Increased precision options for Australia - QZSS, SBAS or Galileo

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Increased precision options for Australia - QZSS, SBAS or Galileo

Alex Sims

Hi,

 

I’m really wanting to have better accuracy from GPS for use with Openstreetmap. I can use survey marks and a laser rangefinder, but having a portable GPS would make so much easier to fix errors where objects have been armchair mapped or even GPS mapped with errors up to 3 meters.

 

I have tried three approaches

  • QZSS – I can see this on my Android mobile phone but it doesn’t seem to be used. It seems as though I need a Japanese market device and even then I’m not sure I’ll get an increase
  • Galileo – looks promising but when I’ve tested on supported devices (friends who have recent phones) the accuracy isn’t delivered. Further investigation shows that there aren’t enough satellites in service yet most of the day to give 4 visible. (Using GNSS View http://qzss.go.jp/en/ English text)
  • Lastly the SBAS trial from Geoscience Australia - http://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system - nothing magical has happened with any of the consumer grade devices I have access to. Also not sure how to test on an Android device if it is being used.

 

Has anyone obtained sub-meter accuracy from any of these approaches, it must be possible?

 

Please discuss.

 

Alex


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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Andrew Harvey-3
If you use RTK https://en.wikipedia.org/wiki/Real-time_kinematic you should get centimeter accuracy, but expect to pay $10k+.

https://www.swiftnav.com seems like a cheaper option but not sure if it works in Australia and it not a consumer device, seems they just sell the boards.
 
...once you obtain sub-meter accuracy, keep in mind the whole continent is moving so even if you had no error in your GPS, a node someone entered in OSM in 2007 from GPS would be almost a meter out from someone entering it into OSM today.

The SBAS trial was only aviable to selected people as part of the trial, does anyone know if it'll will work on regular devices, or will we need to run additional software, for Android, iOS?

On 12 June 2018 at 12:39, Alex Sims <[hidden email]> wrote:

Hi,

 

I’m really wanting to have better accuracy from GPS for use with Openstreetmap. I can use survey marks and a laser rangefinder, but having a portable GPS would make so much easier to fix errors where objects have been armchair mapped or even GPS mapped with errors up to 3 meters.

 

I have tried three approaches

  • QZSS – I can see this on my Android mobile phone but it doesn’t seem to be used. It seems as though I need a Japanese market device and even then I’m not sure I’ll get an increase
  • Galileo – looks promising but when I’ve tested on supported devices (friends who have recent phones) the accuracy isn’t delivered. Further investigation shows that there aren’t enough satellites in service yet most of the day to give 4 visible. (Using GNSS View http://qzss.go.jp/en/ English text)
  • Lastly the SBAS trial from Geoscience Australia - http://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system - nothing magical has happened with any of the consumer grade devices I have access to. Also not sure how to test on an Android device if it is being used.

 

Has anyone obtained sub-meter accuracy from any of these approaches, it must be possible?

 

Please discuss.

 

Alex


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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Nevw
There is expected to be improved gps accuracy in a few years time in Australia but unsure if usual gps units used by the public will show improved results but I expect they will.

On 12 Jun 2018, at 12:56 PM, Andrew Harvey <[hidden email]> wrote:

If you use RTK https://en.wikipedia.org/wiki/Real-time_kinematic you should get centimeter accuracy, but expect to pay $10k+.

https://www.swiftnav.com seems like a cheaper option but not sure if it works in Australia and it not a consumer device, seems they just sell the boards.
 
...once you obtain sub-meter accuracy, keep in mind the whole continent is moving so even if you had no error in your GPS, a node someone entered in OSM in 2007 from GPS would be almost a meter out from someone entering it into OSM today.

The SBAS trial was only aviable to selected people as part of the trial, does anyone know if it'll will work on regular devices, or will we need to run additional software, for Android, iOS?

On 12 June 2018 at 12:39, Alex Sims <[hidden email]> wrote:

Hi,

 

I’m really wanting to have better accuracy from GPS for use with Openstreetmap. I can use survey marks and a laser rangefinder, but having a portable GPS would make so much easier to fix errors where objects have been armchair mapped or even GPS mapped with errors up to 3 meters.

