[gpsd-users] Sending SiRF commands to GPS receiver

[Alexander Carver]

Is it possible to send any SiRF command to a GPS via gpsd or can you 
only send certain commands already in the source code?  I see the -x in 
gpsctl but it's not clear how to send SiRF messages (SiRF isn't one of 
the listed examples).

I specifically want to send message 133 (0x85) which toggles the DGPS 
source of the receiver.  I've discovered that my receiver occasionally 
loses the SBAS satellite and won't recover it on its own.  However, 
toggling the source from SBAS to NONE and then back to SBAS causes it to 
lock onto the satellite again.

The message is seven bytes long:

MsgID (1 byte unsigned), Source (1 byte unsigned), internal beacon 
frequency (4 bytes unsigned), internal beacon bitrate (1 byte unsigned)

The last two are unused when selecting SBAS and are set to zero so 
turning off DGPS should use this message payload (hex spaced out to show 
message divisions):

85 00 00000000 00

And turning it back on set to SBAS is:

85 01 00000000 00


Is it as simple as this:

gpsd -x "85000000000000"

Or have I overlooked something?