Digital frequency synthesizer/modulator for continuous-phasemodulations with slow frequency hopping

摘要

This paper gives a description of a modulator for burst-by-burstncarrier frequency hopping in time-division multiple-access (TDMA)nsystems. The architecture consists of a digital frequencynsynthesizer/modulator for continuous-phase modulations (CPMs) and a fastnfrequency settling RF synthesizer consisting of one phase-locked loopn(PLL). The performance of the digital frequency synthesizer/CPMnmodulator has been analyzed theoretically and simulated by a computernprogram. The analyses show that the proposed digital frequencynsynthesizer/CPM modulator achieves 2.5-W lower power consumption andn18-dB lower spurious levels than the fast frequency hopping systemsnsynthesizing digitally a full frequency band. In the computernsimulations the effect of the digital frequency synthesizer/CPMnmodulator parameters on the power spectrum and the phase error isninvestigated