Operation Manual

SiteNet 450 Operation Manual 47
Using Radios with GPS B
B.2 Selecting Communications Radios
If you do not already have communications radios, and are thinking of
buying them to supplement your survey activities, there are a number
of factors to keep in mind before purchasing:
• Some frequencies can cause interruptions of GPS tracking.
• Some communications equipment creates spurious signals not
related to their frequency that can interfere with satellite
tracking.
• Powerful communications transmitters can create such a strong
radio signal that the GPS signal cannot be identified.
Most communication transmitters emit overtones of their assigned
frequency. If these overtones line up with the GPS frequency, they can
filter into the GPS equipment and interfere with the satellite tracking.
Some communication transmitters emit more of these overtones than
others. But the number of overtones can be difficult to determine and
it is not the most important factor when considering this nuisance
parameter. To avoid being effected by transmitter overtones, avoid
those frequencies that lie within the GPS frequency range.
SN450.book Page 47 Friday, October 5, 2001 5:01 PM