Based On The Shortwave Frequency Number Information Demodulation Of The Ale Modem And Link Protocol

As an important part of High Frequency Adaptive Networking, which is a National Ninth Five梇ear Project, Automatic Link Establishment (ALE) system features with functions such as channel real time evaluation technique, link establishment, signal and graph transfer etc. According to M]L-STD-188-141A and MIL-STD-187-721, this paper focuses on the design of 8FSK Modem used in physical layer of ALE system. As a new way to demodulate 8FSK signal, 搃ndex based demodulation?is proposed. Based on this technique, synchronization, signal detection and decoding techniques are discussed. According to the consideration of characteristics of HF channel and its application, the optimization of the technique is put forward. On the other hand, this paper brings forward the design of real time evaluation of some LQA parameters. As a result, the DSP implementation of 8FSK Modem is given. The second part of this paper, functions in data link layer are concerned. As an instance, ITU-T V.42 is realized based on wired communications.