FIX Takes Too Long to Acquire

Reach RS2 / RS2+ RTK / PPK configuration
1

Background: Reach RS2; ReachView version v.2.20.8; iPhone 6S, iOS 13.3; AT&T Netgear mobile hotspot; NTRIP source = California Spatial Resource Center; Full System Report attached (I hope).

Issue: Wait 5 to 30 minutes or more to achieve FIX.

Steps: Turn on GNSS & connect to ReachView via Wifi from mobile hotspot; Select NTRIP URL, port number, and caster closest to me (preferred) (21 - 44 km away). Takes 5 to 30+ minutes to get FIX, if at all. Sometimes changing to another caster helps reduce wait to 5 - 10 minutes.

Remedy sought:

  1. Why does acquiring a FIX take so long? 2) How does one attain a FIX quicker?SystemReport.zip (2.1 MB)
2

Can you also post the rctm file and .ubx file from the Logging tab?

4

Hi John,

Does this NTRIP support VRS?

5

Yes, according to the statement on this webpage. Reach RS2+ by Emlid | Multi-band RTK GNSS Receiver for mapping

6

Yes, thank you for asking. Here are 4 files: RINEX-3_00, RTCM3, ubx, & XYZ.

raw_202001101926_RINEX-3_00.zip (6.0 MB) base_202001101926_RTCM3.zip (909.8 KB) raw_202001101926_ubx.zip (7.5 MB) solution_202001101926_XYZ.zip (73.7 KB)

7

John, I mean your NTRIP provider

8

Ah. I do not think so. I performed a search for “VRS” on their site, and no results were found. http://sopac-csrc.ucsd.edu/index.php/csrc/

9

Thanks!
Have processed it, seems you have made a measurement of static point, right ?
When on the static point, I have no problem getting a fix. The NTRIP correction start at 19:38, I get a fix at 19:41.

10

Thank you for running the data! I am new to this so your patience and understanding is appreciated. When I tried to capture the location of a target (CP4 in my notes), after waiting 30 minutes, I tried rebooting the GNSS & tried a different caster. Some how I was able to get a FIX solution. Maybe the data for this point is not in the set I sent you. May try to re-run this test in a few days, depending on weather. Do you have recommendations how how to achieve FIX status of a target on the ground within a couple of minutes using an NTRIP 21-43 km away?

11

If you are using it for static work, remember to set it to static. Also be sure to look into your SNR- and Elevation Mask.

If you find that somehow your are not getting a fix, eventhough you are in a good location, switch to kinematic, wait 30 seconds, and then back to static. this is to force a reset of the RTK engine.

12

Interesting. I am doing PPK processing, therefore RTK settings = Kinematic. Therefore you’d suggest switching to Static, then Kinematic? Please excuse my ignorance…what is static compared to kinematic?

13

Ah ok, then it’s a completely different story.

I assume you are using RTKpost.

Keep to static, but remember to limit your processing to exact start/stop time you were on the actual point.

Of of course remember to use both L1/L2 when processing. If only using L1, it will indeed take very long, and the fix will be unstable.

14

Use static? Interesting. Honestly, I do not understand how to interpret the SNR graph on status. What should I look for? As for elevation mask, if I have a hill or tall trees, say on the south side and not on the other 3, should I still set elevation mask to be above the hill or trees in the south?

15

Regarding the SNR, if you choose a specific band (I would recommend L1 for this) and then you can see the SNR Legend buttom right in the window.

Hills, hmm always a difficult size. However, in RTKpost you can set the elevation mask based on SNR. This I find most useful!
In good condition this can also be used to get more sats used for the solution.

17

Hmmm. Been getting 31 / 13-15 satellites with default mask & SNR levels.

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