Geoff wrote. You can also achieve direction finding with two ferrite stick antennas mounted at right angles. You will not get forward and backward definition, but you can sure get two accurate 180 arcs.
If you have a two channel receiver with a phase detector on the end you can get unidirectional response. That would be something I would have a lot of fun building but I think it's far beyond most of the folks on the list. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] ----- Original Message ----- From: "Geoff Eden" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Wednesday, November 28, 2007 8:41 PM Subject: Re: [BlindHandyMan] radio direction finding project >A couple thoughts. I have a very low cost audio tag device comprised of a >handheld transmitter that can alert four different beepers to sound. It >works up to about 50 feet, and the beepers are hardly the size of a hollow >wean chocolate bar. > > You can also achieve direction finding with two ferrite stick antennas > mounted at right angles. You will not get forward and backward > definition, but you can sure get two accurate 180 arcs. > > Geoff > ----- Original Message ----- > From: Dale Leavens > To: [email protected] > Sent: Monday, November 26, 2007 12:12 PM > Subject: Re: [BlindHandyMan] radio direction finding project > > > In order to accurately locate a transmitter you require triangulation. the > wider spaced your receivers are the more accurate will be your location. > You point a very directional antenna swinging it side-to-side judging the > strongest signal then plot that line on a map. where there are two > receivers placed at distance you can plot the intersecting points of the > two directional lines and that should be within a few hundred feet of the > source of the transmitter. Otherwise you have to move your s ingle > receiver then take another direction and plot that. > > If the target is moving of course your lines won't cross in the right > place. > > If you have enough satellites in the air you can judge location more > accurately and readily by comparing the signal from several angles > simultaneously. this is essentially how locater beacons work. > > GPS on the other hand also uses a number of satellites but a little > differently, it knows which satellites it is receiving at any point in > time and where they are supposed to be and how long it takes a signal to > arrive from that distance. Knowing that the device can estimate pretty > accurately just where it is. Well anyway, that is more or less how it was > explained to me. > > I understand that during the bombing of Britain the German forces sent two > highly directional signals out from distant points in Europe pointed to > merge over a particular city, say Liverpool. A flight of bombers could > pick up a signal then follow it and listen for the complementary signal > then drop bombs. It was somewhat approximate but in black-out conditions > there wasn't much else to go on. Jamming further confused the accuracy but > this was a mixed blessing resulting in otherwise non-strategic places bein > g bombed. > > Sorry, didn't intend to drift that far off topic. > > Dale Leavens, Cochrane Ontario Canada > [EMAIL PROTECTED] > Skype DaleLeavens > Come and meet Aurora, Nakita and Nanook at our polar bear habitat. > > ----- Original Message ----- > From: Dan Rossi > To: [email protected] > Sent: Monday, November 26, 2007 10:15 AM > Subject: Re: [BlindHandyMan] radio direction finding project > > I know very little about this radio stuff, but what about using a loop > antenna for direction finding. That's how they do those radio fox hunt > games. A transmitter puts out a signal and a bunch of radio-heads with > loop antenna, run around trying to find the transmitter. > > -- > Blue skies. > Dan Rossi > Carnegie Mellon University. > E-Mail: [EMAIL PROTECTED] > Tel: (412) 268-9081 > > [Non-text portions of this message have been removed] > > > > > > [Non-text portions of this message have been removed] > > > > To listen to the show archives go to link > http://acbradio.org/handyman.html > or > ftp://ftp.acbradio.org/acbradio-archives/handyman/ > > The Pod Cast address for the Blind Handy Man Show is. > http://www.acbradio.org/news/xml/podcast.php?pgm=saturday > > Visit The Blind Handy Man Files Page To Review Contributions From Various > List Members At The Following address: > http://www.jaws-users.com/handyman/ > > Visit the archives page at the following address > http://www.mail-archive.com/[email protected]/ > > If you would like to join the Blind Computing list, then visit the > following address for more information: > http://jaws-users.com/mailman/listinfo/blind-computing_jaws-users.com > > For a complete list of email commands pertaining to the Blind Handy Man > list just send a blank message to: > [EMAIL PROTECTED] > Yahoo! Groups Links > > > > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.503 / Virus Database: 269.16.9/1157 - Release Date: > 11/28/2007 12:29 PM > >
