Unable to decode GPS Positioning from Sepura radio

[gbernaldo]

Hi, good afternoon!

I have to implement a software which decodes GPS Positions from a Sepura radio connected throughth a PEI cable.

I get a lot of messages like this:

+CTSDSR: 12,214000806012228,1,214000806010006,1,84
0A301BB659D8A5A204081

+CTSDSR: 12,214000806012202,1,214000806010006,1,84
0A001BDE31D89B7900081

+CTSDSR: 12,214000806012225,1,214000806010006,1,84
0A301BB981D8A74100081

+CTSDSR: 12,214000806012207,1,214000806010006,1,84
0A001BC4D9D88DA900E81

+CTSDSR: 12,214000806015902,1,214000806010006,1,81
03809213B14EC01BB5FF0

+CTSDSR: 12,214000806012226,1,214000806010006,1,84
0A001BDD01D89C220A081

+CTSDSR: 12,214000806012217,1,214000806010006,1,84
0A201BDC61D89AE102881

Those messages are supposed to contain the locations of the devices.

The problem is I can't get the correct positions. I tried with the ETSI and I tried to follow the steps here: Sepura SDS LIP

But I cannot get the correct positions. The correct positions are supposed to be in the range of 41.518628 - 41.559041 in the latitude and 2.406292 - 2.467589 in the longitude but the results I get are completelly out of those ranges (some of them are: -130,771733522 (lon), 67,824525833 (lat).

In this concrete case:

For the message:
+CTSDSR: 12,214000806012225,1,214000806010006,1,84
0A301BB981D8A74100081

Longitude
======================

Original number: A301BB9 - 1010001100000001101110111001
Longitude: 1460377 - 1010001100000001101110111 - Cause the first bit is 1 the number is negative
Inverted number: B9FC88 - 0101110011111110010001000
Add +1: B9FC89 - 0101110011111110010001001 (12188809)

The result is multiplied by: 360/2^25 (2,14576721191e-05)

Then, longitude equals to: -130,771733522

Latitude
=====================

Original number: 981D8A7 - 001100000011101100010100 (3160852)

The number is multiplied by 180/2^24 (2,14576721191e-05)

Then, latitude equals to: 67,824525833

So please, can anyone help me with this problem?

Thank you so much in advance!

 

[belvdr]

Suggest wrapping all of your data in code tags for readability.

 

[gbernaldo]

Suggest wrapping all of your data in code tags for readability.

Really sorry for that!

I tried but I can't edit my message.

 

[belvdr]

Really sorry for that!

I tried but I can't edit my message.

No worries, just a future note.

I wish I could help on the GPS decoding though.

 

[LimaZulu]

Don't get me wrong but you ask us too much by not telling us too much. Basically you made something but you have troubles with it and ask us where is the problem without showing us "the thing"
Either you have to read a bit (actually a lot) about the protocol or you have to make your piece of code public so we can at least take a look. Or at least provide us with some API that is exposing enough for us to debug.
Again not to be rude but that's how your question looks like
Cheers and good luck with your project!