PPPSEED

Control the seeding of the PPP filter

Platform:

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

The PPPSEED command controls the seeding of the PPP filter. Accurate position seeding can accelerate PPP convergence.

PPPSEED SET is used to explicitly specify a seed position. The seed position must be in a datum consistent with the PPP corrections that will be used. For TerraStar corrections, this is ITRF2014. The PPPSEED SET command can only be used to give seed positions for stationary platforms. If the platform is moving, use the PPPDYNAMICSEED command.

Caution must be exercised when using PPPSEED SET. While a good seed position can accelerate convergence, a bad seed position hurts performance. In some cases, a bad seed can prevent a solution from ever converging to a correct position. In other cases, a bad seed might be rejected immediately. In still other cases, the filter might operate with it for a time period only to reject it later. In this case, the filter position is partially reset, with a corresponding discontinuity in the PPP position.

PPPSEED STORE and RESTORE are intended to simplify seeding in operations where the antenna does not move between power-down and power-up. For example, in agricultural operations a tractor might be stopped in a field at the end of a day and then re-started the next day in the same position. Before the receiver is powered-down, the current PPP position could be saved to NVM using the PPPSEED STORE command, and then that position applied as a seed after power-up using PPPSEED RESTORE.

PPPSEED AUTO automates the STORE and RESTORE process. When this option is used, the PPP filter automatically starts using the stopping position of the previous day. For this command to work, the PPPDYNAMICS command setting must be AUTO so that the receiver can determine when it is static, or the filter must explicitly be told it is static using PPPDYNAMIC STATIC. Additionally, in order for the receiver to recall the saved seed, the PPPSEED AUTO command should be saved to NVM using the SAVECONFIG command.

When PPPSEED is in AUTO mode and a PPPSEED STORE command is issued, there must be a minimum half second pause before a SAVECONFIG command is issued. This ensures the configuration persists through a power cycle.

For more guidance on using position seeding, refer to APN-104 Position Seeding Guide and Recommendations.

Message ID: 1544

Abbreviated ASCII Syntax:

PPPSEED option [latitude] [longitude] [height] [northing_std_dev] [easting_std_dev] [height_std_dev]

ASCII Example:

PPPSEED set 51.11635322441 -114.03819311672 1064.5458 0.05 0.05 0.05

Field	Field Type	ASCII Value	Binary Value	Description	Format	Binary Bytes	Binary Offset
1	Command header	–	–	PPPSEED header This field contains the command name for abbreviated ASCII or the message header for ASCII or Binary.	–	H	0
2	option	CLEAR	0	Delete any stored seed and disable automatic store and restore of PPP seed positions. Sets the PPPSEED state to CLEAR.	Enum	4	H
		SET	1	Immediately apply the specified coordinates as a seed position. Sets the PPPSEED state to MANUAL.
		STORE	2	Store the current PPP position in NVM for use as a future seed. Sets the PPPSEED state to MANUAL.
		RESTORE	3	Retrieve and apply a seed position if a position was previously saved in NVM via the STORE or AUTO options. Sets the PPPSEED state to MANUAL.
		AUTO	4	Automatically store and restore PPP seed positions. Sets the PPPSEED state to AUTO.
		MANUAL	5	Disable automatic store and restore of PPP seed positions. This option does not clear any saved positions. Sets the PPPSEED state to MANUAL.
3	latitude	±90		Latitude (degrees)	Double	8	H+4
4	longitude	±180		Longitude (degrees)	Double	8	H+12
5	height	> -2000.0		Ellipsoidal height (metres)	Double	8	H+20
6	northing_std_dev			Northing standard deviation (metres)	Float	4	H+28
7	easting_std_dev			Easting standard deviation (metres)	Float	4	H+32
8	height_std_dev			Ellipsoidal height standard deviation (metres)	Float	4	H+36
9	Reserved				Float	4	H+40