Wednesday, June 7, 2017

A Simple Reach PPK Tutorial

Written by Brian Christal and posted by Stephanie Pelczar


This is a simple Reach PPK tutorial that can be used with the Tuffwing UAV Mapper.You can learn the basics of PPK by placing one Reach GPS on a Base location (known or unknown) and walking a route with a second Reach GPS (rover). This is the same process you will use for precise camera position, even though there is no UAV camera involved.


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 begin 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 a route with it.
  3. Connect to your Reach base. Download the Raw data (UBX) files that were accumulated during the test. Then do the same for your Reach rover. 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 selet 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 the following 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. To limit the amount of data that you process and to avoid "Memory Error" problems, select Time Start. Note the format of the rover file name. [GPS Time]
  5. Select the Options button.

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 are the positions of the camera events (precision geotags). This file will be empty in this test unless you had a camera connected and were actively taking pictures while you were walking a route 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 toggggle between the two by using the 1  2 buttons on the top left.

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