 

I have tried three approaches

  • QZSS – I can see this on my Android mobile phone but it doesn’t seem to be used. It seems as though I need a Japanese market device and even then I’m not sure I’ll get an increase
  • Galileo – looks promising but when I’ve tested on supported devices (friends who have recent phones) the accuracy isn’t delivered. Further investigation shows that there aren’t enough satellites in service yet most of the day to give 4 visible. (Using GNSS View http://qzss.go.jp/en/ English text)
  • Lastly the SBAS trial from Geoscience Australia - http://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system - nothing magical has happened with any of the consumer grade devices I have access to. Also not sure how to test on an Android device if it is being used.

 

Has anyone obtained sub-meter accuracy from any of these approaches, it must be possible?

 

Please discuss.

 

Alex


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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Warin
On 12/06/18 13:05, nwastra wrote:
There is expected to be improved gps accuracy in a few years time in Australia but unsure if usual gps units used by the public will show improved results but I expect they will.

Government talk 'a few years time' = beyond our next election. Could be 10 years ... or never.


On 12 Jun 2018, at 12:56 PM, Andrew Harvey <[hidden email]> wrote:

If you use RTK https://en.wikipedia.org/wiki/Real-time_kinematic you should get centimeter accuracy, but expect to pay $10k+.

https://www.swiftnav.com seems like a cheaper option but not sure if it works in Australia and it not a consumer device, seems they just sell the boards.
 
...once you obtain sub-meter accuracy, keep in mind the whole continent is moving so even if you had no error in your GPS, a node someone entered in OSM in 2007 from GPS would be almost a meter out from someone entering it into OSM today.

The SBAS trial was only aviable to selected people as part of the trial, does anyone know if it'll will work on regular devices, or will we need to run additional software, for Android, iOS?

On 12 June 2018 at 12:39, Alex Sims <[hidden email]> wrote:
Hi,
 
I’m really wanting to have better accuracy from GPS for use with Openstreetmap. I can use survey marks and a laser rangefinder, but having a portable GPS would make so much easier to fix errors where objects have been armchair mapped or even GPS mapped with errors up to 3 meters.

Ha. 3 meters is the 'best' you might get. Typically it is 10 meters. And both those measurements are at 1 sigma.
 
I have tried three approaches
  • QZSS – I can see this on my Android mobile phone but it doesn’t seem to be used. It seems as though I need a Japanese market device and even then I’m not sure I’ll get an increase
https://en.wikipedia.org/wiki/Quasi-Zenith_Satellite_System

 
Has anyone obtained sub-meter accuracy from any of these approaches, it must be possible?
 
Please discuss.
Theoretically possible. But
1) is it implemented - ie available for use.
2) are units available?
3) what accuracy is available at a 'realistic' price for consumer use?

Don't hold your breath.

You noticed the improvement with the inclusion of the Russian Satellites? ..

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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Leith Bade-2
In reply to this post by Alex Sims
If you want to do RTK you can do it for less then $1000 now. The company I work for makes one of these lower cost options https://www.swiftnav.com. RTK enabled centimetre level positioning with a good $600 antenna.

If you want to use the SBAS trial you need a receiver that allows you to select the SBAS satellite PRN ID of 122 and will allow a good receiver to get about ~1.5m accuracy. For example the Ublox receivers will work, as will most standalone GPS receivers

Galileo is still under development, will offer similar performance to GPS. It will be another 2 years before this system is complete with all 24 satellites.

 Android devices are hard-coded by the manufacturer as far as the GPS settings so you would need to wait for an Android update that knows about the Australian satellite and QZSS (which might take several years to be common place).

My recommendation is to look at standalone GPS receiver like a Ublox M8 based device, that uses an external magnetic antenna you put on your car's roof.


Thanks,
Leith Bade

On 12 June 2018 at 12:39, Alex Sims <[hidden email]> wrote:

Hi,

 

I’m really wanting to have better accuracy from GPS for use with Openstreetmap. I can use survey marks and a laser rangefinder, but having a portable GPS would make so much easier to fix errors where objects have been armchair mapped or even GPS mapped with errors up to 3 meters.

