RS+ Fixed drops to Float after taking a few points

I have 2 RS+ units with firmware 28.4. They communicate via LoRa. I’m not overly experienced with the units and terminology, so please forgive me in advance. I’ve sent off full system reports with the debug feature to support, but they haven’t been helpful yet, so I’m reaching out to the Emlid community.

I had our base unit replaced under warranty a year ago and am not sure the units are still up to par.

I’ve had multiple cases where I set up the base, wait at least 15 minutes for the GPS location to be firmly established, and then get a FIX on my rover. I then begin measuring points in FIX mode, when it abruptly changes to FLOAT. Then it will not re-establish a FIX, no matter how long I wait, nor if I’m back right beside the base with my rover. We have the identical setup in another office and there are no issues (i.e. same settings, etc.). That leaves me to believe I have an issue with my rover or base. I realize I need a clear line of sight and in the problem cases I’ve had, there were clear lines of sight - no obstructions, no power lines, etc. In one instance, I restarted both units 3 times and I could take a few FIX points, and then was stuck with FLOAT.

Does anyone have any suggestions? I could post the system reports here, but am a little concerned about what information I’m sharing within those reports.


Hi @Can-Man,

What about the sky view? Are both base and rover provided with a clear sky view at least 30 degrees above the horizon?

Also, any chance you happen to notice whether the corrections are stopped being transmitted when Reach goes from fix to float?

The issue can be caused by two different reasons here: obstructions blocking the sky view and obstructions blocking the LoRa link between the units. If the corrections keep going, it’s most likely the issue with the sky view. If the corrections struggle, then we need to look into the LoRa transmission issues.

Thanks Tatiana. I had clear sky view - nothing near me, including power lines. I haven’t checked about corrections at that time. Next time this occurs, I’ll check that. When it occurred, my rover was only 20 meters from the base, such that I could see it clearly. I thought it may be a LoRa antenna issue, but everything looks fine. Thanks for the reply!

Okay, thanks for the clarification!

Also, I’d recommend swapping the base and rover roles and checking if it changes the situation. If something is indeed wrong with the LoRa, it should help to eliminate the misbehaving unit.

One more thing – is this behavior repeatable in different locations or you tested everything in one place?

This has happened in multiple locations. Given our minus 30 weather, I won’t be testing anything for a bit. But, I’ve updated to the latest firmware. I’ll swap the rover and base roles after the weather warms up. Thanks for your suggestions!

Sure, hope the weather will get better soon! I’d not go testing outside in minus 30 too :sweat_smile:

Keep us posted

I’ve swapped the base and rover roles, as well as updated to the newest firmware. Unfortunately, I had the same result today - take a few points on FIX and then drops to FLOAT, and will not go back to fix. Today’s test was at another location, so it’s not specific to any one place. The rover is receiving corrections from the base and everything else appears to work fine, until I can no longer get a FIX.

I’m open to suggestions and could buy a replacement unit(s), but want to know what the issue is, and that a replacement unit will solve my issue. Thanks!

Hi Don,

Thank you for testing! That seems to be really odd. Can you send us the raw data, solution, and RTCM3 logs from both base and rover so that we can see what’s happened during the survey? You can just respond to the email where you communicated with us for the last time.

Also, I have noticed you’re running not the latest firmware, so I’d really recommend updating to 29.2 which is the latest stable to eliminate any possibility of the software issue.

The guide on how to update the device: How to update firmware | Reach RS2/RS2+

Thanks Tatiana. I’ve sent the files. Note that I did update to firmware v29.2 last week before swapping base/rover units.

Hi Don. When troubleshooting, nothing beats being able to rotate in a known working device to pin down where the system is breaking down. Any chance of you using being able to substitute the units from the other office to see which one of your units (if any) is the source of the issue?

Thanks for the suggestion Dave. My partner’s 3 hours away, so not ideal, but maybe shipping them up to me for troubleshooting would be the next step. I was hopeful that swapping base/rover would point to the issue, but no luck.

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Hi Don,

I’ve just replied to your email, since there was some sensitive data in the logs. You can check my response in your inbox.

After some troubleshooting and assistance from Kirill, this appears to be a base placement issue. The Lora radio is working fine. My signal-to-noise ratio has several yellow bars and only a few green bars, but all are above 35 when I have good base placement and that’s giving me a FIX. Just wanted to wrap up this thread in case others have this issue - and if so, ensure your base has a fantastic sky view, no power lines, no other power sources near (e.g. cell tower), etc. Base placement may FIX your issue. Cheers!