Electronics > Projects, Designs, and Technical Stuff
Radio Direction Finding
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PA3BNX:
Hello Every Body,

I myself have a okay version ASW board without the errors described above.

You can get this type of switcher working better with
dipoles if you ad a way to disconnect the earth of the coax
at the feedpoint of the 4 dipoles if antenna is not connected.

Having the coax shield connected while antenne is off can give
near field distorsion because half of dipole + half coax shield is resonant
and eats RF spectrum and distorts.

So any one has out there has a tip to add this option easy ?

Could be handy if you have a stationairy 4 dipole array.
and using this ASW (antenna switcher).

hiishaam:
Hello : PA3BNX

First, Thanks for the great program SoundDoppler

I have 2 questions :-

1 - Can I use the program in band of 88 to 107 (FM Station Band) to locate any transmitter in this band

2 - How do the program do the DSP functions? I mean does it use correlation to get the bearing or zero crossing detection?
PA3BNX:
Hello EveryBody,


The program can use SinCos(sometimes called correlation) or Zerocrossdetector.

I think that the SinCos detector works best..

Try under demo-mode 2 and the xy-screen the Adjust button
Than you have a test generator to play with the input hi

Just right click on the pelorus to change the sincos/zerocross detector mode.

Yes you can use it for 88-108MHz.

The reciever must be wide band FM
The doppler antenna must be adjacent 1/4 distance to get as much doppler tone as possible
compared to the music deviation.

There is under menu Info a Doppler_array calculator now

I did draw a 8 antenna SuperSimpleSoundDoppler de Luxe

If you use a stationairy antenna a 8 dipole works the best

The 8 dipole array switcher schould have large chokes in the switcher
because the are all parallel  at 145MHz and 1uH a choke has about 910 Ohm.
So 910/8=133 Ohm

Thats eating some of the recieved input power.

So use bigger ones like 10uH or 100uH in the 8 doppler array switcher.

The picture shows a 8 dipole doppler array with just the 4017 de luxe for 8 antenna
from DL3DW

Today 20-04-2014 Found Errors in 8 switcher circuits.

In the new 8 x switcher unit you can remove one diode 1n4148 in the middle
and you should replace the choke in the antenna feet with a 1 k resistor or something.
I will update the circuits soon.



PA3BNX:
Hello Every Body,

Here is a design for not a doppler

An Am peiler with 16 led pelorus with
2 color leds from green to red indicating much or less signal in that direction
Already from 1993

http://www.ab9u.com/references/Willenweb%201993%20Schematics.pdf

You can do very easy Am direction finding with my software
and the SinCos detector and the plate antenna
Or use just 4 directional LPA's and just the super simplesounddoppler with an reciever
with AM detector.


Here they do it with just 16 stiks that form directional antenne and rotate it.
All the  leds light up from light red to light green indicating signal strength.

Nice to see and nice idea...


PA3BNX:
Hello Every Body,


He is my proto drawing of a HF Radio direction finder with 2 aperiodic loops
and one sense antenna.

I am going to build this one to how it works.

I want to have a HF Direction Finder for HF without tuned
loops.

Today I show you guys some pictures of the above circuit build
R958 inside the PVC flexible tube and the red wire as Sense antenna.

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