User's Manual

RF Integration
Rev 1.8.1 May.08 Proprietary and Confidential 19
In the event of a discrepancy in values between this guide and the Product Specification Document (PSD), the PSD takes precedence.
Device-generated RF
Note: The module can cause
interference with other devices
such as hearing aids and on-
board speakers.
Wireless devices such as the
Mini Card transmit in bursts
(pulse transients) for set
durations (RF burst frequencies).
Hearing aids and speakers
convert these burst frequencies
into audible frequencies,
resulting in audible noise.
AllelectroniccomputingdevicesgenerateRFinterferencethat
cannegativelyaffectthereceivesensitivityofthemodule.
Theproximityofhostelectronicstotheantennainwireless
devicescancontributetodecreasedRxperformance.Compo
‐
nentsthataremostlikelytocausethisinclude:
• Microprocessorandmemory
• Displaypanelanddisplaydrivers
• Switching‐modepowersupplies
Theseandotherhigh‐speeddevice s(inparticular,the
processor)candecreaseRxperformancebecausetheyrunat
frequenciesoftensofMHz.Therapidriseandfallofthese
clocksignalsgenerateshigher‐orderharmonicsthatoftenfall
withintheoperatingfrequencybandofthemodule,affecting
themodule’sreceive
sensitivity.
Example
Onasub‐systemrunningat40MHz,the22ndharmonicfalls
at880MHz,whichiswithinthecellularreceivefrequency
band.
Note: In practice, there are usually numerous interfering frequencies
and harmonics. The net effect can be a series of desensitized receive
channels.
Note: It is important to
investigate sources of localized
interference early in the design
cycle.