How to judge the position where the camera on the expressway measures the overspeed? In addition, is the radar speed measurement on the national highway unidirectional or bidirectional?

Both fixed and mobile speedometers emit a radar wave. The forward speed of the vehicle is reflected to the receiver, and the computer calculates the moving speed of the object (vehicle). If it reaches the set value, start the high-speed camera to take pictures, usually 3-5, and choose the clearest one as the evidence of speeding. The velocity measurement on the national highway is unilateral. If there are two sets, both sides can measure the speed.

The electronic police used by the original traffic control department in China can be roughly divided into:

(1), fix the red light electronic eye;

(2) Constant speed electronic eye;

(3) illegal photography of electronic eyes;

(4) Fixed monitoring electronic eye;

(5) Mobile electronic eye for speed measurement (including mobile tripod type and mobile police car type)

Among them, the principles of (2) and (5) electronic eyes are basically radar-type speed measuring electronic eyes, (1) and (3) electronic eyes are basically wire-pressing electronic eyes, and (4) electronic eyes only have the function of taking pictures.

Because there are fixed and mobile electronic eyes, it is difficult for an electronic dog with a single working principle to have an electronic eye that can warn all kinds, and it needs to be combined and matched to realize a comprehensive alarm. Now briefly introduce the functions and principles of various electronic dogs sold in the market:

At present, navigators and electronic dogs can be roughly divided into three categories:

One: GPS data type+radar type complete set

Principle: GPS data type and radar receiving type are combined to realize comprehensive alarm.

Function: It can fully warn five kinds of electronic eyes, suitable for use anywhere in China.

Advantages: wide application range, both fixed and mobile electronic eyes can give an alarm.

Disadvantages: The newly installed (1)(3)(4) electronic eyes need to be updated online before warning, and some split machines need to be installed.

This kind of goods, mainly the function of electronic dogs, prevent speeding and avoid fines. At present, it is mainly an all-in-one machine, which is suitable for users who often overspeed and get more tickets.

Two kinds: GPS navigator +GPS data electronic dog integrated machine.

Principle: compile the collected fixed electronic eye coordinate data into GPS navigation map data to realize the navigation electronic dog integrated machine;

Function: Early warning can be given to fixed electronic eyes nationwide.

Advantages: the data processing speed is fast, the GPS signal is strong, and the fixed-point position can be displayed on the map, which is convenient for the driver to identify. Road speed limit and speed measurement through electronic eyes can also give voice alarm.

Disadvantages: you can't report mobile electronic eyes.

This kind of goods, mainly navigation function, is suitable for users who often run long distances and are not familiar with the road.

Three categories: GPS navigator +GPS data electronic dog+radar electronic dog complete set.

Principle: The fixed electronic eye coordinate data is compiled into a GPS navigation map, and the radar receiving front end is installed under the front engine and connected with the battery. The front end of the radar is wirelessly connected with the GPS host in the car, and the host sends out voice warning.

Function: truly combine navigation with electronic dog. Realize the navigation electronic eye integrated machine. Applicable to all regions of the country.

Advantages: the early warning is comprehensive, and it can alarm the fixed flow and the inter-road speed and traffic speed in time. The integrated complete set of machines saves the trouble of many lines in the car and complicated alarms of various machines.

This kind of goods not only have the functions of electronic dog, speeding prevention and fine exemption, but also have the functions of GPS navigation, such as MP4 and MP3. Now it is a mainstream product with low price and good cost performance.

In fact, K, Ku and X are radar frequency bands used by speed-measuring radar and are also defined by radio frequency. Attached below is a frequency comparison table:

X-band:10.500-10.ghz9.850-9.950ghz.

K-band: 24.050-24.250 GHz

Frequency band: 33.400-36.000GHz

Ku band: 13.450- 13.500GHz

Many people misunderstand that radar detector is illegal, but in fact, radar detector is only an instrument to detect radar waves and prompts, and will not interfere with the normal work of any speed measuring system. Its main function is to remind drivers that the speed measuring area is ahead, so please control the speed.

At present, the moving speed of police cars on the road is K-band and Band.