Novatel OM-20000041 用户手册

C 

Commands Summary

98

 MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual Rev 1

Invoking this command will result in the GPSCard position being held fixed. A computation will be done to solve
local clock offset, pseudorange, and pseudorange differential corrections. This mode of operation can be used for
time transfer applications where the position is fixed and accurate 

GPS

 time output is required (see the 

 and

 logs, Appendix D for time data).

As well, this command must be properly initialized before the GPSCard can operate as a 

GPS

 pseudorange reference

station. Once initialized, the receiver will compute pseudorange differential corrections for each satellite being
tracked. The computed differential corrections can then be output to remote stations by utilizing any of the
following GPSCard differential corrections data log formats: 

RTCM

, 

RTCMA

, 

RTCMB

, 

CMR

, 

RTCA

, 

RTCAA

 or 

RTCAB

.

The reference station servicing 

RT

-

20

 remote receivers must log 

RTCM3

 and 

RTCM59

(

N

) pseudorange and carrier

phase observation data in order for the 

RT

-

20

 remote receiver to compute double difference carrier phase solutions.

The values entered into the 

FIX

 

POSITION

 command should reflect the precise position of the reference station

antenna phase centre. Any errors in the 

FIX

 

POSITION

 coordinates will directly bias the pseudorange corrections

calculated by the reference receiver.

The GPSCard performs all internal computations based on 

WGS84

 and the datum command is defaulted as such.

The datum in which you choose to operate (by changing the 

DATUM

 command) will internally be converted to and

from 

WGS84.

 Therefore, all differential corrections are based on 

WGS84

, regardless of your operating datum.

The GPSCard will begin logging differential data while tracking as few as three healthy satellites. See Appendix A
for further discussions on differential positioning.

The 

FIX

 

POSITION

 command will override any previous 

FIX

 

HEIGHT

 or 

FIX

 

POSITION

 command settings. Use the

UNFIX

 command to disable the 

FIX

 

POSITION

 setting.

fix position 51.3455323,-114.289534,1201.123,1002,0

The above example configures the receiver as a reference station with fixed coordinates of:

Latitude N 51º 20' 43.9163" (WGS84 or local datum)
Longitude

W 114º 17' 22.3224"

Height above sea level

1201.123 meters

Station ID

1002

RTCM health

0

FIX POSITION 

lat

lon

height

station id

[

RTCM

 stn health]

FIX POSITION

-

Command

unfix

fix position

lat

0 to ± 90.0
(Up to 8 decimal places are shown in the RCCA 
log but more precision is determined internally)

Latitude (in degrees/decimal degrees) 
of fixed reference station antenna in 
current datum.  A negative sign implies 
South latitude.

51.3455323

lon

0 to ± 360.0
(Up to 8 decimal places are shown in the RCCA 
log but more precision is determined internally)

Longitude (in degrees) of fixed 
reference station antenna in current 
datum.  A negative sign implies West 
longitude.

-114.289534

height

-1,000 to 20,000,000

Height (in metres) above the geoid of 
reference station in current datum.

1201.123

station id

0 to 1023 (10 bits) for RTCM output
“xxxx” for RTCA output
where ”xxxx” are four alphanumeric characters, 
entered between double quotes. For CMR, the 
station ID should be < 31.

Specify a reference Station 
identification number (optional entry) 
(see SETDGPSID)

1002

RTCM 
reference 
station health

0-7 
where 

0-5

Specified by user

6

 Reference station 

 transmission not monitored

  7

Reference station not working

Specify RTCM reference station health 
(optional)
(This field will only be reported in 
RTCM message header - word 2.)

6

0