[gpsd-dev] PQXFI NMEA, what is it?

[Juha Nurmela]

Hi,
Apologies for abusing the list with a question outside the charter.

Does anyone know what data is in the PQXFI "Qualcomm extended fix information" 
sentence ?

It comes from a Mini PCI-E card for laptops, mobile network plus GPS. Qualcomm 
Gobi 2000 based. HP stickers in mine.

Full cycle of NMEA looks like this when the view is really good (without the 2 
blank lines, of course)

$GPGSA,A,3,05,07,18,20,21,26,27,29,,,,,1.8,1.0,1.5*3E
$GPGSV,4,1,16,29,33,109,39,07,06,357,36,21,69,189,36,05,27,046,35*7A
$GPGSV,4,2,16,20,46,108,34,26,55,248,33,18,18,167,32,27,15,282,32*75
$GPGSV,4,3,16,04,,,30,31,01,224,21,13,04,075,,15,,,*7A
$GPGSV,4,4,16,09,,,,25,,,,11,,,,17,,,*76
$GPGGA,131021.4,6103.114292,N,02810.455606,E,1,08,1.0,102.3,M,19.0,M,,*5F

$PQXFI,131021.4,6103.114292,N,02810.455606,E,102.3,2.83,2.00,0.03*65

$GPVTG,nan,T,nan,M,0.0,N,0.0,K,A*23
$GPRMC,131021.4,A,6103.114292,N,02810.455606,E,0.0,,200716,,,A*40

First there is time, lat, lon and MSL altitude, then the 3 unknowns. First 2 
unknowns vary from about 250 down to about 2, 3rd one varies between about 5 
and 0.03. All are bigger when sky is blocked, smaller when view is good. First 
ones could be uncertainties, in meters, but the 0.03 ? 


Convenient but brittle little gizmo. It want's to see "$GPS_START" and also 
reacts to "$GPS_STOP" but requires 5 seconds between those commands, or it 
misbehaves. Also, it must not be accessed until the 3G network is up, or both 
misbehave. And, if 3G net gets stuck, reconnect won't succeed until GPS device 
is closed.


Juha