Montréal Doppler III Montréal Doppler III by Jacques VE2EMMby Jacques VE2EMM

by Réal VE2DSK and Serge VE2HLS, May 2005by Réal VE2DSK and Serge VE2HLS, May 2005

History of the DopplerHistory of the Doppler The principles behind the Doppler or Doppler Direction Finding was first discovered The principles behind the Doppler or Doppler Direction Finding was first discovered by Austrian physicist Christian Doppler in the nineteenth century. He published by Austrian physicist Christian Doppler in the nineteenth century. He published his findings in an essay entitled “On the Colored Light of the Double his findings in an essay entitled “On the Colored Light of the Double

Stars and Certain Other Stars of the Heavens” in 1842.Stars and Certain Other Stars of the Heavens” in 1842.

The Doppler effect is readily observed in sound waves, as you have surely noticed The Doppler effect is readily observed in sound waves, as you have surely noticed when a train passes you with the horn sounding. The pitch suddenly drops as the when a train passes you with the horn sounding. The pitch suddenly drops as the engine passes by. The effect occurs when the distance between a source emitting engine passes by. The effect occurs when the distance between a source emitting a wavelength and one that is receiving it is changing, as they are approaching the a wavelength and one that is receiving it is changing, as they are approaching the wavelength appears to be shortening and as they draw apart the wavelength gets wavelength appears to be shortening and as they draw apart the wavelength gets longer. The principles behind the Doppler Effect holds true not only for sound but longer. The principles behind the Doppler Effect holds true not only for sound but also for light and all forms of electromagnetic radiation including (Radio waves).also for light and all forms of electromagnetic radiation including (Radio waves).

The first description of a Direction Finder goes all the way back to 1947 by H.T. The first description of a Direction Finder goes all the way back to 1947 by H.T. Budenbom who used the Doppler modulation with the assistance of a rotary Budenbom who used the Doppler modulation with the assistance of a rotary system of antenna. Today, there is more than 300 inventions or patents system of antenna. Today, there is more than 300 inventions or patents

recorded using Doppler's system throughout the various layers recorded using Doppler's system throughout the various layers of the electromagnetic spectrum.of the electromagnetic spectrum.

Doppler Direction Finder for Amateur Radio began in 1978 when Doppler Direction Finder for Amateur Radio began in 1978 when Terence Rogers (WA4BVY) wrote an article in QST about a Terence Rogers (WA4BVY) wrote an article in QST about a

practical unit using 16 leds for the 2 meters band. Other systems practical unit using 16 leds for the 2 meters band. Other systems with 32 and 36 leds made their appearance on the market using with 32 and 36 leds made their appearance on the market using CMOS and TTL logic technology. W6AOP sold several kits CMOS and TTL logic technology. W6AOP sold several kits

using the CMOS version only.using the CMOS version only.

In 1981 several commercial firms began selling various products In 1981 several commercial firms began selling various products for the Amateur Radio community, like the Dick Smith Doppler for the Amateur Radio community, like the Dick Smith Doppler Direction Finder. A VHF Doppler system made with integrated Direction Finder. A VHF Doppler system made with integrated

circuits was designed by Chuck Tavaris (N4FQ).circuits was designed by Chuck Tavaris (N4FQ).

Conceived to be the simplest possible and the least expensive, Conceived to be the simplest possible and the least expensive, this system was called Roanoke after Chuck's (N4FQ) home this system was called Roanoke after Chuck's (N4FQ) home

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

Here in Montreal Jacques (VE2EMM), user of a PIC Here in Montreal Jacques (VE2EMM), user of a PIC microcontroller produced by the Microchip company, improved microcontroller produced by the Microchip company, improved

the existing Doppler system by adding several options that makes the existing Doppler system by adding several options that makes the Montreal Doppler 3 a very interesting project.the Montreal Doppler 3 a very interesting project.

The characteristicsThe characteristics

11

The MTL Doppler 3 has a 36 led The MTL Doppler 3 has a 36 led display. When the center led is green display. When the center led is green the direction is good, and when it’s the direction is good, and when it’s red it means that there's no signal, red it means that there's no signal, the last good bearing stays on until the last good bearing stays on until

the next new signal.the next new signal.

