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Jan 24, 2009, 04:55 AM
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DiveBombDave's Avatar
Discussion

GPS log flights/Geotag photos for $40 and 18grams


I came across the neatest little device, the smallest GPS logger I have seen to date. While the trend in these devices is going towards bluetooth connectivity over "old fashioned" USB, the little Canmore logger is getting cheaper and cheaper. Since USB power is 5v, it was very simple to hack a $2 USB extension cable for it's A-female end, and wire it to my 5v RX. This way, whenever the plane is on, it's on and logging.

Though I've only "flown" it in the truck so far, the software is great. It is easy to read the log into a KML file for direct opening in Google Earth. You can then "tour" your path in GE by clicking the play button (with appropriate settings under Tools/Options/Tour, like Camera Angle 75deg, etc).

It can be easily configured for different intervals for logging, as well as log after minimum speed or distance moved. It claims 1,000,000 waypoints, but I'm not sure of their math on that one. However, I logged almost an hour at 4 second intervals and used about 0.2% of the memory.... that's in the ballpark of 500,000 for sure, more than enough for our purposes.

But the kicker is geotagging - this is where you use the logger software and point it to your folder of aerial photos from the flight. It associates the timestamps from the photos with the log data (with manual offset if needed), and adds the GPS coordinate data into the extended jpg data. It turns out there are websites like FlickR and others that observe this geotagged data (still looking into this). But check out this cool sample video so you'll get the idea.

3D Virtual Reality Travel Blog from @trip (0 min 41 sec)


Anyway, I thought for $40 and 18 grams, it'd be hard to NOT log your AP flights for a number of reasons... an "odometer" for maintenance intervals, speed vs range vs duration testing, geotagging your photos, FPV range checking, etc. And all this aside from the astonishing "cool" factor.



Just wanted to let everyone know about it.

Dave

edit -

If Vista sees the logger as some sort of "serial mouse device" and you lose mouse control (has been heard of).... reinserting the logger or rebooting the PC will correct but is a pain. Try using the Prolific Driver as it seems to correct the problem entirely.
Last edited by DiveBombDave; May 04, 2009 at 11:47 PM.
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Jan 24, 2009, 09:45 AM
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quailbird's Avatar
Now that was cool! I almost got car sick though! Just kidding! Great find!
Jan 24, 2009, 10:00 AM
I break cameras
sweatyfingers's Avatar
Pretty cool and cheap!

How would one set it up for RC AP?

Too bad I will never own it, its biggest draw back is its non Mac compatibility:

"Please keep in mind that the data logger software (known as GPS Photo Tagger) is only COMPATIBLE with XP / Vista and will not work for Mac OSX or Linux.

You may plug this unit to a USB port of a Mac book / Linux notebook for logging data (with the proper driver installed, see link above) but you could only download the logged data on a XP / Vista PC using the "GPS Photo tagger" software included in the disk"
Jan 24, 2009, 01:42 PM
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DiveBombDave's Avatar
Quail, thanks!

Sweaty - Sorry about the Mac thing... I have problems enough getting stuff to run with Vista 64 bit, so I can only imagine working with a Mac. In order to install it for RC AP, you just cut a USB extension cable and wire the red,black wires to a servo plug for your plane's receiver. This way you use the 5v from your plane to power it - works like a charm. You want the GPS external on top if possible, but it can work through balsa and thin plastic covering also. After your flight, you pop it off the plane, dump your AP photos into a folder, read the GPS log file into the logger software, and then point the logger software at the folder with the photos. Mix until smooth and bake at 350F until golden.

Dave
Jan 24, 2009, 11:04 PM
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BatterysIncluded's Avatar
I may be mistaken or confused (happens sometimes). I know your still in the experimental mode with this but I was wondering how this will actually work when you supply power to the USB plug BUT no data connections? Will it actually begin logging and storing the waypoints without the connection to the software on the laptop?
Jan 24, 2009, 11:33 PM
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DiveBombDave's Avatar
Yes, as soon as the device receives power, it begins logging. When power is removed, logging stops with no data errors etc. The only time it needs to be connected to the PC is to either read/clear the log data, or to change the logger's configuration (interval, etc).

Dave
Jan 25, 2009, 01:19 AM
Registered User
That is cool. What other things can you change in the logger's configuration besides interval?
Jan 25, 2009, 01:52 AM
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DiveBombDave's Avatar
You can set it to only log after a minimum distance is covered, in times when you are stopping during the journey it doesn't keep logging the same basic coords. The other setting is for after a minimum speed is achieved, maybe good for interstate driving where you don't want to log all the slower access stops for fuel and food, etc.

For our purposes, I can see using either of these settings to keep the memory from filling up with time spent on the stand, runway, etc. However, the memory is so large that it's just as simple as to program an interval and let it log all the time (zeros for min dist and min speed).

The other setting is you can set the amount of time that it logs - by default the max time is 3600 seconds (1 hr).... I upped it to 7200, but I'm thinking a zero here *may* make it unlimited. My only gripe about this specific model is the software is vague in these item descriptions (even in the manual), and there are no "units" on the config screen - so setting a minimum speed of "10" is not very specific.

I also bought a Holux M-241 that can be found on that same site - runs off a single AA, weighs about 65g with battery, and the software and manual are much nicer. You push a button on it to start/stop logging, and can connect it with either USB or bluetooth. This way I can toss it into any plane in order to collect data, with no wiring (buddies at the field, etc).

