled, this bit is not

used.

6-0

FAF2-8

Transmit Frame Alignment Frame Bits 2 to 8: These bits are transmitted on the CEPT

2048 kbit/s link in bit positions 2 to 8 of timeslot 0 of frame-alignment frames. These bits

form the frame alignment signal and should be set to ‘0011011‘.