How Police Radar Gun and Laser Speed Gun Work - Coursework Example

How Police Radar Gun and Laser speed Gun work Police Radar Gun The concept of measuring the speed of vehicles is verysimple. According to Neltronics, basic speed gun comprises of a radio transmitter and a receiver all combined into one component. The radio transmitter oscillates an electrical current thus making the voltage go up and down at a particular frequency. As a result, electromagnetic waves are generated by this electricity, and the energy travels in the air as electromagnetic waves when the current is oscillated. There is an amplifier in the transmitter that enhances the electromagnetic energy intensity and an antenna that is tasked with broadcasting it into the air. Radar is making use of radio waves to monitor and detect different objects. The most common function of any radar device is to inform you of how far an object is. To accomplish this task, the radar device usually relays a concentrated radio wave and then listens for any echo. If there exits an object on the radio wave, it will reflect a bit of the electromagnetic energy , thus making the radio waves bounce back to the radar device (Texas). Considering that radio waves travel through the air at a constant speed, the radar device would be able to compute how far away the object depending on the length of time the radio signal takes to return (Neltronics). Pagan argues that a radar speed gun is a device that is utilised to measure the speed of objects in motion. Invented by John Barker Sr., the radar speed gun was actually created for the military during World War II. Currently, it is commonly used by law enforcement agents to measure the speed of moving automobiles, but in some situations it is used in professional spectator sport. A radar can also take measurements of an object’s speed, as result of a phenomenon called Doppler shift (Pagan). The radio waves have a specific frequency. Therefore, when the both the car and radar gun are at a stand still, the echo will emit similar wave frequency as the original signal. Every signal part is usually reflected when it arrives at a vehicle, mirroring the exact original signal. However, when the automobile is motion, every part of the radio signal in space is actually reflected at a different point thus distorting the pattern of the wave. If the vehicle moves away from the radar gun, the signal’s second segment needs to travel to a significantly greater distance in order to reach the car than the signal’s first segment (Texas). This means that when the motor vehicle is moving towards the radar gun, the wave’s second segment moves a shorter distance compared to the first segment before being reflected. As a consequence, the waves’ valleys and peaks get squeezed together, thus increasing the frequency (Neltronics). A radar speed gun is regarded as a hand-held Doppler radar unit, and it can either be static or vehicle mounted. Basing on the manner in which the frequency changes, a radar gun has the ability to work out how fast a vehicle is moving towards or away from it. When the vehicle is travelling away from or towards the gun, the reflected wave’s frequency is different when coming back from the transmitted waves. The gun is able to compute the object’s speed from which the waves have bounced making use of that difference. This speed is given by the equation below (Harville, 23): Where: c- The speed of light (299,792,458 metres per second) f- The frequency of emitted of the radio waves Δf-Difference in frequency between the emitted radio waves and those received back by the gun However, this equation is more precise if the speed of the objects is lower than that of light, even though the in daily situations an object’s velocity is directly proportional to this difference in frequency. Therefore, by rearranging terms, it can be deduced that Δf is actually directly proportional to the absolute frequency and object velocity. Therefore, any change in f results to a change in the calibrated relation between v and Δf as shown the equation below (Harville, 24-25). When the radar gun is utilised inside a police vehicle that is in motion, there is need to factor in its own movement. For instance, if the police car is travelling at 60 miles pre hour and the gun detects that the target is actually moving away at 25 miles an hour, then the target must be driving the vehicle at 75 miles per hour. However, when the gun detects that the target is mot moving away or towards the police vehicle, then the target is driving at exactly 60 miles an hour (Neltronics). Therefore, when a radar device is pointed in a particular direction, it emits radio waves in that specific direction. These waves then bounce off the moving vehicle and back to the receiving station of the gun (Texas). This motion creates the Doppler shift that is computed by the gun’s computer to be relayed as speed. Laser speed gun The fundamental element in a laser speed gun that is also known as a lidar gun (for ranging and light detection) is concentrated light. The modern laser speed gun makes use of laser light in place of the radar. It commenced to replace radar guns during the first 10 years of the 21st century (Neltronics). For instance, some motorists install radar detectors that can alert them of the presence of a speed trap ahead. Besides, the radar’s microwave signals might also alter the reception quality of FM and AM radio signals when tuned to a