DIY DF device

[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

[John]

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

[John]

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

[Mattsson]

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

[Jim Weir]

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

[Jim Weir]

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

[Bill Daniels]

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
>
>

[guynoir]

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.

[Ron Wanttaja]

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

[John]

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

[Bill Daniels]

"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

[John]

Yes there's a time and place for everything and experimenting with 10
aircraft in the pattern is not one of them. But It is an interesting
prospect and educational and fun thing to try out. Isn't that what most of
us are into homebuilts for. Of course I've been working on my plane for 10
years now and am 5% complete! ;-)

Properly placed the display would not need to distract your attention much.
Also there are no operating controls to fiddle with if your are only
operating from your local airport. The only real control is the frequency
dial and once set it is a hands off deal!

I probably wouldn't put one in my plane but hey He asked and I gave a link
to one of many such units out there let him decide if he's interested and
would like to experiment.

John

[Ron Wanttaja]

On Tue, 13 Apr 2004 09:47:20 +0000, John > wrote:

>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!

Don't know much about TCAS, but I believe the system has an voice warning
that actually tells you how to maneuver. In any case, most aircraft
current with TCAS have two pilots. TCAS also is tracking transponder
squawks, not radio calls made at 1 minute intervals.
>
>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.

But isn't that what the system is for...helping you spot traffic that's
close to you? If I'm two miles from the airport and someone transmits from
the pattern, there's already a relatively narrow arc they can be in.

Here's an experiment for you: Next time you're in a busy traffic pattern,
glance down at, say, the oil temperature gauge, note what the reading is,
then go back to your visual traffic scan. *Every* time there's a
transmission on the radio. Then decide whether looking at a panel-mounted
instrument is a good idea.

My home drome is a very busy uncontrolled airport with a single 3,000-foot
runway. I've been in the pattern with ten other aircraft....don't know how
busy the radio was then, 'cause that was in my NORDO days. But my guts get
a little loose at the prospect of one of those ten other people fiddling
with a gauge on his panel when he should have his eyes open for traffic.

>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!

And if the LEDs aren't bright enough in the sunlight, go ahead and paint
the windows black. After all, it's just an "experiment."

Actually, I'm not too worried in this case. I think Ken has an interesting
project on his hands, but will find that it probably isn't all that useful
once it's in his airplane. I doubt we'll be faced with a flood of these
things. And he doesn't fly around here. :-)

Ron Wanttaja

[Mattsson]

> I probably wouldn't put one in my plane but hey He asked and I gave a link
> to one of many such units out there let him decide if he's interested and
> would like to experiment.
>
> John

John and Ron,

Thanks for the link and the wishes for an interesting project!

And by the way, I´m not going to put this gizmo in a plane, I just NEED to
build one...that´s what it´s mainly about. I get this "fantastic" idea, that
I need to do something about. =))

As I said, it would be nice to have such a DF unit to be used with the
scanner, so I could get some help with knowing in which direction to scan
for GA aircraft passing by, somewhere near where I happen to be, that being
at home with my VERY NICE :-) plumber´s delights (thanks Jim and the other
guys) or at the summer cottage or wherever, when gettin the time to stare at
the sky.

I´ll have a look at the link now! And feel free to bomb me with more DIY
project links like this, I didn´t find that many myself!

Cheers, Ken

P.S. You may relax, I´d probably run out of avgas and would have to ditch
before I´d get to your usual flying sites! Since I don´t like the idea of
swimming the last bit over the Atlantic, I think I´ll pass on this one!
=))))

[AL]

What we need is for some bright soul to develop a radio we can all buy
for a coupla hundred bucks that will transmit at some quiet freq every
second. Then a nice little LED in the cabin, linked to the DF, would be
lit whenever traffic is near. We have FM radios in the steel mill that
automatically transmit a morse code ident (per FCC regs) every 30 minutes.

Ron Wanttaja wrote:


> Don't know much about TCAS, but I believe the system has a voice warning
> that actually tells you how to maneuver. In any case, most aircraft
> current with TCAS have two pilots. TCAS also is tracking transponder
> squawks, not radio calls made at 1 minute intervals.
>

[pete365]

try this link....http://www.byonics.com/dsp-rdf/

Mattsson wrote:

>>I probably wouldn't put one in my plane but hey He asked and I gave a link
>>to one of many such units out there let him decide if he's interested and
>>would like to experiment.
>>
>>John
>>
>>
>
>John and Ron,
>
>Thanks for the link and the wishes for an interesting project!
>
>And by the way, I´m not going to put this gizmo in a plane, I just NEED to
>build one...that´s what it´s mainly about. I get this "fantastic" idea, that
>I need to do something about. =))
>
>As I said, it would be nice to have such a DF unit to be used with the
>scanner, so I could get some help with knowing in which direction to scan
>for GA aircraft passing by, somewhere near where I happen to be, that being
>at home with my VERY NICE :-) plumber´s delights (thanks Jim and the other
>guys) or at the summer cottage or wherever, when gettin the time to stare at
>the sky.
>
>I´ll have a look at the link now! And feel free to bomb me with more DIY
>project links like this, I didn´t find that many myself!
>
>Cheers, Ken
>
>P.S. You may relax, I´d probably run out of avgas and would have to ditch
>before I´d get to your usual flying sites! Since I don´t like the idea of
>swimming the last bit over the Atlantic, I think I´ll pass on this one!
>=))))
>
>
>
>