 

I have tried three approaches

  • QZSS – I can see this on my Android mobile phone but it doesn’t seem to be used. It seems as though I need a Japanese market device and even then I’m not sure I’ll get an increase
  • Galileo – looks promising but when I’ve tested on supported devices (friends who have recent phones) the accuracy isn’t delivered. Further investigation shows that there aren’t enough satellites in service yet most of the day to give 4 visible. (Using GNSS View http://qzss.go.jp/en/ English text)
  • Lastly the SBAS trial from Geoscience Australia - http://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system - nothing magical has happened with any of the consumer grade devices I have access to. Also not sure how to test on an Android device if it is being used.

 

Has anyone obtained sub-meter accuracy from any of these approaches, it must be possible?

 

Please discuss.

 

Alex


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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Leith Bade-2
In reply to this post by Andrew Harvey-3
Our receivers work fine in Australia as I live in Canberra and work for the Swift Navigation engineering department. Using one of the free CORS stations here I can get 2cm positions from my car. Mind you the setup cost ~$2000.

Australia has only moved 1.8m since 1994. http://theconversation.com/australia-on-the-move-how-gps-keeps-up-with-a-continent-in-constant-motion-71883

Unfortunately OpenStreetMaps only uses "WGS84" as it's datum which is not that well defined compared to a surveying datum like GDA94/2020 or ITRF, and most existing data has only been measured to a few metres (at most). So I wouldn't worry too much about the drift as there are other larger sources of error in OpenStreetMaps.

The SBAS trial is available to anyone with a receiver that can be set to use PRN 122 (e.g. Ublox devices).


Thanks,
Leith Bade

On 12 June 2018 at 12:56, Andrew Harvey <[hidden email]> wrote:
If you use RTK https://en.wikipedia.org/wiki/Real-time_kinematic you should get centimeter accuracy, but expect to pay $10k+.

https://www.swiftnav.com seems like a cheaper option but not sure if it works in Australia and it not a consumer device, seems they just sell the boards.
 
...once you obtain sub-meter accuracy, keep in mind the whole continent is moving so even if you had no error in your GPS, a node someone entered in OSM in 2007 from GPS would be almost a meter out from someone entering it into OSM today.

The SBAS trial was only aviable to selected people as part of the trial, does anyone know if it'll will work on regular devices, or will we need to run additional software, for Android, iOS?

On 12 June 2018 at 12:39, Alex Sims <[hidden email]> wrote:

Hi,

 

I’m really wanting to have better accuracy from GPS for use with Openstreetmap. I can use survey marks and a laser rangefinder, but having a portable GPS would make so much easier to fix errors where objects have been armchair mapped or even GPS mapped with errors up to 3 meters.

 

I have tried three approaches

  • QZSS – I can see this on my Android mobile phone but it doesn’t seem to be used. It seems as though I need a Japanese market device and even then I’m not sure I’ll get an increase
  • Galileo – looks promising but when I’ve tested on supported devices (friends who have recent phones) the accuracy isn’t delivered. Further investigation shows that there aren’t enough satellites in service yet most of the day to give 4 visible. (Using GNSS View http://qzss.go.jp/en/ English text)
  • Lastly the SBAS trial from Geoscience Australia - http://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system - nothing magical has happened with any of the consumer grade devices I have access to. Also not sure how to test on an Android device if it is being used.

 

Has anyone obtained sub-meter accuracy from any of these approaches, it must be possible?

 

Please discuss.

 

Alex


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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Andrew Davidson-3
On 12/06/18 20:04, Leith Bade wrote:
> Our receivers work fine in Australia as I live in Canberra and work for
> the Swift Navigation engineering department. Using one of the free CORS
> stations here I can get 2cm positions from my car. Mind you the setup
> cost ~$2000.

This is the bit I'm a bit dubious about. The blurb on GA suggests that
we are going to be getting 3cm accuracy from our smart phones, but I'm
wondering how the development of GPS antennas small and cheap enough to
go into phones is coming along.


