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C Commands Summary
82 MiLLennium GPSCard Software Version 4.50 Command Descriptions Manual Rev 1
ASSIGN
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.
NOTE: 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.
Syntax #1:
Example 1: 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.
Syntax #2:
Example 3: 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
Syntax Range Value Description Default Example
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
Syntax Range Value Description Default Example
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