| 摘要 |
Harmonic generator type of frequency synthesizer employing a reference frequency signal equal to the spacing between adjacent channels and a displaced reference frequency signal which differs from the reference frequency by a few hertz. The reference frequency signal is applied to a first harmonic generator which generates a spectrum of harmonics of the reference frequency. The spectrum is applied to a phase-locked loop which produces an output frequency signal equal to a particular one of the harmonics of the reference frequency. The displaced reference frequency signal is applied to a second harmonic generator which generates a spectrum of harmonics of the displaced reference frequency. The spectrum of harmonics of the displaced reference frequency is combined with the output signal of the phase-locked loop in a mixer and the output of the mixer is applied to a low-pass filter. The frequency of the only output signal from the filter is equal to the same particular harmonic to which the phase-locked loop is locked times the difference in frequency between the reference frequency and the displaced reference frequency. Since the difference between the frequencies is a known, fixed value, the signal from the filter is thus a precise measure of the particular harmonic of the reference frequency being produced by the phase-locked loop.
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