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#1
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Like Jim's system most of these DF units do not depend on modulation modes
they use doppler effect and electronically rotate the antenna. Popular Electronics a few years back had a DIY article to built a df unit. They used a 16 bit counter and used its output to diode switch pairs of antenna to get the pattern then used 8 LED's to indicate cardinal direction. They used an external receiver and audio output to drive it so that you could use on whatever band you like changing only the requirements for a resonant antenna. It makes for a nice project though and not overly expensive! John Mattsson wrote: So, this may be an utterly stupid idea, but... I know I can get bearings from an airport, or more specifically the tower, by using my com and talking to them when flying and within range. Also, radio amateurs have these "fox hunts" where they hide a small tx and then hunt it down. Now, I have a scanner that covers the civil airbands on AM and I already have built a few homemade base antennas for it, following some nice designs made by others. This allows me to listen to nearby airfield traffic pattern communication. Now, it would be a lot of fun to be able to use my scanner with a suitable antenna array, to get bearings to an airplane talking to for instance tower. I know I know, you report positions most of the time, but sometimes the small planes give pireps on local weather conditions and the like, sometimes they just give position reports and so on, not being that accurate on their position. At other times, spending time at relative´s summer cottages, having the scanner with me, it would be great to quickly get info on where to scan the sky for nearby airplanes on the air, then get the binoculars. And as the chit chat on the airwaves usually is very brief, there is no time to start pointing that yagi or whatever to get some idea of where the plane is. You would need some kind of automatic direction finding, something that would give a direction for you in a second or two. Is there anything like this for a DIY project? I googled a bit and found a lot on automatic FM DF projects, but not for AM. It´s understandable that most people are interested in searching FM transmissions, especially those interested in finding noise sources and the like, but I´m just interested in spotting and plotting those planes up there! =) Any thoughts and suggestions appreciated, Ken |
#2
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The following site is a similiar setup they give circuit diagrams and all for the complete unit! They call for fm demod though although you can get scanners that will cover the air band with fm also. http://members.tripod.com/~clearRX/PRDFUNIT.HTM John Like Jim's system most of these DF units do not depend on modulation modes they use doppler effect and electronically rotate the antenna. Popular Electronics a few years back had a DIY article to built a df unit. They used a 16 bit counter and used its output to diode switch pairs of antenna to get the pattern then used 8 LED's to indicate cardinal direction. They used an external receiver and audio output to drive it so that you could use on whatever band you like changing only the requirements for a resonant antenna. It makes for a nice project though and not overly expensive! John Mattsson wrote: So, this may be an utterly stupid idea, but... I know I can get bearings from an airport, or more specifically the tower, by using my com and talking to them when flying and within range. Also, radio amateurs have these "fox hunts" where they hide a small tx and then hunt it down. Now, I have a scanner that covers the civil airbands on AM and I already have built a few homemade base antennas for it, following some nice designs made by others. This allows me to listen to nearby airfield traffic pattern communication. Now, it would be a lot of fun to be able to use my scanner with a suitable antenna array, to get bearings to an airplane talking to for instance tower. I know I know, you report positions most of the time, but sometimes the small planes give pireps on local weather conditions and the like, sometimes they just give position reports and so on, not being that accurate on their position. At other times, spending time at relative´s summer cottages, having the scanner with me, it would be great to quickly get info on where to scan the sky for nearby airplanes on the air, then get the binoculars. And as the chit chat on the airwaves usually is very brief, there is no time to start pointing that yagi or whatever to get some idea of where the plane is. You would need some kind of automatic direction finding, something that would give a direction for you in a second or two. Is there anything like this for a DIY project? I googled a bit and found a lot on automatic FM DF projects, but not for AM. It´s understandable that most people are interested in searching FM transmissions, especially those interested in finding noise sources and the like, but I´m just interested in spotting and plotting those planes up there! =) Any thoughts and suggestions appreciated, Ken |
#3
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OK I screwed up I don't know how that P got in there it should be
/RDFUNIT.HTM http://members.tripod.com/~clearRX/RDFUNIT.HTM John Jim Weir wrote: John shared these priceless pearls of wisdom: - - - -The following site is a similiar setup they give circuit diagrams and all -for the complete unit! They call for fm demod though although you can get -scanners that will cover the air band with fm also. - - -http://members.tripod.com/~clearRX/PRDFUNIT.HTM Sorry, but the page or the file that you're looking for is not here. • Please check to see that you've entered the correct URL. • The owner of this site may have chosen to delete their membership. • The site may have been removed due to a violation of Tripod's Terms of Service. • The site may have been moved to a different URL. Please search again for this page, or others like it with the search box above. Jim Weir (A&P/IA, CFI, & other good alphabet soup) VP Eng RST Pres. Cyberchapter EAA Tech. Counselor http://www.rst-engr.com |
#4
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DIY DF device
So, this may be an utterly stupid idea, but...
