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C 

Commands Summary

82

 MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual Rev 1

This command may be used to aid in the initial acquisition of a satellite by allowing you to override the automatic
satellite/channel assignment and reacquisition processes with manual instructions.  The command specifies that the
indicated tracking channel search for a specified satellite at a specified Doppler frequency within a specified
Doppler window.  The instruction will remain in effect for the specified channel and 

PRN

, even if the assigned

satellite subsequently sets.  If the satellite Doppler offset of the assigned channel exceeds that specified by the
Search-Window parameter of the 

ASSIGN

 command, the satellite may never be acquired or re-acquired.  To cancel

the effects of 

ASSIGN

, you must issue the 

UNASSIGN

 or 

UNASSIGNALL

 command, or reboot the GPSCard.

When using this command, NovAtel recommends that you monitor the channel tracking status (

ETSA

/

B

) of the

assigned channel and then use the 

UNASSIGN

 or 

UNASSIGNALL

 commands to cancel the command once the channel

has reached channel state 4, the Phase Lock Loop (

PLL

) state.  See Appendix D, Page 155, the 

ETSA

/

B

 ASCII log

structure and Table D-7, Page 201 for an explanation of the various channel tracking states.

Assigning a PRN to a channel does not remove the PRN from the search space of the automatic 

searcher; only the channel is removed. By default, the automatic searcher only searches for the GPS 
satellites (PRNs 1-32).

There are two syntactical forms of this command, as shown below.

assign 0,29,0,2000

In example 1, the first channel will try to acquire satellite 

PRN

 29 in a range from -2000 Hz to 2000 Hz until the

satellite signal has been detected.

Example 2: 

assign 11,28,-250,0

The twelfth channel will try to acquire satellite 

PRN

 28 at -250 Hz only.

assign 11,idle

In Example 3, Channel 11 will be idled and will not attempt to search for satellites.

ASSIGN

channel

prn

doppler

search-window

ASSIGN

-

Command

unassignall

assign

channel

0 - 11

Desired channel number from 0 to 11 inclusive (channel 0 
represents first channel, channel 11 represents twelfth 
channel)

0

prn

1 - 32

A satellite PRN integer number from 1 to 32 inclusive

29

doppler

-100,000 to 100,000 Hz

Current Doppler offset of the satellite
Note:

Satellite motion, receiver antenna motion and 

receiver clock frequency error must be included in the 
calculation for Doppler frequency.

0

search-window

0 - 10,000

Error or uncertainty in the Doppler estimate above in Hz
Note:

Any positive value from 0 to 10000 will be 

accepted.  Example: 500 implies ± 500 Hz.

2000

ASSIGN

channel

keyword

ASSIGN

-

Command

unassignall

assign

channel

0 - highest channel 
number

Desired channel number from maximum channel number 
inclusive 

0

keyword

IDLE

Idles channel (not case sensitive)

idle