Quick question, if surveying/collecting points in Standalone/single mode is SBAS automatically enabled on an rs2+ or is there a way to do this? Also if in live mode with no need to post process would be ideal.
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@cdhuffman , SBAS I don’t think provides the level of accuracy you are looking for. What you are describing for your result is an RTK solution, which uses a nearby base, probably over NTRIP, and your RS2+ as a rover.
Some Government Departments in parts of the world provide access to these for free, others are commercial and likely require a subscription.
Hopefully this gives you an idea of where to start?
Joel
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No, I know what rtk is. There are places we go cell reception is spotty, or we’d be 100 miles plus from our base. A base brought with you and averaged over 10 minutes over Lora is not exactly very accurate either. SBAS correction/augmentiation would give us meterish accuracy.
If you are only going out with one Reach unit to do point-collection, then you could experiment with PPP service.
But if you are trying to stake-out points, that will not do you any good.
What part of the world are you working in?
And do you have an extra Reach unit that could be used as a base on-site?
(or would you be willing to purchase one)
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Ok, to give you full context, we work about 150mile radius from my office. NW Iowa, NE Nebraska, SE South Dakota, and SW Minnesota. Cell reception can be spotty at times. I have 2 reach rs2+'s, a Trimble SPS 585 on their RTX network, and an old handheld mapper made by spectra precision. I can do RTK with the reach rs2+'s at any time.
-Let’s say I consider the point taken with the Trimble SPS 585 to be truth, because I do
-I can record that same point taken with the rs2+ in single mode, it’s consistently 80+ cm off of Trimble
- I can setup an rs2+ as a base, average it’s position over 10minutes or whatever. Record the same point as the Trimble it’s likely within 30cm
-I can log a base position for a few hours, submit to OPUS to get a solution, use those coordinates in the rs2+ get a fix over ntrip (caster) the rs2+ rover point is dead on trimble’s point within several miles but degrades quickly the further away from the base you get plus we’re talking days of work/waiting. At 90 miles away it’s hard to get a fix and it’s accuracy is 30ish cm at that distance.
-I can collect the same point as my trimble with my handheld mobile mapper and it’s about 30cm or under precise everywhere I go. With the work involved setting up an accurate base, or any base for that matter to get about the same precision from the RS2+'s why mess with it?
-This handheld mobile mapper says it receives about 10 satellites at any given moment and a “differential”. Whatever this differential is, I was assuming SBAS (satellite based augmentation system) It requires no subscription to work, no internet connection, it’s just there when it boots up.
-So you may say just use the Spectra mobile mapper, or the trimble. The spectra mapper is old, 12+ years, battery life isn’t the best, there’s very little to no support for it, etc and trimble is just hard to work with. Their technology is locked down, you need to purchase subscriptions, their software to make things happen.
Thoughts?
I suppose if you don’t want to set up a base within 60km (~37miles) of your rover, then traditional base-rover RTK is not really recommended.
Let’s assume that some of your activities include stake-out, so PPP will not be helpful either.
Also, you are frequently working outside of cellular-range (which rules out RTK using NTRIP to get VRS-corrections from a large network-provider).
So,
to work only with Emlid gear, you must consider a compromise.
- establish a base-coordinate at each work-site and use base-and-rover (PPP/OPUS for base-coordinate and LoRa, or NTRIP)
Or, maybe if you begin at each site with the RTX-enabled unit (assuming it receives over satellite L-band and doesn’t need cell-service), then mark that spot permanently and record the coordinate. Then immediately plop your RS2+ on that spot, enter the base-cordinate manually, then begin doing RTK with the two RS2+ units.
@EBE111057 makes an interesting point about the PointPerfect (L-band) service. You could also contact me directly if you want to discuss a setup for that.
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Yep, you’re right on the money. 95% of the work is on the fly stake out. Generally I’d say 30cm precision is good enough.
Getting a point for the base with the trimble is the best workaround so far without spending a fair amount of money or waiting forever for an opus solution. I’ve seen the trimble point to be within 2cm of an opus solution the majority of the time. Pretty remarkable actually.
It’s unfortunate because I believe the rs2+ to be capable of tracking sbas, it does while logging I’ve read but doesn’t “live” Is that something emlid would consider incorporating in the future?
Yes, it sounds like you have the best workflow for your existing gear.
I can’t speak for EMLID, but working with SBAS-type corrections(or WAAS, etc., etc.) went out after ReachView v0.(updated info in later posts)
it has been all about RTK since the beginning anyway, so I doubt that use-cases for decimeter+ standalone-operation are part of the target-market right now.
Standalone centimeter-level L-Band would be interesting though, but I believe that is carrier-phase corrections (and not free); a separate class than the older code-phase corrections (mentioned above) that are free for sub-meter.
