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Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

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Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#31

Post by cyanydeez »

eqvinox wrote: post #16

It is worth mentioning that you can set up your own RTK installation buy grabbing 2 higher-end GNSS receivers¹, installing one of them in a fixed location with reasonable sky view, and measuring it in for a week or two. You can then feed correction data from that to your 2nd receiver. Search for RTKlib. (Some GNSS receivers even have built-in source & sink handling.) Also, the GNSS software in most phones is sadly un…

From what I can deduce, phone GPS just doesn't measure the proper signal data to do the correction. It's something like the offset of the signal frequency and timing.

It's not the software, it's the hardware.

Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#32

Post by [deleted] »

crtified wrote: post #30

It's always nice to see that RTK for-the-people is edging ever closer. DIY kits from the likes of (no endorsement or vouching-for implied!) SparkFun and Ardusimple prove that the actual cost of basic entry to the tech is already under $2K, and probably under $1K. It is a valuable ability for the average person to have available, because - whether we're talking about space, or time - everything benefits from accurate…

[deleted]

Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#33

Post by Gys »

friendly_capy wrote: post #3
RedlineTriad wrote: post #2

I just learned that Switzerland has a nationwide RTK network for cm level positional accuracy using GPS, Galileo, GALILEO, and/or Beidou, GNSS systems. And they have a nice map of all the station locations[0]. It's a bit of shame that the pricing seems to be rather steep for frivolous use, but it seems to be rather new. It would be interesting to see what possibilities a totally free nationwide RTK system would open…

In Portugal there are 2 already, one free and one paid. The free one was implemented almost 20 years ago. It amazes me that a country like Switzlerland only now implemented such a service, and quite expensive, nonetheless.

Which network in Portugal provides this service for free?

Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#36

Post by skzv »

aantix wrote: post #27
lxgr wrote: post #17

Earlier quoted context omitted.

Is that true even for the relatively new Android "raw GNSS" API? https://developer.android.com/develop/sensors-and-location/s... I believe Google are using that themselves for their "urban canyon" GPS improvements: https://android-developers.googleblog.com/2020/12/improving-...

Does this api improve on GPS drift? Or is it up to the engineer to decide how to best to use these improvements?

The raw measurements API provides raw GNSS measurements so that somebody can implement their own position engine, and do things like RTK.

The corrections mentioned in the blog post are calculated by the phone (in Google Play Services, using Google's 3D building models) using the raw GNSS measurements, and provided back to the chipset to improve its position estimate (correcting for reflections and interference).

Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#37

Post by skzv »

eqvinox wrote: post #16

It is worth mentioning that you can set up your own RTK installation buy grabbing 2 higher-end GNSS receivers¹, installing one of them in a fixed location with reasonable sky view, and measuring it in for a week or two. You can then feed correction data from that to your 2nd receiver. Search for RTKlib. (Some GNSS receivers even have built-in source & sink handling.) Also, the GNSS software in most phones is sadly un…

> Also, the GNSS software in most phones is sadly unable to accept the correction data from any of these systems, regardless of whether it's a nationwide network or your personal setup. This is purely a software limitation on the vendor GNSS stack, but sadly there is not enough demand for this. (An app will not fix this, we're talking vendor specific low level system code here.)

I don't think that's true. Android surfaces raw GNSS measurements including carrier phase (sub wavelength measurements) to do centimeter level positioning through the raw measurements API [0].

There's even an API to specify the phone antenna phase pattern to correct the carrier phase measurements (source: I implemented it [1]). For those that aren't familiar, the idea is that the antenna pattern on phones isn't perfectly symmetrical, and depending on the direction of the incoming signal, it may appear longer. Knowing the antenna pattern, you can correct for this.

[0] https://developer.android.com/reference/android/location/Gns...

[1] https://developer.android.com/reference/android/location/Gns...

Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#38

Post by Anunayj »

skzv wrote: post #37
eqvinox wrote: post #16

It is worth mentioning that you can set up your own RTK installation buy grabbing 2 higher-end GNSS receivers¹, installing one of them in a fixed location with reasonable sky view, and measuring it in for a week or two. You can then feed correction data from that to your 2nd receiver. Search for RTKlib. (Some GNSS receivers even have built-in source & sink handling.) Also, the GNSS software in most phones is sadly un…

> Also, the GNSS software in most phones is sadly unable to accept the correction data from any of these systems, regardless of whether it's a nationwide network or your personal setup. This is purely a software limitation on the vendor GNSS stack, but sadly there is not enough demand for this. (An app will not fix this, we're talking vendor specific low level system code here.) I don't think that's true. Android sur…

I wanted to play around with this! But too bad I have a Samsung Snapdragon :(

And it doesn't expose ADR/carrier phase.

Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#39

Post by summm »

toomuchtodo wrote: post #10
michaelt wrote: post #6

Earlier quoted context omitted.

> It's a bit of shame that the pricing seems to be rather steep for frivolous use The pricing norms for RTK correction networks were set 20 years ago, when operating your own base station meant buying a second $20,000 dual frequency receiver, and taking an extra guy any time you go out to do a survey, whose job is just to guard the base station. This made a $2000 a year network correction service seem like great valu…

This should be another crowdsourced sensor fabric network, like air quality sensors, AIS, ADS-B, distributed SDR, etc.

https://docs.centipede.fr/ Currently only really working in France and Hungary.

Re: Swipos-GIS/GEO, nationwide GNSS RTK correction for centimeter accurate location

#40

Post by bendauphinee »

eqvinox wrote: post #16

It is worth mentioning that you can set up your own RTK installation buy grabbing 2 higher-end GNSS receivers¹, installing one of them in a fixed location with reasonable sky view, and measuring it in for a week or two. You can then feed correction data from that to your 2nd receiver. Search for RTKlib. (Some GNSS receivers even have built-in source & sink handling.) Also, the GNSS software in most phones is sadly un…

Just like this https://news.ycombinator.com/item?id=38820616
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