A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system that permits the photographer to view through the lens and see exactly what will be captured. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image. When the shutter button is pressed on most SLRs, the mirror flips out of the light path, allowing light to pass through to the light receptor and the image to be captured.
Speed limits on road traffic, as used in most countries, set the legal maximum speed at which vehicles may travel on a given stretch of road. Speed limits are generally indicated on a traffic sign reflecting the maximum permitted speed, expressed as kilometres per hour (km/h) or miles per hour (mph) or both. Speed limits are commonly set by the legislative bodies of national or provincial governments and enforced by national or regional police and judicial authorities. Speed limits may also be variable, or in some places nonexistent, such as on most of the Autobahnen in Germany.
A traffic enforcement camera is a camera which may be mounted beside or over a road or installed in an enforcement vehicle to detect motoring offenses, including speeding, vehicles going through a red traffic light, vehicles going through a toll booth without paying, unauthorized use of a bus lane, or for recording vehicles inside a congestion charge area. It may be linked to an automated ticketing system.
Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system introduced in the mid-1970s. A closely related ISO system is used to describe the relationship between exposure and output image lightness in digital cameras. Prior to ISO gaining traction the best known systems were ASA in the U.S. and DIN in Europe.
DX encoding is an ANSI and I3A standard, originally introduced by Kodak in March 1983, for marking 135 and APS photographic film and film cartridges. It consists of several parts, a latent image DX film edge barcode on the film below the sprocket holes, a code on the cartridge used by automatic cameras, and a barcode on the cartridge read by photo-finishing machines.
Secure Digital, officially abbreviated as SD, is a proprietary, non-volatile, flash memory card format the SD Association (SDA) developed for use in portable devices.
A speedometer or speed meter is a gauge that measures and displays the instantaneous speed of a vehicle. Now universally fitted to motor vehicles, they started to be available as options in the early 20th century, and as standard equipment from about 1910 onwards. Other vehicles may use devices analogous to the speedometer with different means of sensing speed, eg. boats use a pit log, while aircraft use an airspeed indicator.
Gatso is the brand that Gatsometer BV use on their speed cameras and red light cameras. The most commonly encountered Gatso speed cameras emit radar beams to measure the speed of a passing vehicle. If it is travelling above the preset trigger speed, one or two photographs are taken. These use a powerful flash, to show the rear of the vehicle, its registration plate, and calibration lines on the road. Newer installations used digital cameras which have limited exposure latitude compared to film, these installations use an auxiliary flash placed close to the position where a speeding vehicle would exit the radar beam and the first photograph would be taken.
An advanced driver-assistance system (ADAS) includes technologies that assist drivers with the safe operation of a vehicle. Through a human-machine interface, ADAS increases car and road safety. ADAS uses automated technology, such as sensors and cameras, to detect nearby obstacles or driver errors, and respond accordingly. ADAS can enable various levels of autonomous driving.
A red light camera is a type of traffic enforcement camera that photographs a vehicle that has entered an intersection after the traffic signal controlling the intersection has turned red. By automatically photographing vehicles that run red lights, the photo is evidence that assists authorities in their enforcement of traffic laws. Generally the camera is triggered when a vehicle enters the intersection after the traffic signal has turned red.
A radar detector is an electronic device used by motorists to detect if their speed is being monitored by police or law enforcement using a radar gun. Most radar detectors are used so the driver can reduce the car's speed before being ticketed for speeding. In general sense, only emitting technologies, like doppler RADAR, or LIDAR can be detected. Visual speed estimating techniques, like ANPR or VASCAR can not be detected in daytime, but technically vulnerable to detection at night, when IR spotlight is used. There are no reports that piezo sensors can be detected. LIDAR devices require an optical-band sensor, although many modern detectors include LIDAR sensors. Most of today's radar detectors detect signals across a variety of wavelength bands: usually X, K, and Ka. In Europe the Ku band is common as well. The past success of radar detectors was based on the fact that radio-wave beams can not be narrow-enough, so the detector usually senses stray and scattered radiation, giving the driver time to slow down. Based on a focused laser-beam, LIDAR technology does not suffer this shortcoming; however it requires precise aiming. Modern police radars incorporate formidable computing power, producing a minimum number of ultra-short pulses, reusing wide beams for multi-target measurement, which renders most detectors useless. But, mobile Internet allows GPS navigation devices to map police radar locations in real-time. These devices are also often called "radar detectors", while not necessary carrying an RF sensor.