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I guess, I get that, but if it could do sbas/waas then why not? I’m likely oversimplifying it and there must be more to it or some kind of road block
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My guess is that if you want to capture a market for standalone, sub-meter receivers, that you would make that specific device and price it for that market (trimming off the excess hardware/software in the process).
And if you are selling an RTK receiver capable of 1-2cm accuracy, then you probably don’t want users talking about how they get 20-40cm accuracy with model “X”. Potential customers might just turn the other way. So there could be a few reasons that take precedence even before the conversation starts about getting users comfortable with another mode of operation.
Here’s one: what happens to the coordinate reference frame in mid-survey when you loose/or pick-up SBAS, and then what happens if you pick up cellular/NTRIP, and the CORS or VRS base-station is in a different reference-frame? Who is going to manage issues stemming from mis-alignment of different corrections-sources? Stuff like this can be handled, but at what cost, and does it make the product better for most users? …decisions, decisions.
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That would be concerning… Make it an option under correction input, not necessarily it’s default positioning system? Example, I’ve selected sbas/waas correction, it tells you when you’re in fix or float. Same with rtk, etc
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See, you’d be fine with it, but not everyone would “get” the difference between SBAS fix and RTK fix. Maybe it could be a good as a hidden function for advanced users who agree to “detune” their accuracy expectations.
“… but if it could do sbas/waas then why not?”
Perhaps because it adds almost nothing in terms of accuracy and sucks extra power?
A Ublox F9P board with WAAS will give you about 1 meter horizontal accuracy (95%) under good conditions. Turn WAAS off and it’s about the same. Maybe slightly worse like 1.2 meters perhaps. It depends.
Now if you have a more expensive board like say the Septentrio Mosaic WAAS will get you down to about 0.6 meters horizontal accuracy (95%). This is because the code psuedoranges are of higher quality and the WAAS corrections help more. This is about as good as you can do with WAAS, but even with the better board WAAS is probably not quite good enough for your use.
I don’t know what’s in your Spectra Precision unit, but if it’s a high quality code receiver that’s probably the best you will do with WAAS and any receiver.
Now Galileo’s HAS service sounds perfect, but it’s still in its infancy and any GNSS board that provides a real time ~20 cm position is still > $1000 as far as I know.
In short it sounds like you will have to spend a little more time and/or money to get what you need.
Cannot remember, but i think the old single band L1 RS/RS+ does SBAS. Not for sure… but either way, still going to have submeter accuracy vs cm accuracy autonomously middle of nowhere. They are obviously lower cost on Ebay etc now and then… and Emlid discontinued them.
Just an idea, but again, not sure.
They have old data collectors such as Trimble Nomad that i think work in SBAS mode (built in DGPS?). You can load MicroSurvey FieldGenius, SurvCE, Survey Pro etc on them. Some come with them installed if lucky. If you don’t need more than 30 points, some have that limit in demo mode.
Again just ideas as I need cm or even mm accuracy, so sub meter doesnt cut it and considered… dated to me. I think Juniper Systems, BadElf, etc may be something u could look at? But for the money… Emlid in my case!
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I always cringe seeing folks talk about RTK when PPK would be better. PPK produces better results, RTK is just for convenience. If you have a single receiver you should be using logs from a CORS station or whatever you have in your area to correct your logs.
NTRIP is only for situations where RTK is absolutely necessary, like controlling a robot or a drone.
I think the lack of knowledge about PPK is because GPS manufacturers have marketed RTK, and people outside of the GIS/Geography field don’t learn about postprocessing by default.
Hi Chad,
I can confirm that multi-band Reach receivers support SBAS corrections. They are turned on by default. You can see how many SBAS satellites Reach is tracking in the Reach Panel or in the Status tab of the Emlid Flow application (SBAS satellites are marked with the letter S).
SBAS accuracy is 1m CEP and can vary in different areas depending on SBAS coverage. If you need higher accuracy, RTK or PPK is required for RS2+.
As a workaround, you can use OPUS, as mentioned by Ceith. You can also shift the data in the office after the survey instead of waiting for the base log to be collected and then for the OPUS solution.
UPD. Changed my answer to specify that multi-band Reach receivers support SBAS corrections.
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Thank you! This is all I wanted to know, I really appreciate the confirmation!
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@olesia.riman This is an interesting surprise to me. When did SBAS corrections for single-mode get merged into Reach firmware?
I was holding the opinion that that SBAS satellites were tracked for positioning only; and that the SBAS correction-messages were not being used.
(neither for single-mode or for RTK)
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Not sure I agree with this. If Reach can provide 7mm + 1ppm by RTK and 5mm + 0.5ppm by PPK, with no additional effort, I’d say that if most people were within 10km of a base (or own base on site), they would probably not know the difference (something like 7mm XY, 4mm Z). When it comes to Staking Out, PPK can’t really help you anyway.
I’m always happy when I hit the same nail on the head.
My 2 cents.
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