LEICA GS15 Rover with Trimble base help

Check if the Trimble base is set to CMRx rather than just CMR or CMR+

The CMRx format is scrambled so only Trimble kit can understand it. You'll probably be getting 100% on your Radio but no fix.?ÿ

Do you know which CMR protocol is being broadcast??ÿ (CMR, CMR+, CMRx)?ÿ More than likely, you will have to change the broadcast protocols to RTCM.

Isnƒ??t CMR a Trimble proprietary broadcast format?

@robertusa

From what I understand, older versions such as CMR and CMR+ are not proprietary any more.

CMRx remains proprietary to Trimble receivers.

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Edit: found this helpful article. A little dated but some more info.

The bigger issue will be using opposing manufacturer equipment. They're always fighting to stay ahead and playing nice isn't their main focus.

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My $0.02

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I have never tried to do that. It might be possible to use NEMA output or RINEX out and in like it is a network rover but the two units are the network?

I have done this sort of thing using Trimble receivers with a client-supplied Topcon base, and with Leica receivers and Trimble bases.

I think @fairleywell has the right solution. RTCM is usable by pretty much any modern-ish receiver out there.

The only caveat is that depending on age of the base and/or rover, you might have to select an older version of RTCM, and depending on the constellations available at the base and/or rover, that in turn might limit your ability to use full GNSS in RTK mode.

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You can use a Leica receiver with a Trimble base with the correct settings (I have done it in the past).?ÿ The first thing to remember is that for radio communications to work you need 3 parameters to match.?ÿ The first and most basic is that the base and receiver need to be on the same channel and spacing which is a no brainer.?ÿ Next, both need to be speaking the same language like CRM or RTCM.?ÿ The GS15 should be able to use the CMR or CMR+ Trimble formats (CMRx is proprietary).?ÿ Finally, both radios need to be on the same signal modulation protocol.?ÿ For the TrimMark3 I think it needs to be GMSK while the Pacific Crest can use GMSK and at least 4FSK.?ÿ Forward error correction (FEC) is also part of the modulation setup.?ÿ For Trimble I think all of these are set as part of channel setup on the base radio.

On the GS15, the modulation type is set as part of the radio configuration under devices while the FEC is set per channel.

I am assuming that your GS15 has the UHF radio module installed.?ÿ The cool thing with the 15 was the ability to swap radios between GSM, UHF & spread spectrum.

@john-putnam John is correct the problem is the Trimtalk V1 protocol, you need to change it to something generic. CMR is no problem per se but if you're transmitting multi-constellation corrections CMR may not have enough bandwidth, you're better off with CMR+ or a later version of RTCM.

While CMR and CMR+ (necessary to use GPS and GLONASS) are now public, I have found that other receivers sometimes do not work well with these, even though they have an entry for CMR. If you want to use multi constellation, they will need to broadcast RTCM V3.x.

In addition, the radio format (trimtalk) may be an issue. And be sure the over-the-air baud rate is correct.?ÿ

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Hi all, thanks for the replies.

The Trimble base is pumping CMR+ (not CMR or CMRx).

I will try changing the base to transmit CMR only and see if it helps.

@lorenzo-giusto any update on if you were able to get it working?

I think CMR is US satellites only, CMR+ adds glonass. You will need to set your Leica to the same frequency and baud, and probably switch the base to a RTCM format, if that wonƒ??t mess up other workflows for the project.