FIELD: radio engineering.
SUBSTANCE: invention relates to radio engineering and can be used in organizing communication systems with increased number of channels, as well as in measurement equipment requiring low frequency tuning pitch. Invention is based on the task of obtaining microwave oscillations with low frequency spectrum pitch, low phase noise and low frequency tuning time. For this purpose the reference generator frequency setting the comparison frequency in the phase detector of the indirect type synthesizer is selected within the band of ultrashort waves. Herewith the high-stable reference generator frequency is preliminarily shifted by a certain small value specifying a small frequency spectrum pitch. For this purpose the reference generator signal is supplied to the radio frequency input of a quadrature modulator modulated with low-frequency quadrature signals of the same frequency and amplitude but with the phases shift of 90°. Thus the comparison frequency differs from the reference generator frequency by the value of those low-frequency signals frequency. Transformed by frequency signal from the quadrature modulator output is supplied to the first input of the frequency-phase detector. Frequency of the microwave generator controlled by voltage is divided by a divider with variable coefficient and supplied to the second input of the frequency-phase detector. With the help of a low-pass filter products of the alternating current comparison are suppressed, and the direct current signal is supplied to the input of the voltage-controlled microwave generator.
EFFECT: such method enables to generate microwave oscillations with a pitch of units of kHz, at the same time without increasing the synthesizer tuning time, without increasing the level of phase noise and maintaining stability of the synthesizer frequency defined by stability of the reference generator frequency, which, for example, reaches 10-7-10-8.
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