Analysis and design of a high frequency modem which utilizes digital signal processing techniques.
Howard K. Winter · 1979
1 I . Introduction 3 I I . Preamble 7 A. Signal Presence Recognition 8 B. Doppler Detection 10 C. In it ia l Synchronization 18 I I I . Hilbert Transform Algorithm 21 IV. Data Demodulation 29 A. Detection Scheme 29 B. Orthogonality of Tones 34 C. F FT Program 34 D. Continuous Doppler Tracking 37 E. Frame Synchronization Tracking 41 Conclusion 49 Bibliography 53 APPENDIX 1 Instructions for Use of Simulation Programs 54 APPENDIX 2 Derivation of Doppler Detection Formula.... 59 APPENDIX 3 Derivation of Frequency Shifting Formula... 63 APPENDIX 4 Derivation of Coefficient for 1760 Hz. Sync Tone 64 APPENDIX 5 Derivation of Differential Phase for Data Demodulation 66 Biography....' 68 iv