weak station. This makes the device to use a more direct method of speed detection that depends on the time of light reflection other than the Doppler shift (How Stuff Works Inc). The laser or LIDAR speed guns have the ability to produce reliable range and speed measurements in distinctive urban and suburban traffic environments that have no site survey limitation and cameras. This is very reliable in city traffic due to the fact that the laser speed gun has directionality that is same to a firearm since the beam is pencil-shaped producing measurement exclusively from the object it has been aimed at. Therefore, a police officer can be able pick out a single car from a group and measure the speed of that individual car. It rests on the principle of time-of-flight of two (or more) short 905 nm wavelength laser impulses. The light form a laser speed gun travels at an approximated 984,000,000 feet per second or roughly 30 cm per nanosecond. The gun shoots short bursts of infrared laser light and waits for them to reflect off the targeted automobile. The laser speed gun then makes counts of the number of nanoseconds it takes for a round trip. Dividing by 2, it is capable of computing the distance to the car (HowStuffWorks Inc). This modern detector provides much more detailed speed information making to more efficient than the radar devices. Jammimg The convention radar detector usually picks up a police’s speed gun signal via a simple radio receiver. Motorists who have installed this device have their own transmitter that emits a jammimg signal. The signal duplicates the police’s radar gun unoriginal signal, except that it combines it with additional radio noise. With the addition of this information, the radar’s receiver obtains a distorted echo signal, thus making the police not abele to make an accurate speed reading (Neltronics). In relation to the laser speed guns, the speeding motorists usually reduce their vehicles reflectivity. A surface that is painted black usually reduces reflectivity since it absorbs more light (Neltronics). Besides, some motorists get special plastic that covers their license plate’s reflectivity. Even though these measures decrease the effective range of the laser system, the range of the driver is always detected. Doubly constrained robust Capon beamformer (DCRCB) and robust Capon beamformer (RCB) approaches are employed to the multiple-input multiple-output (MIMO) radar system to attain a superior interference and accurate parameter estimation, and jamming suppression performance (Li and Stoica, p.2). Improvements With regard to the radar speed gun, numerous errors can occur. The most common one is the cosine error that is caused by radar striking at angle to the target vehicle’s path. When the angle is greater, the error is large too. This can be corrected by measuring a lower speed as compared to what the target is travelling. In addition, some of the radars are programmed in order to compensate for this error by inputting the error (Texas). Another method that has been proposed to overcome the problems of down-the-road radar is the production of video records of the speeding infraction together with a video record of the radar’s evidence. This video record can be utilised to support or disprove a courtroom’s testimony (Fisher 38). The other improvement is the use across-the-road laser devices. For instance, the Autovelox 104-C across-the-road laser system does not need aiming at the vehicle since has been set up along side a road (Fisher 41). The radar systems also need to be improved in order to take 4 or 5 readings before taking a photo. They can take up to 3 photos a second by using a fast drive motor drive camera system. The system also need to be improved to the extent that it can determine if the vehicle if a truck, personal or passenger vehicles. In relation to the laser detector systems, it needs to be small with the front having a shape as a miniature rocket launcher. They also need to be shielded from external interference, as well having a highly targeted beam that is emitted from a parabolic reflector in order to allow focusing (Neltronics). Summarily, a normal radar emits a radio pulse and then waits for the reflection. After receiving the reception, it then measures the signal’s Doppler shift and utilises the shift to establish the speed of the object and how far it is. Some motorists install radar detectors that can alert them of the presence of a speed trap ahead thus jamming the system. On the other hand, the modern speed laser speed gun makes use of laser light in place of the radar, thus making the device to use a more direct method of speed detection that depends on the time of light reflection other than the Doppler shift. This makes it to be more efficient than the radar speed gun. Works Cited Fisher. Improving on Police Radar. New York: IEEE Spectrum, 1992. Harville, D. A. Matrix Algebra from a Statistician’s Perspective. New York: Springer. 1997. How Stuff Works Inc. "How Stuffs Work." 2014. How does a laser speed gun work to measure a cars speed? 5 April 2013 . Li, Juan and Petre Stoica. Target detection and Paremeter Estimation for MIMO radar systems. New York: IEEE, 2009. Neltronics. 2009. How does a Speed Camera. 4 April 2014 . Pagan, Kennedy. "The New York Times Magazine." 30 August 2013. Who Made That Traffic Radar? 5 April 2014 . Texas, Laura. "The Straight Dope." 25 October 2005. How do radar guns work? 5 April 2014 . Read More