I have an Igotu GT-120 GPS datalogger, for GPS-photo correlation. By combining gps-correlate, and any camera with a timer (or timestamps on files, see my previous diary entry for the code…) I can now do correlation. The device has no built-in display of any kind, so it won’t be any use for anyone who needs on-the-fly GPS, with no external connections.

Summary

It works, but the connector is a bit worrying. As a simple mapping tool, it should be enough for those who are happy to do photo-correlation, but don’t have/want or for some other reason can’t use a mobile phone based GPS. It wont be super-high accuracy though!

Specs

The chipset in the device is apparently a “SiRF StarIII low-power” device. The usb A->proprietary connector is a bit dodgy (insertion/removal) at the proprietary end. Not sure why they didn’t use USB mini…

There is a CHM file available on the manufacturer’s website, which give the LED codes. I’ve reproduced them here for posterity

Warm-up times are claimed to be 35 seconds, but my first power on (albeit without a clear view of the sky) took several minutes after being outdoors before it woke up and started logging. I assume this has something to do with GPS almanac data, and that subsequent power-ons will be better.

LED codes

• Turning on the device : press button for 1.5 seconds, until blue LED flashes once.
• Turning off the device : press button for 1.5 seconds, red LED switches off.
• If red LED blinks twice : memory low
• If red LED blinks once: battery low
• Charging : red LED on until charging complete (possibly 2 hrs?)
• Logging individual waypoints : push button once -> log acknowledge.

The manufacturers claim 65,000 records, so at 1/second should give ~18 hrs. The battery only lasts for 10 hours, according to the specs.

Use

After using the device for a very short while (cycling), it seems to work, and I can load the tracks under linux (debian testing) using the igotu2gpx program. The capabilities include setting the logging time, and downloading tracks, as well as an on-screen display for maps. Most importantly, gpx export seems to work.

A deb file can be built by obtaining the .dsc and .tar.gz files from launchpad. This was quite easy, after

• tar -zxf igotu*gz
• dpkg-source -x igotu*dsc
• ln -s igotu*gz igotu2gpx_0.4.0.orig.tar.gz
• cd igotu2gpx-0.4.0; sed -i ‘s@native@quilt@’ debian/source/format
• dpkg-buildpackage -j2 -uc -us;

dpkg complained about missing dependencies. After installing them, everything went smoothly.

I haven’t tried realtime logging with gspd; though gpsd seems to recognise the device, but I have no lock indoors. As a cheap entry-level USB device, so far, so good.

Hopefully some good mapping can be done with it!