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gps speedometer with tachometer 2 in 1
At present, the vast majority of car owners have installed GPS navigation devices on their beloved cars, or their cars come with navigation equipment, which brings great convenience to travel. But the speed on the GPS navigator and the display on the speedometer are not the same, why is this? Firstly, it is necessary for us to understand the working principles of GPS speed measurement and speedometer. After receiving radio waves from more than 4 or more satellites, the GPS terminal can determine the position of the vehicle, calculate the distance traveled through the changes in position in a very short period of time, and thus obtain the driving speed; The signal of the speedometer comes from the speed sensor on the transmission or output shaft, which is synchronized with the speed of the wheels. After processing, the signal is sent to the stepper motor pointed by the control pointer in the speedometer, thereby displaying the current vehicle speed to the user. From the principle of the speedometer, it can be known that there are two main reasons for the difference between the speedometer and the actual vehicle speed. The tire pressure of the car is insufficient or the radius gradually decreases due to wear and tear during use. The signal of the speedometer is synchronized with the wheel speed, and it is not known that the wheel radius has changed. Therefore, at the same actual speed, the speed indicated by the speedometer is higher than in the past.
Tachometer and tachometer:
1. The speedometer reflects how much distance the vehicle has traveled per hour, and the tachometer reflects how many revolutions the engine has made per minute;
2. The speedometer refers to a vehicle's driving speed generally ranging from 0-300km/h;
3. The tachometer refers to the engine speed, which is generally 0-8000r/min;
4. The higher the engine speed, the faster the vehicle speed may not necessarily be. For example, when the transmission is in first gear at 2000 rpm, the vehicle speed may be 15km/h. When the transmission is in second gear, the vehicle speed may be 25km/h. When the transmission is in third gear, the vehicle speed may be 40km/h. It's different, one refers to the vehicle speed and the other refers to the engine speed. A tachometer is one of the essential instruments in the mechanical industry, used to measure the speed, linear speed, or frequency of a motor. Commonly used in manufacturing industries such as motors, fans, paper, plastics, chemical fibers, washing machines, automobiles, airplanes, ships, etc. Most commonly used are handheld centrifugal tachometers. Tachometer measurement is essential in various fields of the national economy.The tachometer is the engine speed, and the speedometer refers to the current speed per hour. The tachometer will process the received digital pulse signal (sent out by the sensor) and directly read it into the counting port of the CPU. The software will calculate the speed and the corresponding position of the pointer, and then amplify it through the control port of the CPU to drive the stepper motor to rotate in the positive and negative directions, indicating the corresponding speed value (the pointer is directly installed on the rotation axis of the stepper motor). The stepper motor only takes 1/3 degrees to step.
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