Research On Shortwave Data Communication Modem

Military telecommunication (MT) is a specific branch of technology, which involves all current advanced technological achievements carrying it out into practice that communication systems can be adapted to complicated physical environment and can bear the attacking or confronting of modern techniques. Shortwave channel has the ability of survivability, which played a main role in MT systems. Electronic counterwork is an important task of MT systems. The adaptability to sophisticated environment of communication devices, is the survival standard of MTS.It's presented that the research of shortwave datacomms modem in the communication equipment test, which is developed to meet the demand of efficient and reliable shortwave little information point to point datacomms by routine communication device in maneuver situation.The shortwave modem can improve the probability of communication and its data rate is 50-600 bps. The digital signal processing and controlling are implemented by microchip 80C196KB, which adopted interleaving coding, mixed error correction techniques and so on. The anti-jamming performance of the modem is greatly improved by time-frequency modulation according to the applying case.By experimentation, it is shown that time-frequency modulation is efficient and effective, which has rake and fault tolerant capacities in passband. The modem has strong ability of anti-jamming and error-correction which can finish the mission of communication under poor channel qualitative properties. The modulation of the modem is implemented by polling software look-up table, which has the merits of coding easily, less data calculation and fast operation, etc. The modem also has the ability of restoration and the communication software in data terminal has strong function of controlling. So it can adapt complexity situation and keep uninterruptible communicating.