Automatic number-plate recognition is a technology that uses optical character recognition on images to read vehicle registration plates to create vehicle location data. It can use existing closed-circuit television, road-rule enforcement cameras, or cameras specifically designed for the task. ANPR is used by police forces around the world for law enforcement purposes, including checking if a vehicle is registered or licensed. It is also used for electronic toll collection on pay-per-use roads and as a method of cataloguing the movements of traffic, for example by highways agencies.
In the United States, speed limits are set by each state or territory. States have also allowed counties and municipalities to enact typically lower limits. Highway speed limits can range from an urban low of 25 mph (40 km/h) to a rural high of 85 mph (137 km/h). Speed limits are typically posted in increments of five miles per hour (8 km/h). Some states have lower limits for trucks, some also have night and/or minimum speed limits.
Automotive tires are described by an alphanumeric tire code or tyre code, which is generally molded into the sidewall of the tire. This code specifies the dimensions of the tire, and some of its key limitations, such as load-bearing ability, and maximum speed. Sometimes the inner sidewall contains information not included on the outer sidewall, and vice versa.
SPECS is an average speed measuring speed camera system introduced in 1999. It is one of the systems used for speed limit enforcement in the United Kingdom.
d-cam is a type of digital speed camera produced by the British subsidiary of the South African company Truvelo Manufacturers (Pty) Ltd. Testing by Transport for London commenced on the A4 Great West Road in London, in April 2007. The camera does not flash and can be used rear or forward-facing. It was the first combined traffic light camera and speed camera to be used in the United Kingdom. The new style of camera housing was designed by Bristol-based firm Crown (UK) Ltd.
A collision avoidance system (CAS), also known as a pre-crash system, forward collision warning system (FCW), or collision mitigation system, is an advanced driver-assistance system designed to prevent or reduce the severity of a collision. In its basic form, a forward collision warning system monitors a vehicle's speed, the speed of the vehicle in front of it, and the distance between the vehicles, so that it can provide a warning to the driver if the vehicles get too close, potentially helping to avoid a crash. Various technologies and sensors that are used include radar (all-weather) and sometimes laser (LIDAR) and cameras to detect an imminent crash. GPS sensors can detect fixed dangers such as approaching stop signs through a location database. Pedestrian detection can also be a feature of these types of systems.
HOTA is an acronym for Home Office Type Approval, a testing and certification process by the Home Office in the United Kingdom that speed cameras must pass before evidence from them can be admissible in UK courts by way of certification in accordance with Section 20 of the Road Traffic Offenders Act 1988 (RTOA). It is a misconception that speed enforcement devices must be Home Office Type Approved before they may be deployed on public roads to gather evidence of speeding offences however if the device does not have UK Type Approval then the evidence from the device is not able to be certified but must be adduced by a witness and perhaps an expert witness who is able to adduce evidence of its accuracy. The Road Traffic Offenders Act route via Section 20 certification is a clear advantage over the unapproved equipment route to court.
Speed limits are enforced on most public roadways by authorities, with the purpose to improve driver compliance with speed limits. Methods used include roadside speed traps set up and operated by the police and automated roadside 'speed camera' systems, which may incorporate the use of an automatic number plate recognition system. Traditionally, police officers used stopwatches to measure the time taken for a vehicle to cover a known distance. More recently, radar guns and automated in-vehicle systems have come into use.
Road speed limit enforcement in the United Kingdom is the action taken by appropriately empowered authorities to attempt to persuade road vehicle users to comply with the speed limits in force on the UK's roads. Methods used include those for detection and prosecution of contraventions such as roadside fixed speed cameras, average speed cameras, and police-operated LIDAR speed guns or older radar speed guns. Vehicle activated signs and Community Speed Watch schemes are used to encourage compliance. Some classes of vehicles are fitted with speed limiters and intelligent speed adaptation is being trialled in some places on a voluntary basis.
