First of all, it is necessary to understand the working principle of the car locator device and the speedometer respectively. After receiving radio waves from more than four or more satellites, the GPS terminal can determine the position of the vehicle, and calculate the driving distance through the change of the position in a very short time, so as to obtain the driving speed. The speedometer's signal comes from a speed sensor on the transmission or output shaft, which is synchronized with the speed of the wheels. After the signal is processed, it is sent to the stepper motor pointed by the control pointer in the speedometer, which shows the current speed to the user.

Through the principle of the speedometer, we can know that there are two main reasons for the difference between the speedometer and the actual speed:

1. The tire pressure of the car tire is insufficient or its radius is gradually reduced due to wear during use. The speedometer signal is synchronized with the wheel speed and does not know that the wheel radius has changed. Therefore, under the same actual speed, the speed indicator is higher than in the past.

2. The stepper motor in the speedometer is faulty, and there is a phenomenon of losing step.

Compared with the speedometer, the car locator device has fewer interference factors, and its accuracy and stability are more guaranteed, but it is slightly delayed. In fact, the speedometer speed is often slightly higher than the GPS speed, because the national standard "motor vehicle operation safety Technical conditions" (GB7258-2004), 4.12 specifies the range of speedometer indication error (unit: KM/H) : 0 ≤ (indicated speed - actual speed) ≤ (actual speed /10 + 4). Therefore, as long as it is a qualified speedometer, the displayed speed will not be lower than the actual speed; And as the tires wear out, the apparent speed gets higher and higher compared to the actual speed.

Reminder: Some owners have a certain misunderstanding of the regulations, thinking that the speedometer indicates that the actual speed is 60KM/h when 70KM/h; When the speedometer speed is higher than 70KM/h, you can exceed the speed limit by 10KM/h without worrying about being fined during speed measurement. This is only the standard upper limit, there may be little difference between the speedometer and the actual speed, pay attention to not speeding.

When your speedometer differs greatly from the GPS speed, you should use another GPS device to confirm that the speedometer is indeed incorrect; If the speedometer is wrong, the tire pressure should be checked first, and when the tire pressure is normal, it is necessary to check and repair at the franchise shop.

car locator device https://www.eelinktracker.com/GPS-Tracker-for-Car/