User's Manual
Table Of Contents
CDMA and GSM / UMTS Mini Card Hardware Integration Guide
18 Proprietary and Confidential 2130114
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
Disabling the diversity antenna
• MC57xx—Ifyourhostdeviceisnotdesignedtousethe
MC57xxmodule’sdiversityantenna,terminatetheinterfac e
witha50
Ωload.
• MC8780/MC8781/MC8785V/MC8790—UsetheAT
command
!RXDEN=0todisablereceivediversityor
!RXDEN=1toenablereceivediversity.
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 lsour cesofinterferencecanaffecttheRFperformance
ofthemodule(RF
desense).Commonsourcesincludepower
supplynoiseanddevice‐generatedRF.
RFdesensecanbeaddressedthroughacombinationof
mitigationtechniquesandradiatedsensitivitymeasurement.
Power supply noise
NoiseinthepowersupplycanleadtonoiseintheRFsignal.
Note: Values in this guide are
taken from the appropriate
product specification documents
(PSDs) (listed in
Related
documents
, page 8) — in the
case of a discrepancy between
this document and the relevant
PSD, use the value listed in the
PSD.
Thepowersupplyripplelimitforthemoduleisnomorethan
200
mVp‐p1Hzto100kHz.Thislimitincludesvoltageripple
duetotransmitterburstactivity.
Interference from other wireless devices
Wirelessdevicesoperatinginsidethehostdevicecancause
interferencethataffectsthemodule.
Todeterminethemostsuitablelocationsforantennasonyour
hostdevice,evaluateeachwirelessdevice’sradiosystem,
consideringthefollowing:
• Anyharmonics,sub‐harmonics,orcross‐productsofsignals
generatedbywirelessdevicesthatfallinthemodule’sRx
rangemaycausespuriousresponse,resultingindecreased
Rxperformance.
• TheTxpowerandcorrespondingbroadbandnoiseofother
wirelessdevicesmayoverloadorincreasethenoisefloorof
themodule’sreceiver,resultinginRxdesense.
Theseverityofthisinterferencedependsontheclosenessof
theotherantennastothemodule’santenna.Todetermine
suitablelocationsforeachwirelessdevice’santenna,
thoroughlyevaluateyourhostdevice’sdesign.