User's Manual

Boomer II User Manual & Integrator’s Guide __________________________________________________ Desense
BM210012WT27 73 Wavenet Technology
Desense
When you integrate wireless data radio technology into computing and
telemetry devices, you must consider hardware issues related to RF
emissions. For example, you must address the technical aspects of
enabling a wireless RF device as an integrated peripheral in a host
device, such as RF performance and inter-operability with the host.
Specifically, this appendix describes the following:
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The term “desense”
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Preferred test procedures
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Acceptable levels of electromagnetic interference (EMI)
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Approaches to solving desense problems
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Pertinent radio and antenna issues
Note: This section considers, but does not attempt to resolve these
technical issues for a particular platform. That is beyond the scope of
this guide.
Receiver desensitisation occurs when an unwanted signal is present at
the radio receive frequency. The signal is usually the result of harmonic
energy emanating from a high frequency, non sinusoidal source. This
noise desensitises or lowers the sensitivity threshold of the receiver.
The radio cannot differentiate between wanted and unwanted signals.
In frequency modulated systems, the radio receiver can capture the
strongest signal present. If wanted and unwanted signals are present,
and there is not a significant difference in level, the unwanted signal
can overtake the receiver, effectively blocking the wanted signal see
the following diagram.
Wanted and Unwanted Signal Levels
Wanted Signal Level
Unwanted Signal Level
Frequency
Fc = Radio Receiver Channel Frequency
Fc
Amplitude