> Unfortunately OpenStreetMaps only uses "WGS84" as it's datum which is
> not that well defined compared to a surveying datum like GDA94/2020 or
> ITRF, and most existing data has only been measured to a few metres (at
> most). So I wouldn't worry too much about the drift as there are other
> larger sources of error in OpenStreetMaps.

Reminds me of a paper I read on the the subject where the author pointed
out that anyone who says they are mapping to "WGS84" doesn't know what
they are talking about. However, I do think you are being a little
pessimistic. So long as there is good aerial photography or some
external dataset available it's possible to get closer. In Canberra,
provided that the mapper traces carefully, you can easily map things to
within 0.3m.

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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Grant Slater
In reply to this post by Leith Bade-2
Hi All,

I have 2 of these for RTK GNSS receivers: https://emlid.com/reachrs/

1 ReachRS unit becomes the RTK static "base" and you needs a very
accurate position measurement and good signal. To get the most
accurate measurement I use my base and connect it to another base
using an NTRIP network. I'm in the United Kingdom and I connect to the
free NTRIP network available here: http://www.euref-ip.net/home . I've
also used the South African free NTRIP network trignet.co.za
Geoscience Australia seem to offer a NTRIP network here:
https://www.auscors.ga.gov.au/
Note that max workable distance between base and rover is only around
20km. I've got it to work at 80km, but needs exceptionally clear area
(unobstructed sky) and a lot of patience to get the position fix.

Once I have my static ReachRS measured, I then connect it up to the
2nd ReachRS as a roving unit via built-in radio or Cellphone. A
reasonable maximum distance between Base and Rover is around 20km.

The rover is good for measuring points, but starts to struggle if
moved above walking pace or has an obstructed sky (read: trees etc)
Repeatable accuracy is <10cm horizontal and similar vertical.

It is possible to do the above with a single unit if you can rely on
an existing NTRIP network, but I believe you then cannot then use the
GLONASS network for getting a fix due to different antenna types
between base and rover.

The ReachRS is a single frequency receiver and needs better signal and
is slower to sync than a dual frequency receiver. In the next year or
2 there are likely to be more dual frequency receivers from the likes
of u-blox. The swiftnav.com unit looks interesting.

The ReachRS receiver uses a u-blox Neo-M8T chip and the rtklib
software. A homebrew alternative would be to use
http://www.csgshop.com/product.php?id_product=257 and rtklib yourself.
See: https://www.blackdotgnss.com/2017/03/25/u-blox-neo-m8t-part-i/

Interest? Highly recommend blog: https://rtklibexplorer.wordpress.com/

Kind regards,

Grant


On 12 June 2018 at 10:58, Leith Bade <[hidden email]> wrote:

> If you want to do RTK you can do it for less then $1000 now. The company I
> work for makes one of these lower cost options https://www.swiftnav.com. RTK
> enabled centimetre level positioning with a good $600 antenna.
>
> If you want to use the SBAS trial you need a receiver that allows you to
> select the SBAS satellite PRN ID of 122 and will allow a good receiver to
> get about ~1.5m accuracy. For example the Ublox receivers will work, as will
> most standalone GPS receivers
>
> Galileo is still under development, will offer similar performance to GPS.
> It will be another 2 years before this system is complete with all 24
> satellites.
>
>  Android devices are hard-coded by the manufacturer as far as the GPS
> settings so you would need to wait for an Android update that knows about
> the Australian satellite and QZSS (which might take several years to be
> common place).
>
> My recommendation is to look at standalone GPS receiver like a Ublox M8
> based device, that uses an external magnetic antenna you put on your car's
> roof.
>
>
> Thanks,
> Leith Bade
> [hidden email]
>
> On 12 June 2018 at 12:39, Alex Sims <[hidden email]> wrote:
>>
>> Hi,
>>
>>
>>
>> I’m really wanting to have better accuracy from GPS for use with
>> Openstreetmap. I can use survey marks and a laser rangefinder, but having a
>> portable GPS would make so much easier to fix errors where objects have been
>> armchair mapped or even GPS mapped with errors up to 3 meters.
>>
>>
>>
>> I have tried three approaches
>>
>> QZSS – I can see this on my Android mobile phone but it doesn’t seem to be
>> used. It seems as though I need a Japanese market device and even then I’m
>> not sure I’ll get an increase
>> Galileo – looks promising but when I’ve tested on supported devices
>> (friends who have recent phones) the accuracy isn’t delivered. Further
>> investigation shows that there aren’t enough satellites in service yet most
>> of the day to give 4 visible. (Using GNSS View http://qzss.go.jp/en/ English
>> text)
>> Lastly the SBAS trial from Geoscience Australia -
>> http://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system
>> - nothing magical has happened with any of the consumer grade devices I have
>> access to. Also not sure how to test on an Android device if it is being
>> used.
>>
>>
>>
>> Has anyone obtained sub-meter accuracy from any of these approaches, it
>> must be possible?
>>
>>
>>
>> Please discuss.
>>
>>
>>
>> Alex
>>
>>
>> _______________________________________________
>> Talk-au mailing list
>> [hidden email]
>> https://lists.openstreetmap.org/listinfo/talk-au
>>
>
>
> _______________________________________________
> Talk-au mailing list
> [hidden email]
> https://lists.openstreetmap.org/listinfo/talk-au
>

