§ 011. PPP post-processing by PENTAP

# Intro

There is need to post-process GNSS observables (raw data) from static rover. But there is no base receiver nearby. So classic differential base-rover approach doesn't work here. And yet there is great need to get receiver accurate position w/ accuracy down to sub-dm.

Precise Point Positioning (PPP) Post-Processing will help here. Instead of differential base-rover processing, precise Global satellites orbits and clocks (SP3 format) are used.

# Input Data

Concrete data set is collected on ANK200TUR IGS station located in Ankara, Turkey.

Station is equipped with Trimble Zephyr 3 antenna (TRM115000.00/NONE) and Trimble NETR9 receiver.

Original raw data may be found here: KSAT011_OriginalData.zip

# What PENTAP is?

PENTAP is Precise Point Positioning post-processing online service. It allows to compute precise rover positions using SP3 orbits and clocks corrections. No base station is needed. Instead of base-rover differential processing, PENTAP uses precise SP3 orbits and clocks corrections automatically downloaded from one of public processing centers.

Drawback of using global corrections (instead of local differential like RTK) is increased time to get sub-dm positions accuracy (called as convergence time). While RTK may be FIXED w/ few centimeters accuracy even instantly, PPP technology (w/o local ionospheric corrections) may require up to 30 minutes to get sub-decimeter accuracy.

Converge time strongly depends on antenna quality and environment. Even more, during convergence process it is recommended the rover be static (no move).

Despite other PPP services, PENTAP allows to process both static and kinematic rover files.

# Run PENTAP

It is time to run PENTAP post-processing. Open PENTAP uploading page and load rover RINEX file.

PENTAP service automatically downloads the best available SP3 orbits and clocks from one of available processing centers.

# PENTAP Results

Here we may see detailed information about rover file:

Input files

General Info

3.02
Hatanaka Compressed (CRX)

Date: 2024.04.09
Time: 00:00:0.00
DOY:  100
Week: 2309

Date: 2024.04.09
Time: 23:59:30.00
DOY:  100
Week: 2309

TRM115000.00    NONE

Post-processing PPP position types statistic is presented further.

Horizontal positions (UTM) are showed on the next interactive plot. Average is subtracted. Absolute coordinates may be found in GGA / CSV files below.

Below zoomed horizontal positions are showed (PPP convergence process is skipped).

Also altitude plot is showed. PPP convergence process is perfectly seen as DGNSS positions (orange).

Finally, reckoned positions (epoch-by-epoch) may be downloaded in CSV text form and NMEA GGA message for further analysis and use.

# Summary

Example of PENTAP Precise Point Positioning (PPP) post-processing is presented. PENTAP downloads precise orbits and clocks (SP3) automatically and process rover observables in PPP mode. No base station is needed.

Convergence process takes about 20-30 minutes (depends on antenna quality and environment). After that positions accuracy reaches sub-dm level.

Despite other PPP online services, PENTAP allows to process both static and kinematic rover files.