Dave
Last edited by DiveBombDave; May 04, 2009 at 11:42 PM. Reason: added screenshots
Jan 25, 2009, 01:09 PM
Whadda YOU lookin' at?
CactusJackSlade's Avatar

Nice...


Very nice,

I'm going to get one and strap it to my cat.... I always wonder where she goes when she goes out at night... Maybe one for my daughter too!
Jan 25, 2009, 01:46 PM
Registered User
rockbus's Avatar
Nice Product. Have you tried it on a plane yet?

At Parker, I met up with Allen (cant remember his last name) who's real job was designing UAV's and electric cars, but he had a consumer GPS on his plane with real time telemetry to a laptop and it tracked fine until he dropped into the backside for DSing, where it then stopped tracking until he straighted out a bit. Allan's explination was the consumer quality GPS predictive algorthims cannot handle hi G turns, its prediction of where the GPS will be in a hi G turn will not be where the unit is physically so it drops its location until the plane is straightened out and pulling less G's. For reference his plane was radared at 140's while DSing with an eyeball estimate of 100 ft radius.

I'm no expert on this, Infact I never knew GPS units do this. So I dont know what he threshold is. According to Allen the Military quality GPS has a higher G threshold.

But it worked great while on the front side tracking speed, position and height.
Jan 25, 2009, 05:35 PM
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DiveBombDave's Avatar
CJS - YES! I thought the same thing - attach my AA powered Holux unit to my Jack Russell to see how much ground he really covers when he's on "patrol" here on the property. One of my friends bought a couple of the Holux M-241's to track vehicles in his fleet (has truckdrivers stopping at places they shouldn't)...

Rockbus - I do UAVs as well (the Canmore's job is to tell me how far my UAV actually flew compared to the theoretical track I sent it on). For live GPS tracking, you do not want a bulky logger unit but an OEM GPS module like the GlobalSat EM406A . It's NMEA stream is then either converted by TinyTrak to be overlaid onto an audio downlink channel, or simply plugged into a radio modem so the resulting signal goes to a laptop that shows the live position on a moving map.

This is where the only problems I've found come in with GPS on a plane. Granted, I fly at about 55mph or less, but I've never had a problem with G load, speed, turn rate, etc. What I HAVE found is what the manufacturer mentions - "Use a USB extension to get the GPS away from your Wifi laptop for best results." Well, of course we have to TRY without, and it worked just fine. However, I was in a restaurant, with GPS logger locked on, and then I plugged in a Wifi high gain/power antenna into my laptop and the GPS immediately was swamped and lost all satellites. Moral of the story: 2.4ghz broadcasts will hamper performance, and if you are sending the data from a plane to the ground, then you have to be very careful about where the TX antenna is located compared to the GPS. I know there's not a lot of room on a DS plane, so maybe your friend was having another problem and just assumed it was because of G load or something. In any case, I've used GPS's of all sorts from full sized handhelds down to the OEM modules, and they seem to work much better once you get them up in the air, as opposed to a vehicle's dashboard etc. Sure the military GPS's may be rated for a higher G shock load, but this is solid state electronics, the cheapest one can take a hit harder than our skulls and still function. Now, not all GPS's are the same - some are more sensitive, etc, and maybe he has experience with a different unit and has kind of filled in the blanks, so to speak, to explain why they perform differently on his plane. If I were him, I'd shield the GPS's bottom side with foil, and connected the foil shield to the battery ground to negate capacitance in the shield. I'd also shield the top side of the TX on the plane, assuming the antenna is lower than the fuse in flight.

As a GPS loses view of satellites (from obstruction or RF noise), it's error will increase - for example, testing the logger on my center console of my vehicle and driving the same track twice, I got a deviation of 50-100' in places with no good view of sky (think mountains). When I relocated the GPS to my windshield, it's deviation dropped to 10-20', right about the width of the lane difference I was driving.

Dave
Last edited by DiveBombDave; Jan 25, 2009 at 05:49 PM.
Jan 25, 2009, 08:25 PM
Registered User
BatterysIncluded's Avatar
On the Specs page it says:
Weight: 18g (Including Battery)

If it has a battery why would it need external power?
Jan 25, 2009, 09:27 PM
Registered User
Dave, looks really interesting, thanks for the info. I'm interested but would like to see what it looks like when you fly.
What about a USB unit that can transmit its location? I assume this would have to be tied to a Cell phone system. This would be nice for lost planes

Larry
Jan 25, 2009, 09:46 PM
Suspended Account
I also have a little Holux M-241 which I keep in my camera bag.
Jan 26, 2009, 01:40 AM
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DiveBombDave's Avatar
Batteries - That is an error in the manual... there is no internal battery on the Canmore unit; it can only be powered through it's USB contacts.

Ridge - Cellular modems do exist but are still pretty expensive. However, check out this nifty little device called TinyTrak that uses the otherwise useless audio channel on our video downlinks, and after wiring the video RX's audio out to the "line in" jack on a laptop - free software decodes what tinytrak is sending back into the original NMEA 0183 data stream, for use with other softwares. Otherwise, you can get a 900mhz radio modem from U-Nav that will do the job as well, but if you already have a video downlink you may as well just use TinyTrak.

Dave


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