Fast frequency hopping transmitter and receiver based on digital signal processing and its performance

Frequency hopping is an effective technique in which error correction is performed by randomizing the bust error due to fading. In this paper, frequency translation based on digital signal processing is applied and the structure of fast frequency hopping transmitter and receiver is proposed. the principles of frequency hopping modulator and frequency translating filter for hopped-signal reception are first described. Then an experimental 1.5 GHz transmitter and receiver (128 kbps, differentially encoded /4-shifted quadriphase-shift keyed (QPSK), differential detection) that can hop among 96 frequencies (12.288 MHz bandwidth) are developed. It is confirmed that a frequency switching time of 2(32) s is realized at the transmitter (receiver) and that the receiver successfully frequency translates and demodulates the hopped signal within approximately 75 s. Finally, the combined effect of frequency hopping in a fading environment and with forward error correction is experimentally evaluated. the proposed structure replaces the conventional frequency synthesizers consisting of frequency divider and phase-locked loop by fixed frequency oscillators so that fast frequency switching can be realized. Moreover, the proposed system uses very little power and is small, making it suitable for miniaturization of LSI.