Nortel Networks 553-3001-211 manual NTBK50 2.0 Mb PRI card Page 767

NTBK50 2.0 Mb PRI card Page 767 of 894

message format; eight are assigned to voice/data (64 Kbps), one to signaling (8 Kbps), and one is a data valid bit (8 Kbps).

The incoming serial bit stream is converted to 8-bit parallel bytes to be directed to padding control. The signaling bits are extracted and inserted by the A07 signaling interface circuitry. Timeslots 0 and 16 are currently unused for PCM.

Digital PAD

The software selects A-Law or µ-Law and one of 32 possible PAD values for each channel. These values are provided in a PROM through which the data is routed. The idle code for A-Law is 54H and for µ-Law is 7FH. The unequipped code is FFH for both A-Law and µ-Law.

As the idle code and unequipped code can be country dependent, the software instructs the NTBK50 to use different codes for each direction. The 32 digital pads available are illustrated in Table 245 on page 767. The values shown are attenuation levels (1.0dB is 1 dB of loss and –1.0 dB is 1 dB of gain.

Table 245

Digital Pad - values and offset allocations (Part 1 of 2)

	PAD SET 0			PAD SET 1
Offset		PAD	Offset		PAD
0		0.6 dB	0		0.0 dB
1		1.0 dB	1		-1.0 dB
2		2.0 dB	2		-2.0 dB
3		3.0 dB	3		-3.0 dB
4		4.0 dB	4		-4.0 dB
5		5.0 dB	5		-5.0 dB
6		6.1 dB	6		-6.0 dB
7		7.0 dB	7		-7.0 dB
8		8.0 dB	8		-8.0 dB

Circuit Card Description and Installation