Two Quadrature Modulation/Phase Shift Keyed (QM/PSK) Voice/Data Modem systems have been developed as part of the satellite communications hardware for advanced air traffic control systems. These systems consist of a modulator and demodulator unti which provides for one-way communication of voice and/or data signals. The modulator and demodulator unit provides simultaneous transmission of analog voice and digital data signals multiplexed on a single carrier, using quadrature modulation techniques. The modem interfaces with the transmitter/receiver at 70 MHz intermediate frequency. The report contains design theory, circuit descriptions, diagrams, calibration procedures, and laboratory test results.
Content Notes:
Introduction, General description, Quadrature modulation techniques, System design, Modulator, voice processing, Data code generator, Quadrature modulator, Up-converter module, Demodulator, Down-converter, Coherent demodulator, C/N measurement, Audio processing, Data decoder and clock synchronization, Code synchronization and error detector, System test results, Voice intelligibility tests, Data error rate tests, Carrier acquisition, C/N calibration, Schematic diagrams, Appendix
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