| PCM/FM is wildly used in nowadays Reentry Remote Sensing (RRS) system. It is difficult to have ideal result by using analog technology because of its specialty, and that the system is short of flexibility. Compared with analog technology, digital technology can improve the low frequency response of PLL-FM circuit.In PCM/FM Reentry Remote Sensing (RRS) system, when the bit rate is above 1 Mbps, the signal suffers frequency select fading, which causes the serious inter-symbol interference (ISI); power allowance can no longer guarantee the system quota. Besides the factual channel is time-varying and totally unknown, there is always ISI affecting. Thus an adaptive filter is needed for equalization before the sample-decision detector in the receiver.Considering to these two problems, two issues are discussed in this dissertation: the digital design of PCM/FM modulation module based on Software-defined Radio (SDR) technique; blind equalization based on the adaptive filter theory.The main content in this dissertation include:1. The basis theories, application technology and problems in recent PCM/FM RRC system.2. Theories and technique of Software-defined Radio are introduced to the RSS system.3. PCM/FM modulation theory and algorithm are presented. Digital waveform synthesis and digital convert techniques are applied in the design of digital PCM/FM modulation modules.4. Blind equalization techniques are introduced to the RSS system. On the base of adaptive filter theory, basic blind equalization theory is presented, and Bussgang blind equalization algorithm is analyzed at length. The convergence and application in PCM/FM RRS system of Bussgang blind equalization algorithm is discussed. |
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