User's Manual

RF Integration
Rev 1.12.4 Oct.09 Proprietary and Confidential 23
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
• Antennacablesshouldberouted,ifpossible,awa yfrom
noisesources(switchingpowersupplies,LCDassemblies,
etc.).Ifthecablesarenearthenoisesources,thenoisemay
becoupledintotheRFcableandintotheantenna.
Disabling the diversity antenna
• MC57xx—Ifyourhostdeviceisnotdesignedtousethe
MC57xxmodule’sdiversityantenna,terminatetheinterfac e
witha50
Ωload.
• MC8780/MC8781/MC8790/MC8790V /MC8791V/
MC8792V/MC8795V/MC8700—UsetheATcommand
!RXDEN=0todisablereceivediversityor !RXDEN=1to
enablereceivediversity.
Interference and sensitivity
Note: These modules are based
on ZIF (Zero Intermediate
Frequency) technologies; when
performing EMC
(Electromagnetic Compatibility)
tests, there are no IF
(Intermediate Frequency)
components from the module to
consider.
Severa lsourcesofinterferencecanaffecttheRFperformance
ofthemodule(RFdesense).Commonsourcesincludepower
supplynoiseanddevice‐generatedRF.
RFdesensecanbeaddressedthroughacombinationof
mitigationtechniquesandradiatedsensitivitymeasurement.
Power supply noise
NoiseinthepowersupplycanleadtonoiseintheRFsignal.
Note: Values in this guide are
taken from the appropriate
product specification documents
(PSDs) (listed in
Related
documents , page 11) — in the
case of a discrepancy between
this document and the relevant
PSD, use the value listed in the
PSD.
Thepowersupplyripplelimitforthemoduleisnomorethan
200mVp‐p1Hzto100kHz.Thislimitincludesvoltageripple
duetotransmitterburstactivity.
Interference from other wireless devices
Wirelessdevicesoperatinginsidethehostdevicecancause
interferencethataffectsthemodule.
Todeterminethemostsuitablelocationsforantennasonyour
hostdevice,evaluateeachwirelessdevice’sradiosystem,
consideringthefollowing:
• Anyharmonics,sub‐harmonics,orcross‐productsofsignals
generatedbywirelessdevicesthatfallinthemodule’sRx
rangemaycausespuriousresponse,resultingindecreased
Rxperformance.
• TheTxpowerandcorrespondingbroadbandnoiseofother
wirelessdevicesmayoverloadorincreasethenoisefloorof
themodule’sreceiver,resultinginRxdesense.