So, here I was at Dayton a few weeks ago and decided to check out the fox hunting/amateur radio direction finding (ARDF) forum. I forgot who did the forum, but it was actually very well done. One of the projects I learned about was “The Montreal Doppler”. This is a really neat project designed by Jacques Brodeur, VE2EMM.
I saw many neat attenuators, offset attenuators….. but this….. well…. it has LEDS! Pretty lights…. OK, I digress. Working with a bunch of these LED’s is pretty kewl and looks sweet. This is a project that is well documented on the web and I’ll provide links below.
The biggest question I had was, where do I get the microcontrollers and firmware. Not only was I able to acquire the PICS (microcontrollers), but I was able to get PC boards and the LCD for a very reasonable price from FAR Circuits! I know I picked up the last one he had at Dayton, but he may be able to do more (they cost $45.00). Check out the FAR circuits website at http://www.farcircuits.net/
A little about this project from VE2EMM’s website, list of features:
– 36 LEDs display; center LED when green = good signal, when red = no signal , the direction is frozen to the last good signal.
– Uses 3 PICs; a PIC16F628A for the display, a PIC18F4520 as the main processor and a PIC12F675 as a frequency divider.
– Filters; a Max 267, the best bandpass filter that I have ever seen, followed by the Roanoke switch cap filter for very narrow band width (+/- 0.5Hz).
– My DopplerII integrating and phase detection software in the main PIC.
– LM386 for monitoring the audio independently from the doppler.
– Simpler menu selection, turning a selection pot and a pushing a DO switch.
– It will switch 4 antennas with a + or – going signal, 4 antennas differential, 8 antennas with a + or – going signal.
– Pushing the DO PB sends the direction to APRS. The protocol is: <cr><lf>%359/Q<cr><lf>. The Q (0<8) is the quality of the signal just before the
extraction of the phase information.
– GPS information goes through the doppler, it will be instantly interrupted when the doppler sends a DF to APRS on a PC.
– Faster main processor, PIC18F4520. **** NEW **** June 06
The model I saw really intrigued me and there are a few really well done websites devoted to this project (it has quite the cult following).
The original site is at:
Here is another page on Jacques site that has some examples from other builders:
KA7OEI has a neat page with a bunch of information on this project:
He has a lot of information about an alternate firmware that looks like the image below:
The alternate firmware page is at:
If you have any more information on this project, resources or anything of the sort, please comment below.