Phone built-in GPS quality

Really interesting!

Depending on where I read, it says it is or is not possible to use an external GPS device instead of Androids.

What is the name of your external GPS and the app you use? I tried google some of the names, but did not come up with something conclusive.

@Amiga4000 I didn’t test it with the Mapillary app because I don’t use it, but it should work, as the app can replace the internal gnss receiver.

@tryl I use BlueGps or Bluetooth GPS
BlueGPS can record the nmea file
Bluetooph GPS can’t record nmea directly (you need another app) but it shows some other informations like satellite reception quality, …

The Gnss receiver is this one:
http://navspark.mybigcommerce.com/navspark-gl-arduino-compatible-development-board-with-gps-glonass/
with
http://navspark.mybigcommerce.com/bluetooth-serial-link/
http://navspark.mybigcommerce.com/sma-to-u-fl-connector-cable-4pcs-set/
http://navspark.mybigcommerce.com/tri-band-gps-galileo-beidou-glonass-active-antenna/

It is possible to use a bluetooth GPS mouse together with an app and the mock location tweak in the developer options:
https://play.google.com/store/apps/details?id=googoo.android.btgps&hl=de

Ah, ok.
So over all ~100 Dollar. What is the quality of this? As stable as the mobile GPS and as good as the mobile GPS?

And the software, how easy for nnobs to get it up and running?

NNobs ? cannot get it up and running, they should buy an iPhone.

I don’t know “Mobile GPS” but the Navspark’s are good,… if you have a good antenna. And it’s even better with the antenna on the car’s roof, as It gives you a better reception and less multipath problems. I didn’t test, but it should be better in urban canyon area.
But you won’t have submeter accuracy, it’s only a standard gnss receiver with Gps, Glonass, and Sbas for dgps.
If you want something really better, you need to look at Real Time Kinematic. I’m testing RTK with another Navspark (NS-HP-5), but it’s another, more complex, world.

As far as I understand, RTK requires 2 GNSS receivers: A “rover” and a “base”. The base is stationary and the precision of the setup depends on how well you know the exact position of the base (as well as how well you have placed the antenna). The rover is the moving part.

Can that be made practical for Mapillary (or OSM) use? Centimeter precision is pointless of I don’t even know the location of the base with that precision.

You’re right, base + rover, and radio/network link between the base and the rover.

Yes, if you don’t know the base coordinates, you will get only centimeter relative precision, which is better than nothing.
There are many workaround to have a good base position:

  • start with a known location, and put your base on it
  • start with an existing base station
  • record the base location for a few hours, then postprocess it to get a more accurate location.