It is a headache to gather the information, but a couple years ago I prepared a list of GPS with only L5 and then using planning software I charted when I'd have a good constellation of only those to see if I anecdotally noticed any performance improvement. Short answer is no, but that was a few years ago and I don't think the current firmware at the time made much use of them.
I can say there's enough Galileo that they make a major impact on performance. My R10 model 1s are certainly fixing where I never thought they would.
I have a crack pipe dream that someone will eventually come up with a robust algorithm using all available signals and their different characteristics with regard to multipath to bring some elegance to all that data.
There are some on this board and in other places that like to gripe "MORE THAN X DOESN'T HELP"! I don't buy it, more data is always a good thing. I think we need to return to the drawing board on how to use these signals together instead of incrementally developing the old fix/float approach. Trimble Catalyst definitely has piqued my interest. I their HD GNSS engine is actually still a working in progress and is a steup towards what I'm thinking about.
I thought the HD-GNSS engine was something of a gimmick when it was first released, but once I had a chance to really play around with it I was impressed.
But it was side-by-side comparisons with fixed-float receivers under challenging conditions that made me a convert. We would have folks working with R8-3 and R10-1 receivers at the same time, and the R8s would supposedly be "fixed" at five hundredths, while the R10s were showing four tenths or more. Control checks with both receivers, verified with total stations, revealed bad fixes and that the R10 precision estimates were bang-on.
Most RTK engines periodically check for bad initializations and will alert the user when a discrepancy is found, but it is great to not have to worry about bad fixes, and trust the estimates that you are seeing in realtime.
I have played around with Catalyst - was not a fan until GLONASS capability was added. I am not sure it is the solution for dedicated land survey crews, but for municipalities doing asset and infrastructure mapping it is pretty awesome, or for construction inspectors who are travelling around a lot. The antenna and the "nunchuck" pole are super compact.
They have added Galileo E1 to Catalyst, also. I think software-defined receivers are currently the most interesting "sandbox" developers are playing in. Just think if you had a few thousand people testing your product at any given time. You could play with algorithm tweaks by pushing updates and quickly ascertain the benefits.
Here is a snapshot taken just now (20:30 UTC on August 1, 2019) from an Alloy at my office (Pittsburgh).
This receiver does not have QZSS nor IRNSS enabled. Base price for an Alloy is $13000, it comes with GPS and Glonass enabled. Galileo and Beidou are each $1500 to enable.?ÿ
Interesting to note that right now GPS, Glonass, and Beidou all have 6 SV's being tracked, Galileo has 7.?ÿ
Here is a snapshot taken just now (20:30 UTC on August 1, 2019) from an Alloy at my office (Pittsburgh).
This receiver does not have QZSS nor IRNSS enabled. Base price for an Alloy is $13000 (external antenna not included), it comes with GPS and Glonass enabled. Galileo and Beidou are each $1500 to enable.?ÿ
Interesting to note that right now GPS, and Glonass, have 6 SV's being tracked, Beidou has 5, and Galileo has 7.?ÿ
I've been seriously considering setting up an alloy on my office building and establishing my own ntrip correction stream for local work. I'd pull the trigger if cell reception was a little better around here. I'd be interested to know what some people's experience with an RTK bridge is. For example, how often do you run into situations with one where you can't get service? Another way of putting it, how much better than a cell phone is it?
There's time found if I just don't have to worry about setting up a base. I could even set the intuicom up on some tree covered ridge sort of "hidden" since it doesn't rely on sky view and rebroadcast into a valley where signal drops off...
I bought the Alloy to use as a local base here at the office and also a portable base (with an external cell modem).?ÿ
We used an RTK bridge for a few years, with an external roof mount antenna (optional item). Worked very well, definitely helped in marginal areas. As I mentioned in a recent post, it is a 3G and will not be usable after the end of this year.?ÿ
We usually use a mifi (we have 2) or a cell phone hotspot (all verizon) when doing RTK or VRS. But, our R10's both have cell modems (AT&T), one is a static IP (to use as a base) and the other is a dynamic IP. The latter can still be used as a base but it sends the data to my office server running SNIP. I can take the AT&T static IP sim out of the cell modem I mentioned above and put it in the other R10 if we need static IP on both.?ÿ
One thing I discovered recently is that using the internal R10 modem (AT&T) to connect to the VRS or RTK base seems to work a bit better in marginal areas than the mifi because the modem is out in the open on a 2 m rod, while the mifi or cell phone is inside the vehicle. In any case we have the option of using verizon (mifi) or ATT (R10), so depends on which has better signal. I live near WV which is notoriously bad for verizon coverage. I recently bought 2 new mifis that can take an external mag mount antenna. The guy at the cell store couldn't understand why I wanted to be able to use an external antenna. But that definitely helps as well.?ÿ
I'm in areas with no cell service often enough I'm thinking about getting one of the satellite hotspots. Knowing I wouldn't need to set up a base or finagle with cell boosters/bridges may be a good enough time savings to just go that route from now on when no cell service.
