DIY DF device

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

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

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.
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above.



Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

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

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

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

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

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.

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 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