62 results about "Beat noise" patented technology

A valve timing control device includes a purge path communicating between a hydraulic chamber allowing the entry of hydraulic pressure on starting an engine and a backward pressurized section in an accommodation hole. When the hydraulic chamber allowing the entry of hydraulic pressure on starting the engine is the retardation side hydraulic chamber, a hydraulic pressure derived from an oil pump is supplied to the retardation side hydraulic chamber on starting the engine. On the way, air-mixed oil is discharged to outside of the device by way of a purge path, a backward pressurized section in the accommodation hole and the discharge hole. When the air is discharged, a residual pressure is produced in the backward pressurized section due to oil supplied thereto. The residual pressure results in the increase of an unlocking hydraulic pressure to prevent a locking member from being unlocked. When the application of a retardation side hydraulic pressure is switched to that of an advance side hydraulic pressure, the pressure presses a front end of a locking member against only a biasing force of a biasing means to unlock a locking relation. The valve timing control device allows the use of any kinds of locking pins, and prevents the occurrence of beat noise (abnormal noise) when air-mixed oil unlocks a locking relation on starting the engine.

A novel Q-switch device enables significant quality and value improvement for a Q-switched laser system by achieving a significant reduction of mode-beating noise during the pulsed output. The origin of mode-beating noise in a Q-switched laser is a result of high gain availability and amplification of competing standing-waves in formation, whose optical frequency is a product of natural selection via spatial hole burning in the gain medium. The novel Q-switch device employs an active, electro-optics or acousto-optics, Q-switch in combination with a saturable absorber device, to provide an optimized soft opening of the optical path and a controlled timing of a Q-switched laser. This novel combination offers larger modulation loss than otherwise possible with the active modulator alone, and it allows for higher gain build-up and energy extraction efficiency. Specifically, it will enable a low-voltage modulator (<100 V) for high gain (small-signal gain>10) and Q-switched operation at high repetition rate (>10 kHz). The combination is devised to slow down the signal build-up and to sweep the fundamental longitudinal mode frequency at least within the free spectral range of the resonator, such that it varies adiabatically during the Q-switched pulse formation. A laser geometry amenable to high gain and high power is proposed for use in conjunction with the proposed novel Q-switch device. The invention will enable the deployment of cost-effective Q-switched lasers operating in both single-longitudinal and single-transverse (TEM00) mode.

A system and method for simultaneous delivery of a plurality of independent blocks of 500 MHz digital broadcast television services, stacking a plurality of RF blocks on a plurality of spectrally sliced WDM optical bands. The method for delivering a plurality of video blocks to a user terminal serviced by a remote node comprises the steps of receiving, by a first WDM, a broadband signal from a broadband signal source, separating, by the first WDM, the broadband signal into a plurality of optical bands, modulating each of the plurality of optical bands with a composite signal representing data in a plurality of independent RF blocks to form a plurality of modulated signals, forwarding the plurality of modulated signals to a second WDM to form a combined broadcast signal, transmitting the combined broadcast signal over feeder fiber to a remote node, selecting a RF block for distribution over a distribution fiber to a conventional satellite set-up box at a user's site and forwarding the selected RF block to the user's site. A novel method and system for reducing spontaneous beat noise is also disclosed.

Methods and systems for processing communication signals in an Orthogonal Frequency Division Multiple Access (OFDMA)-Passive Optical Network (PON) are disclosed. An optical carrier at a wavelength generated at an optical line terminal (OLT) may be reused by optical network units (ONUs) in the network for upstream transmission of data signals to the OLT. In addition, each ONU may perform carrier suppression to avoid broadband beating noise resulting from the simultaneous transmission of upstream data signals on the same wavelength. Further, the optical source at the OLT used to generate the optical carrier may be reused as a local oscillator for coherent detection of received upstream signals to minimize any frequency offsets.

Conventionally, a non-conductive period is provided in a region in the vicinity of zero of an AC power voltage via a voltage detection circuit 14 to turn off reliably. The FET 17 maintains the ON state within several switching cycles after the non-conductive interval to rapidly restore the magnetizing coil current, so that the magnetizing coil current rapidly increases. An object is to suppress beat noise in the electromagnetic device. Within a prescribed interval following the non-conductive interval, a partial voltage at a resistor 19 of an output V2 of a mono-stable circuit 20 is added as a bias voltage to a detection voltage of a magnetizing coil current at a resistor 18, and is detected by the IC 11. The IC 11 drives a FET 17 with a constant switching period after the non-conductive interval, thereby preventing the increase in the magnetizing coil current and resolving the problem.

A vehicle (1, 17) includes an electric drive motor (5, 19), an inverter (4) that provides a drive current to the electric motor (5, 19) and a controller (13) that controls the inverter (4). The controller (13) functions as a beat noise generation system that creates beat noise by generating a second operating noise containing a component an order of which is very close to a value representing an order of an operating noise generated in proportion to a rotation speed of the electric motor (5, 19) so as to create desirable traveling noise corresponding to an accelerating state while the vehicle accelerates.

The invention provides an imbalanced-Mach-Zehnder-based demodulation device for a multiplexing optical fiber interferometer. The device consists of a broadband light source, an optical circulator, an optical divider, a sensor array switching and transmitting optical fiber, an optical fiber sensor array, an imbalanced-Mach-Zehnder optical autocorrelator and an interference signal detecting unit inconnection, wherein the imbalanced-Mach-Zehnder interferometer forms an optical path correlator, narrow linewidth laser complexed in the correlator evaluates scanning amplitude and uniformity of the optical path, the optical path scanning error is compensated, and the measuring accuracy of the sensor is improved; the interference beating noise of the interferometer can be reduced, and multiplexing number of interferometers is improved; the optical autocorrelator demodulates signals of a multiplexing optical fiber sensor; and the unique optical path matching condition suppresses interference noise of secondary optical path matching. The device can be applied in the fields of real-time monitoring and measuring of multi-point stress or temperature and other physical quantities, monitoring oflarge-scale intelligent structures and the like.