I know I can get bearings from an airport, or more specifically the tower, by using my com and talking to them when flying and within range. Also, radio amateurs have these "fox hunts" where they hide a small tx and then hunt it down. Now, I have a scanner that covers the civil airbands on AM and I already have built a few homemade base antennas for it, following some nice designs made by others. This allows me to listen to nearby airfield traffic pattern communication. Now, it would be a lot of fun to be able to use my scanner with a suitable antenna array, to get bearings to an airplane talking to for instance tower. I know I know, you report positions most of the time, but sometimes the small planes give pireps on local weather conditions and the like, sometimes they just give position reports and so on, not being that accurate on their position. At other times, spending time at relative´s summer cottages, having the scanner with me, it would be great to quickly get info on where to scan the sky for nearby airplanes on the air, then get the binoculars. And as the chit chat on the airwaves usually is very brief, there is no time to start pointing that yagi or whatever to get some idea of where the plane is. You would need some kind of automatic direction finding, something that would give a direction for you in a second or two. Is there anything like this for a DIY project? I googled a bit and found a lot on automatic FM DF projects, but not for AM. It´s understandable that most people are interested in searching FM transmissions, especially those interested in finding noise sources and the like, but I´m just interested in spotting and plotting those planes up there! =) Any thoughts and suggestions appreciated, Ken |
#5
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The units designed with dual antennas and switching diodes to electronically "rotate" the antenna are not specific to modulation type. They will work equally as well on AM as they do on FM. Jim "Mattsson" shared these priceless pearls of wisdom: - -Is there anything like this for a DIY project? I googled a bit and found a -lot on automatic FM DF projects, but not for AM. It´s understandable that -most people are interested in searching FM transmissions, especially those -interested in finding noise sources and the like, but I´m just interested in -spotting and plotting those planes up there! =) - -Any thoughts and suggestions appreciated, Ken - Jim Weir (A&P/IA, CFI, & other good alphabet soup) VP Eng RST Pres. Cyberchapter EAA Tech. Counselor http://www.rst-engr.com |
#6
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John
shared these priceless pearls of wisdom: - - - -The following site is a similiar setup they give circuit diagrams and all -for the complete unit! They call for fm demod though although you can get -scanners that will cover the air band with fm also. - - -http://members.tripod.com/~clearRX/PRDFUNIT.HTM Sorry, but the page or the file that you're looking for is not here. • Please check to see that you've entered the correct URL. • The owner of this site may have chosen to delete their membership. • The site may have been removed due to a violation of Tripod's Terms of Service. • The site may have been moved to a different URL. Please search again for this page, or others like it with the search box above. Jim Weir (A&P/IA, CFI, & other good alphabet soup) VP Eng RST Pres. Cyberchapter EAA Tech. Counselor http://www.rst-engr.com |
#7
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Interesting idea.
