Analyze the likelihood of private use and interfering with GPS! The US GPS began construction from 1973 and the spatial part consists of 21 3 satellites. The height is about 20,000 kilometers away. Take 1575.42MHz and 1227.60MHz, with C / A-Civil code and P code - military code to send navigation text, the transmit power is 20-30W. Where L1 = 1575.42 MHz is modulated by the C / A code and P code, and L2 = 1227.60 is only modulated by the P code. 1. In fact, the GPS satellite sends a microwave signal, a signal of high frequency, short-wavelength linear transmission. Therefore, in places with mountains and high buildings, the signal may not be received. At the same time, since it is microwave communication, the GPS signal is difficult to interfere. 2, the navigation text sent by the GPS satellite is a spread spectrum signal. Using the pseudo code spread, it is also called M sequence spread spectrum. It has good anti-interference and confidentiality. M sequence spreading also has many applications in confidentiality technology. If M is greater than 1000, the resulting code sequence is widely distributed, even if the supercomputer needs N years, it can be calculated. At the same time, after the spreading, the effective information is extended to a relatively wide frequency band, and the signal is submerged in white dry. Therefore, the GPS's pseudo code spreading system has good confidentiality and anti-interference. To restore this baseband information, you must have the corresponding key - the modulated pseudo code. In the inside of the receiver, the pseudo code modulated signal, restores it to the baseband signal. Therefore, we must make a GPS receiver, you must know the C / A key and P key. Of course, this information is definitely highly confidential. Get it is definitely difficult. Once this key is obtained, the United States only updates all of its GPS receivers. 3. Use GPS to achieve the US P code military accuracy. 1. Differential GPS ---------- Use known locations as a reference point, receive the GPS signal, calculate the error of the C / A signal of GPS, and then send this information to the nearby GPS receiver. This method can increase the C / A code accuracy by 10 times. Differential GPS has been widely used in the world, including the United States! However, it is a large amount of data to be sent, and to build a large number of base stations. In addition, I heard that in my country's two-star positioning system, the satellite is sent to the GPS correction signal in addition to sending my country's positioning signals. Put the differential GPS base station in space is really a good way to save costs. However, differential GPS needs to receive C / A code. Once the United States stops to send C / A code to my country during war, then the differential GPS is useless! Of course, there is still a solution! After the European Galileo system is completed, due to the Galileo system and GPS signals, as long as the galileo system does not close our civil signal, then my country can also use the civil Galileo signal to use differential GPS to get high precision! Perhaps, this is a major reason for my country's joining Galileo plans! 2, no code GPS ------- No code GPS is to use the GPS satellite as a person to make an electric emission source, use the GPS signal as a noise signal ---- your pseudo code spread spectrum is not to let the signal pretend to be drowned? I just when you are a noise! Using a very large baseline interference measurement method, a new technique of the user location is set up in the user location! However, the non-code GPS cannot know the satellite's ephemeris parameters, for this general non-code GPS receiver, you need to get the satellite's ephemeris parameters with the C / A code. His problems and solutions are like differential GPSs, and can use the civilian code of the Galileo system to solve.
4, GPS interference and anti-interference GPS work with code division multiple access mode --- is CDMA way. The receiver operates at 2 point frequencies in the L-band. The receiver's antenna acceptance range is wide, the sensitivity is high, and these are the weaknesses that are easy to interfere. 1, rude disturbance, use the interference machine as the GPS as the GPS, the continuous wave is transmitted, so that the signal noise received by the GPS receiver is lower than S / N, resulting in unaptive navigation. However, due to the microwave signal, GPS can only be linearly transmitted, so the noise signal directly received by the GPS receiver is not strong, and the effect is not very good. For example, the Iraq war, the United States claims that its precision missile drugs are interfered in Baghdad, causing missiles to attack the people. This may be the result of using coarse arranging interference. But the effect is not ideal. Americans claim to use anti-radiation missiles to destroy these interferencers. But I believe that it is possible still an interference that is not ideal! Americans may use more satellites to increase navigation signals! One reason for the US opposes Galileo may interfere with the signal of the GPS satellite. The best way to interfere with GPS signals is still from space interference! For example, my country's communication satellite and double star positioning satellite can continuously transmit the same frequency as the GPS, rude interference! Moreover, our satellite and GPS satellite are 20,000 to 30,000 kilometers away from place. The United States has no weapons to attack this interference source! 2, deceived interference, simulate the spread spectrum pseudo code signal, sent to the GPS receiver. But this is more difficult because we don't know what the GPS is used to spread. In short, after reading the above analysis, you can know that interference and use GPS are very difficult! Because this is the electronics war, the US electronic experts are not vegetarian! In particular, m-sequence spread spectrum residual random codes are theoretically could be cracked! (Know that the computer's 128-bit encryption algorithm? If you want to crack, the supercomputer has to operate N billion!) Of course, as long as it is wireless transmission, then theoretically, it can be interference!
In other words, if the GPS is so easy to interfere, the United States will not press the treasure full of GPS, my country, Europe, Russia will not find ways to engage in his satellite navigation system! Brothers, if you have a GPS device, please buy a microwave device, try to interference near the L1 frequency, tell me the results! Please interfere with 1.023 MHz or so. If you have a military GPS device, then interfere with 10.23MHz, increase frequencies in 1.023MHz! It is my original: good == Shanghai's first commentator, good QQ: 81279901. Welcome electronic enthusiasts and I contact me!
Good
9CBS certified blog expert
data analysis
Pytorch
Neural Networks
Senior kicked people, proficient in Python, C, Java, JavaScript, Linux kernel, network protocol, virtualization, cloud computing, distributed storage, kubernetes, data warehousing and other technologies. Good at micro service architecture design, Devops. Currently, it is committed to assisting Pleura Finance with Fintech.
