Factors that may cause inaccurate GPS module positioning

Positioning and navigation, this function is used more or less whether it is driving or walking, but the cost of inaccurate positioning is very annoying, and it will always consume more time and energy. We can't help but ask: GPS Is the module not done well? Why is the performance so poor?

　　The operation of the GPS positioning module needs to receive signals from navigation satellites, which are processed and fed back to the vehicle navigation. This process is operated by the equipment itself, and personnel cannot participate in it, so it is not clear about the problem of inaccurate positioning.

               (Beitian GPS module BN-880)

　　First of all, the positioning data information can be obtained only after the GPS positioning module is started. This process of starting is called cold start. In fact, it is the process of running GPS in an unfamiliar environment until the GPS communicates with the surrounding communication satellites and calculates the coordinates, including the first use. , When the ephemeris information is lost due to battery exhaustion, move the receiver to a distance of more than 1,000 kilometers when it is turned off.

　　Cold start is a mandatory start by hardware, which is equivalent to the preparation time to enter the state. If the cold start time is too long, it is easy to cause the problem of slow positioning of the navigation bar. To a certain extent, it can be said that the length directly affects the time to capture positioning satellite signals length.

　　In addition to cold start, there is also hot start, which means that the GPS module is started without too much displacement in the area that was previously shut down. In fact, it is a pure hardware hot start time, usually within 1 second. In addition, there is a pure hardware recapture time. All are less than 1 second.

　　The power-on time directly affects the power efficiency of the GPS positioning module to capture signals, and these parameters need to be paid attention to.

      Secondly, the strength of positioning and navigation capabilities is also related to positioning and communication satellites. Following the principle of solving problems found, let’s check the main parameters of the positioning module first.

                                            (Beitian Beitian GPS module BN-880 )

1: Satellite error

　　The GPS module is only responsible for the receiving role in the positioning of the navigation bar. The positioning of the navigation satellite is the root cause of the problem of inaccurate positioning. It is very likely that one of the reasons is the error of the received signal, that is, the satellite error. This cannot be solved. Yes, you can try to change the location and time point to reposition;

　　Two: Propagation Error

　　Positioning and navigation signals are transmitted from satellites to receiving signals, and they need to span the distance in time and space. There are some high-level delays, tropospheric delays, multi-path errors, and relativistic effect errors. Various factors cannot be attributed to the performance of the GPS positioning module itself. Difference;

　　Three: Signal reception error

　　The environment of signal reception also affects the positioning accuracy. Noise, delay, wireless phase center error, etc. will affect signal reception. You can check whether the antenna is in good contact and whether the environment it belongs to is relatively wide, and then obtain positioning information again.

　　4. Accuracy of positioning module

　　Accuracy includes horizontal positioning accuracy, altitude positioning accuracy, speed positioning accuracy and other azimuth accuracy. It can meet the navigation requirements without excessive pursuit of high precision. You must know that even Beidou and GPS navigation systems have errors.

　　5. Sensitivity

　　It mainly refers to the cold start sensitivity and tracking sensitivity, which respectively represent the minimum transmit power of the satellite signal that can find the star after the cold start, and the minimum signal strength of the GPS signal that can navigate after the satellite signal is captured. The cold start sensitivity needs to be -148dBm Within, the tracking sensitivity is within -166dBm.

　　Generally speaking, most of the GPS modules currently on the market are civilian products, which are sufficient to meet the needs of daily navigation and positioning.