The Montr

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The Montréal Doppler III by Jacques VE2EMM

• Réal VE2DSK and Serge VE2HLS

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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. Its
  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.

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•  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.

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The characteristics
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1

• 36 LEDs 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.

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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.

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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).

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• The Doppler II integration and
• detection software

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• One LM386 acting as a independant audio amplifier
  form the Doopler

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

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

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• Push one button and you send teh direction to an
  APRS system.
• The protocol is CRgtltLFgt359/QltCRgtltLFgt
• The Q (0lt8) is the signal quality taken just
  before the phase extraction.

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

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All 16 menus
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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.
• .

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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.

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Menu 2

• Integration reduction

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Menu 3

• Integration increase

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Menu 4

• Automatic calibration towards
• the front of the car

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Menu 5

• Manual reduction of the calibration

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Menu 6

• Manual increase in the calibration

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Menu 7

• Selection of the minimum factor of quality (0lt8),
  the direction is display for this value and more.
  If quality is less, the display freezes with the
  last
• right direction

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Menu 8

• Futur menu

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Menu 9

• Futur menu

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Menu 10

• Baud rate selection for the TX towards the PC,
  2400,4800,9600,19200

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Menu 11

• Two choices at the bargraph, the
• S-Meter or the MAX267 filter exit level

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Menu 12

• Choice of 3 calibrations for
• various receivers and/or cars

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Menu 13

• Antennas rotation selection, CW or CCW

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Menu 14

• Choice of antennas,
• 4 or
• and 4 différentials
• or 8 antennas or -

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Menu 15

• Choice of antenna in test
• (each antenna can be activated individually)

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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