Double-loop structure carrier tracking method

Abstract

The invention discloses a double-loop structure carrier tracking method comprising the following steps of: compensating for an input signal of a narrow-band phase-locked loop with frequency tracking information output by a broadband phase-locked loop after the frequency tracking information is corrected through cooperative work of the broadband phase-locked loop and the narrow-band phase-locked loop, so as to realize carrier tracking in a low-signal-to-noise-ratio high-dynamic environment; comparing the three-order digital phase-locked loops under different loop parameters through MATLAB simulation and VIVADO simulation and displaying, whereinsimulation results show that standard deviation output by a double-ring structure phase discriminator is 5.4 degrees, the standard deviation output by a common three-order phase-locked loop phase discriminator with loop bandwidth of 1 / 50 symbol rate is 8.1 degrees, the standard deviation output by the common three-order phase-locked loop phase discriminator with the loop bandwidth of 1 / 100 symbol rate is 52.4 degrees, and the standard deviation cannot be locked; results show that under the same high dynamic environment and low signal-to-noiseratio condition, the double-loop structure can effectively consider high dynamic and low signal-to-noise ratio, the performance of the double-loop structure is far superior to that of the common digital three-order phase-locked loop and a common two-order phase-locked loop, and the excellent performance and engineering practical value of the method are verified.

Description

technical field [0001] The invention relates to the technical field of communication systems, in particular to a carrier tracking method with a double-loop structure. Background technique [0002] Satellite communication has been developed in the 1960s, and after decades of development, it has become an important way of modern communication, especially military communication. High-performance carrier recovery technology is particularly important in satellite communication systems, and factors such as satellite signal attenuation, loss, phase mutation and high user dynamics on the link will cause the performance of carrier recovery algorithms to deteriorate. Phase-locked loops are widely used in carrier recovery during coherent demodulation of satellite communication receivers. The traditional second-order phase-locked loop tracking Doppler signal with frequency acceleration will produce non-zero steady-state phase difference and cause the loop to lose lock. After a reasona...

AI Technical Summary

Problems solved by technology

The traditional second-order phase-locked loop tracking Doppler signal with frequency acceleration will produce non-zero value steady-state phase difference, which will cause the loop to lose lock

After reasonable design, the third-order phase-locked loop has zero steady-state phase difference tracking ability for Doppler signals with acceleration under certain conditions, but the loop bandwidth and dynamic tracking ability of a single phase-locked loop are a pair of contradictory indicators

The narrowband loop has excellent noise suppression performance, but the carrier dynamic tracking ability is poor, so it cannot adapt to the high dynamic environment

On the contrary, the dynamic tracking ability of the broadband loop is strong, but it will introduce a lot of noise, thereby reducing the carrier tracking performance

[0003] The stability of the loop above the third order is conditional, and the analysis is more complicated

At the same time, in the case of large Doppler changes, it is necessary to increase the loop bandwidth to lock. Increasing the loop bandwidth will introduce noise, which will affect the receiving performance

Therefore, in such an environment with high dynamics and low signal-to-noise ratio, the existing technology cannot take care of both

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