VECTOR METER DOPPLER FREQUENCY SHIFTS LOCATION SIGNAL BASED ON TANDEM AMPLITUDE-PHASE MODULATION AND A FIBER BRAGG GRATING SUPPORTING POLARIZATION

Abstract

To measure the Doppler frequency shift (DFS) of the radar signal, which is necessary to control the UAV flight parameters when approaching an area closed to air traffic, two main radio photon methods have been developed: scalar and vector photomixing. In the article, after the analysis and determination of the advantages of the latter, the concept of constructing a radio-photon vector DFS meter based on tandem amplitude-phase modulation (TAPM) with the location and reflected signals of an optical carrier and a frequency Doppler shift discriminator built on a fiber Bragg grating that maintains polarization (FBG) is proposed. -PP). As a prototype of the vector meter, the previously proposed radiophoton scalar DFS meter based on TAFM is used with the location, reference and reflected signals of the optical carrier and the Doppler shift frequency discriminator on the FBG with equal average values of the refractive index along the main axes of the fiber in which it was recorded. Compared with the prototype, it is proposed to abandon the use of the reference signal, and reformat the basic part of the TAFM-based circuit into a circuit with the possibility of implementing in-phase I(t) and quadrature Q(t) reflected signal detection. The structure and experimental stand of the radiophoton vector DFS meter, a description of the principles of their operation and the results of the first experiments, which confirmed the possibility of simplifying the design of the meter, increasing the stability of its operation when external conditions change, a method for determining the magnitude and sign of the DFS based on an amplitude-phase radio frequency detector with a measurement error, are given. less than 1^o. The achieved measurement error of the DFS is -1 Hz, +1 Hz.