I lost my TM on my last flight... ughh..... My son misses his rocket I am sure wheat combines need rocket food.
But I have found every flight on my TM thorugh RDF. I use a scanner that sets to a standard frequency. For instance 434.00000 mhz I use an arrow 7 element antenna...http://arrowantennas.com/arrowii/440-7ii.html (they have antennas that are 3 and 5 elements – this reduces tha gain, and increases the width of reception.) The number of elements have their tradoffs between “pointyness- and – gain”. Less pointy, means less gain, ect... I know people who’ve tracked to 20k’ish with 3 elements versions. now, depending on your set up.. if you select 434.00 mhz(whatever channel you specify), your actual emitted frequency is somewhere around that... but not exactly. I use a scanner (from radio shack) where I can set my radio to 434.00000, I then listen for my Telemetrum signals. (continuity at start up is one of them-love that) usually I will step up and down in frequency in .00625mhz. until I find what I consider would be the “strongest”. Even if 434.00625, seems to be best, that is where I lock my scanner. Now,.. the TM signal, with a regular radio is going to be one of the hardest things to “reverse gain” .. I launched am M about a year ago, and up and down, I could not farm a direction from the signal... it was too strong the whole time. however, signal fell dead, upon landing as was expected. I keep my “strongest” frequency untill I get a bead on an on ground signal...a lot of people first search for a signal using just a reqular whip or (omni-directional antenna), but using a yagi usually you can tell within about 30degrees which direction to walk. while using a yagi, the signal can reverse polarize, so as you get close, direction becomes harder. depending on the pattern, you feel like you walk in a circle to get there sometimes. That is when I begin to shift my scanner, up or down .00625mhz, or even in some cases I’ve gone .01250mhz to each side. (usually you have to turn off the squeltch and get a lot of fuzz during this.) But, if you can weaken the signal when its too strong, it makes the rdf easier. I suggest going both up and down, because usually the offset is not evenly divided. so you may be able to offset up .01250, but you cannot receive signal going down that far. With a yaesu, you may want to preprogram these offsets to the channel you select. my scanner I use to listen to the airport frequency we fly rockets from, so its really a dual purpose. In the 8’-0 tall corn I recovered my rocket, this method got me beeping close enough to smell the burnt bp before seeing my rocket... (that smell was ... “oh my gosh my rocket is right here... where is it...”) I haven’t spent the money on an attenuator yet, not sure as if I need one. I have wondered if a potentiometer in line with the yagi would make it easier? aprs is a whole other cat.... Clay “at square one” From: Rob Derstadt Sent: Monday, June 01, 2015 4:35 PM To: [email protected] Subject: [altusmetrum] Direction finding how-to? Hi, Does anyone have any instructions (or good how-to references) on how to do direction finding with a HT and the TeleMetrum or TeleGPS? I read on the website that it can be done: "... you can use that with your antenna to direction-find the rocket on the ground...Keith and Bdale both currently own and use the Yaesu VX-6R at launches." I own the VX-6X (albeit I am only familiar with the basic APRS stuff on it). If anyone can point me at some information on how to use this to direction find with the Tele* units, I'd greatly appreciate it. Thanks. Best regards, Rob -------------------------------------------------------------------------------- _______________________________________________ altusmetrum mailing list [email protected] http://lists.gag.com/mailman/listinfo/altusmetrum
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