External Bluetooth Connected GPS

[LoRaTracker]

I have a Lenova tablet running Android 7.1.1

I have an external device that is emulating a GPS and sending the NMEA sentences over Bluetooth to my tablet.

The tablet is running the 'Bluetooth GPS" application and the position from the external device is showing correctly. The application is set for 'Mock GPS provider'

Alpinquest is displaying 'Outdoor GPS (sats) Waiting for a fix, this message never changes.

Is the 'Bluetooth GPS' application able to provide Alpinquest with GPS fix information or if it cannot, is there a known working way of connecting Aplinquest to an external GPS ?

[LoRaTracker]

OK, perhaps I should have checked before posting, but with a real GPS connected (Ublox7) to the Bluetooth device AlpinQuest does indeed read the Bluetooth connection as Outdoor GPS.

However, what I now need to know is how close to the format of a real GPS NMEA sentence does AlpinQuest need to work ?

My remote application builds and sends two NMEA sentences like this, sent approximatly every 20 seconds;

$GPGGA,000000.000,5128.9380,N,00310.8816,W,1,4,3.16,48.0,M,53.3,M,,*7E
$GPRMC,000000.000,A,5128.9380,N,00310.8816,W,0.00,0.00,010101,,,A*74

Some of the data is obviously missing, the time for instance.

Which NMEA sentences and data does Alpinquest need to see before it assumes its connected to a real GPS ?

[Psyberia-Support]

Hi,
AlpineQuest does read the locations from the Android location service, not directly from the NMEA data.
If you want to use locations from an external device, you need to select "External locations" in the AlpineQuest location source.
It is the work of the "Bluetooth GPS" to read the NMEA data and convert it as "android locations" for use in other applications:
External device --- NMEA ---> Bluetooth GPS --- "mock" locations ---> AlpineQuest (set to listen "External locations").

To change AlpineQuest location provider: "Positioning" menu -> GPS Position -> Setting (wheel) icon right of the side view title.

Let me know if something is wrong
Best regards

[snefnug65]

I too have been using a Bluetooth GNSS from Ublox and so it would be nice if:

1. Alpine Quest incorporated the GPS mock app into itself instead of having to get a different one. I know that the above post allows for external locations and that does work but it would be nice to have it all in one app.
2. I am not sure why the accuracy of the position fix only goes as low as +-7 feet. Is this Alpine setting that won't allow higher accuracy displayed? I was getting HDOP of 0.4 meters.
3. If wishing is not enough...allow for NTRIP corrections via WIFI or internet etc. then I could get accuracy of 2 cm ! Perhaps that is beyond the scope of AQ though...
4. Can AQ take advantage of higher refresh rates from the GPS? Say 5 Hz or 10 Hz? Or is this strictly a function of the "external locations" setting?

Thanks.

[Psyberia-Support]

Hi,
1. All in one app can also select locations from mock provider. It just doesn't have a track recorder yet.
2. Nothing prevents the use of more precise locations, that will just be better!
3. Unfortunately this is not something planned for now...
4. AQ can only update displayed real time location and record tracks up to 1Hz (1 location per second). You can change the track recorder frequency from the track recorder settings.
This is not an hardware or "external locations" framework limit, just an AQ limit: higher frequencies will only drain the battery, produce extra heavy tracks and won't add any precision or accuracy (when using built-in GNSS chips, I guess it's the case more than 99% of the times). With a professional external GNSS, it's not the same, but we need to compromise, and right now this is not the targeted usage...

But if you already have your GNSS receiver, just try the free Lite version to check if and how your locations are handled by the app!
Let me know if something is not clear
Best regards

[snefnug65]

I already purchased full version some time ago and have no regrets... I like it very much!

