Author Topic: Correct time from GPS track (Read 7305 times)

tdcarter · « **on:** November 03, 2004, 02:23:50 PM »

Hello,
I dug through the other lists, but couldn't see this addressed anywhere.

I have a Magellan and a Garmin GPS. I take them both with me on the ride and then dowload them when I'm back. I try to do a simultaneous playback of the tracks (for accuracy comparisions) but the time points from my Magellan are an hour off (later).

I thought maybe it was just a little bug with daylight savings, but now with that gone... I still have the problem.

Is there a menu setting I'm missing somewhere that I need to switch when I switch units? I set the ones under the GPS setting in preferences, any others?

TC

« **Reply #1 on:** November 03, 2004, 09:01:53 PM »

Realized it might help if you knew the specifics... Garmin is a Forerunner 201, Magellan is a 330.

TC

Krein · « **Reply #2 on:** November 04, 2004, 01:41:57 PM »

There is no setting--it should work without doing anything.

This is puzzling because time data comes out correct on my Magellan Sportrak Map. The Magellan protocol just sends over UTC time so I can't see how TF could be the problem.

Have you tried downloading the track with a different program, like expertgps or gpsutility? You should just need to download some of the points, then compare the time stamps.

It's possible it's a firmware bug. There also could be something wrong in TopoFusion. Report back if you find anything.

Thanks.

tdcarter · « **Reply #3 on:** November 05, 2004, 12:13:47 AM »

I have tired other programs. One is trackdown, a MS Excel utility. Each time you download, you set your timezone, and, no problem. I have Mapsend Streets, and MapSend topo. Topo reads the time data, but it dosen't try to correct from UTC. You just adjust the first trackpoint, and it correspondingly updates the subsequent ones. Map streets just download track position, no time/speed data.

But on that note... a little brainstorming here, how does Topofusion know my local TZ? Is it in the output stream of the GPS? I glanced at the GPX file saved from Topofusion and didn't see anything that stood out as being the offset.... course this still dosen't explain why the Z time recordings are off in the Magellan GPX file as opposed to the Garmin file.

Firmware is v4 on my Mag map330. I think I might be able to get ahold of another 330 that has an older firmware. Will try.

Are there any utilites that I can use (or just something like hyperterm) that I can view the tracks raw from the GPS?

TC

tdcarter · « **Reply #4 on:** November 05, 2004, 12:38:31 AM »

Don't you justlove it when you can answer your own questions... It's when the conversation starts making sense I get scared.

Used Trackdown to snag a recent run. It does record the raw time seperate from 'corrected' time.

Sure enough, time is 1 hour different from what i get in the Topofusion GPX file.

Cut/Paste from the two below...
<urlname>TopoFusion Home Page</urlname>
  <trkseg>
   <trkpt lat="38.773800" lon="-90.484100">
   <ele>144.000000</ele>
   <time>2004-10-31T19:43:49Z</time>

RAW PT   pt. #   rawlat   rawlon   rawtime
$PMGNTRK,3846.428,N,09029.046,W,00144,M,204349.77,A*6C   1   38.7738   90.4841   204349.77

Okay, a little hard to read without Excel formatting, but the 204349.77 is the time part.

Does this turn any gears?

TC

Krein · « **Reply #5 on:** November 05, 2004, 11:07:04 AM »

TF gets timezone info from windows, which should be correct since it works for Garmin downloads.

It seems like your raw string from the magellan is missing the date component, so I'm not sure what is going on.

We did have "off by one hours" years ago, and that was with the garmin code as well. So it sounds like there is a bug, but I'm still confused since it works on my Magellan.

tdcarter · « **Reply #6 on:** November 05, 2004, 12:22:58 PM »

Anyother freeware utils out there that I can pull the raw data from both units... or just the Mag.
TC

Krein · « **Reply #7 on:** November 08, 2004, 09:30:58 AM »

Don't know any other utils to get the raw output, other than by sniffing the serial port.

Maybe try another program that can both download from the unit as well as save GPX, like ExpertGPS? It also gets the time from windows, since it doesn't ask for it. If ExpertGPS get the time right there must be a bug in TF.

tdcarter · « **Reply #8 on:** November 22, 2004, 01:05:39 PM »

I was looking at this way too closely.

Forget all the high-tech stuff, just fix it like in the old days of Win 3.1, 'format c: /u /s'

Works just beautiful... now

Moth in the machine?

Krein · « **Reply #9 on:** November 22, 2004, 01:14:48 PM »

Yeah, we should just tell everyone to format c: if they are having problems. Good idea.

I can only guess that there was something screwy with your timezone settings in windows. There are a few different ways to get it, and they may have been giving conflicting answers. Anyway, glad it's solved. Your machine probably runs twice as fast too.

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