The online PPP service offered by the Canadian Geodetic Survey of NRCan has been available since 2003. It processes, on average, about 1,000 RINEX files daily, fulfilling the positioning needs of Canadians and the international community. The PPP landscape having evolved significantly in the last few years, the underlying PPP engine will be replaced by a new version on August 14th 2018.
The team leader in charge of this software transition (Brian Donahue) coined the acronym SPARK for the new engine, which stands for “Simon’s PPP with Ambiguity Resolution using a Kalman filter”! 😊 The software has the following features:
- It processes uncombined observations rather than the ionosphere-free linear combinations
Processing uncombined observations greatly simplifies the inclusion of multi-frequency (and multi-modulation) data. (While the software is a truly multi-GNSS engine, only GPS and GLONASS will be processed until NRCan generates their own orbit/clock products for other GNSS). It also allows modeling the slant ionospheric delay parameters using process noise which is beneficial for fast re-convergence after signal interruptions.
- It uses both code and carrier-phase observations for single-frequency users
The current version of the CSRS-PPP service uses only code measurements for single-frequency users. The new engine will try to harness the precision of carrier phases, providing a smoother solution and improved accuracy.
- It accepts RINEX version 3.x files
While only RINEX 2.x files are currently accepted, SPARK will now process RINEX 3.x files. Note that, due to the limited availability of RINEX 3.x files from users, testing was mainly focused on IGS files so please report any issues you may encounter with RINEX 3.x data processing.
- It is ready for fast convergence
SPARK has built-in capabilities for PPP with ambiguity resolution (PPP-AR) and can accept precise slant ionospheric constraints to speed up convergence. These features will not be activated in August since it was deemed safer to first put the new engine online in float mode. The targeted date for AR is currently the end of the year, although this date may change if any issues are encountered during testing.
SPARK has been extensively tested in the last year and offers a level of performance similar to the current engine. It also fixes an inconsistency in the current version causing a height offset of about 4-5 mm (more on this in the next blog post).
To learn more about the CSRS-PPP transition, please refer to this page. You will find more information regarding changes in the format of output files and examples of the new PDF report (which is very similar to the previous one).
I sincerely hope you will enjoy using this new engine, and NRCan is looking forward to serving you better!