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

I tried to design a new doppler switcher with 4 antenna amplifiers.

Small 4x 2x17cm dipoles and small diagonal distance (About 0.35 * 70cm = 24 cm) 

So the mmic, mar, era or mav is right at the antenna feed.
It's feed through the coax.


The purpose is to have a more sensitive UHF Doppler dipole antenna
witch also can be used for VHF with reduced doppler tone amplitude.

The higher RF level on the coax makes them also less sensible to direct
RF leakage through cables.

The 100 Ohm resistor in the doppler generator should limit the current through the
mmic and diode.

The RF is tapped with a second diode and common resistor witch also forms a load
on the mmic output.

I did not build this yet.

Let me know if somebody out there has comments, hints and or improvements.
 
Have Fun watching intresting

Anritsu YouTube:






PA3BNX:
Hello Every Body,

I have written a nice tool for calculating the doppler antenna array parameters

It's included in the new SoundDoppler141

I also did create a Minimal GPS screen option in my GPS117.exe program.

This is very handy if your Laptop screen is small hi and very full with programs.

The programs can very soon be found on our sites.

The latest one is SoundDoppler141aAll.zip

I did fix a stupide error in the Doppler antenna array calculator

And the new one has now a ft817 S-meter  on the left upper of the map in Mymapping148

I did also upload a new attachment with fixed Doppler Antenna Array Calculator in this message.




abraham1235:
If i want to know the direction of more than one hidden transmitter with the same device?
M0BSW:
You'll scare all those pirate radio stations ;)
PA3BNX:
Hello Every Body,


No problem at al to see more hidden devices.

It is even possible to have two SoundDoppler.exe programs running on one PC and Plot the data on one MAP.

You need then 2  FM recievers and the PC must have 2 SoundCards
and two SuperSimpleSoundDopplers de Luxe with two antenna arrays.


If there are more transmitters from different places recieved  on one frequency sequentieel then the MyMapping software
can show you
Clusters of fixes on the map where the transmitters resides.

My software cannot detect 2 transmitters on the frequency simultaniosly

R&S with MUSIC and Super DF can do that.

A very great tool is to have a RTL2832 DVBT stick running with SDR# So you also have a spectrum analyser
running on the same PC and a second all mode detector to to listen monitor other channels to on the same PC.

I did fix some minor bugs today.

The newest version of my software is now SoundDoppler141aAll.zip
See the PI4WAG site

No I do not scare radio pirates.

It's just fun to design build program and test this kind of equipment

I just like to not only hear the signal strength and audio quality but I also want next to my S-meter a Pelorus hi...

Direction Finding is as old as is radio.
With the PC nowadays it can be done very easy and cheap.



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