Remote communication and control of acoustic detectors
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Publication Number
US-8964509-B2
Publication Date
2015-02-24
Expiration Date
Abstract
A method of controlling a function of an acoustic detector includes storing a reference power spectrum of a reference acoustic signal, the reference power spectrum being associated with a mode of operation of the acoustic detector; receiving an acoustic sound signal, the acoustic sound signal including a tone and harmonic tones; generating a real-time acoustic power spectrum of the acoustic sound signal responsive to the receiving of the acoustic sound signal; and performing the mode of operation when a comparison of the real-time acoustic power spectrum with the reference acoustic power spectrum indicates that the acoustic sound signal is a control signal.
Core Innovation
A control system controls a function of an acoustic detector by using a memory that stores a reference power spectrum of a reference acoustic signal, where the reference power spectrum is associated with a mode of operation of the acoustic detector. The system receives an acoustic sound signal that includes a tone and harmonic tones, and a receiver generates a real-time acoustic power spectrum in response to receiving the acoustic sound signal.
A detector performs the mode of operation when a comparison of the real-time acoustic power spectrum with the reference power spectrum indicates that the acoustic sound signal is a control signal. The comparison includes normalizing each of the real-time acoustic power spectrum and the reference power spectrum, calculating a normalized mean squared error between the normalized spectra, and comparing the normalized mean squared error to a threshold.
The described approach reduces sensitivity to amplitude variation by normalizing the spectra prior to error calculation, and it supports distinguishing a control signal from spurious noise by using the thresholded normalized mean squared error decision. A mode control result is then used to perform detector mode of operation when the comparison indicates a control signal.
Claims Coverage
The document includes two independent claims: one directed to a control system and one directed to a method. Across these independent claims, the inventive features are the use of a reference power spectrum associated with detector modes, real-time power-spectrum generation from a tone and harmonic tones, and a normalized mean squared error comparison to a threshold for control-signal indication.
Reference power spectrum associated with a mode of operation
A memory stores a reference power spectrum of a reference acoustic signal, with the reference power spectrum associated with a mode of operation of the acoustic detector.
Real-time acoustic power spectrum generation from tone and harmonic tones
A receiver receives an acoustic sound signal including a tone and harmonic tones, and generates a real-time acoustic power spectrum in response to receiving the acoustic sound signal.
Control by comparing normalized spectra using normalized mean squared error thresholding
A detector performs the mode of operation when a comparison indicates the acoustic sound signal is a control signal, where comparing includes normalizing the real-time and reference power spectra, calculating normalized mean squared error between the normalized spectra, and comparing the normalized mean squared error to a threshold to indicate that the acoustic sound signal is the control signal.
Both independent claims cover the same core inventive concept: detector mode control is triggered by identifying a received acoustic signal as a control signal through a normalized spectral comparison between a stored reference power spectrum associated with a mode and a real-time power spectrum generated from a tone and harmonic tones, using normalized mean squared error compared to a threshold.
Stated Advantages
Rejects amplitude variation with distance by normalizing each of the real-time acoustic power spectrum and the reference power spectrum before computing normalized mean squared error.
Supports false command rejection by using a normalized mean squared error compared to a threshold to distinguish control signals from spurious noise.
Documented Applications
Remote communication/control of an acoustic detector using an acoustic control signal such that the detector performs a mode of operation when the control signal is recognized.
Detector mode control with a reference signature corresponding to detector mode of operation based on a received acoustic sound signal including a tone and harmonic tones.
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