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Designing an Optimal Waveform for Active Sonar using Multi-Tone Sinusoidal Frequency Modulation (MTSFM)
November 16, 2017 @ 6:00 pm - 9:00 pm
The performance of active sonar could be greatly enhanced by automation in the selection of transmit waveform type and receiver processing. Although the bandwidth of deployed systems allows for the transmission of numerous waveform types of various frequencies nearly simultaneously, this capability is underutilized as the optimal waveform combination is a complex function of a number of parameters including the environment, target type, and system objectives/priorities. Such a problem may not be optimally solved using a suite of existing waveforms but rather by designing an optimal waveform for the current scenario. Over the past 60 years there has been a wealth of research in choosing the optimal waveform to transmit for radar/sonar systems. Efforts in the published literature have largely focused on designing waveforms that possess a desired Ambiguity Function (AF), Auto-Correlation Function (ACF), or Cross-Correlation Function (CCF) [Wilcox: Math. Res. Center Rpt. 157 (1960), Li et al : Camb. Univ. Press (2012)]. Waveforms for active sonar must additionally be well suited for transmission on piezoelectric transducers. This typically requires the waveform to possess a constant amplitude and high Spectral Efficiency (SE) where the vast majority of the waveform’s energy is contained in the band of operational frequencies. This research explores this challenging design problem for active sonar using Multi-Tone Sinusoidal Frequency Modulation (MTSFM). The MTSFM waveform’s modulation function is a finite sum of weighted sinusoidal functions expressed as a Fourier series. The Fourier coefficients act as a tunable set of parameters that may be adjusted to synthesize a waveform with desired AF/ACF shapes. Utilizing a finite number of Fourier coefficients produces a modulation function that is smooth and continuous in time which results in a waveform with high SE. Simulations demonstrate that the MTSFM waveform’s design coefficients can be adjusted to finely control the waveform’s performance characteristics while maintaining the constant amplitude and high SE properties necessary for transmission on practical piezoelectric devices.
Speaker(s): David Hague,
Social hour 5:30 PM followed by dinner at 6:00 PM and talk at 7:00 PM
Room: The Laurel Room
McGoverns On The Water
310 Shove Street
Fall River, Massachusetts