ASSIGN

Assigns a channel to a PRN

Platform:

OEM719, OEM729, OEM7500, OEM7600, OEM7700, OEM7720, PwrPak7, CPT7, CPT7700, SMART7, SMART2

The ASSIGN command should only be used by advanced users.

  1. Assigning SV channel sets the forced assignment bit in the channel tracking status field which is reported in the RANGE and TRACKSTAT logs.

  2. Assigning a PRN to a SV channel does not remove the PRN from the search space of the automatic searcher; only the SV channel is removed (that is, the searcher may search and lock onto the same PRN on another channel). See Table: PRN Numbers for Commands and Logs for the PRN available for the ASSIGN command.

  3. GLONASS SVs cannot be assigned if there is no information on GLONASS frequencies and matching slot numbers.

  4. OEM7 cards have 4 channels available for SBAS. They automatically use the healthy GEO satellites with the highest elevations. Use the ASSIGN command to enter a GEO PRN manually.

  5. The ASSIGN and UNASSIGN commands are not accepted for L-Band channels. The ASSIGNLBANDBEAM command should be used for L-Band channels.

  6. Manually assigned satellites are not reported in the RANGECMP4 log.

This command may be used to aid in the initial acquisition of a satellite by manually overriding the automatic satellite/channel assignment and reacquisition processes. 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 remains in effect for the specified SV channel and PRN, even if the assigned satellite is below the elevation cutoff. If the satellite Doppler offset of the assigned SV channel exceeds that specified by the window parameter of the ASSIGN command, the satellite may never be acquired or reacquired. If a channel has been manually assigned, and the channel is changed to AUTO tracking, then the channel is idled immediately and returns to automatic mode.

To cancel the effects of ASSIGN, issue one of the following:

These immediately return SV channel control to the automatic search engine

Message ID: 27

Abbreviated ASCII Syntax:

ASSIGN channel [state] [prn [Doppler [Doppler window]]]

ASCII Example 1:

ASSIGN 0 ACTIVE 29 0 2000

In example 1, the first SV channel is searching for satellite PRN 29 in a range from -2000 Hz to 2000 Hz until the satellite signal is detected.

ASCII Example 2:

ASSIGN 11 28 -250 0

SV channel 11 is searching for satellite PRN 28 at an offset of -250 Hz only.

ASCII Example 3:

ASSIGN 11 IDLE

SV channel 11 is idled and does not attempt to search for satellites.

For dual antenna receivers:

  • On the primary antenna, the SV channel is from 0 to N-1, where N is the number of channels in the primary antenna channel configuration.

  • On the secondary antenna, the SV channel count is from at N to N+(M-1), where M is the number of channels in the secondary antenna SV channel configuration.

  • Even though L-Band channels cannot be configured with the ASSIGN command, they are included when determining N.

Field

Field Type

ASCII Value

Binary Value

Description

Format

Binary Bytes

Binary Offset

1

ASSIGN header

-

-

Command header. This field contains the command name for abbreviated ASCII or the message header for ASCII or binary. See ASCII or Binary.

-

H

0

2

channel

0 to n-1, where n is the maximum number of GNSS channels in the current channel configuration

Desired SV channel number where channel 0 is the first SV channel. The last channel depends on the model configuration.

Ulong

4

H

3

state

Refer to Table: Channel State

Set the SV channel state. If a value is not given, the default of ACTIVE is used when the additional optional parameters are entered.

Enum

4

H+4

4

prn

Refer to PRN Numbers

Optional satellite PRN number. A value must be entered unless the state parameter is IDLE or AUTO.

Ulong

4

H+8

5

Doppler

-100 000 to

100 000 Hz

Current Doppler offset of the satellite.
(default=0)

Note: Satellite motion, receiver antenna motion and receiver clock frequency error must be included in the calculation of Doppler frequency.

Long

4

H+12

6

Doppler window

0 to 10 000 Hz

Error or uncertainty in the Doppler estimate above.
(default=4500)

Note: This is a ± value.
Example: 500 for ± 500 Hz

Ulong

4

H+16

Channel State

Binary

ASCII

Description

0

IDLE

Set the SV channel to not track any satellites

1

ACTIVE1

Set the SV channel active (default)

2

AUTO

Tell the receiver to automatically assign PRN numbers to channels