Zhone Technologies 800 - Manual (Page 13)

Server Cards IMACS System Release 5.1.6 1-1
ADPCM Card Introduction
Chapter 1
ADPCM Card
1.1 Introduction
This chapter provides installation, configuration, and troubleshooting information for the
Adaptive Differential Pulse-Code Modulation (ADPCM) Card. This card is labeled as the
ADPCM 64 card on its faceplate ejector.
1.2 ADPCM Card Descriptions
1.2.1 ADPCM 64 Card Description (887160)
The ADPCM 64 Card has 32 pairs of voice compression engines that accept inputs directly
from voice, SRU, and/or BRI data cards in the same system unit, or voice traffic from WAN
links through the system. This card requires a matching card at the other end to decompress
the voice channels to normal 64 kbps operation.
With previous versions of the IMACS, signaling conversion was only supported for voice
ports when routed over the WAN and not when routed through an ADPCM card. With version
5.3.1 and higher of the IMACS host CPU firmware, signaling conversion is also supported for
voice channels routed through the ADPCM. The conversion table is the same as for passing
the channel through a WAN, and available from the interface card’s main screen by selecting
“taBs”. Signaling conversion is enabled / disabled using the same SIG CONV parameter as
used for conversion over a WAN. This field is found on Figure 1-1, the E & M Voice Card’s
main screen.
Each pair of compression engines uses one 64 kbps DS0 time slot for two compressed voice
channels. Each engine can compress 64 kbps voice traffic into 24 kbps, 32 kbps, or 40 kbps,
depending on the voice signal quality required.
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.