I have a satellite hotspot, IridiumGO. I cannot get it to work with VRS data. It supposedly has a 2400 baud channel, but I don't know if it is a firewall issue or what. I mainly bought it to use in remote areas for voice, but I was hoping I could use it in a pinch for data, but so far no go.?ÿ
I have Trimble Centerpoint RTX subscription on two receivers, it is very useful but does have some limitations. One is the init time, but they have really expanded the fast init area in the US this year. Once it is initialized it works like RTK, but a bit less accurate in the vertical component. However, I have had projects in remote areas that would not have been doable without RTX, so I make it a point to always have at least one RTX enabled receiver available for projects. My home state has a number of areas with no cell, so having the option of RTX as a backup when doing VRS is a nice fallback.?ÿ
Thanks, I'll look into the RTX trial - it expired a while back. Vertical doesn't really matter on much of anything I do. Mostly LOD, boundary, etc
I should add that it has improved, typical vert accuracy is 5 cm. RTX is in ITRF, but you can use an onboard transformation in the DC, or calibrate to a NAD83 point.?ÿ
Note: the transformation may not be as accurate out west, especially on or near the pacific plate. In that case I would definitely do at least a single point calibration.?ÿ
Question: if you lose initialization using the RTX correction stream does it take a long time to re-converge? Or does it sort of "know" some of the convergence parameters and re-init quickly?
With RTX, one thing to keep in mind is that it is not always easy to mix RTX and RTN data.?ÿ We output corrections from our RTN in NAD83(2011).?ÿ RTX outputs corrections (I believe) in IGS08 2014 epoch.?ÿ You have to use the ITRF to NAD83 transformation in Trimble Access when using RTX and the regular NAD83 transformation with the RTN data.?ÿ Otherwise you will have ~1 meter difference in the data.?ÿ I was recently told by Trimble reps to not use the ITRF to NAD83 transform.?ÿ Their reasoning was that it was an old transformation and did not account for any movement since it was introduced.?ÿ
I have been hounding both the TBC development team and the Trimble Access guys to give us a better solution for working between two reference frames, but it takes time.?ÿ Hopefully they will have something ironed out by 2022.
I rarely need real time coordinates. I use RTK and RTX for photo control/Lidar control where I need coordinates in the office and not in the field. If I use RTX I then use HTDP to convert. But, I feel that the onboard transformation is OK in the eastern and central US, but definitely not on the west coast. Unfortunately HTDP is not being updated, I hope they come out with a good replacement. If they do, I would see no reason why Trimble could not include that as a transformation option, at least on the data collector.
If you are in a fast init area, then it is usually less than a minute. Otherwise it might be up to 15m. You can go back to a previously surveyed point but it MUST be in ITRF. I just looked at a .job file from earlier this year, the RTX data is stored as ITRF08 epoch 2005.0. Looking at the receiver I see a configuration that says ITRF14 (probably not any significant difference from ITRF08) but it does give the option of fixed epoch (2005.0) or current epoch.
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Darker red is fast init...
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Another issue...if you are on the coast I have found there is a very good chance it might not work. Fugro apparently sells the service for offshore, and charges a lot more...usual customer is the oil and gas industry. But the "fence" inside the R10 is very coarse, and I have had multiple instances where I was on dry ground on the coast and it said I was out of bounds. The RTX people said I should just call and they can issue an over the air waiver, but what they don't realize is that probably the reason I am using RTX is because there is no cell service there...
If you are in a fast init area, then it is usually less than a minute. Otherwise it might be up to 15m. You can go back to a previously surveyed point but it MUST be in ITRF. I just looked at a .job file from earlier this year, the RTX data is stored as ITRF08 epoch 2005.0. Looking at the receiver I see a configuration that says ITRF14 (probably not any significant difference from ITRF08) but it does give the option of fixed epoch (2005.0) or current epoch.
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Darker red is fast init...
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Another issue...if you are on the coast I have found there is a very good chance it might not work. Fugro apparently sells the service for offshore, and charges a lot more...usual customer is the oil and gas industry. But the "fence" inside the R10 is very coarse, and I have had multiple instances where I was on dry ground on the coast and it said I was out of bounds. The RTX people said I should just call and they can issue an over the air waiver, but what they don't realize is that probably the reason I am using RTX is because there is no cell service there...
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Here is a plot of RTX derived height over the last day or so. Very consistent. It is deviating a bit at the end because a heavy rain with lightning and thunder just rolled through.?ÿ
For those who may be interested, learned today from my Trimble dealer that the R10(model 1) will no longer be supported. When, my support ends in 5 weeks, I will not be able to extend the support, and no firmware updates will be available after that date.
What a scam. They were sold as future proof, and just as the extra constellations are getting going they make it gradually obsolescent. I'm guessing it would need further updates in time to use the newest constellations properly.
There is a model 1 version 1 and a model 1 version 2. It's the 1.1 (the OG) that will be reaching EOL.
One thing I will absolutely Guaran-dang-tee you: If anyone (Trimble, Leica, Javad, TopCon, Acme Inc.) figures out a way to make GNSS work in the woods slam-dunk real-time, it won't come by way of your "next free firmware update". It will be tied to some new subscription service, or some new whiz-bang piece of hardware that will cost top dollar. And why wouldn't it?
What do you expect??ÿ If you went to a car dealer, would you expect them to still be selling a 1978 CJ5??ÿ Of course you wouldn't.?ÿ Of course Trimble is going to sell a new model every few years.?ÿ?ÿ How about your computer??ÿ Is the Compaq 486 you bought in 1992 still a viable part of your surveying operation??ÿ This goes along with Just A. Surveyor's question about low-balling?ÿ yourself into poverty just to get the job.?ÿ At some point you need to update your equipment, your pricing structure, your vehicle, your office, etc. ?ÿ Why is it the company that makes the equipment's fault??ÿ
What I'm trying to say, is that it is not a scam.?ÿ Topcon, Leica, and all the others do the same thing, but I never hear anyone complaining about them.?ÿ
