Telos Zephyr Xstream User Manual page 221

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COMPATIBILITY TIP!
When two channels are required for transmission (i.e. for Stereo, J-Stereo, and Mono 128) an
"inverse multiplex" (IMUX) scheme must be used to break the standard MPEG data stream
into two streams for transmission.
In Layer-2, the Zephyr Xstream uses the CCS CDQ (TM) IMUX protocol. Most Layer-2
codecs support this method, allowing for compatibility among different codec manufacturers.
The Telos IMUX used in AAC and AAC-LD is published on our web site to support
interoperability with other manufacturers implementing AAC and AAC-LD
L2 Mono 64
This encodes a single mono bitstream using the audio from the A input using the
MPEG Layer‐2 algorithm. Both 32 and 48 kHz sample rates are supported. This
bit stream is fed to both ISDN B channels so it can be used to feed identical
mono to two sites.
Offers 7.8 kHz audio frequency response if the transmission channel is 56 kbps.
It offers 9.8 kHz frequency response when the transmission channel is 64 kbps.
L2 Half 64
This is the only mode in the Zephyr Xstream that supports 24 kHz for the sample
rate. It is a mono mode. Other than the fact the 24 kHz sample rate is internally
(and invisibly) used, its operation is the same as the other Mono 64 modes.
Offers 8.6 kHz audio frequency response.
Receive:
Note that the easiest choice is to use the Auto selection. However, it can take longer to lock and
achieve output audio, than if the correct Receive mode is set.
The appropriate Receive mode will be determined by the encoding or Transmit mode used at
the far end. Section 10 (Applications Guide) includes charts detailing the correct Receive mode
to use with the different Transmit modes for various codecs.
Until the Auto system has determined the correct receive mode to
use, it will display (Search) for Receive mode on the default status
and CODEC status screen. Once the correct Receive has been
determined, that information will be displayed.
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IMPORTANT!
The settings of the Sample Rate and Bit Rate (see below) are important as well as the
Transmit and Receive settings. Note that these must be matched between the two units
before the AUTO Receive mode will be able to function.
Note that if a transmission mode requiring two channels is used, and only one channel is
dialed, the AUTO setting will not be able to find a match.
The bit rate will normally be changed automatically on incoming calls as this information is
conveyed by the ISDN network.
USER'S MANUAL
Section 11: THE WORKS – Detailed Menu Reference 209