Any recommendation for an affordable sub-meter / RTK setup?

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Alex

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May 16, 2021, 10:12:21 AM5/16/21
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Hi all,

I am using the Samsung S20,  just trying to find if there are any affordable solutions (<$800 USD) for a L1 / L5 RTK setup?

And referring to the seminar by Google in 2018, how far are we from getting the RTK correction for the Android's internal GNSS via nTrip?

Cheers,
Alex


Lodro Gyamtso

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May 17, 2021, 9:18:20 AM5/17/21
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at this time, sub-meter accuracy is only for professional use. This has to do only with the cost. If into the future there are cheap solution, i am 100% sure that you will be the first to learn.

we don't need dual band for sub-meter accuracy. We can have one external GPS receiver with SBAS and RTK (with subscription per month)

gpsfan

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May 17, 2021, 5:29:09 PM5/17/21
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I think I've written about it before here but you can get centimeter accuracy with a uBlox 8 USB receiver for about $10 ! Single channel of course but with RTKLib you can get that in real time with a free RTK feed or with post-processing using RTKPost. A small Windows laptop will do the trick or even an Android device with USB Host.
Over Bluetooth it will be decimeter accuracy with an old SiRFStarIII receiver and only with post-processing as SiRF compatible versions of RTKGPS+ do not work with RTK feeds for some reason
The next step up and dual frequency will be a Polaris SkyTraq Bluetooth Receiver, the S100+ for instance but the $ gap is huge, it's going to be around 300€. Other options with the uBlox 9 chip would be Ardusimple, about the same price with a good antenna.

Lodro Gyamtso

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May 18, 2021, 12:20:58 AM5/18/21
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Hi gpsfan,

the user into post 1, also a lot of others are typical consumers. They don't have the knowledge of electronics and programming. They likes products to be small, handheld, to working into real time with no after time procedures of post processing. They don't like DIY (do it yourself) samples. That's why i made this answer.

If he had your experience, he would not ask for such a thing.

gpsfan

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May 18, 2021, 3:19:28 AM5/18/21
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No "typical consumer" needs centimeter accuracy, it's only going to be for the "fun of it". Anyway it's not rocket science, I'm just a hobbyist who likes to piece together information  (everything is available for free on the internet) and "make things work". I started looking into centimeter accuracy around early February and once I received the $10 uBlox 8 USB receiver I got centimeter accuracy with post-processing in a few days and real-time RTK a few days later. Post-processing requires a bit of work but RTK is very simple provided you have access to a free stream (there are many around the world). I thought of getting the Polaris SkyTraq or Ardusimple receivers for DF and faster convergence but I don't really need it, actually I don't need it at all ;-)

Lodro Gyamtso

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May 18, 2021, 5:44:35 AM5/18/21
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Hi gpsfan,

if you read carefully both on 2 lines into post 1 you will understand that the user wants to learn when he can buy his new samsung galaxy s series with sub meter accuracy at a price below 800$

why that ? because google company at year 2018 said that they are working on this project. do you know the answer to this question of the user made ?

Sean Barbeau

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May 18, 2021, 6:18:55 PM5/18/21
to Lodro Gyamtso, GPSTest
>And referring to the seminar by Google in 2018, how far are we from getting the RTK correction for the Android's internal GNSS via nTrip?

Alex,
I recently launched the GPSTest Database to crowd-source device GNSS features - see this article:

If you look at the database:

...Column N "Carrier phase (getAccumulatedDeltaRangeMeters())" indicates which devices return info from the GNSS measurements API necessary to do RTK. See the above article for more info.

As to whether this will get you decimeter-level accuracy/precision - that is a separate question.

Sean


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Lodro Gyamtso

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May 19, 2021, 2:09:34 AM5/19/21
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Ηι Sean,
before say anything, i will remind to you that i am not a programmer, i am the customer - the end user.

1.
You are saying that when we see
Column N "Carrier phase (getAccumulatedDeltaRangeMeters

this means RTK. But we are "end user", not programmers. There is no final android smartphone device into the market

2.
when we go back to 2018, we saw Xiaomi Mi8 with additional gnss receiver (broadcom 47755) inside the android smartphone as one (1) product. But we never saw sub meter accuracy (30 cm), as broadcom promises to the customers.That was a big lie to us.

in the other hand, after one year, there was into europe market, 2 professional android smartphone devices
- Spectra Precision MobileMapper 60
- trimble TDC600
both of them are clone devices. The cost into Europe is 2200-2300 euro (include taxes) . Just like Xiaomi Mi8, they have one additional gnss chip, but this time is from ublox, the model M8N. This is only L1 band chip. Into the market this chip cost around 10 euro. it also support 10 Hz measurements

so, in july of 2019, i test Spectra Precision MobileMapper 60 for 2 days with your application GPSTest. On day 1 i saw 1.1m and day 2 i saw 0.9m. It was into the city, not into the sea or mountain.
YES, this is submeter accuracy. I made PPP measurements, only from satellites. the device was into airplane mode, with no sim card, no internet access

conclusion
i have the necessary proofs, that we can have cm accuracy into one handheld device, BUT this will cost. For now those are the professional android smartphone devices

Lodro Gyamtso

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May 20, 2021, 2:08:19 AM5/20/21
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I will add some more info about professional smartphone devices. I am not suggest anyone to buy those products. I only want to proof that we can have as low as 60cm static accuracy, using only PPP satellite reception, from L1 GPS + SBAS
The company UniStrong makes OEM products for the follow well known professional GNSS companies (maybe others)

- Hemisphere GNSS
- stonex.it
- https://www.janam.com
- Trimble
- Spectra Precision

into those companies, as an example i will choose the smartphone devices. All of them, has the same clone device from UniStrong, the model UT10 (old) or the UT12 (new). When we visit this page
http://en.unistrong.com/ProductShow.asp?ArticleID=279

we can found
GNSS
Channels     72, U-blox M8N, L1
Tracking     GPS/BDS/GLONASS/
GPS + BDS/GPS + GLONASS
SBAS Support
Accuracy Single: 1 ~ 3 m
SBAS: 0.6 m


is there all over the world anyone a typical android smartphone manufacturer, that advertises how well is his product ???  We are talking about a gnss chip (ublox m8n) for the retail price of 10 dollars (1 item).

can anyone from this forum answer .... why one plastic typical android smartphone device of 100-150 dollars, when we put inside a 10 dollars chip (ublox m8n) cost 2200 euro ?????
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