Abstract: An acoustic or mechanical vibration testing system includes a MIMO control system coupled to at least two separately controllable groups of vibration transducers and at least two control sensor transducers wherein the number of control sensor transducers need not be equal to the number of controller output drives or number of separately controllable groups of vibration transducers. The MIMO control system utilizes both a predetermined initial reference specification and a modified reference specification, wherein data acquired during system operation under conventional MIMO control is used to create the modified reference specification based on actual system performance and limitations thereof so as to maintain closer correspondence to the predetermined initial reference specification with less required system drive power, as a function of the predetermined initial reference, and less risk of damage to the test system and the test article during the performance of a test.

Abstract: An acoustic or mechanical vibration testing system includes a MIMO control system coupled to at least two separately controllable groups of vibration transducers and at least two control sensor transducers wherein the number of control sensor transducers need not be equal to the number of controller output drives or number of separately controllable groups of vibration transducers. The MIMO control system utilizes both a predetermined initial reference specification and a modified reference specification, wherein data acquired during system operation under conventional MIMO control is used to create the modified reference specification based on actual system performance and limitations thereof so as to maintain closer correspondence to the predetermined initial reference specification with less required system drive power, as a function of the predetermined initial reference, and less risk of damage to the test system and the test article during the performance of a test.

Abstract: A direct field acoustic testing system comprising a control microphone, a controller operatively coupled to the control microphone such that the controller receives at least one input signal from the control microphone, and a plurality of acoustic transducer groups receiving an electronic signal from the controller, each transducer group including at least one acoustic transducer. An average power density of the direct field acoustic testing system for a pre-determined acoustic test spectrum being equal to or greater than 46 acoustic watts per square meter of total active acoustic transducer radiating surface area.

Abstract: An acoustic or mechanical vibration testing system includes a MIMO control system coupled to at least two separately controllable groups of vibration transducers and at least two control sensor transducers wherein the number of control sensor transducers need not be equal to the number of controller output drives or number of separately controllable groups of vibration transducers. The MIMO control system utilizes both a predetermined initial reference specification and a modified reference specification, wherein data acquired during system operation under conventional MIMO control is used to create the modified reference specification based on actual system performance and limitations thereof so as to maintain closer correspondence to the predetermined initial reference specification with less required system drive power, as a function of the predetermined initial reference, and less risk of damage to the test system and the test article during the performance of a test.

Abstract: A direct field acoustic testing system includes at least one control microphone, a controller operatively coupled to the control microphone such that the controller receives at least one input signal from the control microphone, and at least four acoustic transducer groups operatively coupled to the controller such that each transducer is separately controllable by the controller such that a separate output signal is received by each transducer from the controller. A setup signal is applied to each of the acoustical transducers. The acoustic output of each of the acoustical transducers is monitored using the at least one control microphone. Assumptions regarding the relationship between the acoustic fields measured by the control microphones are made to enable the controller to reduce the number of calculations needed to compute error functions and corrected drive signals to be applied to the acoustic transducer groups.

Abstract: A direct field acoustic testing system includes at least one control microphone, a controller operatively coupled to the control microphone such that the controller receives at least one input signal from the control microphone, and at least four acoustic transducers operatively coupled to the controller such that each transducer is separately controllable by the controller such that a separate output signal is received by each transducer from the controller. A setup is applied to each of the acoustical transducers. The acoustic output of each of the acoustical transducers is monitored using the at least one control microphone. The output signal of each control microphone with respect to each acoustical transducer is compared to a reference spectrum to create a matrix of error functions, and a corrected drive signal computed for each acoustical transducer is applied to the respective acoustical transducer.

Abstract: A direct field acoustic testing system includes at least one control microphone, a controller operatively coupled to the control microphone such that the controller receives at least one input signal from the control microphone, and at least four acoustic transducers operatively coupled to the controller such that each transducer is separately controllable by the controller such that a separate output signal is received by each transducer from the controller. A setup is applied to each of the acoustical transducers. The acoustic output of each of the acoustical transducers is monitored using the at least one control microphone. The output signal of each control microphone with respect to each acoustical transducer is compared to a reference spectrum to create a matrix of error functions, and a corrected drive signal computed for each acoustical transducer is applied to the respective acoustical transducer.

Abstract: A direct field acoustic testing system includes at least one control microphone, a controller operatively coupled to the control microphone such that the controller receives at least one input signal from the control microphone, and at least four acoustic transducer groups operatively coupled to the controller such that each transducer is separately controllable by the controller such that a separate output signal is received by each transducer from the controller. A setup signal is applied to each of the acoustical transducers. The acoustic output of each of the acoustical transducers is monitored using the at least one control microphone. Assumptions regarding the relationship between the acoustic fields measured by the control microphones are made to enable the controller to reduce the number of calculations needed to compute error functions and corrected drive signals to be applied to the acoustic transducer groups.

Abstract: An apparatus and method for adaptively updating the drive signal in a shock testing system so as to produce a desired response signal. The updates to the drive signal are based on measurements of the system's actual response signal and closed loop updates to the test system's transfer function. An initial estimate of the test system transfer function is obtained by using a calibration signal as the drive signal and measuring the response signal. An initial estimate of the actual drive signal is then obtained based on the desired response signal and the initial estimate of the transfer function. The initial estimate of the drive signal is then applied to the test system, and the actual response signal is measured. The present invention then adaptively updates the test system transfer function.

Abstract: A multiexciter digitally swept-sinewave vibration test controller employing an adaptive control method which compensates for nonlinear and time variant physical characteristics of a system under test and for instrumentation errors. A system under test (12) is stimulated using an exciter array (26) and response is measured using a sensor array (28). The exciter array (26) is driven by signals produced by a digital vector swept oscillator (18). A control loop (14) is used to modify signals to the exciter array (26) based upon input from the sensor array (28). A digital processing system (24) processes signals in the control loop (14). Within the digital processing system (24), a system impedance matrix (44) containing values representing the inverse of response characteristics of the system under test (12) is updated to approximate an "actual" system impedance matrix. A drive signal matrix (52) is modified to cause the digital vector swept oscillator (18) to produce updated drive signals.

Abstract: A method for calibrating measurement or analysis systems that is externally traceable, simple, and repeatable, which is particularly amenable to computer control, and a unique programmable phase-gain amplifier which is especially suited for use in the calibration method, are disclosed. Alternatively, a programmable sample clock delay technique is disclosed to provide phase calibration. The method employs an externally traceable digital voltmeter to measure the magnitude of the signal being applied to an input channel of the measurement system; and obtains a digital representation of the output of the channel. When the input magnitude does not match the output magnitude, the programmable phase-gain amplifier gain is adjusted. These adjustments are made for each range of each channel.

Abstract: A method and apparatus for converting a digital signal into a band-limited analog signal with variable bandwidths, a high level of performance, high spurious frequency rejection, and simple implementation, employing polyphase interpolating digital filters, a fixed-sampling rate digital to analog converter, and a fixed-frequency analog low-pass filter.