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The Principle Of Car Satellite TV Antenna

Edit: Dotogo Tecchnologies Co.,Ltd      Date:Aug 14, 2017

The Principle of Car Satellite TV Antenna
   The role of the Car Satellite TV Antenna is to convert the electromagnetic energy of the radio signal from the satellite into the current that the receiver electronics can take up. The size and shape of the antenna are important because these features determine the ability of the antenna to obtain a weak GPS signal The However, these have to serve the principle of the antenna, let us learn the following car satellite TV antenna principle it
1. Car satellite TV antenna principle - Introduction
GPS is through the acceptance of satellite signals, positioning or navigation of the terminal. And the antenna must be used to accept the signal. Car Satellite TV Antenna is divided into built-in antenna and external antenna. Early GPS handheld use of external antenna, this time the antenna and the whole internal isolation, EMI almost no impact on it, the star effect is very good. Car Satellite TV Antenna has gain, standing wave, noise figure, shaft than four important parameters. Most of the car satellite TV antenna for the right-handed polarized ceramic media, its components for the ceramic antenna, low noise signal module, cable, connector.
2. Car satellite TV antenna principle - structure
At present, most of the car satellite TV antenna for the right-handed polarized ceramic media, its components are: ceramic antenna, low noise signal module, cable, connector.
Ceramic antenna, also known as passive antenna, dielectric antenna, PATCH, it is the core technology of Car Satellite TV Antenna. A car satellite TV antenna signal reception capacity, most depending on the composition of its ceramic parts ingredients.
The low noise signal module, also known as the LNA, is part of the signal that is amplified and filtered. Its component selection is also very important, otherwise it will increase the GPS signal reflection loss, and cause excessive noise.
The choice of cable should also reduce the reflection as a standard to ensure that the impedance of the match.
3. Car satellite TV antenna principle
High-frequency and low-noise amplifiers are used in the design of Car Satellite TV Antenna unit to reduce the thermal noise of the satellite satellite TV antenna and the influence of the front-end unit circuit on the receiver performance. GPS satellite is used in the principle of automobile satellite TV antenna When positioning, the main task of the user receiver is to extract the pseudo-random noise code and data code in the satellite signal to further obtain the navigation information such as the position, speed and time (PVT) of the receiver. The signal carrier is in the L-band, and the center frequencies of the two carriers are denoted by L1 and L2, respectively. The satellite signal reference clock frequency f0 is 10.23 MHz, the center frequency of the signal carrier L1 is 154 times the frequency of f0,
FL1 = 154 × f0 = 1575.42 MHz (1)
Its wavelength λ1 = 475.75px; the center frequency of the signal carrier L2 is 120 times the frequency of f0, namely:
FL2 = 120 × f0 = 1227.60 MHz (2)
The wavelength λ2 = 610.5px.
The frequency difference between the two carriers is 347.82MHz, which is about 28.3% of L2, so that the carrier frequency is chosen to facilitate the detection or elimination of the propagation delay error due to the ionospheric effect when the navigation signal propagates from the GPS satellite to the receiver. Car Satellite TV Antenna Pseudo-random noise code (PRN) that distance code is mainly fine range code (P code) and coarse distance code (C / A code) two. Where the code rate of the P code is 10.23 MHz and the code rate of the C / A code is 1.023 MHz. The data code is the navigation and positioning data sent by GPS satellites in binary form to the user receiver. It is also called navigation message or D code. It mainly includes satellite calendar, satellite clock correction, Car Satellite TV Antenna ionospheric delay correction, working status information, C / A code conversion The total message is composed of 1500 bits, divided into five subframes, each subframe in 10s within the launch of 10 words, each word 30, a total of 300, so the data The baud rate of the code is 50bps.