Garmin GPS - Garmin GPS60 Data in GPS Utility...time stamps

Author

Garmin GPS60 Data in GPS Utility...time stamps

Canopus

2006-04-28, 5:48 pm

I've been trying out GPS Utility 4.20.5 with my Garmin GPS60. I've set up
a map OK, downloaded data from my GPS60, the track lines up pretty well
with where I walked, but, I'm a bit bemused by the data I'm seeing. I see
two lists of data, one labelled 09-Apr-06 corresponding to the Saved data
title in my GPS60 and the other labelled Active Log. Data in both are
identical except for time stamps. In the 09-Apr-06 data time stamps seem
to be UTC starting from 13/12/1989 23:59:59 and ending 13/12/1989
23:59:59...all the same time stamp. In the data labelled Active Log it
starts 09/04/2006 15:31:44 and ends 09/04/2006 15:47:14...these correspond
to UK time which I'm using. Why does the first set of data use a time
stamp of 1989 which could be UTC and the second set of data use the
correct UK time stamp? Why are they in fact duplicated except for time
stamp? If I delete the first set (1989) the second set displays on my map
correctly anyway so why the redundancy?

--
Rob

http://www.flickr.com/photos/canopus_archives/

peter

2006-04-28, 5:48 pm

Canopus wrote:
> Why does the first set of data use a time
> stamp of 1989 which could be UTC and the second set of data use the
> correct UK time stamp? Why are they in fact duplicated except for time
> stamp? If I delete the first set (1989) the second set displays on my map
> correctly anyway so why the redundancy?

You created the redundancy by doing a "Save" tracklog operation on the
GPS60 prior to downloading the data to your PC. The Active Log
includes valid timestamps (in UTC as you surmised) and with full
accuracy of the recorded track. When you do a "Save" on the GPS it
creates a 'Saved Log' that lacks any time/datestamps and also generally
reduces the number of trackpoints since each of the 20 Saved Log slots
can only have up to 500 points whereas the Active Log can have up to
10000. So you may notice that the Saved Log didn't have quite as much
detail at corners as the Active Log. The '1989' date and timestamps
were just what GPS Utility shows when there is no date/time
information.

The Saved Logs are handy as a way of being able to save local trails or
other features in your GPS that may not show up on your maps otherwise
and are also used for the TrackBack feature to retrace your steps. But
normally you just download the Active Log to your PC if you want a
record of your trip and don't first create a Saved Log on the GPS.

Jack Erbes

2006-04-29, 5:48 pm

Canopus wrote:

> I've been trying out GPS Utility 4.20.5 with my Garmin GPS60. I've set
> up a map OK, downloaded data from my GPS60, the track lines up pretty
> well with where I walked, but, I'm a bit bemused by the data I'm
> seeing. I see two lists of data, one labelled 09-Apr-06 corresponding
> to the Saved data title in my GPS60 and the other labelled Active Log.

I'm assuming that you saved the track and the data is also still in the
track memory of the GPS. And that you or GPSU downloaded both the saved
file and the track memory.

The track memory will eventually probably start overwriting the oldest
data. A more orderly way to use the track memory is to clear the track
memory when saving the track data to a file. Then you start
accumulating data again with a fresh start.

Make sure you're getting all the data you want when you save it to a
file, some GPS receivers don't save all the data fields that are in
track memory to a saved track file.

Another issue is saving a track to a route. That normally results in a
route with a limited number of waypoints that represent only the major
changes in direction. Not other details (time, speed, alt, etc.) would
be saved to the route.

> Data in both are identical except for time stamps. In the 09-Apr-06
> data time stamps seem to be UTC starting from 13/12/1989 23:59:59 and
> ending 13/12/1989 23:59:59...all the same time stamp. In the data
> labelled Active Log it starts 09/04/2006 15:31:44 and ends 09/04/2006
> 15:47:14...these correspond to UK time which I'm using. Why does the
> first set of data use a time stamp of 1989 which could be UTC and the
> second set of data use the correct UK time stamp? Why are they in fact
> duplicated except for time stamp? If I delete the first set (1989) the
> second set displays on my map correctly anyway so why the redundancy?

