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how accurate is waze speedometer
Let's first look at how the speedometer measures speed. Usually there is a sensor on each tire of the car, the sensor can detect the rotational speed of the tire, and the speedometer can use the rotational speed detected by the sensor to obtain the speed of the car. Of course, there are also some cars that use the gear speed and tire dynamic radius of the sensor on the manual transmission to measure the speed. However, due to the different materials of the sensor and speedometer, incorrect installation, low performance of the car or excessive wear and tear of the tires, the speedometer and the actual speed of the vehicle will not match.
In comparison, the vehicle speed calculated by the GPS locator is more accurate. The speed measurement method of the GPS tracker is to calculate the current speed of the car based on the distance traveled by the car every 5-10 seconds. The calculation method is relatively accurate, and the result will naturally be close to the actual speed. However, the calculation results of the GPS locator are not 100% correct. The actual work of the GPS locator depends on the satellite signal. When the satellite signal is poor or the satellite signal is interfered, it will affect the vehicle speed calculation of the GPS locator. It is very simple to understand. When the GPS locator produces an error, the error range can reach more than 20 meters. When the calculation interval remains unchanged, the error becomes larger, and the distance traveled by the GPS locator will increase accordingly. , then the measured speed will be faster than the actual speed, and the result will not be very accurate. Therefore, the car speed determined by the GPS locator is relatively accurate, but errors will occur when the satellite signal is not good.
When the displayed speed is 120 km/h, the actual speed is about 105.5~120 km/h. Car manufacturers will make different adjustments according to different models. But generally speaking, the higher the car, the smaller the error, and the lower the car, the more unstable the error. Now that more and more cars use digital dashboards, the error value is actually shrinking and relatively stable. In fact, when driving on the expressway, as long as the displayed speed is not greater than 130 km/h, it will not be recorded as speeding. Some people may worry about a question here: Since the speedometer of the car is inaccurate, is the odometer of the car also inaccurate? For example, the displayed mileage is 100,000 kilometers, but in fact only 90,000 kilometers have been run? In addition, the speed of the current car is a very important signal. Many systems need it as the main signal source to control the operation of the system, such as automatic transmission shift, ESP start, airbag detonation, fuel consumption calculation, etc. wait.
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