Incorrect/corrupted Longitude coords in the GPS log file

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1st mini0903 missing Long coord & 2nd mini0903 ?CMOS faulty
#1
Hi,

I see some problems with GPS file from mini0903. In the file are missing some of the Long coordinates..?
Looks like only it incorrectly saved in the GPS log file.
GPS_log_file.jpg
GPS_log_file_1.jpg
A,110717,091829.000,5440.6631,N,2515.7378,E,0.0,+0.10,+0.10,-0.90;
A,110717,091830.000,5440.6631,N,2515.7371,E,0.0,+0.10,+0.10,-1.90;
A,110717,091831.000,5440.6631,N,515.7371,E,0.0,-0.90,+0.10,-0.90;
A,110717,091832.000,5440.6631,N,15.7372,E,0.0,+0.10,+0.10,-2.90;
A,110717,091833.000,5440.6631,N,2515.7373,E,0.0,+0.10,+0.10,+2.10;
A,110717,091834.000,5440.6631,N,2515.7373,E,0.0,+0.10,+0.10,-0.90;
A,110717,091835.000,5440.6631,N,515.7373,E,0.0,-0.90,+0.10,+0.10;
A,110717,091836.000,5440.6631,N,515.7372,E,0.2,+0.10,+0.10,-0.90;
A,110717,091837.000,5440.6636,N,2515.7368,E,0.2,+0.10,+0.10,+0.10;
...
A,110717,091903.000,5440.6914,N,2515.7393,E,1.6,+0.10,+0.10,+0.10;
A,110717,091904.000,5440.6914,N,515.7384,E,1.6,+0.10,+0.10,+1.10;
A,110717,091905.000,5440.6914,N,515.7378,E,1.4,+0.10,+0.10,+0.10;
A,110717,091906.000,5440.6909,N,2515.7373,E,1.4,+0.10,+0.10,+0.10;
...
A,110717,091922.000,5440.6909,N,2515.7339,E,0.2,-1.90,+0.10,-1.90;
A,110717,091923.000,5440.6909,N,2515.7339,E,0.3,+1.10,+0.10,+0.10;
A,110717,091924.000,5440.6909,N,15.7337,E,0.3,+0.10,+0.10,+0.10;
A,110717,091925.000,5440.6909,N,2515.7336,E,0.2,+0.10,+0.10,+0.10;
A,110717,091926.000,5440.6909,N,2515.7336,E,0.2,+0.10,+0.10,+1.10;

To slow sd card for saving GPS log file..?
Contacts in GPS mount..? Any ideas?

Thanks!
 

Nigel

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#3
Looks like it has missed some of the ASCII characters on the serial link from the GPS module to the camera. Could be a bad connection, could be the camera was too busy due to problems elsewhere.
 

Doodle

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0903 nanoq
#4
I have the very same problem with my newly arrived mini0903.
It is running the latest firmware (2017.04.25. v2.0).

Here is an example of my problematic GPS log:
A,150717,091018.000,4732.5239,N,2136.2971,E,28.4,+0.10,-1.90,+0.10;
A,150717,091019.000,4732.5244,N,2136.2852,E,28.4,+0.10,+1.10,+3.10;
A,150717,091020.000,4732.5249,N,0.2733,E,28.4,+1.10,-0.90,-0.90;
A,150717,091021.000,4732.5254,N,136.2617,E,27.9,+0.10,+0.10,-0.90;
A,150717,091022.000,4732.5259,N,2136.2505,E,26.7,-0.90,-0.90,+1.10;
A,150717,091023.000,4732.5264,N,36.2399,E,25.1,+0.10,-0.90,+2.10;
A,150717,091024.000,4732.5273,N,136.2296,E,24.1,+0.10,+0.10,+1.10;
A,150717,091025.000,4732.5278,N,2136.2197,E,23.1,+1.10,+11.10,+2.10;
A,150717,091026.000,4732.5283,N,36.2104,E,22.8,+1.10,+2.10,+0.10;
A,150717,091027.000,4732.5288,N,136.2008,E,23.3,+0.10,-7.90,+3.10;
A,150717,091028.000,4732.5293,N,2136.1909,E,24.1,-2.90,-4.90,+3.10;
A,150717,091029.000,4732.5298,N,2136.1807,E,25.3,+0.10,+0.10,+0.10;
Just wondering, is it something that can be fixed in software, or does it look like a hardware fault?
 

Gigi Duru

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#5
Same issue here !
If we were talking about a week connection or poor signal the data should be completely scrambled. In my situation I'm missing only the first digit of the longitude.
I see also in your logs that sometimes 1 or 2 or more digits are missing from the longitude. Always by the longitude. This looks like a data (longitude data) handling issue in the software. Always the longitude !

@Rayman.Chan :
Please investigate this issue and release a firmware update or provide the source code so we can fix it our self.

Mini 0903 GPS problem.png
 
Last edited:
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1st mini0903 missing Long coord & 2nd mini0903 ?CMOS faulty
#6
Hi,

I am back to the problem of the mini0903 GPS LOG file. I bought new GPS module and changed it.
I separated GPS from cam and placed ~ 40 cm in the distance. Somewhere read about recomended power 3.3 V for
GPS MediaTek MT3337 chip set and I powered GPS through 5V to 3.3V DS-DC module. Nothing helped. Gaps was still here.

So I decided to check and compare what GPS transmits to mini0903 and what save the cam in the LOG in the same time.
I bought RS232 to TTL USB module & wired to mini0903 GPS module. On laptop installed SiRFDemo to get & LOGs NMEA strings from GPS.

After first test and comparing results I have a questions:
- why mini0903 GPS LOG time differ from NMEA LOG: 182137.992, 182135.008 from 182137.000, 182135.000
NMEA time always have "x.000" format but in mini0903 .992 or .008 looks like rounding errors;
- why mini0903 coords differ from NMEA exactly in the same time:
A,131017,182142.000,5441.4951,N,2512.1084,E
$GPRMC,182142.000,A,5441.4949,N,02512.1085,E
-
A,131017,182138.000,5441.4419,N,2512.0603,E
$GPRMC,182138.000,A,5441.4420,N,02512.0603,E

- looks like mini0903 missing some of info during saving files every 3 min: from 182138 to 182141.992 - 2, 3 seconds missing
even GPS transmits data to mini0903.

I thought that mini0903 reads NMEA strings and simply rewrites without additional processing: time, coords. Now looks like
mini0903 makes some processing, changing original GPS NMEA data and after that we have gaps, missing lines...

gap.png
mini0903 LOG:
mini0903_gap_log.png
GPS NMEA LOG:
SIRFDemo_gap_log.png
 

Gigi Duru

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#7
Hi,

I did the same thing, I extended the wire between the GPS base and the camera. I mount the camera to the windshield with a go pro mount and the GPS module is stick in the other corner of the windshield. This fixed the signal interference issue, so I get a GPS lock in a few minutes and it stays locked. Sometimes the data is still corrupt, exactly what I explained in the previous post.
Conclusion: a joke of a product.
 
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1st mini0903 missing Long coord & 2nd mini0903 ?CMOS faulty
#8
Next day I tested mini0903 GPS LOGs with Format card & Restore defaults options. The same - gaps, missing Long.
I am sure which NMEA strings transfer the GPS module. I am not sure only which strings goes inside mini0903.

@Rayman.Chan can you provide script/source code or describe how mini0903 processing NMEA strings from GPS?
For me strange why differs time, coords exactly in the same time from the same GPS module..?