Do all of the brand name GPS RTK systems out there that claim to track GNSSS, Galileo, etc actually do calculations with all of them at the same time??ÿ Looking at their specs makes me wonder if they just claim to track and provide no indication that they use all of them in the position calculations, or if they use more than two constellations at the same time.
In the early days of post GPS tracking, where additional systems were added there were issues. We purchased one of the first units and had problems getting accurate solutions when systems were added to GPS.
To get a good solution we had to only have GPS turned on, a firmware fix corrected the problem and since then it's been smooth sailing. You may be hearing of some early day issues merging the systems together, but since the hiccups the extra satellites have been an enhancement.?ÿ
I use Trimble receivers. I have noticed that by default not all of the constellations/frequencies are enabled. One must go in to the webUI and enable them. I also noticed on an older R10 (model 1) that this seems to get reset (maybe on older firmware only, I haven't checked recently). I believe the newer models and an Alloy that I have do keep the selections after power down.?ÿ
It appears that there are some issues using some of the newer Beidou satellites in the RTK solution. I have not looked at it enough to pin it down, but it will say tracking XX, for example, and then say using YY in the solution, and it is usually some Beidou's that are not being used.?ÿ
In standalone mode, it will track all of them, but depending on whether it is using SBAS (WAAS-GPS Only) or RTX (GPS, GLONASS, and GALILEO) it will not use all of the constellations in the position solution. Only if SBAS and RTX are turned off will it use Beidou, at least that is what it looks like to me. That said, it is tracking and storing all of them in static surveys.?ÿ
Based on the recent discussions here about how short baseline RTK with all constellations being used works really well in obstructed situations, I hope that Trimble is working to resolve the issue with the newer Beidou satellites. The more the better!
In my humble opinion, not all sats are being used, by the final solution, by gps units, that SAY that they are tracking all constellations. Using, (in final solution) is not the same as tracking.?ÿ
It's a fine line, between truth, and false advertising.
Tremble started the lying game, about this matter, years ago, when Topcon/Javad brought in the Russian sats. They told their users that the Russian birds would add error, and publicly made many disparaging remarks about other vendors.
Then again, I think early rtk by all brands, that used Russian Sats, were sometimes using all birds to gain the initial fix. But, to get higher accuracy, we're only using American birds. So, in this sense, maybe Trimbul was right, or part right.
I'm an end user, trying to make sense of a complex issue, that I'm not educated enough to fully grasp.
I'm red-neck enough to pick apart advertising, and to mess with it though.
I still think that "the proof is in the pudding". Go compare, and compare enough shots, to really know. This is time consuming, and is likely done in private, by some GPS companies. And we, the end users are in the dark. This "in the dark" condition, makes me bang the bars of my cell.
I also suspect that at this moment, the top few Mfrs. are producing good gear. Who is best, probably changes daily, or quarterly. Or, at the release of a software/firmware update.
My interest in this is in the fact that my signature, and seal is going on work, generated by complex equations, that are way beyond my hp-11c! I cannot check it, or do not check it, with transit and tape!
It's a TRUST based relationship, between surveyors, Mfrs., and clients. Saying my data is right, is based on some assuming. This makes me prone to dig around the differences in gear.
Will we someday be able to 100% trust our gps? Well, I think given enough TIME, on each point, we are there, within certain tolerances. However, time is money. And, sometimes we "cut it short".
So, it goes on. Someday, with 400 sats up, we will really know how to pincushion things to 0.001' (grin)
Maybe by then, and users will "download a survey, for a week, for $500.00, walk the lines with an I-phone app. Oh gads!
Carry on.
Nate
?ÿ
Unless you might want to call me a liar, I have been using multi-constellation for several years
Well, I'd not do that.
But, a GPS receiver lying to me... That's anathema!
Carry on.
N
I recall a time c.2000 that we were shopping for new RTK and data collectors. The Topcon salesman was making much talk of GLONASS, which Trimble and Leica could not yet do.?ÿ Came time for the demo, and Topcon man had to dial the masking angle down to zero to briefly pick up a single GLONASS satellite 1?ø above the horizon.?ÿ Naturally, his sales pitch was terminally wounded that day.?ÿ
My next personal experience with GLONASS didn't come until I got to OK in 2011. Leica GS15 with VIVA. A world of difference.?ÿ My whole attitude about RTK changed on the spot.?ÿ
Three days ago in the heartland of USA.?ÿ
The improvement in performance in all aspects is felt immediately.?ÿ
So why is it showing 24 out of 32 rather than 32 out of 32? What type of receiver is that connected to? That is similar to what I am seeing and it appears that the "unused" satellites are mostly if not all Beidou.
The picture shown was while using an on-site base and rover pair of iG8 receivers. I can confirm that some Beidou anf Galileo sv??s where being used in the solution and that the unused sv??s were scattered across the constellations. A couple gps, a couple glonass, a couple others. ?ÿWhile I didn??t highlight it in the picture, look at the hsdv, ?ÿvsdv, and PDOP. ?ÿPDOP approaching 1 and sdv??s in the THOUSANDTHS. ?ÿAmazingly tight fix.
I don??t know the high end decision making processes that are going on in the receivers as they evaluate which sv??s to use and which ones to reject. What I do know without a doubt is that this fully enabled receiver allows me to view and USE approximately 10 more sv??s than I typically had using GPS/Glonass alone receivers before. (14/22).
In all my GNSS work, I have never seen the in view and tracking sv counts equal.?ÿ
I agree, the results are really great, I am trying to track down what appears to be a systematic problem with certain satellites. Can't complain about the results I am seeing at all.?ÿ
My assumption was that they are analyzed and then "thrown out" because the combination of their noise and geometry introduced more variables than solutions provided. For example a Beidou satellite near the same area of sky as a Galileo would only be detrimental to the math.
Chopping_Broccoli probably has the SBAS tracking enabled. Only folks using the WAAS signal in their RTK solution that I am aware of is Ashtech, which became the Spectra Precision line of Junior Trimble...
So if the receiver has SBAS tracking enabled, SurvPC will show more tracked than used. Plus the fact that the receiver is tracking a few that are below the Mask Angle setting.
I setup the R10-2 with the upgrade this morning and started streaming RTCM to SNIP (software on my PC) over a cell modem. It is definitely using the BDS-3 satellites, here is a screen shot of the RTCM packets decoded...(Beidou satellites are the "C" lines, R are Glonass, E are Galileo)
With all of the data types it is sending about 2.3 MB/hour.?ÿ
So it seems that maybe the RTK engine at the rover is not using them??ÿ
