Simple Reach PPK Tutorial
 

Overview

You can learn the basics of Reach PPK processing by setting one Reach GPS on a Base location [known or unknown] and walking with a second Reach GPS as your Rover. This tutorial is the same process you will use for precise camera positions even though there is no UAV, camera, or known base location necessary.

Requirements

  • Two Emlid Reach receivers (M or RS) with firmware installed. No additional settings are required for your Reach units. You will only need the raw logs that are automatically created as soon as you power your Reach receiver.
  • Battery power for your Reach receiver.
  • Emlid RTKLIB software: https://docs.emlid.com/reach/common/tutorials/gps-post-processing/

Collect data

  1. Place one Reach on a stationary location [Base] and power it. You do not need to know the precise location. It will start accumulating raw GPS data as soon as you power it.
  2. Power your second Reach [Rover], wait for the LED to turn green, then walk around with it.
  3. Connect to your Reach Rover and Base and download the Raw data [UBX] files that accumulated during the test. Append "Rover" and "Base" to the beginning of the file names.

Convert the Raw files to RINEX

  1. Start RTKCONV [rtkconv_emlid_b27.exe]
  2. Use the ... button to select your raw Base [UBX] file. RTKCONV will automatically set the output path for the RINEX files to the same folder as the .ubx file.
  3. Select the Options button.
  4. Set RINEX version to 3.03.
  5. Click OK.
  6. Click Convert.
  7. Do the same for the raw Rover files.
  8. Now you should have these files.

Correct your Rover positions

  1. Start RTKPOST [rtkpost_emlid_b27.exe]
  2. Use the RINEX OBS: ROVER ... button to select your Rover .obs file.
  3. Use the RINEX OBS: Base Station ... button to select your Base .obs file.
  4. Limit the amount of data you process and avoid "Memory Error" problems by selecting Time Start. Note the format of the Rover file name. [GPS Time] 201705041945. That is Year 2017. Month 05, Day 04, Time 1945. Pick a time shortly before.
  5. Select the Options button
    6. .
  6. Select the Load button and open RoverCorrectionConfig.conf.
  7. Select the Execute button.
  8. Now you should have .pos files in your folder.
  9. Rover_###.pos is the corrected, moving path of your Rover.
  10. Rover_###_events.pos is position of the camera events [precision geotags]. This file will be empty in this test unless you had a camera connected and were taking pictures while you were walking with your Reach Rover.

Plot your Rover path

  1. Start RTKPLOT [rtkplot.exe].
  2. Go to File > Open Solution 1 and select your Rover_###.pos file.
  3. If you had a camera connected you can Open Rover_###_events.pos as Solution 2. You can toggle between the two by using the 1 2 buttons on the top left.

Notes

  • If you know your Base position you can specify it in RTKPOST > Options > Positions > Base Station.
  • How to use Reach data to geotag images.