In the design of GPS antenna unit, high frequency and low noise amplifier are adopted to reduce the influence of the thermal noise of GPS antennas and the circuit of the first few units on the performance of the receiver. In GPS antenna using GPS satellite navigation and positioning principle, the user is to extract the main task of the satellite signal receiver of pseudorandom noise code and data code, to get the position of the receiver carrier, further calculating speed and time (PVT), and other navigation information. Therefore, GPS receivers are critical user devices. We often say the navigation map is, in fact, including the software and the navigation map navigation to Desmond tutu, the graph information is a specific geographical location characteristics and rich POI point of interest, and run software navigation map is carrying navigation tutu, and its effective operation show before the 1st of the software. Interest Point: the Point of interest is the Point of interest, which is the information that is included by the map manufacturer. In order to make it easier for the car friend to find the corresponding destination, such as the restaurant, the building, etc.
The practical application of GPS receiver circuit generally the rf unit, communication unit, the antenna of four parts, such as settlement calculate units in this paper, based on the analysis of GPS satellite signal, the principle and application of rf front-end GP2010 is given.
The integrated GPS satellite signals of GPS satellite signals are synthesized by typical code division multiple access (CDMA) modulation technology, and its complete signal mainly includes three components: carrier, pseudo-random code and data code. The signal carrier is in L band, and the center frequency of the two carriers is recorded as L1 and L2 respectively. The satellite signal reference clock frequency f0 is 10.23 MHz, and the central frequency of signal carrier L1 is 154 times of f0, i.e., fL1=154 * f0=1575.42MHz (1) wavelength lambda 1=19.03cm; The central frequency of signal carrier L2 is 120 times of f0, that is, fL2=120 * f0=1227.60MHz (2).
2. The principle of GPS antenna is analyzed and its wavelength is lambda 2=24.42 cm. The carrier frequency offset is 347.82 MHz, about 28.3% of the L2, so choose the carrier frequency is easy to measure or eliminate from the GPS satellite navigation signal transmission to the receiver when due to the propagation delay of the ionosphere effect caused by the error. The pseudo-random noise code (PRN) is the main precision ranging code (P code) and the coarse ranging code (C/A code). The code rate of P code is 10.23 MHz, C/A code is 1.023mhz. Code is A GPS satellite data in binary form is sent to the user receiver navigation positioning data, also called navigation message or D yards, it mainly includes satellite ephemeris, the satellite clock correction, ionospheric delay correction, working status information, C/A code to capture the P code information and A compendium of all the satellite ephemeris; The total cable is made up of 1500 bits, which are divided into five frames. Each subframe launches 10 characters in the 6s, 30 bits per word, and a total of 300 digits, so the baud rate of the data code is 50bps.
Post time: Sep-25-2018