[ot] Gps Trackback Questions

[kusako]

Hi-

sorry if this is somewhat off topic, but I couldn't think of another forum to post it.

I'd like to use a GPS as sort of a blackbox, to automatically store GPS coordinates as I move, together with timestamps of when the coordinate samples were taken. As I understand it, most GPS units have this kind of functionality.

Now my questions:

 

How long can you record GPS data? The manufacturer's data sheets usually state how many coordinates can be stored, but not how many samples are taken per time interval. I would like to keep record of 3 to 4 weeks of GPS information. Would this be possible? Any recommendation of a unit that would allow to do this?

 

Can the track informations (coordinates + timestamps) actually be exported to a pc in a documented format or do you need some special software?

 

Do you need special drivers to access a GPS unit from a pc, or is it recognized as a standard USB bulk device?

 

Thanks for your answers.

 

-markus

[+GOT GPS?]

Many of the Garmins now can record up to a 10,000 breadcrumb tracklog, and they can record as often as one trackpoint per second. My favorite use of a GPS is not a GOTO device, but a Tracklog recorder.

 

The newest Garmins like the Map60Cx, will now record quite a bit onto the MicroSD memory card, in GPX format, but this requires the latest beta firmware for the new GPS units.

[Neo_Geo]

How long can you record GPS data? The manufacturer's data sheets usually state how many coordinates can be stored, but not how many samples are taken per time interval. I would like to keep record of 3 to 4 weeks of GPS information. Would this be possible? Any recommendation of a unit that would allow to do this?

As GOT GPS? mentioned, they can be set to mark a track point every second - but they're very flexible in how frequently they log a point. It could be every hour or every 24 hours. The frequency can also be determined by distance as well - as frequently as every 1/100th of a mile (53 feet).

 

As Geoff mentioned, Garmins have a tracklog capacity of 10,000 points, so a little math is involved in deciding how frequently to set the track points based on how often and for how long you'll be tracking during the three to four week periods. The new Garmin "x" series units can be set to log the points onto the memory card (which is used mainly for map data storage). If a big enough memory card is used with enough space left over after loading maps, you could conceivably continue tracking for several months or even many years (if tracking is set to log every hour).

 

 

Can the track informations (coordinates + timestamps) actually be exported to a pc in a documented format or do you need some special software?

Absolutely! You do need software to do this. If you buy mapping software for the unit (like Garmin MapSource products), you can use it. But if you don't get a mapping unit, you can use a free program like USAPhotoMaps. That one will allow you to view your tracks over aerial photos! There are other programs you can use to convert the data to various formats for various purposes. Lots of flexibility there as well.

 

 

Do you need special drivers to access a GPS unit from a pc, or is it recognized as a standard USB bulk device?

Some units connect to a standard serial port (RS-232) and some connect via USB port. If it's USB, the drivers will come with the unit.

[+PDOP's]

Can the track informations (coordinates + timestamps) actually be exported to a pc in a documented format or do you need some special software?

 

Here's an example of trackpoints saved to a text file by GPSTrackmaker (freeware)

 

t,dm,53 21.85693',-117 38.67261',03-10-2006,20:37:13,1030.671,0
t,dm,53 21.76186',-117 38.81892',03-10-2006,20:37:22,1021.538,0
t,dm,53 21.62433',-117 39.06791',03-10-2006,20:37:36,1019.615,0

 

If you want more data for points you'd use waypoints which can have names and notes attached.

[+Sputnik 57]

Do you need special drivers to access a GPS unit from a PC, or is it recognized as a standard USB bulk device?

 

The GPSr won't be recognized as a standard USB device, but any GPSr with computer connectivity will come with drivers to allow your computer to recognize it. The GPS unit can export data to a PC in real time, or more useful in your application, can export a track log. As earlier posts demonstrate, the track log can readily be exported in a variety of formats for use in word processing, spreadsheet or database applications.

 

A Garmin 60CS or Vista C will give you not only longitude, latitude, date and time, but also elevation, if that is of interest. Setting a unit to record its position once every 4 minutes would give you just shy of four weeks worth of data points, but battery life for most of these receivers is in the 30 hour range (with some as great as 30 hours).

[kusako]

Thanks for all the help!

 

As GOT GPS? mentioned, they can be set to mark a track point every second - but they're very flexible in how frequently they log a point. It could be every hour or every 24 hours. The frequency can also be determined by distance as well - as frequently as every 1/100th of a mile (53 feet).

Setting frequency by distance would probably be a pretty good option.

 

As Geoff mentioned, Garmins have a tracklog capacity of 10,000 points, so a little math is involved in deciding how frequently to set the track points based on how often and for how long you'll be tracking during the three to four week periods. The new Garmin "x" series units can be set to log the points onto the memory card (which is used mainly for map data storage). If a big enough memory card is used with enough space left over after loading maps, you could conceivably continue tracking for several months or even many years (if tracking is set to log every hour).

Yes, one of those would probably be the best choice. Unfortunately they are also at the upper end of the price range .

 

Do you need special drivers to access a GPS unit from a pc, or is it recognized as a standard USB bulk device?

Some units connect to a standard serial port (RS-232) and some connect via USB port. If it's USB, the drivers will come with the unit.

OK, I asked this because if the device just conects like a digital camera or a usb stick, I might be able to do backups to free memory on the device on public computer terminals.

[kusako]

On more question

Is the memory for the tracklog shared with other data? So if the garmin specs say the device stores 10,000 points, does this mean up to 10,000 if no waypoints or track data is uploaded, or is it always 10,000 points.

 

Thanks again for the great help.

 

-markus

[rickertk]

In the active tracklog, it's 10,000 points free and clear - no other data impinges on it as far as I've been able to tell. You also have the capacity on the unit to "save" the active tracklog - the unit has an additional capacity for up to 20 saved tracks, with up to 500 points each. "Saving" the tracklog on the unit basically transfers the complete active tracklog to a single saved track, strips out time/speed data, and filters it down to 500 or fewer points. Because of this filtering, it's not really a great method to capture the best data for long term use. However, if you are running out of room and you're about to lose data otherwise, this does give you some additional capacity on the unit itself for simplified data.

 

Keith

[+PDOP's]

OK, I asked this because if the device just connects like a digital camera or a usb stick, I might be able to do backups to free memory on the device on public computer terminals.

 

Yes you could do that or if you have a PDA you can back the data up that way. An older Palm with a serial interface and GPilotS freeware is what I use to backup my data when I'm away from a PC.

 

Edit for spelling

Edited March 23, 2006 by PDOP's