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The Montréal Doppler III by Jacques VE2EMM

The Montréal Doppler III by Jacques VE2EMM. Réal VE2DSK and Serge VE2HLS. Doppler history. Basic principles behind Doppler or Doppler Direction Finding were at the beginning discovered by Christian Doppler in the 19 th century

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The Montréal Doppler III by Jacques VE2EMM

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  1. The Montréal Doppler III by Jacques VE2EMM Réal VE2DSK and Serge VE2HLS

  2. Doppler history Basic principles behind Doppler or Doppler Direction Finding were at the beginning discovered by Christian Doppler in the 19th century When the distance between a transmitter and a receiver changes, the frequency received at the receiver is out of phase to the bottom if both s' move away and to the top if both approach. It’s easy to understand the Doppler effect with the train horn of the train, the sound decreases when the train passes in front of you. The first description of Direction Finder goes back to 1947 when H.T. Budenbom used the Doppler modulation with a rotary antenna system. Today, there are more than 300 inventions or patents recorded on the system Doppler for the various layers of the radio spectrum.

  3.  Doppler for radioamateur uses began in 1978 when Terence Rogers WA4BVY wrote an article in review QST about a practical unit using 16 leds for the band 2 meters. Other systems with 32 and 36 leds made their appearance on the market using the CMOS and TTL logic. W6AOP sold many of them using version CMOS only.  In 1981 several compagnies started to sell various types of products for the radioamateur community like the Dick Smith Direction Finder Doopler. The most popular VHF system build with integrated circuits was created by Chuck Tavaris N4FQ. Conceived to be simplest possible and the least expensive, this system was call Roanoke because Chuck N4FQ lives in the town of Roanoke in Virginia, USA.  Here in Montreal Jacques VE2EMM likes to program IC, he is using the Pic models from the Microchip company. With these Pic he improved the existing the Doppler system by adding several options which make this project very interesting to manufacture.

  4. The characteristics

  5. 1 36 LED’s display, when the central LED is green = the signal is good, when the LED stay red = no signal and the direction is fixed on the last information.

  6. 2 Three Pics IC are used one 16F628A for the LCD display, one 16F877A for the main circuit and one 12F675 acting as a frequency divider.

  7. 3 Two audio filters, the first one is a Max 267 it's the best bass band filter, it is followed by the original Roanoke filter for a very narrow total band-width of (+ 0.5Hz).

  8. 4 The Doppler II integration and detection software

  9. 5 One LM386 acting as a independant audio amplifier form the Doopler

  10. 6 All menus are very simple to use, just turn the knob to choose the menu and push a second one to activate.

  11. 7 It can be used with 4 antennas commutated as +V or -V or in differential, you also have the choice of 8 antennas +/-.

  12. 8 Push one button and you send teh direction to an APRS system. The protocol is : CR><LF>%359/Q<CR><LF> The Q (0<8) is the signal quality taken just before the phase extraction.

  13. 9 The GPS information passes through the Doppler, it is stopped when a direction Is sent to a PC.

  14. All 16 menus :

  15. Menu 0 Normal function, the push-button send only one direction transmission to a PC and APRS. (This menu is optional, August 14, 2004) The first line give : the QUALITY FACTOR (signal amplitude at the integrator exit), DIRECTION in degree and the number of returns accumulated. The second line posts: A bargraph of the signal at the exit of first Doppler filter or the signal of your radio S-Meter. .

  16. Menu 1 Normal functioning, the push-button alternates between integration and none integration. The first and the second line gives the same data as Menu #1.

  17. Menu 2 Integrationreduction

  18. Menu 3 Integrationincrease

  19. Menu 4 Automatic calibration towards the front of the car

  20. Menu 5 Manual reduction of the calibration

  21. Menu 6 Manual increase in the calibration

  22. Menu 7 Selection of the minimum factor of quality (0<8), the direction is display for this value and more. If quality is less, the display freezes with the last right direction

  23. Menu 8 Futur menu

  24. Menu 9 Futur menu

  25. Menu 10 Baud rate selection for the TX towards the PC, 2400,4800,9600,19200

  26. Menu 11 Two choices at the bargraph, the S-Meter or the MAX267 filter exit level

  27. Menu 12 Choice of 3 calibrations for various receivers and/or cars

  28. Menu 13 Antennas rotation selection, CW or CCW

  29. Menu 14 Choice of antennas, 4 + or – and 4 différentials or 8 antennas + or -

  30. Menu 15 Choice of antenna in test (each antenna can be activated individually)

  31. Les participants Alex VE2AMT - Claude VE2BLV François VA2FBT - Guy VE2GMP Jean VE2JMK - Jacques VE2EMM Luc VA2LUK - Marcel VE2GMR Martin VE2MJT - Mathieu VE2TMQ Maurice VA2MBR - Maurice VE2MIE Michel VE2TLM - Réal Tremblay Réal VE2DSK - René VA2RDB René VE2MPA - Ronald VE2JOR Serge VE2HLS

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