NorthStar 961 Reference Manual page 351

961/962 Operations and Reference Manual, Rev. A
2. Press the CURSOR PAD left or right to select either ON or
OFF.
3. When done, press the ACCEPT key (or CANCEL to leave
the option unchanged).
Setting beacon frequency and baud rate
You can set the receiver to operate automatically or be
controlled manually.
Automatic tuning
Northstar's two-channel differential receiver enters automatic
differential mode as soon as corrections are received, and
doesn't require any further supervision for differential
operation, automatically tuning to the appropriate differential
frequency as you move from one differential coverage area to
another or as weather conditions change. First, it finds the
differential frequency and data transfer (baud) rate, then it
receives data fully automatically. The receiver constantly
evaluates available radio beacon signals for signal quality, and
selects only the best station. The receiver is prepared to switch
to another frequency automatically, as you travel, as
conditions require.
The 961/962 maintains automatic operation by using its two
independent receiver channels: Channel 1 tracks the best
available differential signal (the one with the lowest data error
rate) and sends the demodulated DGPS corrections to the 961/
962's GPS receiver. Channel 2 continuously scans the entire
differential frequency band (283.5 to 325 kHz), locating and
measuring received DGPS differential signals, which is then
stored as a DGPS differential directory in its battery-powered
memory.
If the signal that's received and monitored by Channel 1
degrades for any reason, such as bad weather between you
and the transmitter, the 961/962 tries to select a better
frequency from the differential directory it has compiled. This
feature enables it to switch to the best differential
signal—before affecting your GPS accuracy.
Chapter 14 - Service and Maintenance Functions
Page 14-7