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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 11: THE WORKS – Detailed Menu Reference 209

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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trans

mission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mon

o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lo

ck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code

cs.

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.

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