TRAK MODEL 9100 MODULAR FREQUENCY/TIME SYSTEM
3-19
TM4400013
Rev
D
Set/Request position source
Average position is the default mode and should be used for most applications. This mode performs an average
of 10,000 2D or 3D position fixes. If the averaging is interrupted, the averaging resumes where it left off when
tracking is resumed. Once the averaging is complete, the GPS receiver automatically enters position hold mode
and the average position latitude, longitude and height is stored in NV memory. On subsequent power up a
mini-average is computed and if the mini-average passes a GPS receiver is placed in Position Hold mode with
the antenna position that was saved in NV memory. If the position source is changed to “N” or “U” during an
average, the averaging operation will be halted and reset. All averaging data will be erased and the GPS
satellite tracking will cease and reacquire. If the user changes the position source to “U”, the unit will enter this
mode on the next power-up and will not perform an average position operation.
User Position mode should only be used if an accurate antenna survey is known. If the GPS receiver is set to
User Position with a wrong position will cause degraded time accuracy and in some cases, the GPS will cease
satellite tracking. However, if the GPS is powered up in User Position a mini-site survey is performed. If the
mini-site survey fails, the GPS receiver is automatically placed in Average Position mode.
The Navigation mode should only be used on moving platforms. In this mode, the time accuracy is degraded.
Warning: Timing accuracy is degraded in Navigation mode or in User Position with the incorrect
position entered in the SLP command.
Request
mode:
Host
sends:
X.SPS<CR>
9100
replies:
X.SPS
m<CR><LF>
Where:
m - is an "N" if the receiver navigation solution is selected
m - is a "NA" if the computed average position is selected and the
average position computation is not complete
m - is a "A" if the computed average position is selected and the
average
position
computation
has
completed
m - is an "U" if the user entered position is selected
X is described on command summary page
Set
mode:
Host
sends:
X.SPS
m<CR>
Where:
m - is an "N" if use of the receiver navigation solution is desired
m - is a "A" if use of the computed average position is desired
m - is an "U" if use of the user entered position is desired
X is described on command summary page
9100
replies:
X.SPS
DONE<CR><LF>
