The The Montréal Doppler III Montréal Doppler III by Jacques VE2EMMby Jacques VE2EMM

Réal VE2DSK and Serge VE2HLSRéal VE2DSK and Serge VE2HLS

Doppler historyDoppler 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.

  Doppler for radioamateur uses began in 1978 when Terence Doppler for radioamateur uses began in 1978 when Terence

Rogers WA4BVY wrote an article in review QST about a Rogers WA4BVY wrote an article in review QST about a practical unit using 16 leds for the band 2 meters. Other practical unit using 16 leds for the band 2 meters. Other

systems with 32 and 36 leds made their appearance on the systems with 32 and 36 leds made their appearance on the market using the CMOS and TTL logic. W6AOP sold many of market using the CMOS and TTL logic. W6AOP sold many of

them using version CMOS only.them using version CMOS only.

  In 1981 several compagnies started to sell various types of In 1981 several compagnies started to sell various types of products for the radioamateur community like the Dick Smith products for the radioamateur community like the Dick Smith Direction Finder Doopler. The most popular VHF system build Direction Finder Doopler. The most popular VHF system build with integrated circuits was created by Chuck Tavaris N4FQ. with integrated circuits was created by Chuck Tavaris N4FQ.

Conceived to be simplest possible and the least expensive, this Conceived to be simplest possible and the least expensive, this system was call Roanoke because Chuck N4FQ lives in the system was call Roanoke because Chuck N4FQ lives in the

town of Roanoke in Virginia, USA.town of Roanoke in Virginia, USA.

  Here in Montreal Jacques VE2EMM likes to program IC, he is Here in Montreal Jacques VE2EMM likes to program IC, he is using the Pic models from the Microchip company. With these using the Pic models from the Microchip company. With these

Pic he improved the existing the Doppler system by adding Pic he improved the existing the Doppler system by adding several options which make this project very interesting to several options which make this project very interesting to

manufacture.manufacture.

The characteristicsThe characteristics

11

36 LED’s display, when the central LED 36 LED’s display, when the central LED is green = the signal is good, when theis green = the signal is good, when the

LED stay red = no signal and the LED stay red = no signal and the direction is fixed on the last information.direction is fixed on the last information.

22

Three Pics IC are used one 16F628A for Three Pics IC are used one 16F628A for the LCD display, one 16F877A for the the LCD display, one 16F877A for the

main circuit and one 12F675 acting as a main circuit and one 12F675 acting as a frequency divider.frequency divider.

33

Two audio filters, the first one is a Max Two audio filters, the first one is a Max 267 it's the best bass band filter, it is267 it's the best bass band filter, it is

followed by the original Roanoke filter followed by the original Roanoke filter for a very narrow total band-width of for a very narrow total band-width of

(+ 0.5Hz).(+ 0.5Hz).

44

The Doppler II integration and The Doppler II integration and

detection softwaredetection software

55

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

66

All menus are very simple to use, just All menus are very simple to use, just turn the knob to choose the menu and turn the knob to choose the menu and

push a second one to activate.push a second one to activate.

77

It can be used with 4 antennas It can be used with 4 antennas commutated as +V or -V or in commutated as +V or -V or in

differential, you also have differential, you also have

the choice of 8 antennas +/-.the choice of 8 antennas +/-.

88

Push one button and you send teh Push one button and you send teh direction to an APRS system. direction to an APRS system.

The protocol is : The protocol is : CR><LF>%359/Q<CR><LF>CR><LF>%359/Q<CR><LF>

The Q (0<8) is the signal quality taken The Q (0<8) is the signal quality taken just before the phase extraction.just before the phase extraction.

99

The GPS information passes through the The GPS information passes through the Doppler, it is stopped when a directionDoppler, it is stopped when a direction

Is sent to a PC.Is sent to a PC.

All 16 menus : All 16 menus :

Menu 0Menu 0

Normal function, the push-button send only one Normal function, the push-button send only one direction transmission to a PC and APRS. (This menu direction transmission to a PC and APRS. (This menu is optional, August 14, 2004) The first line give : the is optional, August 14, 2004) The first line give : the

QUALITY FACTOR (signal amplitude at the integrator QUALITY FACTOR (signal amplitude at the integrator exit), DIRECTION in degree and the number of returns exit), DIRECTION in degree and the number of returns accumulated. The second line posts: A bargraph of the accumulated. The second line posts: A bargraph of the signal at the exit of first Doppler filter or the signal of signal at the exit of first Doppler filter or the signal of

your radio S-Meter. your radio S-Meter. ..

Menu 1Menu 1

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

as Menu #1. as Menu #1.

Menu 2Menu 2

Integration reductionIntegration reduction

Menu 3Menu 3

Integration increaseIntegration increase

Menu 4Menu 4

Automatic calibration towards Automatic calibration towards

the front of the carthe front of the car

Menu 5Menu 5

Manual reduction of the calibrationManual reduction of the calibration

Menu 6Menu 6

Manual increase in the calibrationManual increase in the calibration

Menu 7Menu 7

Selection of the minimum factor of quality Selection of the minimum factor of quality (0<8), the direction is display for this (0<8), the direction is display for this value and more. If quality is less, the value and more. If quality is less, the

display freezes with the last display freezes with the last

right directionright direction

Menu 8Menu 8

Futur menuFutur menu

Menu 9Menu 9

Futur menuFutur menu

Menu 10Menu 10

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

Menu 11Menu 11

Two choices at the bargraph, the Two choices at the bargraph, the

S-Meter or the MAX267 filter exit level S-Meter or the MAX267 filter exit level

Menu 12Menu 12

Choice of 3 calibrations for Choice of 3 calibrations for

various receivers and/or carsvarious receivers and/or cars

Menu 13Menu 13

Antennas rotation selection, CW or CCWAntennas rotation selection, CW or CCW

Menu 14Menu 14

Choice of antennas, Choice of antennas,

4 + or – 4 + or –

and 4 différentials and 4 différentials

or 8 antennas + or -or 8 antennas + or -

Menu 15Menu 15

Choice of antenna in test Choice of antenna in test

(each antenna can be activated (each antenna can be activated individually)individually)

Les participantsLes participants

Alex VE2AMT - Claude VE2BLVAlex VE2AMT - Claude VE2BLVFrançois VA2FBT - Guy VE2GMPFrançois VA2FBT - Guy VE2GMPJean VE2JMK - Jacques VE2EMMJean VE2JMK - Jacques VE2EMM

Luc VA2LUK - Marcel VE2GMRLuc VA2LUK - Marcel VE2GMRMartin VE2MJT - Mathieu VE2TMQMartin VE2MJT - Mathieu VE2TMQ

Maurice VA2MBR - Maurice VE2MIEMaurice VA2MBR - Maurice VE2MIEMichel VE2TLM - Réal TremblayMichel VE2TLM - Réal TremblayRéal VE2DSK - René VA2RDBRéal VE2DSK - René VA2RDB

René VE2MPA - Ronald VE2JORRené VE2MPA - Ronald VE2JORSerge VE2HLSSerge VE2HLS