Automatic detection of underwater propeller signals using cyclostationarity analysis. (1st January 2021)

• Record Type: Journal Article
• Authors: Gao, Yujin; Cain, Tim; Cooper, Patrick
• Is Part Of: Mechanical systems and signal processing. Volume 146(2021)
• Publication Date: 2021-01-01
• Subjects: Cyclostationarity analysis -- DEMON analysis -- Cyclic modulation spectra -- Propeller signals; Structural dynamics -- Periodicals; Vibration -- Periodicals; Constructions -- Dynamique -- Périodiques; Vibration -- Périodiques; Structural dynamics; Vibration; Periodicals; 621
• DOI: 10.1016/j.ymssp.2020.107032
• Languages: English
• ISSNs: 0888-3270

Abstract

Highlights: Equivalence among coherently integrated CMS, CMC and DEMON spectra is established. An envelope signal is in-phase at all carrier frequencies in CMS. CIQDL is proposed to construct cyclo-spectra for detection of propeller signals. Performance of CIQDL vs QDL is derived and assessed using simulation and sea-trial data. Abstract: The second order Cyclostationarity Analysis (CA) is gaining attention for detection and classification of marine vehicles driven by propellers in broadband passive sonar systems, in which the Detection of Envelope Modulation On Noise (DEMON) is a standard tool for the same purpose. In this paper both CA and DEMON are discussed in the form of discrete digital formulae. It is shown that the three cyclo-spectra obtained by the DEMON analysis, the coherent integration of the Cyclic Modulation Spectra (CMS) and the coherent integration of the Cyclic Modulation Coherence (CMC) are equivalent to each other when the same frequency band and duration are chosen for calculating all of them. This equivalence is further explained based on the physical characteristic of cyclic modulation (also called amplitude modulation), that is, the same harmonic of cyclic modulation at different carrier frequencies is in-phase. For detection and/or classification of propeller signals a Coherent Integration and Quadratic Detection Law (CIQDL) is proposed to construct cyclo-spectra from the CMS and CMC. The performance of the thus constructed cyclo-spectra are compared with that of cyclo-spectra constructed using the Quadratic Detection Law (QDL). The SNR gain of the CIQDL over the QDL is derived theoretically and the gain is always larger than unity, indicating that the CIQDL outperforms the QDL. Both simulation and sea-trial data are used to demonstrate the in-phase characteristic. The performances of the CIQDL and the QDL are also quantitatively assessed using both simulation and sea-trial data.