ADPCM Card | Introduction |
Chapter 1
ADPCM Card
1.1Introduction
This chapter provides installation, configuration, and troubleshooting information for the Adaptive Differential
1.2ADPCM Card Descriptions
1.2.1ADPCM 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
5.3.1and 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
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.
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