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

I did some improvements by adding resistors in series with the
rf coils of about 100 ohm so the conducting diodes circuits
are getting  about the same current even if they have different
temps or other differences.

So I know for shure both sections of series diodes are getting about
the same current.

The SWR is much better now about 1.4 on two meters

Also nice is that there is less variation in SWR because of swinging coils because
there is always a 100 ohm series resistor to.

So take a look at my current working PlateAntenna DirectionFinder circuit.

It works quite wel right now.
 
PA3BNX:
Hello Every Body,

Here I will show 2 pictures of my prototype
AM Plate Antenna + Switcher + Pre_Amp and Generator with the MAX232 driver board.

Just put the reciever in mode AM and use my SoundDoppler Software

It all works.

I did test in on 2 meters

Groundplate is 60 by 60 cm hardboard with alu foil
and the antenna itself is a 22 by 22 cm alu plate

PA3BNX:
Hello EveryBody,

I have a update SoundDoppler137All.zip

It has a new future very handy that shows sharp or wide arrow points according
to the quality factor of the doppler signal option in the new software
See picture below.


I didn''t had much time last 2 weaks for working on the software but still some changes and inprovements.


The new AM plate antenna design  does not allow you to put in the vincinity a resonant antenna.
That antenna kills the forward / back ratio.

PA3BNX:
Hello EveryBody


We did have here in the Netherlands 15 september 2013 a nice
balloon-fox-hunt. (PH35BFH)

I had time to test my SoundDoppler doppler direction find software
in conjunction with APRSIS32

It worked great !

-------------------------------------------------------------------------------------------------
The APRSIS32 software from Lynn Deffenbough is excellent for plotting Doppler-Direction-Finding.
-------------------------------------------------------------------------------------------------

It plots automaticly objects through TCP TEXT port
to APRSIS32.


My software sends no data if it doesn't recieve the fox.
So I don't know where I am on the aprsis32 map while driving.


While that is the case I thought it would be nice if it sends
a beacon every 2 minutes so I can see my position on the APRSIS32 map.

So now my software sends a position packet  if it didn't hear anything with
2 minutes time interval.

I can press key-P and then it sends immediately a position packet Like

''Position report without bearing info
PA3BNX-9>APDF01:/094755h5151.00N/00540.00E\135/050<<SoundDoppler I am here!>> /A=000006


''Normal DF Object report
PA3BNX-9>APDF01:;BNX.DF488*095013/5151.00N/00540.00E\135/050/004/835 %DF004°/5 145450kHz Gps On /A=000006


(It can be handy to use ssid-9 like PA3BNX-9 for the doppler-callsign if the APRSIS32-callsign  is PA3BNX)
(Also because you are hunting with in a car so mobile)

The position report can be tracked in APRSIS32  Screen>Tracks
and it deletes older position reports.


While the DF object reports stay on map until the objects are killed
(Option in SoundDoppler)

Objects are not tracked in APRSIS32

With the SoundDoppler position beacon report APRSIS32 has no need to have GPS nmea input
on it's port nor has it to send NMEA through the doppler software.

So its great working together with APRSIS32

The new version SoundDoppler138.zip with the Position report will be soon released on our website's

http://www.pi4wag.nl/index.php/pseudo-doppler-radio-direction-finder
http://members.chello.nl/~w.hofman/pa8w/rdf.htm


Aditionally hints and experience with Doppler Direction Finding Balloon Hunt:
-----------------------------------------------------------------------------

The balloon transmitter had two tones alternating sound (alternating about 2 Hz)
The tones where 336 Hz and 538 Hz and a 667 Hz CWID
So they lay around the most used doppler referency frequency of 500 Hz.


The tones were strong modulated so the Switch Capicitor (SCF) Filter circuit has a
hard task to filter just the 500 Hz tone witch is also much less in amplitude.

It's good to have a switchable reference frequency of lets say 500 and 900 Hz.
So you can get away from audio modulated tones.

My SoundDoppler software with high-samplerate (22050Hz) and SinCos detector (Correlation) gives much better results
than harware SCF filter equipment with a zerocross detector.

The sofswitcher DSSSD   DeluxeSuperSimpleSoundDoppler circuit on the site of PA8W gives much better
results then other hardswitched hardware doppler systems.

