No GPS Signal - Flight Log?

[Gorillaman]

Can anyone explain why in the flight logs... many of the flights show "No GPS Signal" and few show a location. I have tried Phone flight mode... I have turned off WiFi... even tried turning off Location (you need that one).

No matter what I do it seems the location comes up random.

[Mavros777]

I get this too but if you press play in the particular flight, coordinates will pop up. Then when you go back, it will show your location and 'no gps signal' will disappear.

[Gorillaman]

I get this too but if you press play in the particular flight, coordinates will pop up. Then when you go back, it will show your location and 'no gps signal' will disappear.

Excellent !! Too bad the New (Unknown) App update wiped out all my Logs.

[Mavros777]

Yes I know I lost around 30 flight logs. I'm not updating again unless I'm sure the logs won't get deleted.

[Gorillaman]

I had 2 flights today. I checked the logs before I left the park. Both said "No GPS" I started the Log video... for the first time the flight trail turned to orange. But when I stopped the video abd backed out, the "No GPS Signal" was stil there. Not til I got home and re-started the log video (on home WiFi) did the location fill in??

[501Pete]

I had 2 flights today. I checked the logs before I left the park. Both said "No GPS" I started the Log video... for the first time the flight trail turned to orange. But when I stopped the video abd backed out, the "No GPS Signal" was stil there. Not til I got home and re-started the log video (on home WiFi) did the location fill in??

Firstly, without an internet connection, either wifi or mobile, you will never get a location shown (GPS has no concept of "locations" .
From my investigations, at startup, the device always writes "NO GPS Signal" to the logfile.
The log uses data labels (in chinese) to delimit the text file.
The format is:
时间 =Time
地址 = address (where the No GPS Signal is populated)
距离 = distance from.
起始点 = Starting Point
The actual location appears to be a search of this location using Google location services.
If I search google maps for the start location it always shows the same result as Google.
Here's a logfile from yesterday.

log3.png (26.96 KiB) Viewed 4912 times

The Address = No GPS signal and the "Starting Point" Coordinates are

1.时间:2019/01/11 14:56:25
2.地址:No GPS signal
3.距离
起始点:51.868797,-2.08189

It shows No GPS in the app Log.
.

log1.png (142.13 KiB) Viewed 4912 times

.
If I open the log in the viewer and scroll through the route, the log then populates the location as you have found, only of course if you have internet connection.
It then displays the location which matches a Google location search.
.

log2.png (142.01 KiB) Viewed 4912 times

.

log4.png (653.75 KiB) Viewed 4912 times

The interesting bit is that the raw logs are never appended themselves, only the log database (the bit that went AWOL during the last update).
Raw logs always appear to have No GPS as the default address.
One can only assume that there is either a bug in the app which fails to poll google for a location at start up, the request times out, or it purposely does not poll to reduce unwanted network traffic.
Obviously if you switch off network connections or use airplane mode (I don't) then you will never have a real time location anyway.
I'd love it if Hubsan would provide a proper API to query their log database, and also allow restoring all my previous logfiles

I've started working on a parser and script to replay and create my own logs from the raw files. That way as long as I maintain my own backup, nothing gets lost in the future.
With an API, there's scope for all sorts of fun developments down the road

For anyone else interested, the raw logs have a wealth of useful data, and are well worth looking at to identify issues.
The following is a brief breakdown of the remaining data structure.
HTH someone.


The log continues with
结束点 = end point
最大高度 = Maximum Height
高 = Altitude (takeoff)
度 = degree (pitch and roll)
飞机坐标 = Aircraft coordinates
左舵 = Left rudder
右舵 = right rudder
WIFI 信号 = Wifi signal (in dBm but appears not to work)
数量 = quantity
电量= electricity (Batt level in %)
航线距离 = route distance from
最大速度 = maximum speed
起飞高度 = take off height
手机坐标 = phone coordinates (an extremely interesting dataset when looking at the GPS accuracy test )
飞机角度 = aircraft angle
国家代码 = country code
飞机型号 = aircraft type
磁场向量 = magnetic field vector
飞控版本 = Flight control version
云台版本 = PTZ version (Gimbal BGC)
图传版 = photocopy (video signal quality)
电池状态 = battery status
飞机状态 = aircraft status
传感器状态 = sensor status
云台状态 = PTZ status

时间:2019/01/11 14:56:25
地址:No GPS signal.
距离:0.0;0.0;0.0;0.0;0.19239214062690735;0.19239214062690735;0.4007563889026642;0.4007563889026642;0.4134986102581024;0.4134986102581024;0.4134986102581024;0.5279387831687927;0.5279387831687927;
........
起始点:51.868797,-2.08189
结束点:51.868774,-2.081864
最大高度:43.5
高
度:0.0;0.1;0.2;0.4;0.5;0.7;0.9;
飞机坐标:51.8687973,-2.0818899;51.8687973,-2.0818899;51.8687973,-2.0818899;51.8687973,-2.0818899;51.8688011,-2.0818884;51.8688011,
左舵:0,-17;0,-17;0,-17;0,-17;0
etc etc.........