Check out our transponder track while doing the Milt Ingram 'round Anacapa race July 21st:
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<br>http://www.findu.com/cgi-bin/track.cgi?call=kg6bcp&start=225&length=24
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<br>Note that the "start=225" tells the server to display data recieved 225 hours ago (~9days from 7/30/01). If you are trying to see the track at a later time, you'll need to add more hours to this number.
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<br>The transponder works using a 2m HAM radio connected to a GPS. It transmits a position, course, & speed report every 1 minute. The signals (at least most of them) are picked up by local Ham repeater towers up on the mountains and relayed to the internet database. The mountain towers are some ~15-20 miles inland, so the signals were achieving ~30-40 miles range...not bad for only 2 watts output and a little dinky antenna on the boom! Though this map display doesn't show speeds/course, it does show you where we were and where our 2 tacks were on the windward leg. Note the loss of signal as we passed behind the island.
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<br><br><br>Mike Dobbs
<br>Tornado KC 283 "Double Mint"

Mike,
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<br>A few questions. Other than the GPS which I already own, what else would I have to buy to make one of these transmitters? Also how would I find out if there are towers around where I live so that I could transmit the signal? Is there special software that had to be written?
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<br>Thanks,
<br>Mike Hill
<br>H20 #791
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Mike,
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<br>The system I'm using is called "Automatic Position Reporting System" (APRS). The setup consists of a GPS unit capable of NMEA format output (most Garmins and other popular units do this...I use a Garmin GPS III+ because I also use it's great display while sailing/racing), a HAM radio capable of 2 meter output (a HAM operator license is required by law to transmit on these frequencies...see below for details) and finally a device called a TNC (terminal node emulator) that converts the digital code from the GPS into audio sounds prior to being passed to the radio transmitter. My radio (Kenwood TH-D7a) has a built-in TNC unit, making the connections much easier...just plug the GPS into the radio's dedicated GPS jack. The radio is set to automatically transmit whatever it received from the GPS every minute or so. Note that it only sends the last position it got from the GPS, not a series of stored positions since the last transmit. The radio is protected inside a Pelican waterproof box with a cable going out to a small antenna on the boom. Another cable goes out the my GPS (I mount this to the boom on a swivelling mount so I can see it from the helm position). You can also put the GPS inside the box with the radio if you don't need the display. The box is them slung off the boom...I'm considering other mounting places as well.
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<br>To get a HAM radio license is really straight forward and no big deal. There is no longer a requirement to learn Morse code. Pick up a "No Code Technician License" book from any Radio Shack store and spend a few nights reading what you need to know to pass a written, multiple answer test. Contact your local HAM club and arrange a day to do the test. After passing, you have full transmit privileges on the 2meter and 70 cm bands (this is what most handheld HAM radios use).
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<br>The receiving towers ("Repeaters") are found all across the country. As long as you are within ~50 miles (by line of sight) you signals will get out. There is a web site some place that lists all current repeaters across the US, and your local HAM club will surely know more about your region.
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<br>Once the signal is picked up by a repeater, it relays the signal to other repeaters spaced at ~ 50 miles apart. At some point, one of those repeater will be an "I-gate", that automatically uploads position reports to an internet database. At this point, all anyone has to do to see where your are is load the webpagewith your call sign: http://www.findu.com/kg6bcp
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<br>This brings up a map display with an icon showing your position anywhere on the planet! This has all be created by & for the HAM community. There is no additional coding required by the users.
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<br>A fellow HAM and I are also planning on setting up a audio/video transmission system to broadcast live footage from abourd the Tornado. This would use a system called Amatuer Television (ATV) and it can reach 20-30 miles at fairly low power. Imaging being able to watch a live Cat race from the comfort of the club house or your computer screen!
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<br>To find more info, do some internet searching for APRS, HAM radio etc.. You'll find lots of stuff out there.
<br><br><br>Mike Dobbs
<br>Tornado KC 283 "Double Mint"