Before understanding the working principle of a GPS locator, first understand what a GPS locator is?
Simply put, a GPS tracker is a built-in terminal called "GPS module" and "mobile communication module". The positioning data obtained by the GPS module is transmitted to the website through the mobile communication module (GSM/GPRS network). A server can be realized in the computer to check the geographical position of the terminal.
So how does its principle work? Now Henderson Keda will talk about it:
The main task of the GPS signal receiver is to capture the signals of the satellites to be measured selected according to a certain satellite altitude cut-off angle, and then track the operating conditions of these satellite signals, and amplify, transform and process the received signals. In order to measure the propagation time of the GPS signal from the satellite to the receiver antenna, interpret the navigation message sent by the GPS satellite, and calculate the three-dimensional position, position, and even three-dimensional speed and time of the station in real time. When in static positioning, the GPS receiver is fixed in the process of capturing and tracking GPS satellites. The receiver measures the propagation time of GPS signals with high precision, and uses the known position of GPS satellites in orbit to calculate where the receiver antenna is. The three-dimensional coordinates of the location. The dynamic positioning is to use a GPS receiver to determine the trajectory of a moving object. The moving object where the GPS signal receiver is located is called a carrier (such as a ship in flight, an airplane in the sky, a walking vehicle, etc.).
The GPS receiver antenna on the carrier moves relative to the earth in the process of tracking GPS satellites. The receiver uses GPS signals to measure the state parameters (instant three-dimensional position and three-dimensional velocity) of the moving carrier in real time. The receiver hardware, internal software and GPS data post-processing software package constitute a complete GPS user equipment. The structure of GPS receiver is divided into two parts: antenna unit and receiving unit. For geodetic receivers, the two units are generally divided into two independent parts. The antenna unit is placed on the measuring station during observation, and the receiving unit is placed in a suitable place near the measuring station, and the two are connected by a cable. A complete machine. Some also make the antenna unit and the receiving unit as a whole, and place it on the measuring site during observation.
GPS receivers generally use batteries as power sources. Both internal and external DC power supplies are used at the same time. The purpose of setting the internal battery is to keep continuous observation when changing the external battery. In the process of using the external battery, the internal battery is automatically charged. After shutting down, the internal battery provides power to the RAM memory to prevent data loss. In recent years, many types of GPS geodetic receivers have been introduced in China. When various types of GPS geodetic receivers are used for precise relative positioning, the accuracy of the dual-frequency receiver can reach 5mm+1PPM.D, and the accuracy of the single-frequency receiver can reach 10mm+2PPM.D within a certain distance. For differential positioning, the accuracy can reach sub-meter to centimeter level.