.  Hill Country Research Innovations in Telecommunication and Automation   RDD Brochure

Radar Detector Detector  MD-3/S  &  MD-3/D

The Radar Detector Detector was designed to help enforce laws regulating the use of radar detectors. Radar Detectors are illegal in many countries.  In the US they are illegal in commercial vehicles and also in passenger cars in some states.  In Canada they are illegal in the Eastern provinces for all vehicles.  They are also illegal in Australia and most European countries. The MD-3 detects the presence of a Radar Detector.   It indicates proximity/ signal strength by illuminating five red LEDs and sounding distinct audio signals. Two models are available, the MD-3/S with a single receiver and the MD-3/D with dual receivers (dual beam unit).

Radar Detectors, like most receivers are superheterodyn receivers.  These superhet receivers use a local oscillator and mix it’s frequency with the frequency of the incoming signal to convert it to the intermediate frequency for further processing.  This local oscillator is a very week transmitter, which can be detected by a sensitive receiver.  A Radar Detector Detector is such a receiver, looking for this LO signal.

When a signal is detected, it is amplified, filtered, down-converted, amplified and filtered again and demodulated.  The resulting DC signal is digitized in an analog- digital converter and the bit pattern is fed to the registers of a microprocessor.  Here the software takes over and performs some signal processing.  It then decides if the signal is sufficient above the noise level.  If so, the LEDs (light emitting diodes) are switched on under software control and a sound is generated according to the signal strength.
 
 

When the MD-3 is switched on, the system's microprocessor goes through a short test cycle testing the lights and playing the five tones associated with the five levels of signal strength (tones are tuned to C', D', F', G' and A').

Then it performs an auto calibration, measuring the microwave background radiation and defining the relative zero point there.  The unit is now ready for operation. Consequent measurements will only cause an alarm, if the signal strength is above this background noise level.

When a car with a Radar Detector approaches, the first tone will sound and the first LED lights up.  As it comes closer, more LEDs light up and the beeps increase in pitch. As the car drives away, the sequence reverses.

If the unit has been calibrated (switched on) in the country and the patrol car is entering a city, it will start to generate alarms due to the higher background radiation.  In this case the sensitivity can be adjusted (dual beam only) or the unit can be power-cycled to recalibrate it for the new environment.

If the unit has been switched on in a city and the car is moving to the country, the sensitivity will be too low and the unit should be power-cycled again.

This should be done in the absence of approaching cars. That’s because, if a car in the vicinity has a radar detector on board, this higher radiation level would be interpreted as the background noise level during the automatic calibration procedure and would be the new zero reference.  Approaching cars in front are more critical here than cars in the back, because the MD-3/D’s directional antennas are much more sensitive looking forward than backwards.

The blue LED on the bottom transmits an optical data stream when a signal is present which can be used to document the acquired signals. The data stream can be picked up with a photo sensor and read into a laptop computer via the serial port (some additional hardware required). This light also fades in and out every ten seconds if no radar activity is detected to confirm the proper operation of the microprocessor and that the unit is ready for microwave reception.
 
 

Additional MD-3/D (dual beam) information:

Prior to powering up the unit, turn the two sensitivity potentiometers (on top) 80% to 100% to the right (clockwise) to enable correct calibration. Both should be in the same position.
 
 

The MD-3/D Radar Detector Detector uses two antenna beams to provide directional information about the radiation source.  The first one “looks” forward and the second one “looks” approximately 55 degrees to the left.

 

When a vehicle with a radar detector on board approaches from the left, the lowest red LED on the left semicircle will activate first, accompanied by three low beeps. As the vehicle comes closer, the second LED from the bottom also activates and the tone changes to three beeps of a higher pitch. The three beeps repeat as long as the signal strength remains constant. As the microwave signal level increases, so does the pitch of the tone and the next red LEDs light up.
 
 

As the vehicle progresses to the right, the LEDs of the right semi-circle will start to lighten up. While this right side indicates more and more signal amplitude caused by the passing vehicle, the left side will decrease in intensity. When the vehicle drives away, the right-side lights will switch off one by one until all lights are off.

Simultaneously with the lights two sets of sounds are generated.  The left side corresponds to the lower octave and the right side to the higher octave (two different penta scales).

Visual contact with the display is not necessary since the sounds provide the same information as the display.  It might take some practice to correlate the sight and sound to a particular vehicle in denser traffic conditions.

The 50 mm antennas provide good directivity for spatial discrimination between cars.  The dual antenna concept allows for better spatial resolution of the signal source compared to a single beam receiver.
 
 

The MD-3 is typically mounted on the dashboard of a car. There should be no obstacles in front of the unit.  A steel bracket with sheet metal screws and a bolt holding the RDD is provided.  The steel bracket can be bent by hand to adapt to different dashboard angles.

Optional wind shield mounting hardware is available.

With unit switched off, connect it to the car’s cigarette lighter receptacle (using the provided coiled power cable).  Connect the cable to the RDD first, then to the car.
 
 

The operating voltage is 12 Volt DC (from the cigarette lighter receptacle of the vehicle); the unit will work between 10 V and 18 V.

The average current of the MD-3/S is about 300 mA (milliampere) when a signal is detected and 120 mA without a signal.

The average current of the MD-3/D is about 500 mA with signal present and 240 mA without signal.

This unit is protected against over-voltage (spikes), over-current and reverse polarity.

The antennas are decoupled from the local oscillators by two microwave transistors and filters in each of the two receivers to help prevent its detection by Radar Detector Detector Detectors.

The MD-3/S measures approximately 160mm x 78mm x 61mm (6.3’’x 3’’x 2.4’’)
 including knobs.

The MD-3/D measures approximately 152 mm x 172 mm x 65 mm (6''x 6.8''x 2.6’') including knobs.

Unit has been temperature tested between -10 C (17 F) and +70 C (137 F) and performed without failure.

Development, production and service is in Central Texas.  The MD-3 has a warranty of one year.
 
 

The MD-3/D can also be used for:

•  Animal tracking
•  Property tracking
•  Telemetry
•  Data com

With the appropriate transmitter, the tracking distance can be in excess of ten miles
 

HCR also builds K-Band Radar Drones.  They are being used to activate Radar Detectors from a distance.
 
 
 

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