Garmin GPS III Plus - Manual (Page 95)

REFERENCE
Press MENU to restart the
scan. 'View Beacon Log'
allows you to view the last 5
valid frequencies. To use a fre-
quency from the list, highlight
it and press ENTER/MARK.
Setup Menu: DGPS
The III+ can automatically
tune the GARMIN GBR 21 or
GBR 23.
To have the unit automatically scan for a frequency:
1. With the unit set to ‘Garmin DGPS’ or ‘RTCM/NMEA’, use the ARROW KEYPAD to highlight
the 'Tuning Mode' field and press ENTER/MARK.
2. Highlight ‘Scan’ and press ENTER/MARK. The numbers in the 'Beacon' field will change
as the unit scans from 284 kHz to 325 kHz, 200 bit rate, then 100, at 6-second intervals.
To restart the scan:
1. Press MENU, highlight ‘Restart Scan’ and press ENTER/MARK.
To manually enter a frequency and bit rate:
1. With the unit set to ‘Garmin DGPS’ or ‘RTCM/NMEA’, use the ARROW KEYPAD to highlight
the 'Beacon' field and press ENTER/MARK.
2. Highlight ‘User’ and press ENTER/MARK.
3. Highlight the 'Beacon' or 'Bit Rate' field, press ENTER/MARK, then enter a frequency or
bit rate and press ENTER/MARK when done.
The “Status” field will show one of the following:
• Tuning— unit is attempting to tune to the specified frequency and bit rate.
• Scanning— unit is automatically scanning through the frequencies and bit rates.
• Receiving— unit is receiving DGPS signal and ready for operation.
• Check Wiring— unit is not making connection with DGPS receiver.
When the unit is receiving a DGPS signal, the “SNR” (Signal to Noise Ratio) and “Distance”
fields will show data. The SNR range is 0dB to 30dB, with 30 being the best. The Distance may or
may not show data, depending upon the signal being broadcast from the DGPS site.
The DGPS beacon transmitters are operated by the U.S. Coast Guard (or similar government
agency in other countries), which is responsible for their accuracy and maintenance. For DGPS
transmitter problems or to find the most updated list of frequencies & coverage areas, contact your
local USCG, or see their web site at http://www.navcen.uscg.mil/.
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