Frequency offset compensation system under broadband fast frequency hopping system

Abstract

The invention relates to a frequency offset compensation system under a broadband fast frequency hopping system. The system comprises a radio frequency dehopping unit, a matched filter, a timing synchronization unit, a frequency offset correction unit, a phase correction unit, a frequency hopping synchronization unit and the like. The frequency offset relations between different hopping of the frequency hopping system are researched, long and short unique codes are designed, frequency offset estimation is performed by use of long unique codes of pilot frequency hopping, frequency offset compensation is performed on other hopping except the pilot hopping according to the frequency relations between different hopping, carrier synchronization is completed, so that adoption of a coherent demodulation manner by the broadband fast frequency hopping communication system becomes possible, the noise performance of the system can be improved, and besides, the method can adapt extremely large frequency offset ranges.

Description

technical field [0001] The invention relates to a frequency offset compensation system under a broadband fast frequency hopping system, which belongs to the technical field of communication. Background technique [0002] The demodulation of the phase modulation signal under the frequency hopping system in the prior art has the following problems: [0003] (1) Generally, the phase modulation signal in the frequency hopping system adopts non-coherent modulation and demodulation mode. However, under the condition of the same modulation order, the noise performance of the non-coherent modulation and demodulation system is worse than that of the coherent modulation and demodulation system. [0004] (2), PLL-based coherent demodulation algorithm PLL requires a long time to lock in, especially under large frequency offset, which makes the coherent demodulation algorithm based on PLL unsuitable for high-speed A frequency hopping system (that is, a frequency hopping system with fewe...

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Problems solved by technology

[0003] (1) Generally, the phase modulation signal in the frequency hopping system adopts non-coherent modulation and demodulation mode. However, under the condition of the same modulation order, the noise performance of the non-coherent modulation and demodulation system is worse than that of the coherent modulation and demodulation system.

[0004] (2), PLL-based coherent demodulation algorithm PLL requires a long time to lock in, especially under large frequency offset, which makes the coherent demodulation algorithm based on PLL unsuitable for high-speed Frequency hopping system (that is, a frequency hopping system with fewer symbols per hop), and cannot adapt to a wide range of frequency deviations

[0005] (3) The traditional open-loop carrier synchronization method requires high frequency estimation accuracy, which requires lengthening the unique pilot code used for frequency offset estimation

However, for broadband frequency hopping systems, the difference in frequency offset between two frequency points with a large frequency interval is relatively large, which requires setting a length special code at each hop to estimate the frequency offset of the hop, which will result in a hop The number of symbols occupied by useful information is reduced, which seriously affects the communication efficiency

[0006] According to the above analysis, the coherent demodulation under the broadband fast frequency hopping system is very difficult

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