I don't know what happened there. The GPS gets it's time from the GPS
data and does not even need a fix to set the time IIRC.

I'm wondering if GPSU has changed the timestamps in the process of
downloading the data. I use GPSU and it occasionally give me some
chatter about changing the times on downloaded data. I think GPSU Has a
setting for the time used and displayed. If the downloaded data was in
a time base other than the one in GPSU it may want to change that.

Jack

--
Jack Erbes in Ellsworth, Maine, USA - jackerbes at adelphia dot net
(also receiving email at jacker at midmaine.com)

Canopus

2006-04-29, 5:48 pm

peter on 28/04/2006 wrote:

>You created the redundancy by doing a "Save" tracklog operation on the
>GPS60 prior to downloading the data to your PC. The Active Log
>includes valid timestamps (in UTC as you surmised) and with full
>accuracy of the recorded track. When you do a "Save" on the GPS it
>creates a 'Saved Log' that lacks any time/datestamps and also generally
>reduces the number of trackpoints since each of the 20 Saved Log slots
>can only have up to 500 points whereas the Active Log can have up to
>10000

Thanks Peter. I see where the redundancy comes from now. Am I correct in
thinking that if I use my GPS60 for several days creating tracks when I
don't have facilities to download the data it would be best to save
individual tracklogs and reset tracks day by day or even trail by trail?

--
Rob

http://www.flickr.com/photos/canopus_archives/

Canopus

2006-04-29, 5:48 pm

Jack Erbes on 29/04/2006 wrote:

>
>I don't know what happened there. The GPS gets it's time from the GPS
>data and does not even need a fix to set the time IIRC.

Thanks Jack, I think Peter answered this part of my puzzle.

--
Rob

http://www.flickr.com/photos/canopus_archives/

peter

2006-04-29, 11:48 pm

Canopus wrote:
> peter on 28/04/2006 wrote:
>
>
> Thanks Peter. I see where the redundancy comes from now. Am I correct in
> thinking that if I use my GPS60 for several days creating tracks when I
> don't have facilities to download the data it would be best to save
> individual tracklogs and reset tracks day by day or even trail by trail?

Unless it's going to be quite a few days before you get a chance to do
a download, I'd recommend setting your tracklog options so the whole
trip will fit on the Active Log. That way you retain timestamp
information which can be useful later in determing travel speeds,
correlating pictures with locations, etc. If you have a reasonable
idea of how far you'll be going and how long it'll take then you can
make a good estimate of how often or for what distance to take
trackpoints so you don't run out of room in the 10,000 point Active Log.

Ted

2006-04-30, 5:48 pm

I'm sure in the past I've noticed that saved tracks replace the time
stamp with zero. Is this universal or just older GPS units?

Ted

Canopus wrote:
> I've been trying out GPS Utility 4.20.5 with my Garmin GPS60. I've set up
> a map OK, downloaded data from my GPS60, the track lines up pretty well
> with where I walked, but, I'm a bit bemused by the data I'm seeing. I see
> two lists of data, one labelled 09-Apr-06 corresponding to the Saved data
> title in my GPS60 and the other labelled Active Log. Data in both are
> identical except for time stamps. In the 09-Apr-06 data time stamps seem
> to be UTC starting from 13/12/1989 23:59:59 and ending 13/12/1989
> 23:59:59...all the same time stamp. In the data labelled Active Log it
> starts 09/04/2006 15:31:44 and ends 09/04/2006 15:47:14...these correspond
> to UK time which I'm using. Why does the first set of data use a time
> stamp of 1989 which could be UTC and the second set of data use the
> correct UK time stamp? Why are they in fact duplicated except for time
> stamp? If I delete the first set (1989) the second set displays on my map
> correctly anyway so why the redundancy?
>
> --
> Rob
>
> http://www.flickr.com/photos/canopus_archives/

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