I'd like to have one of these in the aircraft. That way if I'm listening in on approach, I'd have an idea of the relative bearing to another aircraft that is transmitting. For example, another aircraft reporting over the same fix - it would be nice to know which direction to look. A circular 8 LED display would be fine. Anybody know how to do this? Bill Daniels "Mattsson" wrote in message ... So, this may be an utterly stupid idea, but... I know I can get bearings from an airport, or more specifically the tower, by using my com and talking to them when flying and within range. Also, radio amateurs have these "fox hunts" where they hide a small tx and then hunt it down. Now, I have a scanner that covers the civil airbands on AM and I already have built a few homemade base antennas for it, following some nice designs made by others. This allows me to listen to nearby airfield traffic pattern communication. Now, it would be a lot of fun to be able to use my scanner with a suitable antenna array, to get bearings to an airplane talking to for instance tower. I know I know, you report positions most of the time, but sometimes the small planes give pireps on local weather conditions and the like, sometimes they just give position reports and so on, not being that accurate on their position. At other times, spending time at relative´s summer cottages, having the scanner with me, it would be great to quickly get info on where to scan the sky for nearby airplanes on the air, then get the binoculars. And as the chit chat on the airwaves usually is very brief, there is no time to start pointing that yagi or whatever to get some idea of where the plane is. You would need some kind of automatic direction finding, something that would give a direction for you in a second or two. Is there anything like this for a DIY project? I googled a bit and found a lot on automatic FM DF projects, but not for AM. It´s understandable that most people are interested in searching FM transmissions, especially those interested in finding noise sources and the like, but I´m just interested in spotting and plotting those planes up there! =) Any thoughts and suggestions appreciated, Ken |
#8
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http://members.tripod.com/~clearRX/RDFUNIT.HTM
Jim Weir wrote: John shared these priceless pearls of wisdom: - - - -The following site is a similiar setup they give circuit diagrams and all -for the complete unit! They call for fm demod though although you can get -scanners that will cover the air band with fm also. - - -http://members.tripod.com/~clearRX/PRDFUNIT.HTM Sorry, but the page or the file that you're looking for is not here. • Please check to see that you've entered the correct URL. • The owner of this site may have chosen to delete their membership. • The site may have been removed due to a violation of Tripod's Terms of Service. • The site may have been moved to a different URL. Please search again for this page, or others like it with the search box above. Jim Weir (A&P/IA, CFI, & other good alphabet soup) VP Eng RST Pres. Cyberchapter EAA Tech. Counselor http://www.rst-engr.com -- John Kimmel I think it will be quiet around here now. So long. |
#9
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On Mon, 12 Apr 2004 18:27:05 GMT, "Bill Daniels"
wrote: I'd like to have one of these in the aircraft. That way if I'm listening in on approach, I'd have an idea of the relative bearing to another aircraft that is transmitting. For example, another aircraft reporting over the same fix - it would be nice to know which direction to look. A circular 8 LED display would be fine. Ummm. Personally, I think it's better to keep one's attention OUTSIDE the cockpit at a time like this. It takes a finite amount of time to remove your attention from the exterior, focus on a panel-mounted dial. By the time you've realized the guy is reporting the same location and look at your readout, he's probably let loose of the mike button and the LED is dark. Sure, you could set up some sort of latching system, but on busy days, as soon as one guy quits transmitting someone else punches the button. Inaccurate data is far worse than no data at all. If you're close and maneuvering, the relative positions are probably changing rapidly, anyway. Ron Wanttaja |
#10
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I guess one of these newfangled TCAS systems that monitor for nearby
transponder squalks are out of the question since you would have to take your eyes out of the skies to look at the little led's! Hey go to the listed web page and look at the display. It only takes a quick glance at the display to get an idea where its coming from. If you've let another plane get so close to you that you can't glance at the display to see where neigboring traffic is then you weren't flying your plane. Sure there will be times when you miss one transmission and view a second but they will be few and your still looking all around for traffic anyway. Your main advantage is most of the time you will start your scan where the display indictes it originating from and if you don't see it contiunue on from there. Last I looked the last word in this newsgroup was "homebuilt" to me that screams "EXPERIMENT", go for it try a new project and enjoy the process and journey! As far as antennas you need 4 each 1/4 wave antenna's which is no biggy unless your driving around in one of these 200+ mph monsters and are concerned about drag. One idea for antennas since this is a receive only concern is to use an electically shortened antenna say take a piece of pc board and etch an inductor/antenna on it and cover it with a layer of foam/fiberglass suitable shaped aerodynamically, should be able to get away with only a 4-6 inch antenna especially since you really don't want a long range system anyway. Good luck and go play with it John Bill Daniels wrote: "Ron Wanttaja" wrote in message ... On Mon, 12 Apr 2004 18:27:05 GMT, "Bill Daniels" wrote: I'd like to have one of these in the aircraft. That way if I'm listening in on approach, I'd have an idea of the relative bearing to another aircraft that is transmitting. For example, another aircraft reporting over the same fix - it would be nice to know which direction to look. A circular 8 LED display would be fine. Ummm. Personally, I think it's better to keep one's attention OUTSIDE the cockpit at a time like this. It takes a finite amount of time to remove your attention from the exterior, focus on a panel-mounted dial. By the time you've realized the guy is reporting the same location and look at your readout, he's probably let loose of the mike button and the LED is dark. Sure, you could set up some sort of latching system, but on busy days, as soon as one guy quits transmitting someone else punches the button. Inaccurate data is far worse than no data at all. If you're close and maneuvering, the relative positions are probably changing rapidly, anyway. Ron Wanttaja I'd still like to have the DF on the comm radio. When somebody is talking, I'd like to know what direction they are coming from. So, maybe instead of LED's we need a 3D aural display so the voice seems to come from the direction of the transmitter. Bill Daniels |
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