Aircraft ID in Track File

[Richard W]

In the $PFLAA sentence, an aircraft ID string follows the 24 bit address, separated by a pling.  On a recent flight with another PAW equipped aircraft, the string was "#G-XLAM#" at the start and end of the flight, but plain "G-XLAM" for the middle section.  Why is this?  Both aircraft were in the same (default) group, and had no other equipment apart from PAW.

Richard

[Admin]

Hi Richard

Was there a period of no contact ?
The group id is not sent instantaneously, it is sent over a series of packets, so if there is a break in comms, the entire sequence of frames must be received.

Thx
Lee

[Richard W]

Yes, contact was intermittent, so that probably explains it.  We were two Skyrangers, with PAWs on the coaming.  However G-XLAM was generally 700' below at probably 5 o'clock, so just about a worst case situation.

Thanks,
Richard

[Admin]

Interesting what kind of range, can you supply the track file to take a look ?

Thx
Lee

[Richard W]

Max range was 11.5 km, min was 6 m, on the ground, not close formation    Most of the time we would have been around 4 km apart.  I would be glad to send the file, there are some other issues with it that I would like to understand.  Further to the ID string, sometimes I see the 24 bit address repeated after the pling.  Is this because no other ID has been received yet?

How shall I send the track file, which is 8.6 Mb?  I can't see a way via PM or the email button, I could put it in my Dropbox if required.

Thanks,
Richard

[Admin]

Max range was 11.5 km, min was 6 m, on the ground, not close formation    Most of the time we would have been around 4 km apart.  I would be glad to send the file, there are some other issues with it that I would like to understand.  Further to the ID string, sometimes I see the 24 bit address repeated after the pling.  Is this because no other ID has been received yet?

How shall I send the track file, which is 8.6 Mb?  I can't see a way via PM or the email button, I could put it in my Dropbox if required.

Thanks,
Richard

Hi Richard
Dropbox is perfect, please email/pm a link to the file
the text after the !(bang) depends upon some of your setting regarding what to display
it could be the Reg, FlightID or repeated ICAO code

How are you writing your parser ?
I would recommend TCL or PERL for ease of modification, or if you are a C programmer strtok_r() is your friend, and great with regular sentences such as a comma separated format 

(apologies for tech geek speak to other forumites)

Thx
Lee

[Richard W]

Hi Lee,
I have sent a PM with the link.  The parser is in C, with a nod towards C++, and is already written the hard way.  Thanks for the pointer to strtok_r(), my code is not defensive in places, and could do with better parsing.  Enough geeking.

Richard