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Radio Direction Finding
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jackdev23:
Hello everybody,
thank for this good thread.
I made a ARDF with Arduino Nano.
Check the prototype here
http://youtu.be/jm0Q4p4GudA?list=UU17SR_h8OR9WCBrsh_ak_sQ
PCB READY :)

73 IW2NDH
PA3BNX:
Hello Every Body,

I see some have a problem with the max232
do not connect  or tap the internal voltages from the pins 2  and 6 from the max232


Nice to see the Arduino experiments IW2NDH.



I have done now a simple ne555 circuit to drive manually the AMPlate antenna

So easy only adjust the 4 stands turn switch NSEW
and a scanner or portofoon with S-meter while drving in a car
So no more stopping and using a Yagi or HB9CV for the balloon fox hunt.

Nice experimenting

 


PA3BNX:
Hello everybody,

Subject: Doppler RDF on the 100 MHz 3 metres FM broadcast band


The problem with RDF on a FM broadcast TX
with about 150 kHz bandwidth is in the fact that the
standard doppler rotation tone is 500 Hz
With my standard SuperSimpleSoundDoppler 4017 generator (about .5-.6 kHz)
That's compared to modulated audio from the TX 150 kHz undetectable.

If I use mono FM TX with 150 kHz bandwidth:

At 100 MHz and a 500 Hz doppler tone.

With my 8 bits sound-card channel there is almost no
doppler tone to detect.
A 8 bit sound card has 256 samples so maximum amplitude contains 127 bits


(This is also true for a conventional doppler with classic 8 caps SCF)
(They have also a problem with the low pass filters in hardware)

150 kHz / .5 kHz = 300x if I take just one bit
for doppler tone then I still have  256 - 300  = -44 bits short.


I do not have enough bits to process undistorted FM audio by
the soundcard and detect the doppler tone.


This works better I think
Higher doppler rotation frequency and
bigger antenna plate diameter.
There is a maximum diameter with 4 antenna
(Of course it may not become unhandy large)
(See:  SoundDoppler.exe menu Info>Doppler antenna array calc)

Larger Doppler tone deviation by higher rotation frequency

I found that 4 dipoles and a doppler tone rotation frequency of
3 kHz gives 12 kHz doppler deviation on 100 MHz
Antenna diameter for 100 MHz about .93 metres
and optimal antenna plate diameter for monopoles 2.43 metres


150 kHz / 12 kHz = 13 steps

256 / 13 = 19x

This is possible with a 8 bit sound-channel.

(You must set the sample rate higher or the same as 22050 samples per second)

It's simple to set the multivibrator on about 4 x 3 = 12 kHz
by change the 15nF by 2n2

(Divide all by 3 kHz /.5 kHz = 6x)

In the SuperSimpleSoundDoppler de Luxe also change the 1n5
by 220 pF

Also change the 3x 100nF lowpass filter cap's for the reference frequency output in 3x 10nF

With the AM-Plate and Correlation detector mode this is different.

If I create on a FM broad cast RX a broadband AM detector
just before the AM limiter then I have excellent AM detected modulation.

This demands a broadband AM detector added to the WFM detector

Hint:

Maybe it's handy to modify an 'old' mono 12v car-radio with an extra
AM broadband detector because car radio's are well shielded and have
a coax antenna plug.


73's


YD2WPE:
Hi,..PA3BNX,...i search a sound doppler program,...where could i found.,.?

thanks before
PA3BNX:
Hello EveryBody

My software can be found on:


http://www.pi4wag.nl/projecten/doppler-peiler-radio-direction-finder

Download button at bottom of page

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