User's Manual

Table Of Contents

APPENDIX F – Guide to Desense ______________________________ Boomer II User Manual & Integrator’s Guide

Appendix F – Guide to 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/terminal, such as RF performance and inter-operability with the

host/terminal.

Specifically, this sections describes the following:

 The term “desense”

 Preferred test procedures

 Acceptable levels of electromagnetic interference (EMI)

 Approaches to solving desense problems

 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

Amplitude