Spread spectrumcommunication is a kind of information transmission method, which is often usedin military communication, mobile communication, satellite communication, andranging positioning. Spread spectrum communication plays an important role inmilitary or civilian applications, and its technology is further matured tomake its application more Wide range, the development trend is very good, andwill make a greater contribution to human society in the next few years. So,what is the principle of spread spectrum communication, and what are theadvantages?
Characteristics of spread spectrum communication
1, is a digitaltransmission method;
2. Broadening thebandwidth by using a function (spreading function) that is independent of thetransmitted information to modulate the transmitted information;
3. At thereceiving end, the same spreading function is used to demodulate the spreadspectrum signal to restore the transmitted information.
Basic principles of spread spectrum communication
Spread spectrumcommunication is no different from traditional data communication in terms ofits modulation method, including ASK, FSK, PSK and recently developed QAM. Thedifference is that a spread spectrum processing link is added beforemodulation. The symbols to be transmitted are spread by the feature code, andthe expanded symbols are called chips; at the receiving end, a despreadingprocess is also added, and N chips are restored to one symbol.
Advantages of spread spectrum communication
(1) Spreadspectrum communication has the characteristics of message concealment, lowintercept probability and anti-interference, and has great potential formilitary communication. Foreign military communications have been equipped withfrequency hopping stations in the HF, VHF and UHF bands, and direct sequencespread spectrum stations have also begun to enter the practical phase.
(2) Usingdifferent predetermined spreading code (address code) sequences, code divisionmultiple access (CDMA) and location communication can be implemented in thesame frequency band, and used in satellite communication and indoor wired andwireless communication.
(3) Directsequence spread spectrum signals have the same distance-independenthigh-resolution ranging capability and are used in global positioning system(GPS) and deep space exploration.
The above is theprinciple and advantages of spread spectrum communication, spread spectrumcommunication anti-interference, concealment, good confidentiality andexcellent performance characteristics, making it widely used in various fields.Throughout the history and current situation of spread spectrum communication,it can be expected that the development trend of spread spectrum communicationis good and plays an important role in many applications.