SPEED MEASURING DEVICES
Police use microwave Doppler Radar that transmits a narrow beam (9° to 18° wide) in 1 of 3 frequency bands (X, K, or Ka band). The radars can operate from a stationary position or a moving patrol car. Range depends on target size, shape, and reflectivity, and varies from less than 500 feet to over a mile.
Police also use Lidar, also called Laser Radar. Lidar uses infrared (IR) pulsed laser light at a 904 nanometer (nm) wavelength (invisible to the eye), has a very narrow beam (less than 0.2° wide), and only radiates when targeting a vehicle. Lidar's have some limitations; they are relatively short range (150 yards), can only be used in clear weather / conditions, and cannot be used from a moving patrol car.
Radar | Lidar | |
---|---|---|
Operation | Stationary or Moving | Stationary only |
Aim | Easy Aim | Exact Aim |
Transmit |
Continuous or Instant-on |
Instant-on only |
Traffic Conditions | Light to Moderate | Light to Dense |
Range | Short or Long Range | Short Range |
Measures |
Speed Some can measure 2 targets |
Speed and Range |
Location | Inside or Outside Patrol Car |
Outside Patrol Car Should not be operated from behind glass / windshields etc. |
RADAR DETECTORS
A radar detector can identify a police radar a good mile or more if the radar is continuously transmitting. However, there must be a relatively clear line-of-sight (no hills, woods, or other obstructions) between the radar and the detector.
Some police using radar, and all using lidar, only transmit when targeting a vehicle, this leaves little or no time for a driver to react. In most cases a detector can identify a radar faster than the radar can establish a track, but the difference is fractions of a second. At longer ranges the radar may require a second or more to get a track, giving a driver a second or so to react.
DETECTOR PLACEMENT
A radar / lidar detector should have a clear line-of-sight, no obstructions in front of the microwave antenna or infrared (IR) aperture. The detector should be located high for best radar detection, but low for best lidar detection. Lidar operators aim the narrow beam low, at the license plate, head or tail light, bumper, or grill. A low mounted detector has a slightly better chance of detecting a lidar.
LEGALITY
Radar Detectors are illegal in:
Radar detectors are illegal in some provinces in Canada and some states in Australia.
SIGNALS DETECTED
All radar detectors can detect police radar and lidar, some also detect other signals.
Radar Signal Strength bars -- works in conjunction with audio beeps, the stronger the signal the faster the beeps.
(1) -- Burglar Alarms, Automatic Door Openers (stores, truck/car/train entrances), Obstruction Detectors (railroad locomotives, rolling stock, specialized cars), object detection (production lines), speed measuring radar (train yards, sporting events).
(2) -- Dummy radar (to setoff radar detectors).
RADAR POP MODE (irrelevant) more...
ADDITIONAL OPTIONS
Additional options can include wider coverage area (rear/side), a more informative display, and voice alerts. Some detectors use GPS and a database of fixed Red Light and/or Speed Camera locations for alerts. The locations change and the database should be kept up to date.
Coverage |
- Front - Rear / Sides |
Indicators |
- Radar Band - Radar Signal Strength - Radar Frequency - Signal Direction - RDD model - Safety Message decoded |
Audio |
- Beeps and Tones - Beeps, Tones, Voice |
Power |
- Vehicle DC plug - Internal Battery - Vehicle or Battery |
GPS |
- Lat/Long, Elevation, Direction - Red Light Camera Data - Speed Camera Data |
other |
- NOAA Weather Radio (VHF) - Outside Temperature |
Driver Alert | - Beeps periodically to keep driver awake. |