Best settings for base mode

I want to optimize my base mode settings for a Reach RS2 base. Currently I have GPS, Galileo and Glonass enabled at 1 Hz. Is there any advantage in increasing the sample rate? Will I get faster fix if I had 10 Hz instead of 1 Hz?

I am located in northern Europe (Denmark). I read that BeiDou now has world wide coverage. Can I get any advantages from enabling BeiDou? The documentation says “Remember, that you can not use GLONASS and BeiDou systems together”. Will I have to disable Glonass if I want to try BeiDou? If so, which one is the better satellite constellation in late 2020?

We are using rtk2go.com as an easy way to access the base:

http://rtk2go.com:2101/SNIP::MOUNTPT?NAME=GlostrupDK

The base has a data SIM card that allows it to connect to rtk2go to publish the NTRIP stream. The clients likewise have data SIM cards and download the NTRIP stream through rtk2go. That way we do not have to worry about the base changing IP address. Do I lose anything by doing it this way compared to connecting directly?

PS.: if Emlid reads this, please make it possible to update the Reach RS2 without wifi or usb. The device has a perfectly fine data SIM that provides internet with plenty of data. Why am I not allowed to update the device without disassembling everything and bringing it to the office wifi?

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Nice to see a fellow dane here!

Let me try to answer your questions:

For the base, not really, 1 hz is more than plenty for normal usecases.

Nop

This is the case for the Single frequency RS/RS+ only. For the RS2/M2 you have run both GLO and BEI at the same time.

If I had to prioritize (which we don’t have to with the RS2), I would say GLO.

I will suggest using a GNSS planner for seeing available signals at any given time and place on Earth: GNSS Planner with Obstructions

Yes and no. Yes, as RTK2go only supports up to 30 sats for base correction. Most times, with all constellations enabled on the RS2, there will be more than 30 sats for the base correction stream. However, we are usually talking 2-5 lost sats to this limit, so not a big thing, hence the “no” also.

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With the RS2 I have everything turned on with a 1Hz base and 5Hz rover. With the RS+ we were limited on what combinations. The only thing a faster data rate does is collector more data, but I have not run it on an RS2 so it may limit what all you can have turned on at the same time if the system can crunch all that data at once. It does fine at 5Hz.

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I use M2’s for tractor guidance. Same settings as above. When i was using m+ same settings.

Base satellites and refresh 1hz, arp 0.1hz

Rover 5hz

The higher refresh rates would be handy if you want to drive really really really fast.

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I also use the higher refresh when I have it mounted to my truck.

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I too set my rover to 5hz because I like driving 90mph on the freeway with my survey rod hanging out the window going between GCPs!

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Hello Christian

Thanks for your detailed reply.

I asked SNIP support about the limit of 30 satellites and they deny that such a limit exists.

Regards,

Baldur

I think there is a distinct difference between using RTK2go via snip or directly via the rtk2go:

“Send your Base Station data to RTK2go® if you do not wish to run your own NTRIP Caster.
Please download your own copy of SNIP® if you want to run your own NTRIP Caster.”

I have only used rtk2go directly from the RS2, where I, at least last year, only saw 30 sats.
I have no experience with using SNIP through RTK2go, so there might not be that limitation there.

How about elevation and SNR settings? What is the best setting for a RS2 in base mode? Is it better to lower the filters to get more satellites and then the clients can filter the ones that are not good enough?

I use a 17 mask and 35 ratio. This one really depends on the situation. If I am having trouble getting satellites then i’ll bring the mask down one and the SnR up two with the minimum mask being 13. In another scenario if I have plenty of satellites, but and not get good data and they appear to be bouncing all over the place I drop the SnR. Lastly if you are in trees you can just increase the maks sometimes to go green.

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I would leave the degrees at 15 no matter what. At such a shallow angle the poor signal has to fight through a bunch more dense atmosphere.

Ever watch the sun get huge just as it rises or sets. From google:

The larger size is caused by a refraction of light when the moon is at the horizon because the light has to pass through greater amounts of atmosphere to reach you compared to when it is overhead. The same is true of the setting sun .

Key word there is refraction, the gps signals are high frequency emf like light. They may not bend, but you can refract or reflect them. This is why that setting is there to get rid of the really noisy signals.

5ghz wifi will also do this off of a thermal inversion, causes rural internet outages here in spring and fall.

As for signal strength i would leave it at the stock number as well.

I have had very little issue with the M2 dropping out, even with the antenna vibrating. The only places that i lose fix are very obvious; inside metal buildings, directly under 40ft tall spruce tree canopy.

I have tried both M+ and M2, the 2 is the champ! best gps unit I have ever owned or operated machines with. It always has 20 to 30 sats at its disposal where I am at. (one time 34)

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I can assure you from our experience this is not necessarily true. While we do not push it too far an extra degree here or there can make the difference in whether you are able to work or not. Of course atmospheric conditions have allot to do with it, but we have seen occasions where satellites above 15-degrees had high enough SnR values that we had to include a few lower lying satellites just to be able to go. While this may not be the most desirable scenario it is sometimes necessary and is perfectly fine in the right environments. If the PDOP, ADOP and SnR values are acceptable keeping lower lying satellites as part of the solution can actually help accuracy because of the much stronger geometry that is created. Inversely if you cut too many low-liers then you can weaken the geometry and precision will start to suffer. We have seen occasions in forested and urban environments where we couldn’t get an initialization until about 40-degrees because of the limited sky view so that combined with the fact that we were probably going to run into issues maintaining a fixed-solution we would then decide to use the total station instead.

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Hi @baldur.norddahl,

Generally, I agree with Christian, Michael, and @PotatoFarmer. However, I would add some comments on the discussed questions:

Will I get faster fix if I had 10 Hz instead of 1 Hz?

I want to emphasize that the update rate only defines how often the receiver calculates its position per second. It doesn’t affect the time-to-fix.

If Emlid reads this, please make it possible to update the Reach RS2 without wifi or usb.

Firmware updates are usually heavy and capacious. In that case, the Wi-Fi connection is more reliable. That’s why we haven’t got the support of updates via mobile data.

How about elevation and SNR settings? What is the best setting for a RS2 in base mode? Is it better to lower the filters to get more satellites and then the clients can filter the ones that are not good enough?

The elevation mask filters the satellites by their height above the horizon. The SNR mask filters the noisy signals. Elevation and SNR masks allow excluding satellites with a poor signal that might affect the solution in a bad way.

Our default recommendation is setting the elevation mask to 15 and the SNR mask to 35. However, sometimes it may be useful to change these values. For example, if there are not enough data to calculate a fixed position, you can set a lower elevation mask to track more satellites. In another case, if there are too many noisy signals, you may increase the SNR mask.

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