Method of Doppler Frequency Shift Measurement Based on Dual Polarization Modulator

Abstract

The invention discloses a device and method for realizing Doppler frequency shift (DFS) measurement based on a dual polarization modulator, relating to the fields of microwave technology and optical communication technology, and mainly applied to the measurement of DFS. The device is as shown in attached drawings, and comprises a light source (LD), a transmitted signal source, an echo signal source, a 90-degree phase shifter, a dual polarization modulator (DPol-MZM), an optical amplifier (EDFA), an optical filter (OBPF), a polarization beam splitter (PBS), a photoelectric detector (PD) and a hybrid coupler. According to the method disclosed by the invention, the echo signal is down-converted to a low-frequency electric signal based on the DPol-MZM, and the size and direction of the Doppler frequency shift can be simultaneously estimated in combination with the hybrid coupler; and when the Doppler frequency shift is positive, only the positive port of the hybrid coupler has output signals, and when the Doppler frequency shift is negative, only the negative port of the hybrid coupler has output signals. The method disclosed by the invention has the advantages of wide carrier frequency tuning range, high frequency measuring accuracy and the like.

Description

technical field [0001] The invention relates to the technical field of optical communication and microwave technology, in particular to the photonic Doppler frequency shift measurement of microwave signals. Background technique [0002] The Doppler effect is a phenomenon in which there is a deviation between the transmitting frequency and the receiving frequency due to relative motion. Its frequency difference is defined as Doppler shift DFS. At present, Doppler frequency shift measurement has important applications in radar, wireless communication, electronic warfare, medical imaging and other fields. For example, in wireless communication, the Doppler effect is manifested as the time-varying characteristic of wireless multipath fading channels, and the channel parameters can be accurately estimated by measuring the Doppler frequency shift, so that a reasonable design of the communication system can be carried out. In clinical medicine, the Doppler effect is used to detec...

AI Technical Summary

Problems solved by technology

[0004] There are two ideas in the proposed microwave photonics Doppler frequency shift measurement scheme: one is to map the Doppler frequency shift to power, and use the one-to-one correspondence between power and frequency offset to measure more indirectly The Doppler frequency shift, but the direction of the Doppler frequency shift cannot be obtained; the other is to convert the Doppler frequency shift into a low-frequency electrical signal through an optical down-conversion link, and use a spectrum analyzer and an oscilloscope to analyze the low-frequency electrical signal. Spectrum, phase relationship to obtain the magnitude and direction of Doppler frequency shift respectively

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