Simrad CE33 ChartSounder Manual page 46

Chapter 4-2 CE33 Position menu
Status indicator for reception of satellites:
a (A)= good, b (B)= acceptable, c (C)= fair, or *= no update - see
also "Status indicator and accuracy" below.
With built-in or connected DGPS receiver:
dGPS= differential data received.
DGPS= differential data received and used for corrections.
SDGPS= satellite differential data received and used for corrections.
Status indicator and accuracy
Small letters (a,b,c,) indicate that SA is active, and the position
accuracy is expected to be better than 100 meters in 95% of the time.
Capital letters indicate that SA is OFF, and the position accuracy is
then expected to be 15 meters or better in 95% of the time.
dGPS indicates that differential data is received, either via built-in
differential receiver or from external receiver.
DGPS or SDGPS indicates that the position is corrected by the dif-
ferential data. The accuracy will typically be 1-3 meters for DGPS
and 2-6 meters for SDGPS.
In order to utilize the high accuracy of the GPS system, it is neces-
sary to align the lat/long calculations to the paper charts you are
using. Refer to Position setup display on next page.
When using C-MAP electronic charts, the datum will be aligned
automatically.