Direct Sequence Spread Spectrum Signal’s Demodulator Acquisition Implementation Based on Fast Fourier Transform. Part 1. Problem Statement and Solution Approach

Brusin, E.

doi:10.31854/1813-324x-2022-8-4-21-27

Cited by 4 publications

(2 citation statements)

References 4 publications

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“…Spread-spectrum signal acquisition, in essence, is the identification of the correct code phase and carrier Doppler in signals that are received through two-dimensional searches in both the time and frequency domains by taking advantage of the excellent autocorrelation properties of the spreading spectrum codes [12]. Early spread-spectrum signal acquisition methods typically relied on time-domain sliding correlation, sequence estimation searches, and the matched-filter technique, which gradually improved the search efficiency.…”

Section: Introductionmentioning

confidence: 99%

Research on Acquisition Performance of FFT Algorithm for Low-Frequency Spread-Spectrum Signals Using Acoustic Sensors

et al. 2023

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An essential precondition for the effective use of low-frequency spread-spectrum acoustic signals is their synchronous acquisition. Due to the low bit rate that low-frequency spread-spectrum signals have, the length of the spreading spectrum code and the number of intra-chip carriers need to be precisely designed to balance the acquisition performance and the bit rate in low-frequency spread-spectrum signals. Furthermore, the selection of the acquisition method and sampling frequency depends on the specific application and system requirements, which will directly affect the processing speed and accuracy. Firstly, this study uses a cyclical stepping search combined with a fixed threshold and maximum correlation discriminant method to improve the FFT acquisition algorithm with a low Doppler frequency. Secondly, the effects of the spreading spectrum code parameters and sampling frequency on the acquisition performance are also investigated through simulation and experiments with acoustic sensors. The results show that both lengthening the spreading spectrum code and increasing the number of intra-chip carriers can greatly improve the acquisition performance. Increasing the sampling frequency can improve the ranging accuracy but has a very limited improvement effect on the acquisition performance.

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Section: Introductionmentioning

confidence: 99%

Research on Acquisition Performance of FFT Algorithm for Low-Frequency Spread-Spectrum Signals Using Acoustic Sensors

et al. 2023

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“…The underwater acoustic (UWA) PN signal acquisition technology extensively utilizes synchronization algorithms in global navigation satellite systems (GNSS) [1]. In general, the PN code acquisition technology comprises the serial search algorithm (ambiguity function algorithm) [2], the circle correlation-based parallel search algorithm of time domain [3][4][5], and the parallel search algorithm of frequency domain in accordance with Partial Matched Filtering-Fast Fourier Transform (PMF-FFT). The PMF-FFT algorithm was proposed by Povey for the first time [6]; Spangenberg [7] proposed a windowing algorithm to reduce scallop loss by investigating the principle of PMF-FFT in depth.…”

Section: Introductionmentioning

confidence: 99%

Capturing mobile underwater pseudonoise synchronous signal using multi‐strategy in waveform domain

Hu,

Han,

Zhao

et al. 2023

Electronics Letters

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Capturing pseudonoise (PN) synchronous signals is an important issue in spreading spectrum underwater acoustic communication. In this letter, local waveform domain information is combined with multi‐strategy to enhance the Doppler tolerance of conventional Partial Matched Filtering‐Fast Fourier Transform (PMF‐FFT) acquisition algorithm under low signal‐to‐noise ratio (SNR). First, an optimized algorithm based on partial reconstruction in waveform domain was proposed, such that the Doppler tolerance increased by 38.9% when the SNR = −15 dB. Second, a local baseband multi‐waveform compression algorithm was proposed to further enhance the Doppler parallel search ability multiply. At last, frequency offset estimation was completed after searching the multi‐waveform serially. The effectiveness of the proposed algorithm was verified through the experiment at sea.

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Direct Sequence Spread Spectrum Signal’s Demodulator Acquisition Implementation Based on Fast Fourier Transform. Part 2. Carrier Frequency Estimation

Brusin

2023

jour

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Signals with direct spread spectrum are widespread in modern communication and navigation systems. Often for communication channels in which such signals are used, significant changes in the carrier frequency in relation to the information speeds of the received signals are characteristic. In particular, for communication channels with significant Doppler shift. Therefore, estimation of the carrier frequency plays a key role in solving the problem of initial synchronization of demodulators of signals with direct spectral broadening. In the first part of the paper, the main approaches to solving the initial synchronization problem were presented. In this part of the paper an algorithm for estimating the carrier frequency based on the analysis of the received signal uncertainty function cross section in the delay plane was proposed. The carrier frequency estimation is based on the fast Fourier transform using an iterative dichotomous search procedure. The results of its efficiency analysis are presented; the variance of the estimates obtained in the implementation of the proposed estimation algorithm are compared with the Cramer-Rao boundary.

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Direct Sequence Spread Spectrum Signal’s Demodulator Acquisition Implementation Based on Fast Fourier Transform. Part 1. Problem Statement and Solution Approach

Cited by 4 publications

References 4 publications

Research on Acquisition Performance of FFT Algorithm for Low-Frequency Spread-Spectrum Signals Using Acoustic Sensors

Research on Acquisition Performance of FFT Algorithm for Low-Frequency Spread-Spectrum Signals Using Acoustic Sensors

Capturing mobile underwater pseudonoise synchronous signal using multi‐strategy in waveform domain

Direct Sequence Spread Spectrum Signal’s Demodulator Acquisition Implementation Based on Fast Fourier Transform. Part 2. Carrier Frequency Estimation

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