FRS foxhunting for model rockets

posted Apr 5th 2008 6:00pm by Will O'Brien
filed under: misc hacks

Since we had a FRS radio hackit a while back, [Weirdguy] sent this in. [Scott] gutted a frs radio and added it to his rocket chassis. It’s powered on for the flight, and he can listen to the rockets progress. To locate the rocket once it’s on the ground, he built a 462Mhz Yagi antenna to use with a Radio Shack hand held scanner. This is old hat for most Ham Radio guys – they do ‘Fox Hunts‘ for hidden transmitters just for fun.

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Comments [10]

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ive gotta get one of those

SGArts-design.blogspot.com

Posted at 8:00 pm on Apr 5th, 2008 by samuel gamlin

Some types of antennas look just like a cross, with wires strung in a flat coil. I’ve heard an old story told where a fellow was pulled over by the police during a fox hunt. An elderly woman had complained about a madman driving up and down her straight waving a cross out of his car’s window :)

Posted at 8:16 pm on Apr 5th, 2008 by wackyvorlon

Not to put too much of a damper on it, but do you realize how many FCC regulations are being violated with this hack, not to mention radio etiquette with the continuous transmission? You really should read over the section of the FCC regs for the family radio service before making mods of this nature… especially with the public posting… Nice work on the receiver antenna…

Posted at 10:21 pm on Apr 5th, 2008 by Nathan Neulinger

this is pretty “old hat” for Rocket guys as well. we’ve been doing various radio tracking schemes for quite some time now. nothing sucks more than a lost rocket.

Posted at 10:42 pm on Apr 5th, 2008 by Man On Fire

Actually, im not sure that and regulations are being violated. Mabe the modification to the radio, but its only .25W, so its not likely to cause much interferance. and on that note, the frs radios are so crappy anyway that its not like anyone will be complaining.

Posted at 10:53 pm on Apr 5th, 2008 by Abbott

You could use a timed recording to trigger a VOX circuit.

I did something similar when I did some rage tests with a set of FRS radios.

I used a Palm Pilot with a Morse code tutor app set to send my call sign but with an extremely long pause before repeating.
I then simply placed my Palm pilot next to the VOX-enabled radio and bingo! Instant beacon.

I was able to drive around with the other radio and get an idea how well the signal got out and at what distances.

The beacon thing would work well for this application.

Posted at 11:35 pm on Apr 5th, 2008 by strider_mt2k

Why use specifically a Yagi antenna? I thought that Yagi antennas were for non-directional type stuff.

Posted at 2:21 am on Apr 6th, 2008 by What is a Yagi-Uda antenna?

The FRS band radios are a bit more strictly regulated than people think. Though less restricted than CBs. Specifically
http://a257.g.akamaitech.net/7/257/2422/16nov20071500/edocket.access.gpo.gov/cfr_2007/octqtr/47cfr95.193.htm
details communications allowed on FRS bands. Section A specifies that communications must be between persons. I remember reading in the past that someone had set up their PC with voice recognition software, and some text to speech tools, so that they could speak commands to it via an FRS radio and have it read back information. As one side of this FRS communication didn’t involve a person the FCC smacked the guy with a fine.

The other FCC rules basically ban you from doing internal mods to an FRS radio, or boosting it’s output power / antenna gain. Supposing he simply swapped the guts of his radio into a new chassis it *might* pass muster, but if he tweaked anything while doing so then he’s screwed.

Posted at 5:33 am on Apr 6th, 2008 by Smilr

So if FRS is a bad idea for a radio beacon, what frequencies would you recommend for a future project with similar needs?

Posted at 11:48 am on Apr 6th, 2008 by turqy

Thanks for the link to my blog….

I’m not really familiar with FRS regulations, but one way to ensure that you’re not violating them is to get an amateur radio license and use amateur radio for this kind of project. Last February, the Morse Code test was eliminated for all classes of licenses, and it’s relatively easy to get a Technician Class license. Cerainly any of you doing hardware hacking could pass the test with just a bit of study.

To make it even easier, there’s a free study guide on my blog, http://www.kb6nu.com/2006techstudyguide.pdf. If you’d prefer a printed version, you can purchase one by going to http://www.booklocker.com/books/3408.html.

Let me know if you have any questions……73, Dan KB6NU

Posted at 10:23 am on Apr 18th, 2008 by Dan KB6NU