Carrier synchronizer for demodulating low signal-to-noise ratio burst signals

A burst signal, low signal-to-noise ratio technology, applied in the field of carrier synchronizer, can solve the problem of high implementation complexity, achieve the effect of expanding application range, improving estimation accuracy, and reducing length requirements

Active Publication Date: 2013-12-25
XIAN INSTITUE OF SPACE RADIO TECH
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Problems solved by technology

Literature [5] proposed an improved APPA algorithm, which can be applied to carrier phase estimation with a certain residual frequency offset, but its implementation complexity is very high

Method used

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  • Carrier synchronizer for demodulating low signal-to-noise ratio burst signals
  • Carrier synchronizer for demodulating low signal-to-noise ratio burst signals
  • Carrier synchronizer for demodulating low signal-to-noise ratio burst signals

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Embodiment

[0051] Assuming that a burst communication system has an information rate of 2Mbps, adopts LDPC coding with a code rate of 0.5, and the maximum frequency deviation during transmission is 10KHz. The burst frame structure is 128 preambles, 32 unique words and 2048 effective information, the modulation method is QPSK, and the working signal-to-noise ratio Eb / No is required to be 0dB. In order to reduce the cycle skip probability, the normalized loop bandwidth of the Costas ring is 0.004. The specific steps of using the present invention to perform carrier synchronization are as follows:

[0052] 1) Store the input information after symbol synchronization in the input buffer;

[0053] 2) Use the data-assisted algorithm to estimate the normalized initial frequency offset value fc using 128 leading headers;

[0054] 3) When the signal-to-noise ratio Eb / No is 0dB, after the initial frequency offset is estimated, the possible normalized residual frequency offset range is [-0.001, 0.001], a...

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Abstract

The invention discloses a carrier synchronizer for demodulating low signal-to-noise ratio burst signals. The carrier synchronizer comprises an input cache module, an initial frequency deviation estimation module, a frequency deviation partition preset module, N two-way capture tracking modules, N unwrapping phase ambiguity and soft de-mapping modules, an iterative decoding module and an optimal judgment module. Each two-way capture tracking module corresponds to one unwrapping phase ambiguity and soft de-mapping module. Initial frequency deviation is estimated based on preceding heads of the burst signals, then, after an initial frequency deviation estimation result is preset in a partition mode, two-way capture tracking is utilized to conduct carrier synchronization, the optimal judgment module selects an optimal carrier to conduct synchronous output according to judgment soft information statistical values output by the iterative decoding module, and eventually the iterative decoding module conducts decoding on the carrier and outputs a final result. By the adoption of the carrier synchronizer, optimization design is conducted on burst signal carrier synchronization under the low signal-to-noise ratio, and the problem of low signal-to-noise ratio carrier synchronization of TDMA system communication is solved.

Description

Technical field [0001] The invention discloses a carrier synchronizer for demodulating burst signals with low signal-to-noise ratio. Background technique [0002] The core issue in the demodulation of burst signals with low SNR is carrier synchronization. Carrier synchronization methods can be divided into feedback type closed-loop carrier synchronization and feedforward type open-loop carrier synchronization. For burst signal demodulation, traditional feedback-type closed-loop carrier synchronization has problems such as long acquisition time and “hanging”, which cannot meet application requirements well. Therefore, open-loop carrier synchronization methods based on parameter estimation are generally used. The adaptive signal-to-noise ratio range of open-loop carrier synchronization is mainly limited by the parameter estimation accuracy, and the parameter estimation accuracy depends on the estimation algorithm and the length of the preamble used for estimation. However, under ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04L7/033
Inventor 龚险峰惠腾飞田嘉杨磊
Owner XIAN INSTITUE OF SPACE RADIO TECH
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