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• The range of a DGPS beacon transmitter (see the
accompanying Beacon Reference Card) is typically
a few hundred miles, or less. Beyond this range,
the beacon signal cannot be reliably received.
• Interference to the beacon signal can be experi-
enced during periods of thunderstorm activity.
Other sources of static interference, such as
alternator motors and ignition systems, can also
affect signal reception. Alternator/ignition
interference can be minimized through proper
shielding of the ship’s wiring, by using an EMI/RFI
filter, and by mounting the beacon receiver’s
antenna away from these sources of interference.
Sources of Error
Using a DGPS Beacon Receiver with your existing
GPS Receiver can provide substantial improvements in
accuracy; however, there may be occasions when the best
possible accuracy will not occur. Several factors, which
you should be aware of, can contribute to a degraded
DGPS accuracy.
Loss of DGPS Beacon Signal—Obviously, the lack
of DGPS correction data will result in reduced accuracy.
Accuracy will be the same as if no beacon receiver was
being used. Several conditions can cause a loss of the
beacon signal:
• Poor data or ground connections between receiver
and the GPS receiver can result in intermittent or
nonexistent correction data.
After entering the beacon’s
operating frequency, set the
bit rate as indicated on the
Beacon Reference Card.
Beacon information is also
available from the other
sources listed on the card.
The Beacon Log Page lists the
last five beacon frequencies
used. As an alternative to
retyping the frequency and bit
rate each time, you may select
a beacon from this list.
Sources of
Error
Individual stations vary and the user may wish to
verify the suitability of the signal for the intended
application with the station operator. The station power is
normally set to provide a usable range somewhere near
300 km. Other factors such as local interference,
lightning, time of day and season, and if the path to the
station is over ground or water, and antenna selection or
installation affect the usable signal range.
Reference