Carrier phase error discrimination method based on decision feedback

Abstract

According to the carrier phase error identification method based on decision feedback, the carrier phase error is obtained through frequency multiplication and point selection, the modulation order of a signal after frequency multiplication is reduced, and the symbol decision frequency is preliminarily reduced; then, the constellation diagram subjected to frequency multiplication is clockwise rotated by 90 degrees, constellation points located on the X axis are equivalent to multiple groups of BPSK modulation with different amplitudes, therefore, the constellation points located on the X axis are selected, extraction of coherent integration and phase errors is facilitated, and the symbol judgment frequency can be further reduced. Compared with a conventional decision feedback loop carrier phase error discriminator, the rotation operation of the improved decision feedback loop carrier phase error discriminator does not bring extra calculation, and therefore, only multiplication operation brought by frequency multiplication is added, but the phase of a received signal does not need to be extracted, and the judgment and phase rotation on various modulation phases are not needed, so that the judgment times and the total calculation amount are greatly reduced.

Description

technical field [0001] The invention belongs to the field of aerospace measurement and control communication, and in particular relates to a carrier phase error identification method based on decision feedback. Background technique [0002] As a means of communication between heaven and earth, satellite-to-earth digital communication technology has expanded to high-speed services such as image, video, and video calls on the basis of satisfying traditional voice call services. With the maturity of high-resolution video images and high multi-spectral resolution technologies of remote sensing equipment, a large amount of information such as ultra-high-definition video images needs to be transmitted in real time, and the data rate of satellite-ground link transmission is getting higher and higher. The increasing data transmission rate has brought about the problem of spectrum expansion. If the classic low-order modulation is still selected, the spectrum expansion will be aggrava...

AI Technical Summary

Problems solved by technology

The Costas loop eliminates the modulation phase through phase compensation and filtering. The phase extraction accuracy is affected by noise, and when the modulation order of the signal is too high, the loop structure is complex, which is not suitable for satellite-to-earth high-data transmission with limited resources.

The M-th power ring eliminates the modulation phase by frequency doubling. For high-order modulation, multiple frequency doubling is required to meet the requirements of phase difference extraction. Multiple frequency doubling strengthens the noise term and reduces the sensitivity of the receiver.

The decision feedback loop first performs symbol judgment on the received signal, eliminates the influence of modulation information, and then extracts phase error information. It has the same performance as the maximum likelihood method when the bit timing error is small, but the target symbol and constellation diagram of the decision are required. The number of points is related. When the number of points in the constellation diagram is too high, a large amount of calculations are required to determine where the received signal is located in the constellation diagram, resulting in a surge in the amount of calculations.

[0004] For satellite-to-ground high-speed data transmission, the relative movement speed of the transceiver equipment is fast, the signal dynamic range is large, the signal power is limited, the receiving signal-to-noise ratio is low, and the real-time requirements for carrier error estimation are high.

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