Sine wave

About: Sine wave is a research topic. Over the lifetime, 12183 publications have been published within this topic receiving 93013 citations. The topic is also known as: sinusoid.

Composite seismic signal

Abstract: This invention provides for transmission of composite swept sine wave seismic signals wherein auto-correlation side lobes of such signals are reduced. The frequency spectrum of a desired swept sine wave seismic signal is divided into a number of consecutive segments, and the segments are arranged to form a sequence of segments by the order of frequency content. Component swept sine wave seismic signals each covering a segment in the sequence are generated simultaneously from the same location to produce the desired seismic signal. The component swept sine wave seismic signals are generated in a manner so that they alternate as upsweeps and downsweeps for consecutive segments in the sequence of segments. The seismic signal comprising the sum of the component swept sine wave seismic signals will have an auto-correlation function with reduced side lobes. Alternatively, the component swept sine wave seismic signals may be generated successively from the same location in a manner so that they alternate as upsweeps and downsweeps for consecutive segments in the sequence of segments. The reflections are successively recorded and stacked prior to correlation with the sum of the component swept sine wave seismic signals. Used in this manner, the sum of the component swept sine wave seismic signals will also have an auto-correlation function with reduced side lobes.

Active vibration reducing apparatus and method for identifying transfer function in active vibration reducing apparatus

Abstract: Described are a vibration actively reducing apparatus and a method for identifying a transfer function in the vibration actively reducing apparatus. An identification signal which is a quantization of at least one sinusoidal wave is supplied from a controller of the vibration actively reducing apparatus to a controlled vibration source in synchronization with a predetermined output sampling clock (SCo) to develop an identification vibration therefrom. The controller reads a residual vibration signal from a residual vibration detector of the actively reducing apparatus in synchronization with a predetermined input sampling clock (SCi). After read of the residual vibration signal as a time series data for each frequency, an FFT calculation is carried out for each time series data to extract a frequency component of the original sinusoidal wave. An inverse FFT calculation is, then, carried out for the result of the synthesis of each extracted frequency component to derive an impulse response as the transfer function.

Switch mode sine wave driver for polyphase brushless permanent magnet motor

Abstract: A switch mode sine wave driver circuit selectively sources and sinks driving currents to and from a dc brushless motor. A signal waveform monitoring circuit (58) puts out motor phase reference signals. A phase clock generator (102) provides a motor-synchronized clock signal. A phase counter (62) is clocked by the motor clock signal and is reset by the phase reference signals. A motor state decoder (116) generates state control signals based on the phase reference signals. A pulse width modulator circuit (84) responds to the output and generates phase pulses in order to rotate the motor.

Analog-to-digital conversion for low-frequency waveforms based on the Josephson voltage standard

Abstract: A waveform synthesizer adopting a superconductor–normal metal–superconductor junction array has been developed, which can generate arbitrary stepwise waveforms with a number of quantum-voltage steps up to 1 V level amplitude. As an application of the synthesizer, we have built a sampling voltmeter that measures the differential voltages between a sinusoidal waveform produced by a semiconductor-based ac source and the Josephson waveforms. We carried out extensive sampling measurements for a 50 Hz sine wave with 1 V amplitude, applying sampling apertures in the range of 55 µs ≤ta ≤ 130 µs and using Josephson waveforms with 32, 60, 80 and 100 quantum steps. From the measurements, the amplitude of the ac waveform was determined with a type A uncertainty (k = 2) of 0.15 µV. Also, we elucidated how the phase jitter in the ac waveform is reflected in the overall uncertainty for the measurements. The type B uncertainty due to the jitter is at least one order of magnitude smaller than the type A uncertainty.

Motor control apparatus and motor control method

Abstract: When a switch between sine wave voltage drive and rectangular wave voltage drive is effected based upon the motor rotation speed and a motor torque command value, an AC voltage forming an intermediate wave is generated by combining the sine wave and the rectangular wave and is applied to the motor.