New approaches are presented to the process of measuring the chromatic dispersion of a high-speed communication channel based on the classical method for determining the ratio of the radio frequency signal power. The power ratio is recorded at the output of two identical photodetectors, one of which is equipped with a Bragg notch filter at the carrier frequency. New approaches are based on preliminary amplitude modulation of an optical carrier with a radio clock signal frequency with the formation of an additional two-, three or four-frequency radiations to determine the shift between the central wavelengths of the communication channel and the Bragg notch filter, and also the use of methods to increase the signal-to-noise ratio of the measurements. The registration of information at the probing frequency or doubled probing frequency allows obtaining a gain in the signal-to-noise ratio of measurements up to 10-13 dB and performing chromatic dispersion measurements at a signal-to-noise ratio at a clock frequency of 3-5 dB. The penalty for using additional probing frequencies is up to 1 dB.
The problems of synthesis and application of fiber Bragg gratings with special spectrum shapes in measurement and information channels of quazi-distributed fiber optic systems for climatic test systems are introduced. In particular, gratings with concave, triangular symmetric and triangular asymmetric spectrum shapes are considered, also the new poly-harmonic methods of its interrogation are presented. Projects of system decisions and results of experimental researches of its blocks are discussed.