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DGPS Interface (continued)
To enter a DGPS beacon frequency:
1. Highlight the ‘freq’ field and press
F
.
2. Enter the desired frequency and press
F
.
3. Highlight the ‘rate’ field and press
F
.
4. Use
U
and
D
to select the desired transmission
rate.
5. Press the
F
key to confirm your entry.
When the GPS 120XL is receiving DGPS correc-
tions from the GBR-21, the ‘beacon receiver’ section of
the I/O setup page will display the beacon frequency
and signal strength, as well as the distance from the
transmitter to the beacon receiver. At the bottom of the
beacon receiver field, a status message will keep you
informed of DGPS activity:
• A ‘Tuning’ message will be displayed while a bea-
con signal is being tuned.
• Once the beacon signal has been tuned, a
‘Receiving’ message will be displayed.
• If a beacon signal is tuned and no corrections are
being received, a ‘No Data’ message will be dis-
played.
• If a beacon signal cannot be tuned, a ‘No Status’
message will be displayed.
The GPS 120XL will also display one of three alert
messages concerning DGPS operation through the mes-
sage page:
No DGPS Position— not enough data is available
to compute a DGPS position.
No RTCM Input— the beacon receiver is not
properly connected or the baud rates do not
match.
RTCM Input Failed— DGPS data was being
received but has been lost.
45
Once a RTCM option is
selected, you must manual-
ly tune the beacon receiver
from the frequency field.
REFERENCE
DGPS Interface
& System Setup
Alert messages will signal
any problems with DGPS
operation.
120XL Man RevB 7/10/98 10:55 AM Page 45