Abstract: Infrared sensing systems having improved vibration cancelation, and methods of achieving improved vibration cancelation. In one example, an infrared sensing system includes an infrared sensor configured to produce a sensor output signal representative of a response of the infrared sensor to infrared excitation and vibration excitation, an accelerometer configured to provide an acceleration signal responsive to the vibration excitation, and a controller, including an adaptive digital filter, coupled to the infrared sensor and to the accelerometer, and configured to receive the acceleration signal and to adjust coefficients of the adaptive digital filter so as to minimize coherence between a residual signal and the acceleration signal, the residual signal being a difference between the sensor output signal and a filter output signal from the adaptive digital filter.

Abstract: Acoustic sensing systems having improved vibration cancelation, and methods of achieving improved vibration cancelation. In one example, an acoustic sensing system includes an acoustic sensor configured to produce a sensor output signal representative of a response of the acoustic sensor to acoustic excitation and vibration excitation, at least one accelerometer configured to provide an acceleration signal responsive to the vibration excitation, and a controller, including an adaptive digital filter, coupled to the acoustic sensor and to the at least one accelerometer, and configured to receive the acceleration signal and to adjust coefficients of the adaptive digital filter so as to minimize coherence between a residual signal and the acceleration signal, the residual signal being a difference between the sensor output signal and a filter output signal from the adaptive digital filter.

Abstract: Optical sensing systems having improved vibration cancelation, and methods of achieving improved vibration cancelation. In one example, an optical sensing system includes an optical sensor configured to produce an unprocessed sensor output signal representative of a response of the optical sensor to at least an optical signature of interest and a local vibration excitation, a reference sensor configured to provide a reference signal responsive to the local vibration excitation, and a controller, including an adaptive digital filter, coupled to the optical sensor and to the reference sensor, and configured to receive the reference signal and to adjust one or more coefficients of the adaptive digital filter to minimize coherence between a residual signal and the reference signal, the residual signal being a difference between the sensor output signal and a filter output signal from the adaptive digital filter.

Abstract: Infrared sensing systems having improved vibration cancelation, and methods of achieving improved vibration cancelation. In one example, an infrared sensing system includes an infrared sensor configured to produce a sensor output signal representative of a response of the infrared sensor to infrared excitation and vibration excitation, an accelerometer configured to provide an acceleration signal responsive to the vibration excitation, and a controller, including an adaptive digital filter, coupled to the infrared sensor and to the accelerometer, and configured to receive the acceleration signal and to adjust coefficients of the adaptive digital filter so as to minimize coherence between a residual signal and the acceleration signal, the residual signal being a difference between the sensor output signal and a filter output signal from the adaptive digital filter.

Abstract: Acoustic sensing systems having improved vibration cancelation, and methods of achieving improved vibration cancelation. In one example, an acoustic sensing system includes an acoustic sensor configured to produce a sensor output signal representative of a response of the acoustic sensor to acoustic excitation and vibration excitation, at least one accelerometer configured to provide an acceleration signal responsive to the vibration excitation, and a controller, including an adaptive digital filter, coupled to the acoustic sensor and to the at least one accelerometer, and configured to receive the acceleration signal and to adjust coefficients of the adaptive digital filter so as to minimize coherence between a residual signal and the acceleration signal, the residual signal being a difference between the sensor output signal and a filter output signal from the adaptive digital filter.

Abstract: The systems and methods described herein include an acoustic sensor having piezoelectric material housed in a cartridge and sealed with a solid nonporous stainless steel cover. The systems include additional elements to tune the performance of the acoustic sensor for measuring shockwaves on the surface of an aircraft, such as a helicopter. In particular, the system includes several vibration isolating elements including foam pads and O-rings disposed between the cartridge and the cover for isolating the piezoelectric material from aircraft vibration and turbulence. Additionally, the systems and methods include circuitry for converting analog electrical signals generated by the piezoelectric material, in response to acoustic signals, to digital electrical signals.

Abstract: The systems and methods described herein include an acoustic sensor having piezoelectric material housed in a cartridge and sealed with a solid nonporous stainless steel cover. The systems include additional elements to tune the performance of the acoustic sensor for measuring shockwaves on the surface of an aircraft, such as a helicopter. In particular, the system includes several vibration isolating elements including foam pads and O-rings disposed between the cartridge and the cover for isolating the piezoelectric material from aircraft vibration and turbulence. Additionally, the systems and methods include circuitry for converting analog electrical signals generated by the piezoelectric material, in response to acoustic signals, to digital electrical signals.

Abstract: The systems and methods described herein relate to an airborne shooter detection system having a plurality of sensors coupled to the body of an aircraft such as a helicopter. The sensors are arranged to receive shockwave-only signals. The received signals are analyzed to determine an unambiguous shooter location. The analysis may include measuring the arrival times of the shockwaves of projectiles at each of the sensors, determining the differences in the arrival times among sensors, computing a set of ambiguous solutions corresponding to a shooter, and clustering this set of solutions to determine the unambiguous shooter location. The systems and methods described herein may also be used to determine if multiple shooters are present, and subsequently determine the shooter locations for each of the multiple shooters.

Abstract: The systems and methods described herein relate to an airborne shooter detection system having a plurality of sensors coupled to the body of an aircraft such as a helicopter. The sensors are arranged to receive shockwave-only signals. The received signals are analyzed to determine an unambiguous shooter location. The analysis may include measuring the arrival times of the shockwaves of projectiles at each of the sensors, determining the differences in the arrival times among sensors, computing a set of ambiguous solutions corresponding to a shooter, and clustering this set of solutions to determine the unambiguous shooter location. The systems and methods described herein may also be used to determine if multiple shooters are present, and subsequently determine the shooter locations for each of the multiple shooters.

Abstract: Methods and systems of parasitic sensing are shown and described. The method includes, measuring, at a first time using one or more electrical elements native to a domain, a parameter of a circuit within the domain and measuring, at a second time using the one or more electrical elements native to the domain, the parameter. The method also includes, comparing the parameter measurement from the first time to the parameter measurement at the second time and determining, in response to the comparison, that an activity occurred within the domain.

Abstract: A method and apparatus of performing power line sensing is presented. The method and apparatus includes a three-axial vector magnetic sensor for detecting a magnetic field radiated from a power line. An active isolation system is used to determine the effects of noise and other magnetic fields on the three-axial vector magnetic sensor. Power line status information is then determined from data received from the three-axial vector magnetic sensor and the active isolation system.

Abstract: An active noise and vibration control system is constructed such that the residual signal from the residual sensor is fed back into the controller and used to generate the probe signal. Measurements of the residual signal are used to create a related signal, which has the same magnitude spectrum as the residual signal, but which is phase-uncorrelated with the residual signal. This latter signal is filtered by a shaping filter and attenuated to produce the desired probe signal. The characteristics of the shaping filter and the attenuator are chosen such that when the probe signal is filtered by the plant transfer function, its contribution to the magnitude spectrum of the residual signal is uniformly below the measured magnitude spectrum of the residual by a prescribed amount (for example, 6 dB) over the entire involved frequency range. The probe signal is then used to obtain a current estimate of the plant transfer function.