141 results about "Low frequency modulation" patented technology

For measuring the rotational frequency of a movable game device, one resorts to an existing radio signal in the form of a broadcast signal or mobile communication signal within the framework of an open system, or to a radio signal of an evaluation unit within the framework of a closed system, so as to obtain, by means of an antenna having a directivity characteristic, a time-varying radio antenna receive signal which has a low-frequency modulation portion, the frequency of which corresponding to the rotational frequency of the movable game device.

A power supply apparatus and method of regulating is provided. A clock generator circuit is configured for generating a clock signal at a predetermined frequency. An amplifier circuit is coupled with the clock generator circuit. The amplifier circuit includes a gain circuit coupled with the clock generator circuit. The amplifier circuit is configured to receive the clock signal at a switching element of the gain circuit. A controller circuit is configured for receiving a modulated error signal of the amplifier circuit and is configured for generating a pulse width modulated signal for controlling a duty cycle of the switching circuit. The switching circuit is configured for receiving the modulated error signal. The error signal is modulated using the clock signal to vary a gain value of the gain circuit according to the predetermined frequency. An output circuit is coupled with the switching circuit and is configured for generating a regulated voltage signal. The controller circuit uses the modulated error signal to substantially reduce harmonic distribution in a switching frequency of the switching circuit. Harmonic distribution in the switching circuit can be reduce by 10.0 db or greater.

The invention discloses a two-dimensional ISRA imaging method of an object with micro rotation in the air. The method comprises the following steps that: (1), a radar matriculates an ISAR echo; (2), translation compensation is carried out; (3), time frequency distribution map is drafted; (4), micro doppler distance units are determined; (5), echo separation of a distance unit; (6), it is determined whether all distance unit have been traversed; (7), a distance-doppler method is used to carry out imaging on a rigid body echo; and (8), imaging is carried out on a rotary part echo. According to the invention, a low frequency modulation rate matched filtering method is employed to carry out echo separation, so that an adaptive chirplet decomposition imaging method's disadvantages including large calculated amount, high time consumption and insufficience of real-time property are overcome; therefore, the method has advantages of simple realization, high efficient and high real-time property. According to the invention, an I-Radon conversion is employed to carry out imaging on a rotary part; therefore, defects of an EHT algorithm are overcome, wherein the defects include high image sidelobe of a rotary object, low precision of estimation position and inaccuracy of object identification; and the method has advantages of good image focusing, high position estimation precision and accurate object identification.

The invention discloses an aluminium alloy twin-wire dipulse welding method and a welding power supply thereof. The specific method is as follows: carrying out low frequency modulation on pulse wave shapes on the basis of high frequency to obtain periodically varied pulse bursts; and carrying out efficient and superior welding on aluminium alloy through the active phase match of two branches of the pulse bursts. The welding power supply comprises IGBT soft switching main circuits which are integrated into a whole, a DSP control circuit and a man-machine interactive system. The invention puts forward realizing dipulse aluminum alloy welding on a twin-wire welding machine for the first time, realizes all digital control, directly generates eight branches of PWM signals by utilizing a software module, controls the two main circuits, and reduces the control problems caused by communication; and simultaneously, the two main circuits are concentrated on the same welding machine so that the overall structure is much smaller than the master-slave mode welding machine, in addition methods such as instantaneous energy control and the like are adopted to realize the fine control of dipulse.

A method of processing a color digital image having a luminance channel and one or more chrominance channels to improve the tone scale characteristics of the image, includes the steps of: producing a control signal from the one or more chrominance channels; generating a pedestal signal containing mainly low frequency modulation by filtering the luminance channel with a spatial filter, whereby the operation of the spatial filter is modulated by the control signal; and producing a texture signal by subtracting the pedestal signal from the luminance channel.

Radio-frequency (RF) excitation is used for direct detection of hybridization events at microelectrodes with surface-attached DNA oligomers. A homodyne reflectometer operates on a high frequency carrier to detect the presence of a low-frequency modulation signal. Without non-linearities in an interface, the modulation signal is not impressed upon the carrier signal. As such, the reflectometer can sensitively measure changes in dielectric properties without interference from other sources of capacitance/resistance unrelated to the reaction at the surface.

An integrated data jitter generator for the testing of high speed serial interfaces is provided. A transmit timing generator for use in a transmit data path includes a high frequency clock generator such as a phase-locked loop or a delay-locked loop having an input for receiving an oscillator or reference clock input. A clock modulator receives both an existing low frequency modulation signal and a high frequency modulation signal. A high-speed modulated clock signal is generated to enable jitter testing by a downstream-coupled receiver. Fixed frequencies such as 3, 6, 125, 150, 250, 300, 750, or 1500 MHz are used for the high-speed modulation signal, but any high-speed modulation frequency can be used to generate the desired amount of jitter. Likewise, the amplitude of the high frequency modulation signal can also be varied as desired.

