Detection of FSK and DPSK data signals by pulse compression

Abstract

The paper examines the application of pulse-compression techniques used in radar systems to FSK and PSK detection. Noncoherent FSK and differentially coherent PSK detection schemes using a mixer followed by a pulse-compressor matched filter are investigated. The mixer-PCMF combination, which acts as a predetector processor, converts the FSK modulation into pulse-position modulation and the PSK modulation into pulse-polarity modulation. A microprocessor-supervised experimental system for the FSK and DPSK detection schemes has been constructed and used to perform error-rate measurements for both schemes in the presence of additive white Gaussian noise and carrier interference. Some practical imperfections were also examined to determine their effect on system performance. The results show that both detection schemes are worthy of further consideration for use in the field of digital data communication, especially in HF communication applications, where carrier interference is a common impairment.

Orthogonal Chirp Division Multiplexing

“…In spread-spectrum systems, digital binary information is encoded by modulating the frequency of a carrier, sweeping the frequency linearly from low to high as 'up-chirp' for bit '1' or from high to low as 'down-chirp' for bit '0', as shown in Fig. 1 (c) and (d) [8][9][10][11][12][13]. The chirp signal uses a wideband spectrum for transmission and is resistant to detrimental effects, such as channel noise, multipath fading and Doppler effects within the mobile radio channel.…”