Simrad CE34 ChartSounder Manual page 92

Chapter 6-10 CE34/44/54 Miscellaneous menu
Status - can either be:
LOCKED = locked on a beacon and receiving differential data.
NOT LOCKED = not locked on a becon and receiving no differen-
tial data.
NOT INSTALLED = there is no built-in DGPS module in unit.
NOT IN USE = external DGPS receiver applied.
Beacon is monitored - YES or NO.
If YES it should be safe to rely on the received differential data,
because the beacon station's performance is under observation.
If NO, then you have to use the received differential data with cau-
tion, as there is no guarantee it is not faulty.
Frequency - the frequency of the beacon station can be set manually
if known. However, when left in AUTO the navigator will always
search for the nearest station with a good signal strength.
Bit rate - indicates bits per second, and can be set manually to 25,
50, 100 or 200 bps.
Signal strength - a good signal strength is 20 and up.
Signal to noise ratio (SNR) - should be 8dB and up.
Message - type 16 message will be displayed when received from
the DGPS system. The contents of this message could be something
to do with the performance of the system. Temporarily out of service
etc.