Hi all,
has anyone tried concatenating 24 hours worth of gps data to submit to OPUS for a base station location?
I dunno if it’s some linux issue i’m too dumb to understand but when I concatenate a hundred files or so it has no problem but in 24 hours pygpsclient can generate around 800 log files.
how do we wrestle this data into a readable file to submit for an accurate base station location?, I just get utc-8 and coding errors when i try to look at the file.
Hi
I am not an OPUS user but I will try to help.
Have you followed these tips from the OPUS website:
So you need to upload RINEX file only for GPS and L1/L2, with rate 30 sec. and more than 10° above the horizon. This can significantly reduce file size.
If you want calculations for GLONASS, Galileo, Beidou there is https://beta.ngs.noaa.gov/OPUS/.
If you have one RINEX file I can try to suggest how to do the calculations with https://github.com/rtklibexplorer/rtklib, but it will take time on this forum. I am not an expert in the US. We may get stuck.
Maybe someone else will suggest something.
I wonder if it’s any more accurate than the position I got from Skylark NTRIP, their base is almost 50 miles away.
We’ll see
It’s hard to say because satellite systems are still in the development phase, especially Galileo.
OPUS writes:
“Under normal conditions, most positions can be computed to within a few centimeters.”
It only uses GPS L1/L2.
I don’t know what kind of receiver you have, but the antenna indicates something good.
I have ZED-F9P and its accuracy for RTK is stated as 0.01m+1ppm for a maximum distance from the base station of 20km which gives 0.01m+0.02m=0.03m. 50 miles would be about 80 km, which is too much for my receiver.
If you are using ntrip I suggest you do tests for:
GPS+Galileo
GPS+Galileo+BeiDou
You can try to find a public CORS station closer and then perform calculations with RTKLIB demo5, the so-called static measurement. The map of the station is probably available here ArcGIS Web Application
I ran comparisons with the commercial correction service and plugged that into my base as it’s location, then checked places I’d marked before with the commerical, it’s pretty close but there’s something with the height I can’t get right. it’s good enough for what i’m doing around my property, i figured i’d give opus a try since i laid out a thousand bucks for all this stuff
@steve1428, That’s sometimes an indication that we are comparing 2 different Vertical Datums or the Reference Frame of the Correction Source.
What State are you in ?
I can look through my lists for a NTRIP in your area that might not be widely published.
I know where they are, I bought a couple months of skylark, it was the best deal, there’s a free one but, still too far, it’s over by wikiup. I have the right geoid in there too for SW maps.
there must be something funny cause i put my rover right on top of my base antenna and got the location from skylark. then put that into the base location for pygpsclient and then the rover gave different heights than with skylark.
I’ll look into the datum thing.
mohave county, AZ
How close to AZFM ?
that’s even farther than the skylark one in Needles.
There’s one over in Wikiup but it’s too far.
we’re between havasu and kingman
I have acces to skylark, I paid for it, I just want my own base station.
I got the Phat Ls290 for a base, I already had the RTK postcard as a rover
I think there is still an opportunity for a mix-up.
Google says: The Skylark correction service provides corrections in the ITRF2020 reference frame. However, for some regions, like the contiguous United States, Skylark also supports corrections in the NAD83 reference frame.
When you established the Base Position (using Skylark), was that ITRF2020 or NAD83 ?
When you enter the Base Position into pygpsclient, is that expecting WGS84 perhaps ?
Do you have the option to use ECEF in pygpsclient ( I’ve never used it ) ?
i’ll def check all that but I cancelled my skylark, I think I lose it next day or so.
I’m going to try feeding opus some smaller files when i get some time here
If you have a SparkFun Postcard with LG290P module, it has Position acuracy for RTK 0.8cm + 1 ppp which means that for your NTRIP station about 80km away the accuracy will theoretically be 0.8cm + 8cm = 8.8cm. I don’t know how much difference in heights you had in your tests.
You have to be careful what position you read in the programs for RTK (ntrip client), whether the last measurement or the averaged position. If the averaged position, you have to clear the measurements before reading, because there were probably points with the float status at the beginning.
Very close to your location is the public reference base station AZYC. Although it is equipped with a very good receiver and antenna, it provides its observation data only for GPS and GLONASS in RINEX 2.11 format. Therefore, determining the position of your base station relative to AZYC can be done with the RTKLIB demo5 package only for GPS, similarly as OPUS does.
In Europe, public base stations provide rinex files for GPS, GALILEO, GLONASS, BDS, etc.
I didn’t know about the one in yucca, that’s only about 5 miles from me, i’ll try and tap into it
If you are only interested in accurate positioning relative to your base station, and not existing maps, you can configure your base station based on the obtained RTK position (ntrip client).
The position of your base station will be with an error of +/- 10 cm relative to the maps, but the rover will be able to accurately determine the position relative to this station.
If you are interested in such a solution, configure your base station with the RTK position. Take two rover measurements of different places, e.g. 10 m apart. Check if the distance between the measurements is 10 m.
The measurement results will be in NAD83 (2011) i.e. 3D system. They can be transformed to 2D system appropriate for your zone in the USA using the Proj program to check the distances.
i’m surveying my land so I want it the same as on the maps.
There is a professional survey marker on my land and my postcard, using skylark, found it exactly where the county property maps (GIS) showed the boundary should be
when I made the Phat my base the location was good too, it’s just the height is off.
height is important because I’m also trying to create topographical maps of the land and building site
This looks like Good News !
The Arizona Continuously Operating Reference Station Network (AZCORS) is operated and managed by the Arizona Department of Water Resources (ADWR). All users will need to re-register for an AZCORS account at: htps://azcors.azwater.gov/sbc/Account/Index?returnUrl=%2Fsbc%2F. AZCORS is open to any users and has an open-data policy for both real-time and rinex data files.
Links:
It takes about 2 minutes to Register for an Account.
The NTRIP stream is at:
159.87.113.135 and port 8080.
Your MountPoint will be :
Or you can use the “Nearest” MountPoint-
I get to update my list 
You can still create your own Base Station, but you appear to be in a good location for the Statewide CORS Network.
Just for fun, I took a peek at the Site Log. Station AZYC was commissioned with 20 days of Data. People sometimes laugh at me when I say weeks of GNSS data are required to start talking about absolute accuracy 
But you could absolutely use the CORS Network to obtain the RTN position for your Base and feel pretty good about it. Just check the RTN solution several times over a few days.
But if it were me, establishing a local base in this area would just be for fun/learning.
we got wide open skies in yucca.
thanks for that info, i’ll def hook up to the yucca station.
I setup long range wifi and got that sparkfun Phat to make the base station with.
it’s annoying to keep losing RTK fix when you’re walking around trying to do a top survey
