GPSTest v2.1.10 is now available

[Sean Barbeau]

Hi all,

Over the weekend I rolled out GPSTest v2.1.10, which includes a few new things:

Enhancements

1. #19 - Add Help Menu - Tap on the 3 dots and then "Help", and it will show you information about the various data that the app shows
2. Show satellites in Sky view that don't have signal strength (i.e., aren't in view) - Now you can actually see the location in the sky where these satellites should be
3. #71 - Show PDOP, HDOP, and VDOP values - If your device supports particular NMEA sentences, the app will show you these values in the Status view
4. #70 - Give used sats bold outline in Sky view - Makes it easier to see which satellites were used in the last fix without having to switch to the Status view
5. #22 - Show altitude above mean sea level (geoid) - The "Alt" field is the WGS84 altitude (meters above the WGS84 ellipsoid), which isn't very meaningful for most general users.  This adds a field "Alt (MSL)" if your device supports particular NMEA sentences, which will be more useful to most general users.  More info on the difference between these values is at http://www.esri.com/news/arcuser/0703/geoid1of3.html.
6. #68 - Add a count of the number of sats used/in view on the Status view - Makes it easier to see your device's progress towards acquiring a fix, without having to manually count the rows.
7. #69 - Add "What's New" dialog - For this and all future versions, when you install an update, on the next execution the app will show a popup with a summary of what's new since the last version
8. #67 - Only prompt user to install Google Maps once - Google Play Services and Google Maps are no longer required to install and use the app - the Status and Sky views will still work.  If you want to use the Map tab you'll need to install them.  In previous versions, the app would nag you to install them every time you started the app.  Now, you'll only be notified once.

Available to download on Google Play:

https://play.google.com/store/apps/details?id=com.android.gpstest

...and as always open-source on Github:
https://github.com/barbeau/gpstest

Thanks, 
Sean

[Adam Horak]

Hi,
can you explain why the GPS, Glonass, Galileo have the same ID numbers?

It is probably an issue on Samsung Galaxy S8/S8+ only ?

Should numbers not be NMEA compliant as below:

"NMEA IDs can be roughly divided into the following ranges:

• 1–32: GPS
• 33–54: Various SBAS systems (EGNOS, WAAS, SDCM, GAGAN, MSAS) – some IDs still unused
• 55–64: not used (might be assigned to further SBAS systems)
• 65–88: GLONASS
• 89–96: GLONASS (future extensions?)
• 97–192: not used
• 193–195: QZSS
• 196–200: QZSS (future extensions?)
• 201–235: Beidou"

[Sean Barbeau]

Adam,

With Android 7.0 and higher, the IDs provided by the Android platform for each satellite are specific to each GNSS constellation:

https://developer.android.com/reference/android/location/GnssStatus.html#getSvid(int)

Gets the identification number for the satellite at the specific index.
This svid is pseudo-random number for most constellations. It is FCN & OSN number for Glonass.
The distinction is made by looking at constellation field getConstellationType(int) Expected values are in the range of:

• GPS: 1-32

• SBAS: 120-151, 183-192

• GLONASS: One of: OSN, or FCN+100

• 1-24 as the orbital slot number (OSN) (preferred, if known)

• 93-106 as the frequency channel number (FCN) (-7 to +6) plus 100. i.e. encode FCN of -7 as 93, 0 as 100, and +6 as 106

• QZSS: 193-200

• Galileo: 1-36

• Beidou: 1-37

So, there is some overlap.

Prior to Android 7.0, the IDs you mention were used on some OEM implementations, but this was never officially standardized on Android.  These IDs had to be globally unique on Android because prior to Android 7.0 Android didn't have a concept of more than one GNSS - everything was crammed into a legacy GPS model.

If you want to replicate this older configuration on devices with Android 7.0 and higher, you can go into the GPSTest app "Settings" and uncheck "Use GNSS APIs".  This will show the IDs provided by the deprecated GpsStatus API:

https://developer.android.com/reference/android/location/GpsStatus.html

...and the IDs from the GpsStatellite.getPrn() method:

https://developer.android.com/reference/android/location/GpsSatellite.html#getPrn()

I'd be interested to know what the Galaxy S8 shows for the legacy API - again, Android behavior isn't standardized for multiple GNSS using the legacy API, but I'd expect to see the ID ranges from your post.

More on this topic at:

• https://gis.stackexchange.com/questions/65412/is-there-an-industry-standard-official-mapping-of-glonass-satellites-to-prn-va
  
• https://gis.stackexchange.com/questions/163912/is-there-an-industry-standard-official-mapping-of-galileo-satellites-to-global
  

Sean

[Adam Horak]

It's looks like on the screenshot attached below.
This app do not recognize the nationality of the satelites :-)

I'd be interested to know what the Galaxy S8 shows for the legacy API - again, Android behavior isn't standardized for multiple GNSS using the legacy API, but I'd expect to see the ID ranges from your post.

Sean

[Sean Barbeau]

Thanks for the screenshot!  Yeah, that doesn't look right - it should be showing the flag for each GNSS constellation, based on ID ranges in https://github.com/barbeau/gpstest/blob/master/GPSTest/src/main/java/com/android/gpstest/util/GpsTestUtil.java#L45.  I can reproduce this on an LG G5 with Android 7.0 too.

I've opened an issue on this bug here, hopefully I'll have a chance to fix soon:

https://github.com/barbeau/gpstest/issues/82

Sean

Sean J. Barbeau, Ph.D.

sjba...@gmail.com

http://www.linkedin.com/in/seanbarbeau

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