The Holux M-241 GPS logger (available from Amazon.com in the USA) has a similar cylinder form to some other loggers, but adds a new feature: an LCD display which can show current location and GPS time, as well as enabling the changing of settings on the device itself.
It takes a single AA battery, and although it can run off of USB power, it can't recharge the battery. It uses the 32 channel (51 channel) MTK chipset. It comes with very basic
photo geocoding software for inserting photos into Google Earth tracks, the software is Windows-only. It has Bluetooth serial support, so it can work with compatible devices (e.g. mobile phones, laptops, PDAs) as a Bluetooth GPS. The device itself is also Mac compatible, using BT747 software, including track download over Bluetooth. 130,000 log points with user-settable time interval or distance trigger.
See my GPS logger comparison spreadsheet for a full feature comparison with other loggers.
If you want to be able to check your location in real-time or change settings on the fly, this may be the logger for you. However the Windows software is very basic, and I found some minor sensitivity issues. As well, it does not automatically start logging as soon it gets a satellite fix (you have to watch and manually start it once it has a signal). You may find some of the other models I have reviewed better suited to your needs.
Note: Although you may see mention of a Holux GR-241, there is no such device. It may have been an early model number for the M-241.
My colleague Chris actually noticed the design is reminiscent of a film canister. There is a small plastic cylinder on top through which you can thread the provided thin string that attaches to a strap.
Here's what it looks like, compared to some other loggers, it's the one in the centre
You can see that in colour (orange), size and shape, it's almost identical to the GiSTEQ DPL700 PhotoTrackr Lite. They are strikingly similar models, even down to the GPS chipset (MTK), with the M-241 LCD display being the main differentiator in terms of hardware.
Here's the packaging and what comes in it
It includes a USB cable, a strap, a battery, a car adapter for power, and a 7-day license for smart2go mobile (cellphone) map software (which works only on Windows Mobile 5 and some Nokia phones, unfortunately). You can get an optional and rather oddly-named "travel adapter" which is just a wall-socket USB power cable.
Using the LCD display, you can control logging settings (time interval or minimum distance). You can also see a count of remaining log record storage (continuously decremented if the log is running) - a very nice feature so that you know exactly how much memory you have left. As well, for the first time with a GPS logger, I actually can find out where I am in real-time, since it has a lat/long display. GPS time is also displayed (you have the option to adjust the time display for you timezone). This time display will make it very easy to keep your camera synchronized with the GPS.
It also has a sort of "odometer" mode, where you can measure distance travelled.
Surprisingly, despite the elaborate controls and display, I could find no way to set a waypoint (perhaps because it considers every track record location a "waypoint").
The included Windows software (Holux Logger Utility) is quite basic (as is common for most loggers other than the GiSTEQs).
Once you have the serial driver installed, you can connect to the device
The logger settings can also be controlled from software
"Upload" brings up a small dialog box
Files will have the device name ("user name") you have chosen prepended.
"Combine JPEG file" is one option for photo processing. It will "combine" matching photos into the Google Earth .kml
"Write Total Track Log" means one file combining all the tracks, in addition to all the individual logs.
The software will save both a Holux datafile (.trl tracklog filename) and a Google Earth .kml file, with start, end, and every intermediate datapoint included as a waypoint. Here's an example of me walking to work from my bus. Waypoints are in yellow, with date/timestamps in white, the track runs through the middle of the image.
and here's the .kml file itself
It does not produce time-based .kml
There are various other output formats available
The software has no concept of true photo geocoding with EXIF stamping, instead it will only create KML tracks with embedded photos.
It will let you make time adjustments to sync your photos with the GPS time of the track points
[Here's where I wrote about photos and the software, and TypePad ate it, so let's try again.]
The matching worked fine, I did some photos from my K790a camera, offset by -5 (my timezone).
However, all the photos are embedded in the .KML in the same section as the "waypoints" (the track log points), distinguished only by a camera icon. If you have dozens or more photos, you will have a heck of a mess trying to sort them out from the yellow track points.
Photo icons manually selected (purple with white date stamps)
Default appearance with everything selected. Good luck trying to find your photos.
Just to emphasize, there is no way to select just your photos all in one click, you have to manually scroll through the waypoints directory and select them one by one.
The waypoints directory showing one photo
Photos are not auto-rotated in the Google Earth display.
Here's what a single photo looks like (it's a snow groomer, in case you're wondering)
Please note: this is not true photo geocoding, the GPS coordinates are not embedded in the photos (I checked the processed images with IrfanView using the EXIF extension - no changes to the EXIF or IPTC). The photos are actually completely untouched and unaltered as far as I can tell.
To do true photo geocoding, you will have to convert your .trl files to a standard format (e.g. GPX) and use some other software (not provided by Holux) to embed the locations into the photo EXIF.
The M-241 will also work on Windows and Mac using the BT747 software, see my posting "BT747 support for Holux M-241 on Mac over USB and Bluetooth" for more information.
I tested the Holux M-241 against various other loggers:
M-241 with 5s logging interval, BT-Q1000 with 10s logging interval, not sure of HGE-100 (TrekBuddy recording interval), AGL3080 always fixed 1s interval (1Hz), Sony GPS-CS1 always fixed 15s interval
20080117 - roughly the same as the Qstarz BT-Q1000 and Sony HGE-100
20080119 - this is a problematic set of tracks from skiing at Vorlage - the M-241 overall does well, but there are a few tracks (the ones I am certain are wrong marked with "X") where it is clearly not correct (fortunately for my health, I didn't suddenly start skiing through the woods). M-241 (cyan track) and BT-Q1000 (orange) both in ski jacket pockets. This may be an antenna issue, the Holux does have a "this end up" indication, and I can't guarantee what direction that was pointing as it tumbled around in my pocket.
The original Holux .kml is quite large, so I have saved .kmz out of Google Earth.
20080123: roughly the same, keeping in mind the different logging intervals, except for the Sony GPS-CS1 (green) which not surprisingly is a bit more off-track given its SIRFstarII chipset
20080126: Back at Vorlage. Again an anomalous track (big loop at top). Could be due to battery I suppose, the Holux battery died part-way through the day. Cyan is Holux again, Orange is Qstarz again, Red is AMOD AGL3080.
Here are two of the tracks. There is more in the Qstarz because the Holux battery died (the advantage of having a 32-hour rechargable battery in the Qstarz).
Download Voralge-Holux-M241-20080126.kmz (just noticed filename typo, sorry)
These are just my observations in terms of the GPS performance, I don't have the equipment or software to do extensive sensor tests - I hope someone will do some detailed testing about the impact of the orientation of the M-241 and the antenna sensitivity.
UPDATE 2008-02-11: I did some additional testing and I got good tracks as long as the M-241 stayed with the antenna pointing upwards. ENDUPDATE
Things that could be improved:
- no way to have it auto-start logging when a satellite fix is obtained
- no way to set a waypoint (UPDATE 2008-02-11: May be possible in Lat/Long display mode.)
- awkward battery door (common problem with this type of design)