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How to create fake timestamps with gpsbabel?

I am trying to use the below command to process some NMEA files, but it's resulting in trackfilter-init: Track points badly ordered (timestamp)!

../gpsbabel/gpsbabel \
    -i nmea -f $DATE.nmea \
    -x track,pack,sdistance=0.5k,faketime=f19780705200000+2 \
    -x transform,wpt=trk,del \
    -x radius,distance=20K,lat=-31.995815,lon=115.73512,nosort,exclude \
    -x transform,trk=wpt,del \
    -o gpx -F $DATE.gpx

Can anyone shed some light on what I'm doing wrong?

Thanks!

gpsbabel timestamps faketime

asked 22 Oct '10, 02:10

samwilson
336●2●5●12
accept rate: 20%

2 Answers:

Okay, I've got it all sorted. It seems a bit hacky, so if anyone's got any suggestions I'm open to them.

../gpsbabel/gpsbabel \
    -D -w -t \
    -i nmea -f $DATE.nmea \
    -x track,faketime=f19700101000001+1 \
    -x track,faketime=19700101000001 \
    -x track,move=+1s \
    -x track,pack,sdistance=3k \
    -x transform,wpt=trk,del \
    -x radius,distance=20K,lat=-31.995815,lon=115.73512,nosort,exclude \
    -x transform,trk=wpt,del \
    -o gpx -F $DATE.gpx

This

modifies all timestamps (the two faketime filters are because the first one removes the <time> element from the first trackpoint; weird);
then splits into separate track segments where points are more than 3km apart;
and lastly deletes everything within 20km of (roughly) the mouth of the Swan River (i.e. metro stuff that is already well-mapped).

answered 22 Oct '10, 05:20

samwilson
336●2●5●12
accept rate: 20%

It is suggested to use

-x track,start=19700101000000

to start a track file timestamp at 1970 Jan 01, 00:00:00 in the new OpenStreetMap book by Jonathan Bennett. This example is from a free chapter, here.

http://www.packtpub.com/article/openstreetmap-gathering-data-using-gps

Both new OSM books are worth having. http://weait.com/content/two-new-osm-books

answered 22 Oct '10, 02:47

Richard Weait
3.0k●13●34●52
accept rate: 17%

I saw that page, but I think start is just to tell it to ignore times before that date. I tried whittling down my command, and am getting 'faketime=f19700101000000' is an unknown option to track. So I think I might just give up on changing the timestamps!

(22 Oct '10, 03:13) samwilson