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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Appendix 10 – Glossary 352

FourWireAcircuitpathusingseparatepairsforsendandreceive.Thistermisalsousedwhen

referringtodigitalchannelsthatinherentlyhavediscretesendandreceivepaths,regardlessof

thenumberofpairs(orothermedia)used.SeealsoHybrid.

FrameAunitofdatawhichisdefin

edbythespecificcommunicationsprotocolused.SeeLine

Format,T1.

GlareOnaPOTSlineanincomingcallissignaledbyperiodicallyapplyinganACringvoltageto

theline.Sincethereisasemirandomperiodbeforethering,andpausesbetweenrings,itis

possibletoseizeali

newhichis“abouttoring”(andansweracall)whenattemptingtoplacean

outgoingcall.Whenthisscenariohappensitiscalledglare.GlareismuchlesslikelyifGround

StartorISDNtrunksareused.SeealsoGroundStartTrunk.

GR‐303SeeSLC‐96

Gradeofserv

iceThisissimplytheratioofcallsblockedtototalcallsinadecimalform.

Therefore,agradeofserviceofP.08wouldrepresent8%blocking.Telephonetariffsregulate

theacceptableaveragegradeofservicewhichmustbeprovidedonpublicnetworks.Seealso

Blocking.

GroundStartTrunkAty

peoftelephonetrunkwheretherequesttomakeanoutgoingcall(i.e.

requestfordialtone)ismadebybrieflygroundingtheTipconductor.ManyPBXsystemuse

groundstarttrunksastheyarelesspronetoglarethanLoopstarttrunks.Groundstartlinesare

sometimesusedwithe

quipmentdesignedforLoopStartlines.Thismayormaynotwork‐

generallyitservestopreventoutgoingcallswhileincomingcallsworknormally.Telcosmaycall

these“groundstartlines”.SeeLoopStartTrunk.SeealsoGlare.

HDB3‐HighDensityBipolar3AnE1linecodingmethod.Thisisthemoremod

ernlinecoding

methodofthetwocommonlyavailable.SeeLineCoding,T1.SeealsoAMIandB8ZS

HuntgroupAgroupoftelephonechannelsconfiguredsothatifthefirstisbusy(engaged)the

callgoestothenextchannel,ifthatchannelisbusyitgoestothenextchannel,etc.Huntgro

ups

mayhuntfromthehighesttothelowest,thelowesttothehighest,oronsomeotherarbitrary

pattern.Buttheorderofhuntingwillusuallybefixed,beginningwithonechannelandworking

through(“hunting”)untilanunusedchannelisfound.Thetermmayhaveoriginatedba

ckinthe

oldmanualswitchboarddayswhentheoperatorliterallyhuntedforanunusedjacktopluga

cordinto.Thisarrangementisverycommoninbusinessscenarioswhereasingleincoming

number(theListedDirectoryNumber)isgiventothepublic,butmultipleincomingchannelsare

supported.Se

ealsoLDN.

HybridAdevicewhichconvertsfromatwo‐wiresignalsuchasPOTSlines(ora2‐wire

intercom)toafour‐wiresystem(separatesendandreceivepaths)suchasusedinthepro‐audio

world.Whilethistaskistheoreticallyquitesimple,thefactthei

mpedanceofmostphonelines

varieswidelyacrossfrequencycomplicatesmatters.TheTelos10telephonesystemwasthefirst

practicalDSPbasedhybridandappliedthethenbrand‐newtechnologytothisproblem.

IEC‐1)InterExchangeCarrier“LongDistance”carrier.HandlesInterlataandinterstatecalls.

AlsoreferredtoasIXC.2)In

ternationalElectrotechnicalCommitteeAEuropeanstandards

bodybestknownforthepowerplugnowusedthroughouttheworldforACpowercordsforuse

onofficeequipmentandcomputers.

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