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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Leith Bade-2
In reply to this post by Andrew Davidson-3
The GA claim is bit exaggerated. An cell phone is unlikely to ever get 3cm as you just can't build a good GPS antenna in the form factor. Future self driving cars however will be designed to meet this specification with mass market RTK receivers (think sub $100) and correctly integrated antennas. I think it will be 5 or more years before cm level car positioning is common place.

Yes you can map to within 0.3cm, but what reference frame? E.g. the Canberra imagery I've seen is in GDA94 which is ~1.8m away from the current WGS84 reference frame. So I guess locally it might be accurate street-to-street. But if you were to survey the road compared to data in NSW it could all be shifted by a metres.


Thanks,
Leith Bade

On 12 June 2018 at 20:29, Andrew Davidson <[hidden email]> wrote:
On 12/06/18 20:04, Leith Bade wrote:
Our receivers work fine in Australia as I live in Canberra and work for the Swift Navigation engineering department. Using one of the free CORS stations here I can get 2cm positions from my car. Mind you the setup cost ~$2000.

This is the bit I'm a bit dubious about. The blurb on GA suggests that we are going to be getting 3cm accuracy from our smart phones, but I'm wondering how the development of GPS antennas small and cheap enough to go into phones is coming along.


Unfortunately OpenStreetMaps only uses "WGS84" as it's datum which is not that well defined compared to a surveying datum like GDA94/2020 or ITRF, and most existing data has only been measured to a few metres (at most). So I wouldn't worry too much about the drift as there are other larger sources of error in OpenStreetMaps.

Reminds me of a paper I read on the the subject where the author pointed out that anyone who says they are mapping to "WGS84" doesn't know what they are talking about. However, I do think you are being a little pessimistic. So long as there is good aerial photography or some external dataset available it's possible to get closer. In Canberra, provided that the mapper traces carefully, you can easily map things to within 0.3m.


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Re: Increased precision options for Australia - QZSS, SBAS or Galileo

Leith Bade-2
In reply to this post by Grant Slater
Yes the Emlid unit should work if you don't find the initialisation time. They are internally using Ublox so will even be able to be configured for the Australian SBAS.

The AUSCORS link are the stations I use here in Canberra. All the Geoscience Australia owned ones are free to use. however a number in NSW, Victoria, and Tasmania can only be used via a commercial RTK network reseller who has a licence to use those state's infrastructure. GA is working hard to improve this however and a lot of the funding announced in the budget is to allow them to purchase these stations from the states and open them up to the public, so expect things to be much better next year.


Thanks,
Leith Bade

On 12 June 2018 at 20:34, Grant Slater <[hidden email]> wrote:
Hi All,

I have 2 of these for RTK GNSS receivers: https://emlid.com/reachrs/

1 ReachRS unit becomes the RTK static "base" and you needs a very
accurate position measurement and good signal. To get the most
accurate measurement I use my base and connect it to another base
using an NTRIP network. I'm in the United Kingdom and I connect to the
free NTRIP network available here: http://www.euref-ip.net/home . I've
also used the South African free NTRIP network trignet.co.za
Geoscience Australia seem to offer a NTRIP network here:
https://www.auscors.ga.gov.au/
Note that max workable distance between base and rover is only around
20km. I've got it to work at 80km, but needs exceptionally clear area
(unobstructed sky) and a lot of patience to get the position fix.

