Radio Direction Finding

[oe6rke]

Hi Lodewijk,

first of all cudos und big thanks for your software and work you put into. With help of this software we are enabled to narrow down some qrm on local repeaters.
Using primary this software and setup in a mobile configuration we experianced some issues, which would be cool to have within the software.
1) i identified, that selectivity in notebooks sound cards are pretty poor. especially on weak signals the trigger sinus wave is recognized also on the other channel. This produces wrong bearings to sort out. A big help would be being able to select two soundcards (one for rig audio and another the trigger) or having both on one channel (checkbox selection would be fine)
2) often craft builders are not capable to differ beween clock counter wise and reverse . A checkbox regarding that would be also very handy
3) wavelog creation is something fine, but its hard to relate them to postion and time. Therefor a general log with dde current gps, currently save wav filename and datetime would be a cool thing. If this would be a peramanent log with adding data always at the last would be perfect. This helps to analysis data afterwards
4) some replay feature would be cool, especially playing with some parameters could bring out more results so i hope

big wishes, but all generated from practical usecases .
if i can give you a helping hand on coding vb please le me know. to contribute and not just taking from the project would be highly appreciated by me.
pse drop me a line if you like.

thanks again for the software, 73 de oe6rke, ciao Robert

[KD0CAC John]

How much of an issue would it be to use / modify for many bands ?
Being a ham , the 1st thing for me would be for RF in the area that is causing issues , bad power-line transformers , insulators etc.
Then as a 2nd , [ but as soon as I had something like this , it would create its own demand ] deliberate interference .
Thanks John

[oe6rke]

the qrm i mentioned is man made. in other words i an unknown person bothering and insulting hams on the repeater.
this is pretty bad and authorities and hams too are already on the seek mission for that person ...

[PA3BNX]

Hello Every Body,


I see some have  troubles with separation of left and right channels
in software.


Well let me say this you need a stereo soundcard
on the inputs.

Many laptop soundcards are just  stereo output
and have one mono microphone input.

That's not okay for my application !

You can however take a USB stereo input soundcard.
with 2 line inputs.

Separating the reference input on one soundcard and audio input on another is not possible

because the left and right input needs to be taken in one conversion

So a soundcard has one digital sampled word with two channels in it.

My software uses a double word for both channels and then separate that in
left and Right channel so low-byte and high-byte

The two 8 bit channels can vary between 0 and 255
so 127 is the zero line of the audio.

This makes sure the audio sample and reference audio sample are exact taken on the same time.

You need not to have a good sound card just an ordinary one is okay with 16 bits and 22kHz is enough.

You can hear the reference on the right speaker and the audio on the left pc speaker

You can off course set the balance to the left so you only hear the audio from the FM reciever through the
pc speakers.

New info:


I am still working on the kml logging option for Google_Earth
in SoundDoppler.exe

It is still not ready as is wished

I am also working on a SoundDopplerNet.exe program in VB 2005

SoundDoppler119.exe and gps112.exe are in good old VB6

Let me now if you want to help programming on SoundDopplerNet.exe
 

[PA3BNX]

Hello Every Body,


I think my software has possibilities to save the audio in a wav files with name
that contains heading quality time and data

All squelch controlled by squelch from rig or squelch from dopplertone

A CW or CCW option is includes it's called 0 /180 degrees.

It has a waterfall and SCF scoop to see the quality of the dopplertone.

It has also a Scoop screen with left and right audio lines.

Some Window Versions have a error in the winmm.dll

Then the left and right channel are changed.

You can by clicking on the do events label
The numbers under the Freq and Dcd checkbox
reset the soundcard buffer of winmm.dll pointer

The label Will be yellow for a moment

So the reference is again up in upper line of the inputXY scoop.


The frequency range of the antenna is as follows

The diagonal distance must be smaller then .35 lambda
of the working frequency because otherwise you Will get ambiguity

Of course you must adjust the length of the whips to about .25 lambda of the receiving wave length.

That's not critical at all is even quite good if the are not all 4 same length. but vary a bit in length
so they do not resonate and influence each other fields.

In general with about diagonal 34 cm apart you can easy do 2 meters and 70 cm

Just put on some shorter whips for 70 cm.

 

[PA3BNX]

Hello every body,

I got a tip from to get easy a nice beautifull sinus out of the
SuperSimpleSoundDoppler

I want a nice sinus because it looks better on the inputXY screen
It has less harmonics so the left right preamps are heving less
trouble with crosstalking of the soundcard.

Just hook the lowpassfilter with the transistor at the end on one of the
outputs of the 4001 output ports hi...

Why didn't I thought of that before.

I have to change the PCB layout just a little bit.

Another errro on some circuits is that a 4060 has no Q10 output..

