What to log in "NMEA Items"

General talk
1

hi

just got my BGT-31 (NaviGPS?Locosystec)

In SD Card logging it has options for logging various NMEA items.

ITEM : DEFAULT : Meaning…

GGA : ON 1sec : Time, position and fix type data.
GLL : OFF : Latitude, longitude, UTC time of position fix and status.
GSA : ON 1sec : GPS receiver operating mode, satellites used in the position solution, and DOP values.
GSV : ON 5sec : The number of GPS satellites in view satellite ID numbers, elevation, azimuth, and SNR values.
RMC : ON 1sec : Time, date, position, course and speed data.
VTG : OFF : Course and speed information relative to the ground.
ZDA : OFF : PPS timing message (synchronized to PPS).
SBN : OFF : Don’t KNOW

Can anyone explain what each means and what I should log to map accurately for OSM ?

Also besides OSM I am going to use this unit to

  1. create a log of all places I have traveled/hiked/biked, to watch on google earth in the future
  2. accurately geotag my pictures.
    In view of this what items do I need to log, to get it right ?

I am a newbie, please help…

2

I don’t know about which programs to use for geotagging pictures, but those settings seems fine, now you just need tools todo what you want. GPSbabel and JOSM could show you your pictures on OSM map, but not convert to KML for Google Earth.

Just saving your NMEA logs will be enough most of the time.

3

I believe logging only GGA on 1 sec. intervals would be sufficient for OSM. I have the same GPS with a 16 MB SD-card insterted and have every item on a 1 sec. interval though. The 16 MB allows me to tracks days before the SD-card is full so I never took the time the find out which NMEA sentences are really required.

BTW. make sure you use a proper SD-card with this GPS as it is very picky about it. I used a 1GB card once which seemed to work until I powercycled the GPS after which it failed to create a new file on the SD-card.

4

I have the same GPS device. I’m not sure what to log either. I’ve got a 1GB card, so I’m just going to turn on everything to the max. It’s better to collect more data now and then trim it if needed later.

I think SBN is a binary protocal for storing NMEA tracks. I haven’t had a chance to play with my SD card, so I’m not sure.

5

Many geotagging programs will expect a GPX file, which GPS babel can create for you from the NMEA logs. GPS babel also converts to KML for when you want to look at the traces in Google Earth.