流动测速及原理

流动测速及原理 Flow speed and principle Is not fixed speed, different from the fixed point in terms of speed. Such as roadside stop speed car use mobile velocimeter, holding a speedometer, etc., through the machine was carried out on the vehicle speed detection, doppler radar can free mediation direction, can be taken from different directions of speeding vehicles. In other words, the license plate can be taken as well as the license plate, but the difference is that the station is in a different direction than the speed meter. In practice, mostly to take license after the shooting method, if using the method of pre-sale license plate when the vehicle is more, may not capture the real speed, for each moving vehicle easy blocking speeding vehicle plate. There are some equipment professional doppler radar system, through the built-in radar tube, receiving speed measuring radar wave signal in advance, can undertake early warning, such as road traffic e Ev5 radar edition, by GPS navigation and machine combination of doppler radar, at the same time of GPS voice navigation, can carry on the early warning to the fixed and flow speed. Is the new way of multi-function of speed. There are several kinds of monitoring methods used in traffic regulation Across our country more wide road, the traffic administrative department of the city when purchasing products also have diversity, on the one hand, is closely connected with performance of the device itself, also with the equipment cost, around the country roads, traffic regulation policy have close relations, the current domestic common regulatory products are the following: The surface embedded induction coil (or sensor bar) This method is more classic, the detection effect is also good. Such as the south of China, such as Shanghai, guangdong etc. Judge the speed of the vehicle by the speed of the parallel coils. The disadvantage is that the test method is that the ground embedding construction of induction coil, road once changes need to be heavy buried coil, other walden high latitudes and low latitudes summer road and the road surface quality is bad place to coil maintenance work is huge. We have the video test This method, by analyzing the continuous video image, tracks the behavior of the vehicle, and then analyzes and controls the photo for the illegal capture. The advantage of this system is not restricted by the road, the installation does not need to be tearing up the road, induction coil, or buried under the road, through set up cameras to detect above the road traffic data, is the new generation of road vehicle detection method. The downside of video is the difficulty of identifying mobile vehicles. On the one hand, you need to have a fast enough shutter (at least 1/3000px) for high-speed moving vehicles and a sufficient number of pixels and image algorithms. At intersections, on the other hand, crossing and highway import and export, the vehicle's speed is generally slow, see more illegal behavior is running a red light, and lines of lane and wrong choice, etc., they don't need a radar with high speed camera, the slower shutter can achieve monitoring. In addition, video technology is affected by light and weather. Radar microwave radar As mentioned above, the distinction is measured by the video test, which is usually multilane, and has the complexity of multi-vehicle and multi-pedestrian. Single use of doppler effect of microwave radar to detect the same intersection peccancy vehicles has bigger difficulties, for the faster, the direction of a single highway, microwave radar is currently the best partner with high-speed cameras, high-speed cameras received microwave radar detected by high-speed mobile vehicles, quickly enter a state of rapid capture, cooperate with fast shutter speed in illegal evidence collection. The main international product is the radar co-operating with a high-speed camera. Ultrasonic testing, The principle of ultrasonic ranging is used mainly. Ultrasonic sensing head is used for a maximum of several weeks in this dusty, dusty environment, so the testing method does not apply. Infrared detection and laser detection Infrared and laser detection have something like that, because the laser is a little bit of measuring behavior, theoretically possible and the detection process is pretty high, But compared with microwave radar, also face crossroads, roads, vehicles, pedestrians many, the influence of measuring efficiency cannot be full regulatory requirements, the most important thing is: the laser detection of laser beam on the human body is mainly the human eye damage is in particularly serious problem. In Europe and the United States and other countries and with laser guns traffic speed measuring instrument, its performance indicators should not only meet international safety standards, at the same time in use must be artificial manipulation, in order to avoid people eye damage. In Japan is strictly prohibited to use laser detection equipment, so the laser detection is good in theory, but currently in the process of using security issues are still unresolved. The common webcam is built in a way and how it works Actually camera driver ran a red light at an intersection can through many kinds of technical implementation, and in this respect there is no uniform standard and methods, depends entirely on the bid of construction unit. Typically, a camera can be triggered by a radar, a sensor coil that triggers a photo or image recognition of the way to trigger a photo. When using radar to trigger a photo, when the red light is on, a radar area is formed in front of the stop line, and when the car passes, the electronic shutter is activated. Radar speed detector is likely to work at this moment, in the induction coil, when you take a photo in road construction, buried under the road have induction coil, when cars running red lights, induction coil car start electronic shutter release. When using image recognition technology, is alert area with white line on the ground, when the red light vehicles, obscured white line on the ground, trigger camera, because technology is different, so there is no any kind of device can forecast through a red light take photos. Unlike the radar laser technology, the radar speed detector can fully predict the speed detection. In the domestic one of the most common radar speed cameras are usually installed on the highway, the top of the loop, called single radar speed measuring system often desire to detect road above erect a radar detector, formed on the road ahead in the distance radar a warning zone 5 meters long and 1.6 metres wide, in order to reduce false positives (usually require system false alarm rate is less than 5%), so the power of radar will not too big, lest produce false positives. Depending on the conditions of the vehicle on the road at the time, the radar speed detector would have a different warning range. Handheld radar characteristic is cheap, strong flexibility, can move the operation, so the handheld radar speed measuring device is the most commonly used police equipment. Effective speed according to different transmission power distance between 300-800 meters, but due to the handheld radar speed measuring device using the fuzzy aim, so according to different road traffic condition, the police will not far away in the distance speed, on the highway, usually in the range of 150-300 - m speed, the intercity highway, highway speed range in 100-200 meters. If the police don't have radar signals, the radar speed detector won't call the police. Vehicular radar speed photograph system, can be all-weather work, convenient operation can work more comfortable, more and more wide range of equipment to troops and high-speed road management organizations. In order to improve the accuracy of the capture, the radar will form a warning zone about 100 meters ahead of the radar so that the speeding driver can take a picture. So users should pay attention to using radar speed detector, when driving in the open field to receive alarm (e.g., national highway, the loop line and highway), and 90% are radar speed. There are two broad categories of radar speed use: fixed and handheld, which usually combine with the camera to form a capture system. Fixed in the use of detection waves will continue to produce, but due to the requirements of the camera and avoid false positives, the trigger area will be very close, usually at around 30 meters, but that doesn't mean detection wave only 30 meters, because of the ground, speed detecting receives the radio waves will go farther in the distance and provide an alarm. For hand-held radars, there is no continuous detection of radio waves, and only when the push button is held to detect the radio waves, while the handheld radar USES a blur of aim, So it takes more time. First principle is the detector receives waves, then LeiDaCai reflected, receives the radio waves and start calculating speed, but need to receive the eight consecutive doppler radar reflected signal to calculate the speed, so the speed and adjust speed have been found in you can avoid fines. Generally think that the radar velocity detector sensitivity, the higher the better, but the assessment index of radar speed detector in addition to sensitivity, and assessment of radar velocity detector of false positives. Because there are so many electrical signals around us, the increase in the number of false positives increases with sensitivity. Pure driving on the highway still good, once in the City is nervous, everywhere, and the edge of the warning is a fuzzy concept, so use City mode will become complicated. Is not, therefore, the sensitivity is higher, the better, it is important to provide enough warning distance, according to the practical use in the range of 100-400 meters can satisfy the use requirement, 100 kilometers from deceleration slowed to usually need to 60 meters distance, do not need to slow down while speeding to 0, as long as there is a few seconds to slow down to normal levels is enough so drivers also need to constantly improve skills.