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how accurate is gps speedometer
The positioning accuracy of the GPS civil system is within 10 meters, the positioning accuracy of the Beidou satellite is 10 meters, and the speed measurement accuracy is 0.2 meters / second. Precision reflects the influence degree of random error in the measurement results, and it is the degree that the measured values obtained by continuous repeated measurements are close to each other under certain conditions. If the random error is small, the precision is high.
The signal quality of Beidou system is generally equivalent to that of GPS. In the middle and low latitudes within 45 degrees, the dynamic positioning accuracy of Beidou is equivalent to that of GPS, and the horizontal and elevation directions can reach about 10 meters and 20 meters respectively.The horizontal accuracy of Beidou static positioning is meter level, which is also equivalent to GPS. The elevation direction is about 10 meters, which is slightly worse than GPS. In the middle and high latitudes, due to the small number of visible satellites in Beidou, the satellite distribution is poor, and the positioning accuracy is poor or unable to locate. The horizontal accuracy of the Beidou dynamic PPP at cut0 station converges to 0.40 m in about 50 minutes, and the RMS in the neu direction after convergence is 0.150, 0.125 and 0.200 m respectively. The horizontal accuracy of Beidou dynamic PPP based on the clock difference obtained by the fusion solution model is about 0.15 m, and the elevation accuracy is about 0, 20 m. The horizontal accuracy of Beidou dynamic PPP is about 0.10 m and the elevation accuracy is about 0.20 m using the post event multi GNSS precision track clock difference (GBM) provided by GFZ.
For example: the navigation obtains our location information every 0.1s, and then according to the distance difference between the two location information, for example, 2m, it can calculate that you have moved 20m in 1 s, which is 72km / h. So as long as the mobile phone signal is normal and can be connected to GPS or Beidou satellite, the calculated speed per hour is more accurate. It shows that there is an error in the speed itself. Some models are even more inaccurate. The speedometer is different. There is an error in the speedometer itself of some models.The speedometer shows 120km/h, the actual speed will be between 120 and 104km/h, and the actual speed will be between 60 and 50. That is to say: when some models leave the factory, the speedometer may not be accurate. Some friends may joke that this is called a "happiness meter". Moreover, the speed measurement principle varies according to different models, and the error size is not certain.
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