The electronic dog in the car navigation or mobile navigation can detect various radar probes on the road, can distinguish the radar measurement violation or the measurement overspeed, and know the speed limit. What is the working principle?
In general, there are two types of electronic dogs that are commonly found on the market today:
First, the "fixed speed measurement" of the electronic dog
In advance, the staff will bring the GPS positioning machine to collect the coordinate points of the fixed electronic eye nationwide, and then make the electronic dog data and input it into the electronic dog machine. The electronic dog itself has a GPS positioning chip that calculates the speed and direction of the car. Alerts are issued in advance when the vehicle travels to a fixed point. If you speed, the electronic dog will broadcast a voice "You have already speeded."
Second, the electronic dog's "mobile speed"
If you drive a car, you may encounter a speed camera that is temporarily set by the traffic police. Such a temporarily placed device is not marked in the electronic dog data. This requires the built-in chip of the electronic dog to be monitored.
When the electronic dog receives the radar signal transmitted by the "speed measuring camera temporarily set by the traffic police", it immediately alarms to prompt the owner to decelerate. To determine whether the electronic dog's mobile speed measurement is accurate, the most important thing is to look at the built-in chip of the electronic dog.
Third, the principle of electronic dog
1. Ordinary electronic dog (early) The so-called electronic police early warning machine is actually not an early warning. It is only a wireless signal receiver. It is simpler than the principle and cost of the radio. The manufacturer of the electronic dog has hidden a radio transmitter in the place with electronic eyes and fixed speed. It sends a radio signal containing the information code according to the characteristics of the route. The car is near here and the receiver receives the transmitter. The radio signal decodes the alarm type, and the sounding chip emits a voice alarm. The speed limit of the road section is such that there is an electronic eye at the intersection. In fact, the floor-mounted S-coil does not generate a signal (some electronic experts in the jar think that the electronic dog may detect the oscillating signal from the S-coil, which is actually too high to look at the "dog"). Usually the manufacturer will pre-empt the transmitter. It is buried 300 to 1000 meters before the fixed camera. As long as the voice type early warning machine is installed on the vehicle passing through the road section, it can receive the warning signal.
The advantages of an electronic dog are simply low cost, and its shortcomings are outstanding:
(1) The signal transmitter will signal regardless of whether the camera is actually working, and it is a false alarm for the driver.
(2) If all the traffic lights are equipped with electronic eyes, the electronic dog will not stop, not only lose the meaning of the alarm, but also very noisy.
(3) Due to changes in roads and fierce commercial competition, manufacturers destroy each other's transmitters, or the transmitter battery is exhausted. The AWACS will not generate an alarm at all, which will cause huge losses to consumers, so be careful of this. Class goods.
(4) The use of radio frequency in China also needs to be approved by the non-commissioned committee, but the P-frequency is not submitted for approval, so it will be detected by the non-commissioned detection vehicle and can be banned or interfered at any time.
(5) The electronic dog cannot distinguish the direction. If there is an electronic eye in the opposite lane or the cross lane, it will also be falsely reported.
2, radar detector
The principle of the radar detector is very simple, that is, after receiving the radar signal, immediately alarm, prompting the owner to slow down. Its price is generally between 800 yuan and 2,000 yuan, and the performance is very different. The biggest difference is that the frequency bands of radar waves that can be sensed are different. Because the radar speed measuring devices of various urban roads in China are imported from different countries, the radar frequencies used are mostly different. Some radars in different frequency bands of three or four countries in the same city are installed. Low-end radar detectors can only sense radar waves in one frequency band, while high-end radar detectors can sense radar waves in multiple frequency bands. In addition, the proximity of the sensing distance also reflects the performance of the radar detector. If the sensing distance is too close, the owner has not been able to slow down and has already been photographed; if the speed is too slow, it is easy to cause a rear-end collision. High-end radar detectors can sense radar waves about a kilometer away, and the difference can only be sensed at around 200 meters.
The current common speed radar warning devices are as follows:
(1) Single frequency speed radar warning device. That is, only the X-band or K-band can be received. Such devices can only be used in some monitoring devices in some areas, with more false negatives, low cost, and low price;
(2) Multi-band speed radar warning device. Generally, the X, K, and Ka frequency bands can only be applied to some areas, and can deal with several police devices;
(3) Full frequency speed radar warning device. Can receive all frequency bands, such as X frequency, K frequency (commonly known as tripod), Ku frequency, new K frequency, Ka frequency, LASER laser, Ka-Laser, P frequency, etc. These speed-measuring radar warning devices are effective all over the country and are particularly sensitive at high speeds, generally forecasting 500 meters to 2 kilometers in advance. However, the interference in the urban area is also large, and the alarm will also be given when the electronic automatic door is passed.
3, GPS radar detector
This type of device adds a GPS positioning warning system based on the full-frequency radar. The principle is based on the latitude and longitude data that is pre-stored with a fixed speed point or a red light, and is located by GPS. When the distance is close to the target point, the alarm is triggered. GPS radar detectors can not only do speed radar warnings, but also do traffic light electronic eye warnings; whether the electronic eye monitoring method uses radar waves, lasers, or ground induction coils, GPS radar detectors can alarm. Compared with the electronic dog, the electronic dog system has to steal a transmitter every time an electronic eye is added to the traffic control department. The GPS radar detector only needs to add a landmark to the Internet for downloading and updating, and the cost is low and the response is fast. Compared with the radar detector and the electronic dog system, the GPS radar detector can also discriminate the direction of the electronic eye, such as the electronic eye in the opposite direction or the cross direction, it will not alarm.
In addition, the GPS radar detector can also set the alarm advance amount, such as 300 meters or 500 meters; if the car is not overspeed at that time, it can not alarm, eliminating the annoyance. In addition, regardless of whether there is an electronic eye, the GPS smart dog can remind the owner of the speed limit of the section, and now it is speeding.
Electronic dog burglar alarm circuit diagram and working principle
And to determine whether the electronic dog speed is accurate, the most important thing is to look at the electronic dog data. Regarding the electronic dog data, pay attention to the following questions when purchasing an electronic dog.
Question 1, is the electronic dog data comprehensive?
At present, the best electronic dog data made in China is the DSA data, Kay LiDE and Gao De. Car owners need to pay attention to the fact that the domestic electronic dog brand is very numerous, but many small manufacturers do not have the ability to collect fixed electronic eye data across the country. In order to save costs, these small manufacturers will use the cracked version of the big brands. However, this cracked version of the data is often not comprehensive, and the cracked version of the data upgrade is very troublesome.
Question 2, is it convenient to upgrade the electronic dog data?
It is very common to re-plan and construct traffic roads across the country or to rebuild new roads. This requires electronic dog data to be constantly upgraded. Some big brands of electronic dog data can be updated once a week. But if you buy a cottage electronic dog, it is very troublesome to update the electronic dog data.
Question 3, about "Cloud Electronic Dog"
Cloud electronic dog has appeared in the last two years, can achieve electronic dog data update, the first time to update the latest data to the electronic dog. When upgrading, it takes 1-2 minutes. If you buy a cloud electronic dog, there will be a SIM flow card in the package. Generally, this SIM card is free of charge for three years.
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Zhejiang Kaimin Electric Co., Ltd. , http://www.ckmineinverter.com