In order to use RTK, it is necessary to have a GPS receiver that can extract the “carrier phase” and the result and the software to perform positioning using the correction information from the reference station. The latter software can use the famous freeware RTKLIB, but usually you need the hardware.
Therefore, in order to carry out RTK experiments even on rainy days, we prepared a simulated mobile station in a location somewhat inferior to the reference station. Like the reference station observation data, observation data of the pseudo mobile station is also broadcasted.
Click “I” at the top of the window and check (1) Rover and (2) Base Station. Click on each of Rover and Base ‘s Opt to make settings. After that, set “Option …” at the bottom.
For Opt of (1), write “ntrip.phys.info.hiroshima-cu.ac.jp” to the host, “80” to Port, “ROV” (Rover … abbreviation of mobile station) to Mountpoint. Then press OK. For Opt of (2), enter the values same as (1), except that Mountpoint is set to “F9P”.
As for Option …, select “Kinematic” for Positioning Mode, select “L1” for Frequencies, select “Broadcast” for Ionosphere Correction, select “Saastamoinen” for Troposphere Correction and select “Broadcast” for Satellite Ephemeris. Also select all the bottom satellites. Since these are important parameters of satellite positioning, I would like to explain it again. Since we can not help using these values except Mask angle this time, we set this way. Then click the Position tab at the top.
Since this reference station is broadcasting its own coordinate value (RTCM 3 Type 1006 message), select “RTCM Antenna Position” in the Basestation field. In this way, click “Start” on the first screen to start positioning.
With the positioning result of the simulated mobile station in several seconds to several tens of seconds, it becomes “Single” (single positioning) state.
Within 5 seconds or so since clicking start positioning, we may see “Float” state, since the reference station coordinates are broadcasted every 10 seconds. This state “float” indicates the distance from the satellite to the user is searching for several times the wavelength of the radiowave.
After waiting for about 30 seconds to 1 hour or so, the distance from the satellite to the user will be in a “Fix” state that indicates consistent with no discrepancy. Occasionally it may be in fix state in a few seconds and soon be in the float state. This is often called miss fix, and it is a phenomenon that it judgeed that it was correctly determine the position by mistake.
Setting 2 to fix faster by their parameters.
(1) Download the RTKLIB source code.
$ Is the prompt.
$ git clone https://github.com/tomojitakasu/RTKLIB.git
On Mac PCs, delete
RTKLIB/app/*/gcc/makefile. It is a realtime library, and is unnecessary for compiling on Mac.
$ cd RTKLIB/app $ ./makeall.sh
(3) Edit configuration with a file named
RTKLIB/app/rtkrcv/gcc/ as follows (you can download it from Gist.
$ cd rtkrcv/gcc/ $ git clone https://gist.github.com/00587e3767ab01e6b61410c1d69364d6.gitmv rtkrcv.conf
(4) Execute rtknavi
$ ./rtknavi rtknavi> start rtknavi> stat 1 ... Ctrl + C rtknavi> shut
After waiting for a while, it will be in fix state.
This is the enlargement of the above screen. The solution status indicated fixed, and the ratio of validation showed 3.19. It is possible to be miss fix. The ratio of validation would rapidly increase from around 10 and becomes the maximum value of 999.9 after waiting for a while.