| Popis: |
This paper presents a microwave photonics method for the instantaneous frequency measurement of microwave signals, based on the generation of a two-frequency laser radiation in the Mach-Zehnder modulator with a difference frequency equal to the measured, and the "frequency - amplitude" conversion in the π-phase-shifted fiber Bragg grating. Frequency measurement occurs in two ranges: 0.3 - 3 GHz in the passband of the FBG and 3 - 30 GHz in its reflection band. Using the specific conversion of two-frequency radiation in the π-phase-shifted fiber Bragg grating allowed us to obtain measuring characteristics, that are independent of the amplitude fluctuations of the optical carrier and to organize additional circuit for monitoring the spectral characteristics of the used elements to reduce measurement inaccuracy caused by their temperature instability. |
