Forum: General Topics

Hi Chris,

" Just found a config program for my GPS Bluetooth thing (what IS the correct name for one of these?) "
I tend to favour 'GPS Thingy', seems to cover all bases! ;-)

If you're only using the Thingy with TMJ then theres no need to enable the GPVTG sentences since they're ignored by TMJ - most of the data in this sentence is duplicated in the GPRMC sentence anyhow. As far as I can tell the VTG sentence just repeats the current track direction and speed from the GPRMC field. Velocity Made Good as used in TMJ gives the velocity relative to the selected waypoint, so this can't be calculated by the GPS anyhow.

Incidentally if you can enable/disable other sentences, these are the ones that TMJ will make use of:

GPGGA - Lat, Lng, Alt, Time, Sats, HDOP
GPRMC - Date, Speed/Bearing (used if the Settings/Use Speed & Bearing From GPS option is enabled)
GPGSV - Satellites locations
GPGSA - HDOP/VDOP, Satellites used in fix

Some good sentence info on this page.

Cheers,
Stephen

Ok,
So I've had a read of the website, and a look at the GPS NMEA log from my 'thingy'. What d'you know, it actually seems to make sense! (well, apart from geoids and WGS84 ellipsoids... I'm still working on those!!)

So once you get that positional data from the GPS, 'all' you and TMJ then have to do is convert it into meaningful information that you can show on all those useful screens... :-)

Interesting stuff! (seriously)

Cheers,

Chris.

" If I enable GPS logging, will TMJ record ALL sentences from the 'thingy' or just those that it makes use of? "

It currently records ALL sentences. I could add an option to only record the ones it uses (to reduce the size of the log file), but most GPS devices (that I've tested) only give the 4 mentioned above plus the GPVTG anyhow...