Satellite communication terminal module within the integrated satellite communications, cellular communication module for multi-mode communication; internal integration Beidou / GPS positioning module for multi-mode positioning; reserve multiple I / O ports, enabling switch, the amount of digital to analog signal acquisition.
LEO satellite communication network, its frequency band is susceptible to electromagnetic interference existing, especially in large cities, walkie-talkies, mobile phones cause significant interference to their signals. The project, due to the satellite positioning communication terminal is mounted on the surface of containers and other metal equipment, the signal facing the weak strong signal interference complex bad channel environment, but also because of the small low-orbit satellite signal power, are more susceptible to interference affecting the data link road. In order to ensure that the design of the system both applications, but also in the densely populated city in isolated areas, LEO satellite communication ground communication network system needs to have strong anti-jamming capability, and have multiple communication network adaptive automatic switching function.
Interference LEO satellite communication system can be broadly divided into the following four categories:
a).Interference between satellite communication system. Using the same frequency band, from the spatial interference between different satellite communication systems in close.
b).Electromagnetic interference between terrestrial radio systems and satellite communication systems. Including interference with terrestrial microwave communication system between the band, interfering interference from the radar system, interference from radio and television system, from engineering, scientific and medical equipment, as well as the quality of the work of the same frequency gateway earth station does not meet the standards, or operation interference errors.
c).Electrical interference from the nature of day. Cosmic rays, meteor showers and other astronomical phenomena natural disturbances.
d).Anthropogenic interference with satellite communications. Including anthropogenic interference with satellite communication uplink signal and downlink signal, such as spectral congestion and misappropriation.
Satellite communication systems, the commonly used anti-jamming technology are: anti-jamming antenna technology, spread spectrum technology, coding modulation technology, processing technology onboard, limiting and linearization techniques. Specific to the commercial areas, anti-jamming technology including direct sequence spread spectrum, frequency hopping, time hopping multiple mixed mode, multi-beam antenna, adaptive nulling antenna.
Anti-jamming technology basic idea is: in the R & D stage to fully consider the satellite communication module, satellite communications antenna must have a strong anti-jamming capability, the terminal device designed to support dual satellite communications and cellular communications communication network in remote areas using satellite communication network in large cities use a cellular communication network.
The main anti-jamming technology R & D include: multi-technology communication networks and algorithms using adaptive technology communication module, communication antenna anti-jamming technology, anti-jamming technology terminal equipment, terminal equipment.
Schematically shown in Figure 3-14 multiple communication network access:
Multi-network access schematic
The following initial formation of a multi-communication network adaptive switching algorithm, as shown in Figure 3-15, 3-16, as follows: According to the priority of each communication method is used in order to determine the current communication method is valid, should the effective based on the highest priority and effective means of communication with the back-office operations platform for communication, should the invalid queries through the next level of communication is valid, should the next level and the next level is valid based on effective communication with the back-office operations platform for communication, followed by cycle to query and use a valid means of communication, and the communication mode priority may be refreshed; when refreshed every communication sent to the back-office operations platform data priority flag is valid, the communication priority mode can be used to refresh, and then to change a variety of communication methods is recycled queries and priorities. Communication priority refresh There are two main ways: the first is based on human input, artificially setting switching priority; the second is based on the relevant standards, the global tariff database, analysis and processing terminal controller status information feedback form new the communication priority; new communication ultimately formed by the current priority of a downlink communication sent to the terminal, and thus the formation of new communication method switching method; when the first and second communication priority refresh when the methods are effective, using the first refresh mode. Based on the priority of each communication mode of communication is currently being used effectively handed down query using the expanded query, the query expansion handed down refers to the next level of communication for each query is valid , as long as the next level of communication than to query a higher priority communication should query.
Multiple Communication Network Switching Algorithm Schematic
Multiple Communication Network Switching Algorithm Flowchart