Wow thats strange they where out of pins on the dil package hi..


oe6rke

My SoundDoppler can save only wave files and has no gps latitude an longitude info stored
in the filename.

But  wave file audio-loggen was meant for stationairy logging purposus.

But MyMapping has logging facilities of the packet.txt.

In packet txt is al the needed info for finding out at witch time date and place the logged
wave file belongs.






 

[PA3BNX]

Hello Every Body,


Here are the PCB Layouts of the pe0ssb
softswitcher antenna boards

Upper and lower side of the HF part

[PA3BNX]

Hello Every Body,


Here I send the lower part where the
PLL RF and softwitch pulses are made.

These boards are connected by wires close together.

[PA3BNX]

Hallo Every Body,


Today i did some playing with the SuperSimpleSoundDoppler

generator and I wanted to improve the sinus output of it.


I come up with minor changes.


I did replace the elco for a 1k5 resistor
after the bc547 buffer emittor follower.

and I did put a smaller elco 2u2 in series with the potmeter.

Amazing on my scoop to see that the envelope of the output sinus is much better
looking now.

The lowpass filter now has a series extra resistor (1k5)
and is feed ed without the Xc of the elco.

The PCB layout is very simple to change.

So suk6

See the circuit diagram in the fl yer for details

[PA3BNX]

Hello Every Body,


Some notes about the 4 whips
and running it at 2 meters and 70cm.


The optimal diagonal distance between the antennas for
2 meter

is about

300/145 * 0.35 = 0.72 metres

For 70 cm
is about
300/.70 * 0.35 = 0.24 metres

(Factor 0.35 comes from sqr( 0.25^2 + 0.25^2)
The maximum distance between 2 adjacent antenna may be 0.25 wave length

If the frequency gets  above the calculated then the distance between antenna diagonal
then you get ambiguity.

So lower frequency is okay only you will have lesser doppler-tone-amplitude.

Ideal would be 4 J-antenna's they don't need a ground plate and the coax cables are not
in between the antenna fields like with the GroundPlanes or center fed dipoles.

On 70cm the capacity in the off situation becomes more important.

Also the cables must be of better shielded quality.

If you use the SuperSimpleSoundDoppler antenna switcher the 4 coax cables must be for

2 metres:

300/145 * 0.25 * 0.66 = 0.34 meters

0.70 metres:

300/435 * 0.25 * 0.66 = 0.11 meters

Very important with 1/4 antennas is the ground connection from the coax
to the base plate.

The biggest current is in the feed point of the 1/4 antenna so base plate must be connected okay
there.

Do not make the coax shield become an antenna and make sure the whips are have omni directional patterns
so there must be more place on the groundplate (Do not put them on the edges of a base plate)

I use for 2 meter a circle base plate of about 60 cm diameter and about 30 to 40 cm
diagonal space between antenna's


I hope this is some help for building the antenna system.

[steve_w]

I don't understand your antenna system are you using a rotatable loop antenna and a sense antenna or are you using 4 fixed directional antennas?

I worked on an auto ADF system that had a rotating loop antenna that was null seeking that gave you an ambigous bearing then there was the sense antenna that resolved the direction. the bearing was read from a position sensor in the rotating antenna.  this could give bearings down to +- .5 Degrees.

There is a picture of one here:
http://austradesecure.com/radschool/Vol29/Page8.htm

[PA3BNX]

Hello Every Body,


My SuperSimpleSoundDoppler  (VHF and UHF)  antenna system consist of only 4 whip antenna.

They are switched on one by one so there is always just one antenna connected to the VHF Receiver.

You must receive with a FM receiver.

The FM detector in the receiver is basically a frequency to voltage device.

Remember now the doppler tone frequency of a car coming to you at
constant speed.

The tone of the motorsound  will increase en then if the car passes you it will decrease

That's the doppler Principe.

My other design I am working on is called HF Peiler.

That are two crossed loops with a sense antenna that's meant for HF.

I still do not have the HF Peiler working.

So I am working on two systems one for HF and one for VHF/UHF

Today I did work on the zerocrosdetector again.

I found that it is possible to have more acurate bearings even at the 8000 samples / sec
input soundcard mode.

Just detect where the zero cros does happen in the SCF filter array

And then take in account the amplitude values storen in the 2 adjacent array elements.
And so calculate the bearing + the right portion of the 2 element zero cross elements.

