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4-14 Reference Guide
Model No.
Running Head
ADPCM Voice Compression Server (8000-ADPCM) Applications
In G.703 Co-Directional mode, the Transmit Data and Receive Data leads are supported. The
clock information and the data make up a composite signal and the clock must be derived from
the data stream. In G.703 Contra-Directional mode, the port provides separate Transmit and
Receive Clocks to the attached device. Both clocks are 64 Kbps clocks with embedded 8 kHz
Bipolar Violations (BPVs) to mark the byte boundaries.
Software-initiated diagnostics supported on the DS0-DP/G.703 card include the setting of
local loop backs towards either the network or the attached DTE equipment. In addition, a
remote loop back function allows the DS0-DP/G.703 card to generate four DDS-compatible
latching loop back codes for the far-end OCU, CSU, DSU or DS0-DP equipment respectively.
A time-out option authorizes the DS0-DP/G.703 port to automatically release the loop back
after ten minutes.
4.4 ADPCM Voice Compression Server (8000-ADPCM)
The 8000-ADPCM (Adaptive Differential Pulse Code Modulation) server cards are designed
to compress digital and analog voice traffic for transmission over wide area network links. The
level of compression for an individual channel is software configurable at 24Kbps, 32Kbps or
40Kbps. A single ADPCM card is capable of compressing 64 channels of voice
simultaneously. The ADPCM card is a RoHS-compliant card, and utilizes different
technology to accomplish the task for the ADPCM function. Both cards are identical in form
and function, and can be used interchangeably.
Since the ADPCM card is a server card, these 64 channels can be originated from a variety of
interfaces, including FXS, FXO, E&M, SRU, BRI, and T1/E1. Up to two ADPCM server
cards can be supported per Integrated Access System for a total of 128 compressed voice
channels. A third ADPCM server card can be utilized for 1:N redundancy.
The sum of the compression rates for the engine pair must equal 64Kbps. A 32Kbps circuit
can only be paired with a 32Kbps circuit. A 40Kbps circuit can only be paired with a 24Kbps
circuit and vice-versa. The ADPCM server card can also pair a low speed asynchronous data
transmission (19.2Kbps or less) from an SRU port with a 40kbps engine. This data path will
occupy a 24Kbps engine. Group II FAX is supported in 32Kbps channels and Group III FAX
is supported in 40Kbps channels.
Modem support up to 4.8Kbps, and V.32bis to 9.6Kbps is supported in 32Kbps channels.
Modem speeds up to 12Kbps, and V.32bis speeds up to 14.4Kbps is supported in 40Kbps
channels. Modem data is not supported in 24Kbps channels.
The ADPCM card supports Transition Signaling as defined by ANSI T1.302-1989 with the
exception of the Alarm bits. ANSI T1.302 specifies signaling at the 32Kbps compression rate.
The ADPCM card uses this scheme for 24Kbps and 40Kbps although it is not included in the
standard.
The ADPCM card can be used in a variety of applications to reduce the number of
transmission lines for efficient transport of voice traffic. It can be used in: