User`s manual

EAGLE - ANNEX A.4. ANCILLARY DATA CHANNEL 65
A.4. ANCILLARY DATA CHANNEL
AEQ audio codecs have the capability of inserting a configurable, two-way, transparent end-to-
end auxiliary data channel in communications that have been established.
The link used by audio codecs on which the data channel is defined may be ISDN (64 Kbps or
128 Kbps), or using the V35/X21 interface (64 Kbps, 128 Kbps or 256 Kbps in some models)
connected to modems or external terminal adapters.
AEQ’s first generations of audio codecs (ACD3001, ACD5001, MPAC-02, TLE-02D) already
had this feature incorporated, but they only had a limited number of binary speeds that could be
assigned to that data channel (300, 1200, 4800, 9600 bauds).
The new generation of audio codecs (EAGLE, COURSE, SWING) improves and expands the
use and configuration capabilities of the data channel.
The new AEQ audio codecs use the capacity of the channel available for the transmission of
audio circuits, and are also able to model a transparent data channel, as represented in the
following diagram:
A – Represents the channel capacity or bandwidth available in the link. It may be 64 kbps, 128
kbps or 256 kbps.
B – Represents the effective bit rate of the data channel or the part of the bandwidth available in
the link used for inserting the data channel (configurable by the user).
C – Represents the bit rate available for transmitting audio. The audio codec transmits the
audio, compressing it according to the available bit rate.
 If data channels with reduced binary rates are used, there is no perceptible degradation
of quality in the audio signal transmitted.