Comparison precision REACH vs. REACH-RS

Dear community

During a test to stack-out a straight line with an old “EMLID-REACH” module using the official and precise NTRIP-correction (using a VRS with very short base-line) of the federal-land-survey in an optimal flat region, the points varied up to 30cm from the planned straight line.

For the planned application, we have to stack-out the points along straight lines of 150m (one point every 5m) within a margin of about 3cm.

So, I have to get about a factor of 10 better than with the old “EMLID-REACH”.


  • Could you imagine, to get such kind of accuracy with one RS-2 (using NTRIP) or two RS-2 (local base-station at known survey-station)?

Looking for any suggestions, ideas and hints.

Best regards,

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Oh yes …and then some! The newer technology will be leaps and bounds better and the ability to get that kind of accuracy should become commonplace. I have a pair of RS+ receivers and can easily attest that my success rate of maintaining a 90th-percentile fix was pretty horrendous in comparison to other survey gear I had become accustom to. They would RTK “just ok” in near perfect conditions, but were great for PPK use. no that I have the RS2 receivers I don’t miss my Topcon setup much at all.

This is a typical example of RTN survey (not RTK, not PPK) where you should get easily required accuracy using only a single Reach module. To determine very short vectors, here at most a few dozen meters, no more sophisticated receivers are required (here the need for one rover is mentioned, because the base is VRS).

If your test was performed with ‘fixed’ only solutions and you have raw.ubx and base.rtcm3 files for this session, I’d love to check where the reason for the failure is. For this I need this post-control survey file with assessment of these errors. Nothing more, although it is worth ordering one VRS postprocessed for some point.

These three files are enough.

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You say you haven’t had good RTK results with RS +?

In comparison to the Topcon and RS2, no.

Yeah, the L1 is the sinner here, i would think.
I tend to agree with @chascoadmin where L1 used with RTN network (VRS too) in comparison with with other dual/multiband, they just have leverage, forgiving in bad condition and less affected with less optimal setup when you mix in different brand and gear.

BUT, and its a great BUT with L1 (Reach, RS, RS+). If you know why its performing less then it should and know how to counteract, ususally with a second unit. This combination could kick some seroius but(t) :rofl: (Phun intended). Yes it’s a bit cumbersome but still viable.

I am not going into details, that story would grow bigger than a phonebook.

One example of Bigbrand in dont mention with VRS vs short baseline (RS and RS+).
I happen few months back when subcontractor working on fundation had to lay a point on the ground where the cell coverage was poor, lot of skyview blocked. Had no luck getting FIX, but putting up a RS on a tripod nearby, borrowed his VRS service and FIXed that base, swapped from VRS to Base/Rover configuration with LoRa. Got a short baseline with more common visible satellites, i managed to place a solid FIX.

My point is, know your way around to make things work (yes of course, sometimes its more cumbersome and throwing money at it with better tools is the less painfull way, i understand. Time is money, I am there too).

Edit: To speculate in the topic. I would think something went wrong. VRS and RS in ok surroundings should have no problem getting result equal to any other gnss tool.
I would also like to see files from this survey to investigate further.


Unfortunately, there are no VRS stations in Argentina and I cannot comment like you. I always use my own base without any problem with RS + and RS2


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