| 摘要 |
Method for FM modulation of a digital carrier signal with a digital AF signal by means of a feedback-type phase accumulator and a carrier oscillator which generates the samples of the modulated FM oscillation, characterised in that the carrier oscillator operates at a sampling rate fA = 1/T which is greater than the FM bandwidth, in that a complex-value FM carrier signal is generated, the carrier frequency of the unmodulated carrier being fC = M.fA + f0 with the integral number M>1 and the FM centre frequency f0, in that band-limiting then takes place by means of a complex-value filter and interpolation takes place by means of a complex-value interpolation filter. Fully digitised frequency modulator with reduced nonlinear distortion after the demodulation, integrable as VLSI/ASIC chip, general application in the field of frequency modulation and especially in digital FM broadcasting and for transmitting its signals via optical fibre. <IMAGE> |
