Radio Direction Finding

Arduino forum,

I want to have a ISR routine that runs
about 2000 or 12000 Hz

1/2000 = .5 mSec or 500 uS
1/12000 = .0833 mSec or 83.3 uS

Witch timer must I use on a Arduino Uno Rev 3 on 16 MHz

It may not interfere with the UART

So witch timer and prescaler to use and set ?

So far I have done this
Timer0 seems to give about 1 mSec interrupts
So function MyDoThings runs at about 250 Hz right now


void Setup()

Any help would be very much apreciated

See my site for the Radio Direction finder Arduino Doppler’s

Arduino.txt (17.4 KB)

Hello Every Body

I fixed it myself

I use timer2 now in OVF mode and starttimer variable
to set the frequencies 500 700 or 900 Hz

Doppler rotations

it runs fine bussiness now.

Arduino.txt (17.8 KB)

Hello Every Body,

I upload a much better Arduino doppler INO file

Stil working on it.

Arduino.ino (19.7 KB)

Hello Every Body,

I did again some bug fixes in the Sketch I wrote

It now works quite okay !

You can switch through the termianl program now also the Average on and off.

Arduino3.txt (21.2 KB)

Hello Every body,

I send a picture of the antenna circuits needed for the arduino doppler.

So for the Am recieve Plate antenna
and the classic FM recieve 4 mono or 4 dipole antenna array.

The software to show on map with GPS can be found on the

PI4WAG site MyMapping.

That has an Arduino terminal and a Pelorus
with opacity so you can ovelay that on any shown map on your PC.

Or use the maps in MyMapping it self.

Hello Every Body,

I did fixed some errors in the SuperSimpleArduinoDoppler


Now it does right CW/CCW with the plate antenna and AM reciever mode

and it had a MultiPath detect bug thats fixed also in this sketch

In new releases of the software on the site of PI4WAG

it will be there ofcourse to.

Arduino.ino (22 KB)

Hello Every Body,

Updates from my arduino doppler now with

a Homming in lm3914 10* led pelorus.

There is new software on this site

Arduino.ino (23.6 KB)


very good!Thank you!I want to DIY it,but I need more infomation,I want more Circuit diagram and Picture of real products。Thanks!

sorry,my English is poor!:)

@pa3bnx: Please read the two posts at the top of this Forum by Nick Gammon on posting your source code here using the </> icon in the posting bar. It will make it easier for us to read.

Jack, W8TEE

Hello Every Body,

Here a Picture of the LapTop running Win7 and MyMapping.exe

and here the working circuits on hole PCB

All circuits run on the USB power of the laptop

(Not the bearcat scanner hi)

Connected to the Arduino uno rev3

with the 10 led Homming in Pelorus (lm3914)

I am stil working on improvements !!! in MyMapping.exe and arduino.ino

I have not done Art PCB work an a Arduino Shield Yet

It did work quite okay 13 september in the Netherlands
with the balloon fox hunt …


Hello Every Body

Today I wrote RightLeftRotating in Arduino.ino

With command R in ArduinoTerminal or button RL(in new MyMapping.exe) you can change the Doppler antenna rotation sequence from the antenna array

1234 1234 1234 1234 to
1234 3214 1234 3214

So one round right and then one round back to begin situation

What is the advantage of this?

The FM discriminator curve in the receiver can have a wrong
measurement if it’s not symmetric.
This happens when the receiver is not exact adjusted to centre TX frequency or when the S-curve of the frequency discriminator is not

By rotating up and down you can average +/- frequency discriminator

If you switch between NormalRotation and RightLeftRotation
you hear the Doppler tone frequency halve.
The pelorus degrees stays the same

Of course CW/CCW adjustment stays the same.

Also with the plate antenna this is possible but it wil not give
benefit with AM detector

If you switch to RightLeftRotation you cannot use the arduino
on the sound-card with my soundDoppler.exe program.

So switch back to NormalRotation



:slight_smile: :slight_smile:

Arduino102.ino (26.2 KB)