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Telos Zephyr Xstream Two-Way Radio User Manual

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USER’S MANUAL

Section 13: Deep Tech Information and Troubleshooting 274



Letusnowcovereachstepofthetroubleshootingsequenceindetail.

Step1.Observethebehaviortofindtheapparentbug.Inotherwords,determinethebug's

symptoms.Rememberalwaysthatmanyproblemsaresubtleandexhibitthemselvesviaa

confusingsetofsymptoms.

Step2.Observecollateralbehaviortogainasmu

chinformationaspossibleabouttheproblem.

DoestheLCD'sproblemcorrelatetoanLEDflashing?Trytoavoidstudyingaproblemin

isolation,butatthesametimebewaryoftryingtofixtoomanyatthesametime.Nooneis

smartenoughtodealwithmultipl

eproblemsallatonce–unlesstheyareallmanifestationsof

somethingmorefundamental.

Understandthatifaproblemrelatestotelephonenetworkrouting,thatyourresultsmayvary

calltocall.Ifyoususpectthismaybethecase,youshouldmakerepeatedcalls(asmanyas15!)

andnotethesuccessrate.Youcanthe

nchangesomethingandretesttoseeifthesuccessrate

wasaffectedbyyourexperiment.Networkrelatedproblemswillfrequentlyvarybasedon

whichpartyplacesthecall,thelongdistancecarrier,andthebitrate;youcantryvaryingthese.

Step3.Roun

duptheusualsuspects.Atthesystemlevel,alwayssuspectthemenuset‐up,the

cables,thePhoneCompanylinesetup,thepunch‐blocks,etc.Atthecomponentlevel,many

computerproblemsstemfromthesamesources.Never,never,neverforgettocheckVcc!

Step4.Generateahypothesis.Beforechangi

ngthings,formulateahypothesisaboutthecause

oftheproblem.Youprobablydon'thavetheinformationtodothiswithoutgatheringmore

data.

Sometimesyouwillhavenocluewhattheproblemmightbe.Sometimes,whenthepangsof

desperationsetin,it'sworthwhiletotryanythingpracticallyatrandom.Youmi

ghtfindabad

plug,anunconnectedline,orsomethingunexpected.Lookaround,butbealwaysontheprowl

foraworkinghypothesis.

Step5.Generateanexperimenttotestthehypothesis.ChangetheISDNconnectiontoa

knowngoodline;callknowngoodphoneorhybridattheotherend;iflong‐distancedoesn’t

work,tryalo

calcall.

NOTE:Youshouldplanyourteststoeliminate50%ofthepossibleproblemsinonetest,if

possible.Justkeepcarefultracksoyouknowwhatyouhaveeliminated.

Step6.Fixtheproblem.

AFinalThought…

Constantlyapplysanitych

ecks.ManyyearsagotheFiresignTheaterputoutan

albumcalled"EverythingYouKnowisWrong".Usethatasyourguidingphilosophy

introubleshootingaZephyrXstream.Forexample,justbecauseyoucheckedthe

Telcolinelastnight,anditwasfine,doesnotmeanthatit'sOKno

w.

At3:00AMwhentheproblemsseemintractableandyouarereadytogiveup

engineering,rememberthatthesystemhasworkedandwillwork.Neverpanic–you

aresmarterthanitis.



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