The softswitching makes you detect much weaker-signals and its less prune to loud signals on neighbour channels.

And its cheap and easy to build !


73's PA3BNX
PA3BNX:
Hello Every Body,

Some new hints and tips for RDF

New SoundDoppler138.zip Soon on our sites.





Hello Everybody,


Sofisticated Radio Direction Finding


Whats needed for a SoundDoppler Mobile Foxhunt
----------------------------------------------

==============================
Go with at least two persons.
One driver and one operator.
Safetey first !
==============================

Download the latest version SoundDoppler and APRSIS32


Just buy
--------

1 LapTop with XP/Vista/Win7/8
1 USB Stereo input SoundCard if the PC doesn't have it like UCA202
1 GPS mouse with rs232 or USB with NMEA
1 FM Rx porto or scanner or a FT817 with cat62 cable
1 Maybe you need USB to RS232 cables to

To build assemble yourself
--------------------------

1 SuperSimpleSoundDoppler Generator
1 4x Antenna Array

You can buy the PCB's from PA8W
http://members.chello.nl/~w.hofman/pa8w/rdf.htm

The best SuperSimpleSoundDoppler generator is the hardware with 4 softswitch
transistors connected to the 4017 chip.
This let the doppler detect weaker signals and it has less influence from
strong neighbourh channels.


1 50 ohm coax cable(rg58) with connectors BNC /SMA
1 Control cable with 5p Din connectors
1 USB or rs232 db9 cable to make the GPSmouse cable longer so it can
  reside on top of the car roof.

1 shielded audio cable with 3.5mm stereo jack to lsp rx and sounddopplergenerator
1 Maybe a Switchable monitor loudspeaker
1 Maybe Needed a simple stereo-preamp for the USB SoundCard with isolation
  1:1 transformers to avoid ground loops.

 
1 12V board supply volt connector block
1 adapter to feed the Laptop from 12 volts (Home brew?)
(Maybe you need a upconverter many laptops have adapters on 16 Volt)

Try to create a box or assembly where all the hardware resides.
Make shure you can see the laptop screen and try to shield it from sunlight.

If using APRSIS32 then also cache the tiles from the region where the hunt happens.
Play with the software at home so you know how the software and hardware works!

I think anyone can become a profi-hunter with this equipment.

In the mean time I try to make the software as good as it can be !

Happy Mobile (Fox/Balloon) Hunting

PA3BNX


Hello Every Body,


Some hints to get SoundDoppler working with APRSIS32 from KJ4ERJ


Under SoundDoppler
------------------

Press F11  PacketLog

You must enter a

callsign (Maybe nice to take another SSID then APRSIS uses like -7 or -9)
latitude
longitude

To send to APRSIS32
If you have a GPS working then the latitude and longitude
are coming from there.


Check TCPIP checked
check Kill  checked (wil grey Older DF Objects)

If you have a GPS-rx  and a recent APRSIS32 then
Check Cse+Hdg  :Unchecked   (It adds GPScourse and DopplerHeading)
This must only checked if using an older APRSIS32

 
Under APRSISIS32
----------------

Create a new port called something like Doppler

Configure>Ports>New
Adjust in popup screen
Type       :Text
Name       :Doppler

Then press TCP/IP
IP or DNS   :Localport
Port        :1024

Quit Time   :0
Enabled     :checked
Bulletin/Obj:checked

Screen>Direction Finding>Enabled
Screen>Direction Finding>Opacity (15)
Screen>Brightness>Dim (Better visability for DF sectors)

If you don't like many DF objects in the scroller then
Screen>Scroller>Not Mine :checked

Enables>Port>All
Enables>Port>Doppler


Sometimes there is no connection to SoundDoppler
Then simply close and reopen the Doppler port
Enables>Port>Doppler :uncheck
en right after that
Enables>Port>Doppler :check


You can also switch SoundDoppler.exe TCP/IP with the checkbox
left from the start/running button in SoundDoppler


If it shows Doppler OK
Just above the scroller then there is a connection

APRSIS32 can send the DF objects to Internet
--------------------------------------------
Configure>Ports>Doppler
RF to IS :checked
Of cource you need a passcode to send to IS


I hope this wil help you all to get SoundDoppler.exe running with APRSIS32.exe


73's PA3BNX

Happy Foxhunting
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