Active acoustic resonator for abating noise
AssigneeDaimlerChrysler AG
InventorRudolf Maier
Life of this patent
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Abstract
An active acoustic resonator is provided for noise reduction, with a sound generator having a membrane, with a sensor for measuring the membrane motion, with an actuator for driving the membrane, as well as with a controller receiving the measured signal of the sensor and generating control signals for the actuator. A transfer function (F.sub.R) of the controller is proportional to a quotient, whose numerator (F.sub.BP) has the transfer behavior of a band pass filter with variable center frequency (f.sub.0), and whose denominator represents the transfer function (F.sub.U) of the actuator.
Claims4
An active acoustic resonator for noise reduction, comprising:
- a sound generator having a membrane;
- a sensor for measuring membrane motion;
- an actuator for driving the membrane;
- a controller receiving the measured signal of the sensor and generating control signals for the actuator, said controller having a transfer function (F.sub.R) which is proportional to a quotient, whose numerator (F.sub.BP) has the transfer behavior of a band pass filter with variable center frequency (f.sub.0), and whose denominator represents the transfer function (F.sub.U) of the actuator.
An active acoustic resonator for noise reduction, comprising:
- a sound generator having a membrane;
- a sensor for measuring membrane motion;
- an actuator for driving the membrane;
- a controller receiving the measured signal of the sensor and generating control signals for the actuator, said controller having a transfer function (F.sub.R) which is proportional to a quotient, whose numerator (F.sub.BP) has the transfer behavior of a band pass filter with variable center frequency (f.sub.0), and whose denominator represents the transfer function (F.sub.U) of the actuator;
- a circuit embodying the band pass filter has, between its input and its output, two mutually parallel forward branches each with an integrator arranged between two multipliers as well as a return branch that contains an amplification member and feeds the output back to the input, wherein a sinus signal is applied to said multipliers in one forward branch and a cosine signal with the center frequency (f.sub.0) of the band pass filter is applied to said multipliers of the other branch.
Dependencies are inferred from the claim text.