Abstract: A vibration generation system and method independently controls both frequency spectrum and amplitude distribution. Sensed vibration is used in feedback as a control to generate a controlled drive signal applied to a mechanical actuator. The amplitude distribution has a specified statistical characteristic adjusted to match a target characteristic, such as kurtosis, by adjusting a relative proportion of a coherent component in a randomized phase, which is then combined on a frequency-by-frequency basis with the separately adjusted frequency spectrum while in the frequency domain.

Abstract: A circuit and method of analog data acquisition synchronization from an analog sensor in multiple channels associated with a USB hub. An analog to digital converter connected to the sensor that is part of a USB device has a time and phase corrected sampling clock that is referenced to a start-of-frame traffic signal with a preconfigured message indicating a time offset or delay seen upstream through a USB port. A plurality of similar devices are autonomously synchronized by the same message for multi-channel data acquisition by a locally generated trigger signal that allows a preset amount of delay set by the message. An accelerometer is a preferred sensor for such multi-channel data acquisition.

Abstract: A control method for a mechanical vibration system independently modifies the higher and lower frequency components of the drive signal satisfying a target profile in a manner that limits displacement in the driven vibration. In particular, phases of the lower frequency components in a preliminary drive spectrum are independently adjusted so that peaks of the respective components are non-simultaneous and distributed in time to avoid contributing constructively. For example, the lower frequency components may be applied as a filter to a narrow-band time waveform, such as one with a swept frequency, to obtain the lower-frequency time waveform. The higher frequency components are randomized in their phase, transformed into the time domain, and recombined with the lower frequency part to obtain the drive signal.

Abstract: A vibration generation system and method independently controls both frequency spectrum and amplitude distribution. Sensed vibration is used in feedback as a control to generate a controlled drive signal applied to a mechanical actuator. The amplitude distribution has a specified statistical characteristic adjusted to match a target characteristic, such as kurtosis, by adjusting a relative proportion of a coherent component in a randomized phase, which is then combined on a frequency-by-frequency basis with the separately adjusted frequency spectrum while in the frequency domain.

Abstract: The present invention utilizes multiple A/D (analog-to-digital) paths and cross-path calibration to provide accurate and reliable measurements for each input channel in a data acquisition system. When the system and method are applied, user and automated methods of selecting among a number of alternative input range settings can be reduced, or even eliminated. That is, there is a significant reduction or complete elimination of input range settings in a measurement system. For each measurement channel of interest, the input signal is directed to at least two paths, e.g., Path A and Path B. The first path measures the full range (e.g., +/?10 volts), while the second path includes a high-gain amplifier. Each path includes an analog-to-digital converter (ADC), so that there is a one-to-one correspondence between the number of paths and the number of ADCs, which sample the input signal simultaneously.