What is GPS module

What is GPS module

The GPS module is a GPS signal receiver, which can only pass the GPS signal received by the serial port to the GPS software in a computer or mobile phone for processing. We often say that the GPS positioning module is called the user part. It receives and demodulates the broadcast C/A code signals from satellites like a radio and records the relevant position, speed and time information, etc. The GPS module does not send a signal and is a passive positioning.

The protocols of all GPS modules on the market are NMEA.

The GPS module uses the distance rendezvous method to find out the receiver's derived longitude, latitude, altitude and time correction amount of these four parameters by computing the pseudo distance with each satellite. It is characterized by the fast point speed, but the error is large. The first positioning module requires at least 4 satellites to participate in calculations. It is called 3D positioning. 3 satellites can achieve 2D positioning, but the accuracy is not good. The GPS module continuously outputs the positioning information and auxiliary information in NMEA format through the serial communication port for the receiver to select the application.

(GPS02-TD)

GPS module positioning principle

The 24 GPS satellites run around the earth at a high altitude of 12,000 kilometers above the ground with a 12 -hour cycle, making it possible to observe more than 4 satellites simultaneously at any point on the ground at any given moment.

Due to the accurate position of the satellite, in the GPS observation, the distance from the satellite to the receiver uses the distance formula in the three -dimensional coordinates, and the three satellites can be used to form three equations to solve the position of the observation point (X,Y, Z). Considering the error between the clock of the satellite and the receiver’s clock, there are actually 4 unknowns, X, Y, Z, and clock difference, so you need to introduce the fourth satellite to form 4 squares for solving, so as to obtain the observation point of the observation point levels and heights.

In fact, the receiver can often lock more than 4 satellites. At this time, the receiver can be distributed in several groups according to the satellite constellation, and then the group with the smallest error is selected by the algorithm to be used for positioning, thus improving the accuracy.

Due to the errors of satellite orbit and satellite clocks, and the influence of atmospheric troposphere and ionosphere on the signal, making the positioning accuracy of civil GPS only 10 meters. In order to improve the positioning accuracy, the differential GPS (DGPS) technology is generally used to establish a reference station (differential platform) for GPS observation, and the accurate coordinates of the known benchmark stations are used to compare the observation values to obtain a correction number and release it outside the outside world. Essence After receiving the correction number, the receiver compares it with its own observation value, eliminates most of the errors, and obtains a more accurate position. Experiments show that the positioning accuracy can be increased to 5 meters by using differential GPS.

Application of GPS module

The GPS module is mainly used in the combination of smart transportation and smart city for positioning tracking and vehicle information services, urban public asset management, logistics tracking management, accurate positioning in agriculture, geological disaster monitoring and meteorological monitoring.

Briefly introduce the application of GPS module in logistics tracking management:

In the traditional logistics process, due to the lack of relevant information acquisition and communication, it is often possible to make full use of transportation resources. The GPS module can monitor the location of the vehicle, facilitate the dispatch management center to master the real -time transportation progress of the cargo, and share the current location information through the network method, facilitate the owner to inquire, grasp the time of the goods, and prepare for the receipt. In addition, if there is a driving failure and blocked traffic during transportation, you can quickly learn about the incident through the GPS module and dispatch the nearest vehicle from the accident point for rescue to ensure that the transportation progress is not affected. Using the GPS module can also help build a reasonable driving route and save transportation costs. By monitoring vehicle lines, it can prevent the occurrence of theft and plundering incidents and ensure the safety of vehicles, goods or drivers.

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