For best results, set the camera settings on your drone in the DJI Go4 App as follows:
Turn camera mode to Photo
Go to camera settings and turn on A or Auto mode
ISO should be 100, but sometimes you may use 200 or 400, depending on light conditions
Aperture: 2.8 - you should increase this value when shutter speed is 1/1250 or shorter
Watch out: the shutter speed must not be shorter then 1/1600, because the camera will start using rolling shutter instead of mechanical shutter.
Rolling shutter photos are not as good as mechanical shutter photos.
White balance is Sunny or Cloudy
Colour None or Normal
Image size 3:2
Image format JPEG
Mechanical Shutter is On if your drone is Ph4 adv/pro
Camera Focus mode is Manual - put focus roller to ∞
Download GNSS RAW data from Receiver
Prepare your Laptop/smartphone with Wi-Fi connection turn your drone on and follow the manual below.
Download files from Reach M+/M2
To download GNSS data from Emlid Reach you need to make the following steps.
Install GNSS antenna to drone, put drone to open sky view, turn Teodrone on and after a few minutes, web-interface of Reach will be available. Be sure, that at least 6 satellites are available to the drone.
Turn on Wi-Fi on your PC and connect to the network "reach-XXXX" with the password "emlidreach". Type http://192.168.42.1 in browser and get into the web app of Reach.
Go to the Logging page. You'll see the list of all ubx files. Date and a time UTC in the file-names mean the start of the GNSS-data recording. For example, the filename "raw_201911050455.ubx" means that the begining of GNSS data recording was on November 05, 2019 at 04:55 a.m., UTC.
Download the files into your PC and Unzip them.
Download files from AGNSS L2
To download GNSS data from VD AGNSS you need to make the following steps
Turn Teodrone on and after 40 seconds, the web-interface of AGNSS will be available.
Turn on the Wi-Fi on your PC and connect to the network "AGNSS_XXXX" with the password "12345678".
Paste http://192.168.0.1 into the browser and access the web app of AGNSS.
Go to the Logging page. You'll see the list of all ubx files. A date and a time UTC in the file-names mean the start of the GNSS-data recording. For example, the filename "201911050455.ubx" means that the begining of GNSS data recording was on November 05, 2019 at 04:55 a.m., UTC.
Download the files onto your PC.
Converting UBX files
After you have downloaded all the data from Teodrone, check to make sure that
the number of .ubx files is equal to the number of times Teodrone was turned on.
Every *.ubx file is about 4Mb for 20min flight with GPS+GLONAS 5Hz L1 solution and 8 Mb L1/L2 solution.
The quantity of photos depends on time interval between them. If AShot interval was 1.3s, there would be about 1000 photos. If Ashot interval was 1.8s there would be about 700 photos.
For converting UBX into RINEX format, use free RTK lib software or Telegram TeokitBot.
To convert files with RTK lib, run rtkconv.
Make step-by-step operations (see pictures below) and click Convert button.
To convert UBX with TeokitBot, send files to it and wait for a few minutes. Bot will convert UBX to Rinex and send Rinex files to you back.
After that there will be 2 files in UBX dir. *.obs and *.nav files.
Checking OBS data
If you did everything right, there will be the following lines in the bottom of RTK Conv window:
0=… - observation,
N=… - ephemerides,
T=… - number of timemarks.
To be sure that the quality of the GNSS measurements is good, click the button Plot in RTK Conv window.
There will be a window with satellites seen during the flight (see the screenshot).
For good measuring there shouldn't be any gaps and cycle-slips in the data. Cycle-slips occur for example when the buildings block the GNSS signal.
If you click SNR/MP/EL (see the screenshot), you'll see the quality of GNSS data and if there is any noise in it.
For good measuring SNR must be 30–50 dB/Hz and there should not be any cycle-slips.
To be continued...