Reach M+ and u-blox ZED-F9P compatibility

Is the M+ and the F9P (SimpleRTK2B) compatible with each other? Can I use the M+ as base and the F9P as rover and vice versa? (I know that the M+ is single band, so I can’t take advantage of the F9P being multi band.)
Thank you!

I’m pretty sure you can use as a local network RTK, i.e. Emlid caster. However I’m not sure of Lora method unless you have the same radio.

Another issue is that you’ll have to have a separate rover software for the ZED-F9P. I don’t think their software will work with the ZED.

I’ve got 2 of the ZED-F9P evaluation kits I bought about 3 years ago. They are pretty neat devices. I’ve been meaning to set up one as a base at my office but just haven’t had the time. It appears to be a pretty easy process to setup per the manual.

I’ve got one running using the UBLOX software with the antenna on my desk. They are very sensitive receivers.

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Hi @Lloyd,

Welcome back to our community!

As you mentioned, the Ublox Zed-F9P is a multi-band GNSS module. In this case, it should require multi-band base corrections. Reach M+ is a single-band GNSS receiver, so it can hardly be the base for this module. The situation is really similar to what we described in this support tip.

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Thank you for your replies Bryan and Zoltan!

Bryan,
I want to use a network connection for the correction data.

Zoltan,
Hi, isn’t a multi band receiver backwards compatible with a single band receiver, so that the multi band receiver would work as if it were a single band receiver?
According to the post you linked and assuming that it is true for any receiver (not just for RS+ and RS2+):

  • [single band base] and [multi band rover] shouldn’t work
  • [multi band base] and [single band rover] should work

So that means that an M+ rover is supposed to work (and able to achieve fix) with an F9P base (without the benefits of multi band, of course), but an F9P rover and M+ base would not work?

Hi Lloyd

Why don’t you buy the dual frequency M2 ? When using single frequency and dual frequency together you’re not taking full advantage of what 2 dual frequency receivers can do.

The M2 cost is very reasonable for a dual frequency receiver. You’ll have to buy an antenna and power pack, but it’s far cheaper than getting a RS2/RS3.

I’ve got 1 M2 and an RS2. I usually use the M2 as base. It’s an economical solution if you’re on a low budget

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So that means that an M+ rover is supposed to work (and able to achieve fix) with an F9P base (without the benefits of multiband, of course), but an F9P rover and M+ base would not work?

Exactly! That’s the conclusion! But Bryan is also right. Using a multi-band rover, you would have the benefits of the multi-band ZED-F9P module.

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I wanted the question to be general, so I didn’t include more information than necessary.
I already have two M+-es and a SimpleRTK2B (F9P), I think single band is good enough for my use case, so I don’t want to buy any new hardware. I need two rovers and one base station.

With my current setup, consisting of one [M+ as a base] and a [custom PCB] designed for an F9P but I used it [with another M+] instead of an F9P (didn’t have the F9P at the time), I was able to achieve fix and worked well. Now I’m trying to add an F9P, I bought it since I needed an extra rover and the PCB is designed for one anyway.
When I tried to use the [M+ base] and the [PCB + F9P] (F9P replacing the M+ in the previously working setup) I was only able to achieve float in the same situation (time of day, location, etc.).
Using the [F9P] (SimpleRTK2B + UART to ethernet converter) [as base] with the [M+ integrated into the PCB] (the same way as it was in the originally working setup), in the Flow app I can see that it is receiving the correction data but it still stays “single”.

In an attempt to find out what’s wrong I’m trying to understand compatibility, so can somebody point me to a resource or help me to understand how does compatibility work regarding the combination of an M+ and an F9P, or just in general? Why is it supposed to be compatible as F9P base and M+ rover, and not as M+ base and F9P rover? I know one is single band and the other is multi band, but why can’t a multi band receiver work as a single band receiver when used as a rover with a single band base station?

The reason why you can’t properly use a single-band receiver as a base for a multi-band one is that the single-band operates only with L1 correction. If a single-band rover obtains extra L2 corrections from the base, it can just ignore them. But a multi-band rover requires multi-band corrections, so single-band ones won’t be enough to fix all the uncertainties for both frequencies. Since the uncertainties are not fully fixed, the rover shows a Float solution.

Using the [F9P] (SimpleRTK2B + UART to ethernet converter) [as base] with the [M+ integrated into the PCB] (the same way as it was in the originally working setup), in the Flow app I can see that it is receiving the correction data but it still stays “single”.

But it’s curious why you can’t get Fix with this setup. Could you please double check in the Zed-F9P’s documentation if the unit can provide 1006, 1074, 1084, 1094, and 1124 RTCM3 messages?

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Thank you for the explanation!
According to the docs at the bottom of page 7 it can provide 1074, 1084, 1094, 1124, but not 1006 only 1005.

Thank you for checking it! 1005 should work just fine instead of 1006. So I think we should search for the source of this somewhere else. Could you please detail your setup? How did you set up your base? Did you set it up with manually entered coordinates or average it?

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Since then I tried without the custom PCB (only SRTK2B and M+), but the results are still the same: it receives correction data but stays single.

Setup:
[SRTK2B + UART to ethernet converter{TCP server}] <-ethernet cable-> [local network] <-wifi-> [M+ {TCP client}]

SRTK2B:

  • Firmware update: official instructions
  • Config: official instructions using “Automatic Survey-In” (so averaging)
  • I set the messages to both the recommended defaults from the instructions and to the list you’ve asked about except 1005 instead of 1006, same results.
  • Using ncat I can see that the messages are broadcasted.

M+:

  • Correction Input set to TCP client
  • Status overview says:
    • Solution: single
    • “Receiving corrections” (I can also see the grey bars on the Satellites page)
    • Satellites in view 29
    • Empty (“-”): Age of corrections, Baseline, Base position

In the same situation with my other M+ as base instead of the SRTK2B I can achieve float (as expected since antenna has bad placement).

Can anybody help me, please?

Sorry, it took me so long to reply, Llyod. Your setup looks fine, so I think we should search for the source of this somewhere else. As a next step, I’d like to check the quality of your log. Please record the following logs for at least 10-15 minutes with your Reach M+ outside:

If your SRTK2B is also capable of recording logs, please record some with it as well. Once the logs are recorded please send us to support@emlid.com. Thank you!

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