22

Three PICs microcontrollers are used, Three PICs microcontrollers are used, a 16F628A for the display, a a 16F628A for the display, a 16F877A for the main circuit and a 16F877A for the main circuit and a

12F675 as a frequency divider12F675 as a frequency divider

33

Two audios filters are used, the max 267 Two audios filters are used, the max 267 is the best pass band filter and it's simple is the best pass band filter and it's simple to use, it’s followed by the original filter to use, it’s followed by the original filter Roanoke which has a very narrow total Roanoke which has a very narrow total

band-width (+/- 0.5Hz)band-width (+/- 0.5Hz)

44

The Doppler II phase integration The Doppler II phase integration and detection software is usedand detection software is used

55

A LM386 is used as an audio amplifier A LM386 is used as an audio amplifier that's independent of the Dopplerthat's independent of the Doppler

66

A simpler menu selection is used, A simpler menu selection is used, turn a button to choose and press turn a button to choose and press

the switch "to activate"the switch "to activate"

77

It can be used with 4 antennas It can be used with 4 antennas commutated towards +V or - V or out commutated towards +V or - V or out

of differential like 8 antennas +/-of differential like 8 antennas +/-

88

Activating the switch sends the direction Activating the switch sends the direction towards APRS. The protocol is: towards APRS. The protocol is:

CR><LF>%359/Q<CR><LF>CR><LF>%359/Q<CR><LF>

Q (0<8) and is the quality of the signal Q (0<8) and is the quality of the signal taken right before the extraction taken right before the extraction

of the phaseof the phase

99

The information of the GPS passes The information of the GPS passes through the Doppler and stops when the through the Doppler and stops when the

direction is sent to a PCdirection is sent to a PC

The 16 menus : The 16 menus :

Menu 0Menu 0During normal operation, the push-button starts During normal operation, the push-button starts

only one transmission towards the PC and the APRS only one transmission towards the PC and the APRS (This menu is optional, August 14 04) (This menu is optional, August 14 04)

The first line displays : The first line displays : The QUALITY FACTOR (amplitude of the signal on the The QUALITY FACTOR (amplitude of the signal on the

outlet side of the integrator), and the outlet side of the integrator), and the DIRECTION in degree and the number of at present DIRECTION in degree and the number of at present

accumulated returns.accumulated returns.

The second line posts : A bar-graph of the signal present The second line posts : A bar-graph of the signal present on the outlet side of the first filter of the Doppler on the outlet side of the first filter of the Doppler

or the signal of the S-Meter of your radio.or the signal of the S-Meter of your radio.

Menu 1Menu 1

Normal operation, the pushbutton Normal operation, the pushbutton alternates between integration and no alternates between integration and no

integration. The first and the second line integration. The first and the second line displays the same data as in menu #0displays the same data as in menu #0

Menu 2Menu 2

Reduction of the integrationReduction of the integration

Menu 3Menu 3

Increase of the integrationIncrease of the integration

Menu 4Menu 4

Automatic calibration forwards the carAutomatic calibration forwards the car

Menu 5Menu 5

Manual reduction of the calibrationManual reduction of the calibration

Menu 6Menu 6

Manual increase of the calibrationManual increase of the calibration

Menu 7Menu 7

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

the last good direction.the last good direction.

Menu 8Menu 8

Future MenuFuture Menu

Menu 9Menu 9

Future MenuFuture Menu

Menu 10Menu 10

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

Menu 11Menu 11

Two choices for the bar-graph, the S-Meter Two choices for the bar-graph, the S-Meter or the exit level of the MAX267 filteror the exit level of the MAX267 filter

Menu 12Menu 12

There is three calibrations choices There is three calibrations choices for various receivers and/or carsfor various receivers and/or cars

Menu 13Menu 13

Antennas rotation selection, Antennas rotation selection, CW or CCWCW or CCW

Menu 14Menu 14

Two antennas choices 4 + or - and 4 Two antennas choices 4 + or - and 4 differentiels of 8 antennes + or -differentiels of 8 antennes + or -

Menu 15Menu 15

Choice of the antenna under test Choice of the antenna under test (each antenna can be activated (each antenna can be activated

individually)individually)

The participantsThe participants

Alex VE2AMT - Claude VE2BLV Alex VE2AMT - Claude VE2BLV François VA2FBT - Guy VE2GMP François VA2FBT - Guy VE2GMP Jacques VE2EMM - Jean VE2JMK Jacques VE2EMM - Jean VE2JMK

Luc VA2LUK - Marcel VE2GMR Luc VA2LUK - Marcel VE2GMR Martin VE2MJT - Mathieu VE2TMQ Martin VE2MJT - Mathieu VE2TMQ

Maurice VA2MBR - Maurice VE2MIE Maurice VA2MBR - Maurice VE2MIE Michel VE2TLM - Réal Tremblay Michel VE2TLM - Réal Tremblay Réal VE2DSK - René VA2RDB Réal VE2DSK - René VA2RDB René VE2MPA - Ronald VE2JOR René VE2MPA - Ronald VE2JOR

Serge VE2HLSSerge VE2HLS