Earlyer I did just take the first element + 0.5 * zerocrossingfactor  of the two adjacent arrswitchcap elements

In basic it looks like this:

Public Function ZeroCrossDetector() as Single

'Arrswitchcap() contains all the values summed from FM audio
'at right reference frequency.

dim x as int32
dim y1 as int32
dim y2 as int32

dim j as single
dim zerocrossfactor as single
 
zerocrossfactor = 360 / ubound(arrswitchcap)

for x = 0 to ubound(arrSwitchCap) - 1

y1 = arrswitchcap(x)
y2 = arrswitchcap(x+1)

if y1 > 0 and Y2 <= 0 then
   j = math.abs(y1 / (y2 - y1))
   return  (x + j)  * zerocrossfactor   
end if

'If zerocross is between arrswitchcap(ubound(arrswitchcap) and arrswitchcap(0) then
 
y1=arrswitchcap(ubound(arrswitchcap)
y2=arrswitchcap(0)

if y1 >0 and Y2 <=0 then
   j=math.abs(y1/((y2-y1)
   return   j  * zerocrossfactor   
end if

'If not yet  found then return

Return 999  'No bearing found

End Function


I will do some hardware and software testing before I upload it to
The site of PI4WAG

[PA3BNX]

Hello Every Body,

My Software:

Today I did make the waterfall display spectrum in 64 steps
instead of 32 in SoundDoppler.exe

So now the steps are 360 / 64 = 5.625 degrees and that about the
maximum precision of a pseudo-doppler-direction-finder.
It looks nice in graphics.

I was also thinking of streaming 2 channel audio over internet
So sounddoppler application can decode/save  all on distance.
Not done yet.


I have some other thoughts about building a
Radio Direction Finder hardware

Okay my software runs on a PC with GPS and supersimple sounddoppler
through the 2 channel input soundcard.

But I want something smaller (wireless)
running on a iPad or android.

and/or maybe hardware control done on an Aduino board

I think it is possible to make the sounddoppler
running on an Arduino

The Arduino:


It has to generate the 4x antenna switch (hard or softswitching) signals.
and has to decode the audio from the RX receiver audio
and then output agrelo out on the comport %BBB/Q

or maybe it can display the bearing on some leds or
a small dot matrix display ?

The RDF wants a Gps-Rx and Mapping plot possibility.

The Arduino will never have the possibility to show bearings on a map
directly.

Other things not so nice is to save the audio of the RX squelch controlled

WB6EYV Bob Simmons (PicoDopp) did already something nice with pic16f628.
That outputs Gps ($GPRMC) and Agrelo (%xxx/q) mixed on a comport.

So there is some thoughts needed to find out what I maybe will be
trying to create in software and hardware on small tabloids.

It would be very nice if the Gps was build in the iPad or android.

And a wireless connection from arduino to the iPad (infrared or bluetooth).

Just programming the arduino will be a challenge.   

It should emulate some sort of audiocard 

Also on the ipad or android must the software written.

But maybe if there exists gps software then the Arduino could
modify the $GPRMC  Course field and calculate a new CRC for $GPRMC string.
The Gps-Rx-input must be inputted in the Arduino with this method.

(My Mapping.exe and SoundDoppler.exe and gps.exe have this modified $GPRMC already) 

So lots of things to do (All much time consuming)...

Let me know if you have better ideas.

[PA3BNX]

Hello Every Body,


I did gain some improvements on my SoundDoppler.exe software.

I increased the amount off bars in the waterfall from 32 to 64

so no that's 360 / 64=5.625 degrees wide bars.

It look nice.

I also made a freeze button on the SCf and Waterfall screen
To stop it from running That's nice to precisely check the graphic data.

In the back ground all software runs of course.

The next version will be SoundDopplerbAll.zip on the site of PI4WAG.

[PA3BNX]

Hello every Body,

I think I got the kml logging okay now in sounddoppler.exe

So you can log to kml files with 100 records

Nice for displaying in Google-Earth.

I am right now busy with a new future in MyMapping.exe

My own RDF plot program on UI-View32 Maps.

It will not get a zoom function but a AutoTrack Smallest Map
auto track mode and a just once button to track to smallest Map.

It's again quite complicated I am already working on it for 3 days now.

But I hope I get it working soon.


I let you know wen its on the PI4WAG Site available.

That's all foo ks for now.

[PA3BNX]

Hello Every Body,

I just saw that wb6eyv has a external SCF Hardware Audio filter

Available on his pico dopp sites .

That connects in series with the audio and the picodopp input
controlled by the antenna switch signals.

It Looks nice.

PreDopp Audio PreSelector : US$ 109
http://www.silcom.com/~pelican2/PicoDopp/XDOPP.htm#FDDF

My Software has a DSP SCF filter but his hardware is nice too.
 

[PA3BNX]

Hello Every Body,


I did put SoundDoppler120 and Mymapping on the PI4WAG web site.

SoundDoppler120cAll.zip

KML logging for Google-Earth works and also the
AutoMapTracking in MyMapping for about 150 maps in a directory.


I can still make improvements on the software but it does work.

