menace3397
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Not sure if this is the right folder to ask this in, but does anyone know where to get a inexpensive DF unit. I could have sworn i saw one on a Big 5 ad for a few hundred dollars last year. Any suggestions......
Directional Finding
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WisconsinRailfan
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Not sure if this is what your looking for, but have a look - DDF1 - Doppler Direction Finder Kit - Ramsey Electronics
Dee effing AKA fox hunting is fun because it's a real challenge when the fox is hiding and/or moving from place to place. Oh it gets worse in the mountains when the fox uses a directional antenna and bouncing his signal around, some are foxier than others. The foxiest one of all was a repeater jammer who is a professor of applied psychology and having extensive knowledge of VHF propagation drove us nuts but being a long story the short version is "we got 'em".
I've never personally used a Doppler array but know they work exceptionally, only what do you do when in close proximity and the fox is somewhere overhead? That may be overcome with a hand held Yagi antenna but unless you know where the side lobes and nulls are, that means being real good at it you may be at a distinct disadvantage. Here's where a loop antenna comes in handy, it has a figure 8 pattern with two deep, sharp nulls so rather than looking for peak signal you null it out and looking through the loop gives you the directions.
Yup, plural so triangulation with a loop becomes even more important than with the previously mentioned methods. Once you are at the intersection of those lines you drew on the map, like I said it gets tricky, especially when the fox is above you. Then you start wondering where the little bugger could be, the signal looks like it's everywhere and for all practical purposes it is until you rotate the loop vertically and check the approximate elevation. Being surrounded by antennas at night I was stumped so I came back the next day and there it was, I was looking at an antenna atop a 75' tower. Yeah, it took some doing but we got that one too. (;->)
I've never personally used a Doppler array but know they work exceptionally, only what do you do when in close proximity and the fox is somewhere overhead? That may be overcome with a hand held Yagi antenna but unless you know where the side lobes and nulls are, that means being real good at it you may be at a distinct disadvantage. Here's where a loop antenna comes in handy, it has a figure 8 pattern with two deep, sharp nulls so rather than looking for peak signal you null it out and looking through the loop gives you the directions.
Yup, plural so triangulation with a loop becomes even more important than with the previously mentioned methods. Once you are at the intersection of those lines you drew on the map, like I said it gets tricky, especially when the fox is above you. Then you start wondering where the little bugger could be, the signal looks like it's everywhere and for all practical purposes it is until you rotate the loop vertically and check the approximate elevation. Being surrounded by antennas at night I was stumped so I came back the next day and there it was, I was looking at an antenna atop a 75' tower. Yeah, it took some doing but we got that one too. (;->)
menace3397
Member
Gentlemen, thanks for the responses.
Probably NOT cheap, but it is always nice to dream;
http://www.l-3com.com/products-services/docoutput.aspx?id=1296
L-3 has LOTS of really cool toys. If I ever win the lottery....
http://www.l-3com.com/products-services/docoutput.aspx?id=1296
L-3 has LOTS of really cool toys. If I ever win the lottery....
RDF Device
Check out this website Firestorm Emergency Services
The device is called the Tigerstrike as far as DF equipment is concerned there is nothing else like it.
Check out this website Firestorm Emergency Services
The device is called the Tigerstrike as far as DF equipment is concerned there is nothing else like it.
Geocaching taught me that in directional finding you should find two bearing from the target either determined longtitude or latitude..and with a little help from GPS..bingo, you got it...(Geocaching for dummies) LOL
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