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19-2 Server Cards
Model No.
Running Head
ADPCM Card Descriptions ADPCM Card
The rate of a DS0 time slot is 64 kbps, so the sum of the compression rates for engines 1 and
2 must equal 64 kbps. For example, if you assign a 32 kbps circuit to engine 1, engine 2 can
only accept another 32 kbps circuit. Also, a 40 kbps circuit can only be paired with a 24 kbps
circuit, and vice versa.
The ADPCM compression engines always work in pairs. Engines 1 and 2, 3 and 4, 5 and 6,
and 7 and 8 are paired. Each member of the pair must have the same ADPCM WAN port and
ADPCM time slot. Also, both members of the compression engine pair must be active
before either port will operate.
The ADPCM 64 Card can transport low-speed asynchronous data transmission (19.2 kbps or
less) from an SRU user card port that will occupy a 24 kbps engine. Each data circuit must be
paired with a 40 kbps voice channel. The card can also compress B-channel voice traffic from
a BRI card without restricting compression rates.
The Integrated Access System can have up to three ADPCM 64 Cards (two normal cards and
an identical redundant card).
The ADPCM 64 Card supports Transition Signaling as defined in ANSI T1.302-1989, with
the exception of the Alarm bits. ANSI T1.302 specifies signaling at the 32 bps compression
rate. The card uses this scheme for 24 bps and 40 bps, even though those rates are not included
in the standard. Table 19-1 summarizes the signals supported by each transcoder data rate.
Your DS0 time slot configuration must adhere to these specifications.
Table 19-1. ADPCM Compression Rates
* MOS = Mean Opinion Score based on subjective evaluation
19.2.1.1 Card Jumper/Switch Settings
The ADPCM 64 Card does not have any jumpers or switches on its motherboard.
19.2.1.2 Installing the ADPCM Card
Insert the ADPCM card into one of the server card chassis slots (P1 to P3). The system can
accommodate up to three server cards.
Transcoder
Rate
Voice Quality
(MOS)*
Modem Data DTMF FAX
24 kbps 3.6-3.8 Range no nounder
study
no
32 kbps 4.0-4.3 Range up to 4.8 kbps
V.32 9.6 kbps
OK Group II
40 kbps 4.0-4.3 Range up to 12 kbps
V.32 14.4
(no/yes/tbd)
OK Group III