74 G12 OEM Board & Sensor Reference Manual
The G12 does not calculate ionospheric parameters on its own. The ionospheric data, listed in Table
4.20, are obtained from subframe 4 of the GPS navigation message.
LPS: Third-order Loop Tracking Parameters
$PASHS,LPS,d1,d2,d3
This command allows you to set third-order loop tracking parameters to optimize
loop tracking performance for a specific application, where d1 is the ratio of the
carrier loop, d2 is the carrier loop parameter, and d3 is the code loop parameter.
The carrier and code loop parameters are set independently. The G12 uses default
loop tracking values until new parameters are set through this command. Loop
tracking parameters set through this command are saved in battery-backed
memory and used until new settings are selected, battery-backed memory is
cleared, or the RST command is issued to the receiver.
float 4 b
3
ionospheric parameter (sec. per semicircle)
double 8 A
0
Constant term of GPS/UTC polynomial
double 8 A
1
Constant term of GPS/UTC polynomial
unsigned long 4 t
ot
Reference time
short 2 W
nt
reference week
short 2 Dt
LS
Delta UTC-GPS time at reference time
short 2 WN
LSF
Week of leap second correction
short 2 DN day of leap second correction
short 2 Dt
LSF
Delta time between GPS and UTC
short 2 WN Current GPS week number
unsigned long 4 tow Current time of week
short 2 bulwn Current GPS week number when message was
read
unsigned long 4 bultow Time of week when message was read
short 2 Checksum (word)
Total characters = 76 bytes
Table 4.20. $PASHR,ION Format (Continued)
Type Size Contents
G12RevD.book Page 74 Tuesday, April 2, 2002 4:33 PM
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