Cameras are operated in areas identified as having recurrent speed-related problems, high risk roads and/or traffic accident black spots. They can be used anywhere throughout Victoria at any time of the day or night.Photo radar Speed Camera Set-upThe radar unit may be set up on a tripod or mounted in an unmarked police vehicle positioned at the side of the road. The radar beam is transmitted at an angle of 20 degrees across the road.

The Camera Control Unit is set up by connecting it to the camera and programming it with certain information such as the time, date, film magazine number, speed zone, film type, threshold speed, and direction of the traffic to be covered. The 35mm camera operates as an ordinary camera, but it is controlled by the Camera Control Unit and Radar Control Unit and can photograph two speeding vehicles per second.How photo radar Camera OperatesThe radar unit transmits a radar beam at a frequency of 24.125 GHz, which is five degrees wide, 20 degrees high, and slanted at an angle of 20 degrees across the road.

As a vehicle travels through the beam, the reflected radar frequency is altered by the Doppler effect, and the beam is reflected back to the radar antenna. The antenna receives any signals which arrive from the same coordinates and converts this into the speed of the vehicle. If the vehicle’s speed is greater than the threshold speed set by the operator, a photograph is automatically taken. A radar camera is capable of taking two photographs every second and can detect the speed of vehicles traveling in either direction.Determining the Speed and Travel Direction of the Vehicle Using the Doppler Principle.

The radar unit emits a continuous wave with a frequency of 24.125 GHz at a 20 degree angle across the roadway. When a vehicle enters the radar beam, the reflected frequency changes due to relative motion between the radar and the vehicle.If the relative motion brings the target closer to the radar, the reflected frequency will be increased. If the relative motion takes the target away from the radar, the reflected frequency will be decreased. Conceptually, the returning beam will be compressed if the vehicle is traveling toward the radar unit, and it will be expanded if the vehicle is traveling away from the unit. The extent to which the frequency is increased or decreased is directly proportional to the speed of relative motion. What is most important about the Doppler effect is that the frequency change happens only when there is relative motion between objects.

If both objects are standing still, i.e. parked vehicles, there is no relative motion, and the reflected signal has the same frequency as the transmitted signal. In sum, without a change in frequency there can be no speed estimation. Police traffic radar merely measures this change in frequency and converts it to a speed reading. Most photo radar technology can determine the direction and speed of a target by isolating the increase or decrease in reflected frequency and determining the rate of these changes.

Further explanation of the Doppler effect can be obtained at your local library.Calculating the Speed of a VehicleTrigonometry is to calculate the speed of a vehicle detected by a radar beam. Because the camera unit’s radar beam is slanted across the road at a 20 degree angle, the Doppler frequency shift recorded will indicate a speed that is slower than the target’s true pace. Incorporated into the radar unit is an automatic calculation for the slant angle, so that the true speed and direction of travel can be determined.

The PhotoRadar system produces indisputable photographic evidence of vehicles exceeding the speed limit. The system consists of a narrow-beam, low-powered Doppler radar antenna aimed across the road, a high-speed traffic camera and flash unit, and a computer -- all of which are easily mounted on a police vehicle.

Unlike traditional wide-beam, down-the-road radar systems, PhotoRadar uses the latest in slotted wave-guide antenna design and technology to emit a beam just 5 degrees wide, at a 20-degree angle across the road. The system’s advanced design eliminates the possibility of measuring more than one target vehicle at a time.

After more than 30 years of use, photo radar has been proven to: ·

• Save police departments time and money
• Promote the safety of police officers and the general public
• Improve conviction rates in traffic court
• Maximize city resources available for traffic enforcement and public safety
• Automate traffic counting and analyses
• Increase individual insurance rates and influence driver credit reports, if tickets issued are not paid

More than 25000 PhotoRadar systems are currently in use worldwide.

Photo-Radar and camera

Photo camera