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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 9: The V.35/X.21 Interface Option 156

TheseconfigurationswouldbesimilartousingDDSlines(seebelow),howeveritgivesthe

remainderoftheT1capacityforsomeotherpurposebetweenthetwositesinquestion.

t

DEEP TECH NOTE!

If you can afford a full T1 for your application, then you should be considering options that

do not require use of audio compression.

We recommend that option for STLs and other critical audio paths. Equipment is available

from a variety of vendors to allow uncompressed audio transmission over T1 circuits.

Zephyr Xstream's V.35 Single offers audio connectivity at an intermediate cost while

offering the high fidelity and robustness possible with MPEG at low compression ratios.

h

HOT TIP!

When ordering dedicated lines, such as DDS or T1, which will not be used for interstate

access, be sure to file an “Interstate Access Charge Exemption Form”. This should result in

significant savings in monthly fees.

Digital Data System (DDS)

ADDScircuitisadedicated,“nailed‐up”connectionbetweentwospecificlocations.Also

referredtoasdedicateddigitalservice.Technically,DDSserviceincludesratesupto56kbps.

Twosuchlinescanbeusedtoprovidestereoaudio.However,“dedicateddigitallines”arealso

availableathigherratessuchas64kbps.InEuropewe

'veevenseen128kbpsdedicatedlines.

UseofthisservicerequiresanappropriateCSU/DSU(ChannelServiceUnit/DataServiceUnit)at

eachendtointerconnectthelinewiththeZephyrXstream.OnepopularmodelistheAdtran

DSU56/64(Adtranpart#1200062L1)seewww.adtran.com

oryourAdtrandealer.

Other Possibilities

Anytransmissionchannelthatcanconveysynchronousdigitalsignalsinrealtime,maybeused

withtheZephyrXstream.PossibilitiesincludeT1,satellitelinks(IncludingtheportableInmarsat

terminals),spread‐spectrumRFtransmissionsystems,andATM.Theerrorrateshouldbe1e‐7

orless.Th

ecommunicationsequipmentmustsupportV.35orX.21.Anadaptorcablemaybe

requiredifthisequipmentdoesnotsupporttheusualconnector.TheXstreamexpectsthis

communicationsequipmenttoprovideaclockontheX.21orV.35connector.

Whenconsideringatechnology(suchasATM)itisessentialthatyourservicehasa“Committed

InformationRate”e

qualtotherequiredbitrate(i.e.56,64,112,128,256,or384kbps)andthat

itisa“ConstantBitRate”service.

.

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