The reason I like higher frequency rates is that if I am going faster (like a boat) and going up difficult to navigate rivers it is nice to see where I went before (exactly) and was successful so that I can retrace that track and not run into a sandbar etc. When it is raining it is hard to see what is in the water etc. If the update rate is slow then I can be significantly off while going around corners in the rivers. For example at 25 miles per hour I am moving 36 feet/sec so I can be 36 feet off course before I would know it...and the river is about 50 feet wide...but the channel is only about 20 feet wide. Anyway my bluetooth GPS can give me up to 20 Hz (I would like 5-10 Hz). Also the bluetooth GPS is accurate to 1 meter or less most of the time so it works well. I have the tablet plugged into power so I do not mind extra power draw...those are my reasons.

I only asked about the accuracy because no matter what I only see at best +-7 feet displayed for accuracy even though other software (not mapping just GPS signal analysis) says that I have about 1 meter. I was curious why AQ did not display accuracy = +- 3 feet or so when this was the case?

Thanks again for a fantastic product...I am glad I bought it!

[snefnug65]

One other reason to allow faster than 1 Hz update rate is using with faster vehicles like airplanes. AQ has a bunch of good aviation maps and there are several bluetooth GNSS units that do better than 1 Hz. Bottom line is whenever a vehicle is used it would be nice, and power is not a concern. If it is implemented one could turn off or hide points in the track and just display the lines.

[Psyberia-Support]

Hi again and sorry for the delay.

Here are some updates:

- It is actually possible to display location updates at an higher rates than 1Hz. It can be changed using the user setting "geolocation.localisation.real_time_delay_ms". For example, to get an update of 20Hz, use:

Code: Select all

geolocation.localisation.real_time_delay_ms=50

- Concerning the accuracy, the application uses the ones from the locations provided by the system (or the mock provider). However, they are rounded (ceiled) to the meter. So an accuracy of 3 feet will be reported as +/-1 meter (=3.3 feet), whereas an accuracy of 4 feet will be reported as +/-2 meters (=6.6 feet, rounded to 7 on display). I think it explains why you see 7 feet.

- For the next version, I've added a new user setting that adds a new entry in the rates list setting, allowing to record all location updates. If you're interested, you can get it right now by requesting beta versions of the app from the Play Store app page. The user setting is:

Code: Select all

agent.track_recorder.add_real_time_rate=1

Hope it helps

[snefnug65]

Thanks so much. Yesterday switched to a better mock provider app called Drogger GPS. I gathered right away that there must have been ceiling or truncated numbers from the previous app. Now I get 3 feet accuracy in AQ. Drogger only has metric units and displays my best accuracy as 0.45 or so meters.

I did set the GPS to 5 Hz and Drogger did show it as such. I will try the things you mentioned above. Especially want to get rid of the lag in displayed position vs. reality. Thanks so much for the encouraging response!

[snefnug65]

Well I added the settings to the .conf file and they work great. The update rate is fast etc. Only one problem is that it seems that there is a lag between reality and what is displayed by about 2 seconds or so. Any thoughts why? This might not be anything to do with AQ, will try doing more testing tonight. I will also try to up the baudrate of the bluetooth higher than 38,400 to 115,200.

Anyone have any thoughts on why the lag? The update rate is great...but it just lags reality by a couple seconds.

[snefnug65]

Ok lag solved....I am soooo happy! I increased the baud rate on the bluetooth radio to 115,200 and now it works super well at 5 Hz. So I can wallk/run around and the tracking is super responsive! Thanks SO much for the user .conf settings you added. Wonderful.

Summary: Bluetooth mock provider = Drogger GPS
GNSS unit = Ardusimple (ublox F9 dual frequency) + bluetooth with the bluetooth UART2 set to 115,200 baud and the GNSS set to 200ms (5 Hz) refresh.

[Psyberia-Support]

That's a good news.
Thanks for the feedback and info!

[SukiEgan]

Hi..i am also facing an issue. I have had a go at giving full consents for the application, I have had a go at incapacitating all the force the board for this application and still the issue is the equivalent.

I have associated with precisely the same GPSs with my other Samsung telephone without issues. Likewise a seared attempted now to associate with his Android telephone to this GPS and he additionally doesn't have issues. So I am speculating something with the telephone .. be that as it may, what precisely?

[Psyberia-Support]

Sorry but this is beyond my knowledge.