[PA3BNX]

Hello Every Body


MyMapping 131 is on the PI4WAG site now
SoundDoppler120dAll.zip


MyMapping has now scroll through the maps with
mouse wheel and pgUp and pgDown keys with the last
bearing always on it.
Wen AutoMapTrack is switched off.


Further I am  trying to create new SuperSimpleDopplerPeiler design in DipTrace

For me the first time ever to try to create a diagram and PCB in a specialised Diagram / PCB program.

http://www.pi4wag.nl/index.php/pseudo-doppler-radio-direction-finder

[PA3BNX]

Hello Every Body,

I had the flue so
I didn't work a lot on the software.

But today I started again some programming.

In program SoundDoppler.exe
I made the turnprompt grey orange and red
depending on the level of the Rx sound.
So more then 90% is orange and 100% is red now.

In program MyMapping.exe I wanted to have the Map.inf editor for the
UI-VIEW32 maps in two input modes.

GPSDegrees and DecimalDegrees (Like Google-Earth uses).

So it's possible now to do that.

The Map.inf files keep ofcource the same format in GPS degrees.
(GpsDegrees is the same as NMEA0183 has for latitude and longitude)


0000.00N, 00000.00E
0000.00N, 00000.00E
Netherlands

So Upper-left-corner and Lower-right-corner
coordinates and a name description
Coordinates are always in GPSDegrees
That is Degrees Minutes.Decimalseconds

So every Map in BMP, JPG, GIF or PNG format
must have a same name.inf file in the same directory.

Extra menu for displaying a legend on the map
as km by km.

I also made kml logging possible in MyMapping (kml files are for Google-Earth)
only if you have a VRZA2011 or Picodopp + GPS connected to
MyMapping.exe



I will soon put the updated files on the site of PI4WAG.

[PA3BNX]

Hello Every Body,

I have a new updated version SoundDoppler120fAll.zip on
the Pi4WAG site now.

Some things again improved hi...

Like the KML logging and plotting route lines on MyMapping.

Further some improvement on Gps113.exe


So have fun trying radio foxhunting,

[PA3BNX]

Hello Every Body,

I did work quite some time on the MyMapping.exe software this week
but I also have a nice antenna hardware hint.

Just clamp 3 a 5 ferrite clamps around the coax and control cables that
go  vertical under from the antenna switcher.

The vertical cables act as field disturbance for the 4x 1/2 wave length dipoles
So make them more or less invisible for the radio field by using clamps so the length in the field
never reaches a 1/4 wave length of the Doppler reading frequency.
Sort of stealth technique.

Of course also use a wooden or PVC tube to hold the 4 antenna's support.
 

Take a look at this link to from DopplerSystems.

http://www.dopsys.com/products/Series%207000/Antennas.html

Have fun.

[PA3BNX]

Hello Every Body,

I found some new stuff about getting the most out of the
doppler antenna system.

[url=http://members.chello.nl/~w.hofman/pa8w]http://members.chello.nl/~w.hofman/pa8w] [url]http://members.chello.nl/~w.hofman/pa8w]http://members.chello.nl/~w.hofman/pa8w]http://members.chello.nl/~w.hofman/pa8w] [url]http://members.chello.nl/~w.hofman/pa8w ... Arrays.htm[/url]

http://www.qsl.net/df9ie/

Today I heard even more antenna information.

The 1/2 wave antennas may not be 1/2 wave dipoles with gamma match
because the antenna is resonant and influenced the near field.


So you definitely need to use 1/2 wave open dipoles.

Make sure the antennas are not resonant so use some resistors in series
in the dipole from 10 ohm to 1k ohm from current center to top
to make sure they do not resonate

Take also a look at the nice R&S DDF007 Handheld Portable Direction finders.

http://www2.rohde-schwarz.com/en/products/radiomonitoring/direction_finder/DDF007-%7C-Side_View-%7C-32-%7C-7349.html

Have fun,

[PA3BNX]

Hello Every Body,


Some pictures of my Super Simple Sound Doppler
with 1/2 wave dipole antennas.

I did use a extra diode in series of the coax shield at the end of the

open dipoles of about 1 meter length.

And I used some ferrite cores around the control and coax to the switcher unit
and used a PVC pipe

So take a look...

[PA3BNX]

Hello Every Body,


Today I saw a other improvement from PA8W
for the dipole 1/2 wave antennas.


Not only add a series diode between the coax shield
but also a 1 m Ohm static discharge resistor across the (PIN)diode.
so the antenna elements never can get static charged.

When the no control voltage there  the antennas can be static charged.

I have an update software version of my SoundDoppler120Gall.zip on the site of PI4WAG

[PA3BNX]

Hello everybody,

I did some drawing work on the antenna switcher circuit diagrams
for the Super Simple Sound Doppler.

You can see the circuit if you use 4x 1/2 wave dipoles.

With the diodes and bleeder resistor at the antenna feed points.