Page | 20 March 5, 2019
PPPRESET (Reset the PPP Filter)
The “PPPRESET” command is available on OEM7 receivers and can be used to reset the PPP filter. After
issuing the command, the PPP filter is restored to its initial state and PPP convergence will start over.
If deletion of the NVM-saved PPP seed information is also required, the “PPPSEED CLEAR” command
must be applied before “PPPRESET” is used. See PPPSEED, page 20, for more details.
There is an “option” field that can be used with the PPPRESET command, but it is not required and the
default is “FILTER” when not specified. For example, these commands are equivalent:
PPPRESET
PPPRESET FILTER
PPPSEED (Control Seeding of the PPP Filter)
The PPPSEED command controls the seeding of the PPP filter. Accurate position seeding can accelerate
PPP convergence. The command “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 NovAtel CORRECT
with PPP, this is ITRF2008.
Caution must be exercised when using “PPPSEED SET”. While a “good” or accurate seed position can
accelerate convergence, a “bad” or inaccurate seed 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 or the filter might operate with it for a period of time only to reject it later. In the
last case, the filter position is partially reset with a corresponding discontinuity in the PPP position.
The available options with the PPPSEED command are as follows:
• CLEAR – resets the stored seed, and prevents any auto seeding from occurring
• SET – immediately apply the specified coordinates as a seed position
• STORE – store the current PPP position in NVM for use as a future seed
• RESTORE – retrieve and apply a seed that was saved in NVM via the STORE or AUTO options
• AUTO – automatically store and restore PPP seed positions
The “STORE” and “RESTORE” options 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 can be saved to NVM using the
command “PPPSEED STORE”, and then that position applied as a seed after power-up using “PPPSEED
RESTORE”.
The “AUTO” option automates the “STORE” and “RESTORE” process. When this option is used, the PPP
filter automatically starts using the stopping position of the previous day. The PPPDYNAMICS command
(page 19) must be set to “AUTO” when using PPPSEED so that the receiver can determine when it is