Once I have my static ReachRS measured, I then connect it up to the
2nd ReachRS as a roving unit via built-in radio or Cellphone. A
reasonable maximum distance between Base and Rover is around 20km.

The rover is good for measuring points, but starts to struggle if
moved above walking pace or has an obstructed sky (read: trees etc)
Repeatable accuracy is <10cm horizontal and similar vertical.

It is possible to do the above with a single unit if you can rely on
an existing NTRIP network, but I believe you then cannot then use the
GLONASS network for getting a fix due to different antenna types
between base and rover.

The ReachRS is a single frequency receiver and needs better signal and
is slower to sync than a dual frequency receiver. In the next year or
2 there are likely to be more dual frequency receivers from the likes
of u-blox. The swiftnav.com unit looks interesting.

The ReachRS receiver uses a u-blox Neo-M8T chip and the rtklib
software. A homebrew alternative would be to use
http://www.csgshop.com/product.php?id_product=257 and rtklib yourself.
See: https://www.blackdotgnss.com/2017/03/25/u-blox-neo-m8t-part-i/

Interest? Highly recommend blog: https://rtklibexplorer.wordpress.com/

Kind regards,

Grant


On 12 June 2018 at 10:58, Leith Bade <[hidden email]> wrote:
> If you want to do RTK you can do it for less then $1000 now. The company I
> work for makes one of these lower cost options https://www.swiftnav.com. RTK
> enabled centimetre level positioning with a good $600 antenna.
>
> If you want to use the SBAS trial you need a receiver that allows you to
> select the SBAS satellite PRN ID of 122 and will allow a good receiver to
> get about ~1.5m accuracy. For example the Ublox receivers will work, as will
> most standalone GPS receivers
>
> Galileo is still under development, will offer similar performance to GPS.
> It will be another 2 years before this system is complete with all 24
> satellites.
>
>  Android devices are hard-coded by the manufacturer as far as the GPS
> settings so you would need to wait for an Android update that knows about
> the Australian satellite and QZSS (which might take several years to be
> common place).
>
> My recommendation is to look at standalone GPS receiver like a Ublox M8
> based device, that uses an external magnetic antenna you put on your car's
> roof.
>
>
> Thanks,
> Leith Bade
> [hidden email]
>
> On 12 June 2018 at 12:39, Alex Sims <[hidden email]> wrote:
>>
>> Hi,
>>
>>
>>
>> I’m really wanting to have better accuracy from GPS for use with
>> Openstreetmap. I can use survey marks and a laser rangefinder, but having a
>> portable GPS would make so much easier to fix errors where objects have been
>> armchair mapped or even GPS mapped with errors up to 3 meters.
>>
>>
>>
>> I have tried three approaches
>>
>> QZSS – I can see this on my Android mobile phone but it doesn’t seem to be
>> used. It seems as though I need a Japanese market device and even then I’m
>> not sure I’ll get an increase
>> Galileo – looks promising but when I’ve tested on supported devices
>> (friends who have recent phones) the accuracy isn’t delivered. Further
>> investigation shows that there aren’t enough satellites in service yet most
>> of the day to give 4 visible. (Using GNSS View http://qzss.go.jp/en/ English
>> text)
>> Lastly the SBAS trial from Geoscience Australia -
>> http://www.ga.gov.au/scientific-topics/positioning-navigation/positioning-for-the-future/satellite-based-augmentation-system
>> - nothing magical has happened with any of the consumer grade devices I have
>> access to. Also not sure how to test on an Android device if it is being
>> used.
>>
>>
>>
>> Has anyone obtained sub-meter accuracy from any of these approaches, it
>> must be possible?
>>
>>
>>
>> Please discuss.
>>
>>
>>
>> Alex
>>
>>
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