gps speedometer with tachometer

• 2022-04-24

Generally, the speedometer of a car has an error of 8%, which is allowed by law, that is, the speed on the speedometer is generally about 8% faster than the normal speed, so the speed of the speedometer is not the actual speed. Of course, the speed display of GPS is calculated by the distance between points, which is relatively accurate, but it has a certain lag. That is, your current speed is actually the speed of the last time point, generally with a time difference of half a second to one second.

Generally speaking, the speed of the car code meter is accurate. The error of GPS is relatively large through signal transmission, while the error of the code meter is small through wheel speed calculation. He said the speedometer is more accurate than GPS. Because GPS has some problems such as signal delay, but the speedometer is calculated according to the wheel circumference and axle speed, so it is much more accurate.

Positioning only uses GPS signal, so GPS receiver does not need network and navigator does not need it. What needs the network is the auxiliary positioning through the base station, which is more accurate, and the base map and so on.

The tachometer measures the engine speed. The unit is rpm. The speedometer measures the real-time speed of the car. The unit is kilometers per hour. The engine speed is high, and the vehicle speed is not necessarily fast. For example, in the first gear, the engine speed is 2000 rpm, and the vehicle speed may be only 15 km / h; When the transmission is in second gear, the speed may be 25 km / h; In third gear, the speed may be 40 km / h. The unit of the speedometer on the car is km / h, which is the driving speed per hour. 100 yards is 100 kilometers per hour.

It is normal that the mileage displayed by GPS recorder is different from that displayed by car odometer. 1. The GPS recorder records the driving path and calculates the straight-line distance between two points according to the longitude and latitude of each positioning. The actual driving is much more complex than positioning. 2. The automobile odometer calculates the mileage according to the diameter of the wheel and the number of turns of the wheel. There is basically no error in the actual mileage, which is very accurate. 3. The difference between the two calculation methods will cause the kilometers of GPS recorder to be less than that of automobile odometer. The longer the positioning interval, the greater the error 4. The actual mileage should be subject to the mileage displayed by the car odometer, because the fuel consumption, parts wear and oil loss of the car are related to this value, which is far from the straight-line distance calculation method of GPS recorder.