RTCM3 MSM compatibility issues?

Today I attempted to receive corrections via NTRIP with the RS2. I have an account with a local provider here in Canada (CanNet). Achieved connection with the server no problem but couldn’t get RTK fix at all. Reachview status was acting strange as well. The position display would jump between zeros/dashes and a Single point solution. Very occasionally I’d see a flash of ‘Float’ in the fix status. See attached screenshots.

I checked the Corrections Input tab and confirmed I have connections and was receiving RTCM messages. I tried several different mount points on the service.


Looking at the RTCM messages I see they are MSM 1073 (GPS) and 1083 (GLONASS) which are MSM type 3. So can someone at Emlid confirm if RS2 is compatible with MSM Type 3? I’m using latest version of Reachview (2.20.7). Thanks.

Hi Chris,

Could you please share with us:

  • raw data log from Reach RS2 in ubx or RINEX format;
  • position log;
  • RTCM3 base corrections log

You can download it in the Logging tab of ReachView.

Chris,

May I ask you to try another mount point providing MSM4 corrections? It’s possible that MSM3 doesn’t provide enough data.

I will check with the provider but I suspect that only MSM type 3 is available with the RTCM mount points. All the other mount points were either CMR+ or CMRx message styles. This provider is a Trimble equipment dealer and I believe one of the messages, 4094, is Trimble proprietary.

I will dig up the logs and upload.

Hi Chris,

Sorry it took so long to get back to you!

I can confirm that Reach RS2 required MSM4, MSM5, or MSM7 RTCM3 messages to calculate the RTK solution.

Have you tried to reach out to your provider? Have they got other mount points that can provide required corrections?

Yes I reached out to the provider and they confirmed that they are only providing the MSM3 messages. They did mention that they would look into providing the newer messages but had to check with Trimble to confirm backwards compatibility.

Good to know about RS2 requiring MSM4, 5 or 7 types.

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I became aware last week that the RS2 - in base mode - only sends out MSM4 corrections. Hence my other thread in Getting Started.

…BUT I hadn’t clocked that an RS2 rover will similarly only utilise the more modern MSM4, MSM5 or MSM7 type RTCM3.2 correction messages from the base.

I’ve only successfully tested my RS2 rover with another RS2 as a base and a handful of public mount-points from the RTK2go public caster. As it turns out they happened to all be sending out MSM messages…

I haven’t tested with my own Leica GR50 base just sending out bog standard 3.1 corrections as it’s off being repaired at the moment.

So @tatiana.andreeva will an RS2 rover not be able to successfully utilise “classic” (GPS + GLO only) corrections - that is RTCM 3.1 messages?

Hi @DirtyHarry,

Reach RS2 should work with RTCM3.1 without any issues.

However, different receivers may provide different correction messages, so it’s hard to say certainly how it will work without knowing which exactly messages a base transmits or without testing.

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Hi @tatiana.andreeva,

Would you be able to provide a list of supported RTCM3.1 messages? I think this would be handy for anyone looking to verify compatibility with other receivers. Thanks,

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Indeed that would be super useful.

Perhaps the RS2 online docs / wiki could be likewise updated with supported inbound RTCM 3.1 MT’s?

Hi @conehead, @DirtyHarry,

Please take a look at the table of supported RTCM3 input messages below:

Message Description
RTCM 1001 L1-only GPS RTK observables
RTCM 1002 Extended L1-only GPS RTK observables
RTCM 1003 L1/L2 GPS RTK observables
RTCM 1004 Extended L1/L2 GPS RTK observables
RTCM 1005 Stationary RTK reference station ARP
RTCM 1006 Stationary RTK reference station ARP with antenna height
RTCM 1007 Antenna descriptor
RTCM 1009 L1-only GLONASS RTK observables
RTCM 1010 Extended L1-only GLONASS RTK observables
RTCM 1011 L1/L2 GLONASS RTK observables
RTCM 1012 Extended L1/L2 GLONASS RTK observables
RTCM 1033 Receiver and antenna description
RTCM 1074 GPS MSM4
RTCM 1075 GPS MSM5
RTCM 1077 GPS MSM7
RTCM 1084 GLONASS MSM4
RTCM 1085 GLONASS MSM5
RTCM 1087 GLONASS MSM7
RTCM 1094 Galileo MSM4
RTCM 1095 Galileo MSM5
RTCM 1097 Galileo MSM7
RTCM 1124 BeiDou MSM4
RTCM 1125 BeiDou MSM5
RTCM 1127 BeiDou MSM7
RTCM 1230 GLONASS code-phase biases

We’ll add this to Reach RS2 docs as well.

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Many thanks @tatiana.andreeva :+1:

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