The invention discloses a microwave flow meter which comprises a microwave signal source, a microwave sensor, a signal preprocessing circuit and a signal processing circuit. In the invention, two receiving sensors respectively convert received signals into electrical signals; the two signals sequentially pass through a radio-frequency (RF) amplifying circuit, a demodulation circuit for demodulating low-frequency modulating signals, a low-pass filter (LPF) for filtering out high-frequency noise, and a low-frequency amplifying circuit; then the two signals are transferred to an analog-to-digital converter for analog-to-digital conversion, and the converted data is transferred to an upper computer; and finally, correlation algorithm processing is carried out on the two paths of received low-frequency noise signals so as to acquire the flow velocity, thereby acquiring the needed final data information such as flow quantity, accumulated flow quantity and the like. The microwave flow meter has the advantages of real-time property, high efficiency, high accuracy and the like.

The invention relates to a method for creating a control channel in an optical transmission signal, wherein the optical transmission signal (S_DS,i, S_US,i) includes an optical carrier frequency component, a higher frequency modulation component carrying user information to be transported from a first end to a second end of an optical transmission link and a lower frequency modulation component carrying control information, the higher frequency modulation component realizing a user channel and the lower frequency modulation component realizing the control channel, and wherein the lower frequency modulation component is created by amplitude modulation. According to the invention, the lower frequency modulation component includes a binary digital pilot tone signal component which corresponds to a pilot tone signal having a predetermined pilot tone frequency (f_i).

The invention discloses an even-number closed loop optical fiber magnetometer for achieving working point control and magnetism return-to-zero, which comprises a light source drive circuit, a light path sensing unit, a photoelectric conversion unit, an A/D conversion unit, a digital signal processing unit, a D/A conversion unit and the like, wherein the light path sensing unit comprises a DFB laser, a three-port optical circulator, an integrated optical phase modulator and the like, and has simple structure; the digital signal processing unit various control time sequences, low-frequency modulation square wave and a synchronous clock of a high-frequency sine modulation signal, completes relative demodulation of low-frequency phase drift and generates compensation phase shift digital quantity, secondarily demodulates a signal subjected to relative demodulation of the low-frequency phase drift to generate the magnetic field signal feedback quantity, forms the even-number closed loop detection, achieves the stable control and magnetism return-to-zero feedback of an interferometer orthogonal working point, improves the anti-jamming capability and the stability of the system, expands the dynamic range of measuring, and improves the sensitivity for measuring the magnetism.

The invention discloses a device for improving the output frequency stability of a laser and the laser with the device, which belong to the technical field of lasers. The device comprises a first absorption chamber, a frequency modulation module, a second absorption chamber, a first photoelectric detection module, a first servo module and a piezoelectric crystal driver, wherein the first absorption chamber is used for selecting laser signals with preset frequency from laser beams of the laser; the frequency modulation module is used for performing low-frequency modulation on the laser signals selected from the first absorption chamber; the second absorption chamber is used for selecting laser signals with preset frequency from the modulated laser signals; the first photoelectric detection module is used for detecting the intensity of the laser signals selected by the second absorption chamber and outputting a first photoelectric detection signal; the first servo module is used for outputting a first correction voltage according to the difference between the first photoelectric detection signal and the preset signal; and the piezoelectric crystal driver is used for adjusting the frequency of the laser beams according to the first correction voltage. The laser comprises a laser tube and the device. The device disclosed by the invention can be used for improving the output frequency stability of the laser.

A set of implements for shaving a body part capable of reducing skin irritation, preventing or promoting faster healing of skin cuts through delivering of a low frequency modulation magnetic field therapy. The set includes a shaving brush and a razor. The shaving brush includes a handle, magnetically conductive bristles, and a permanent magnet contained in the handle of the shaving brush. One set of ends of the bristles of the shaving brush are embedded in the permanent magnet, with the bristles extending axially therefrom and out through the handle of the shaving brush. The magnet forms a magnetic field directed towards the body part and oriented so the positive end of the magnet is directed also towards the body part. During application of shaving cream, repetitive motions by the user cause low frequency modulation of the magnetic field to be applied to the body part that possesses prophylactic and healing properties. The razor includes a handle, a blade cartridge, a razor blade, and a plurality of bi-polar magnets positioned on the blade cartridge away from the cutting edge of the blade. In a preferred configuration, the magnets are spaced apart so as not to interfere with one another and are oriented in parallel to cause a combined magnetic field to be directed towards the body part during shaving. It is preferred that the magnets are positioned on the razor to be in direct contact with the body part in order to deliver the magnetic therapy of maximum efficacy.

The invention discloses a digital ultrasonic transcranial Doppler digital demodulation signal processing method and device. The method comprises the following steps: performing the A/D (analog/digital) sampling on an input frequency-modulated wave which is a non-demodulated ultrasonic echo signal, and then performing the amplitude limiting through a digital comparator; detecting a modulation signal reflected on the frequency conversion in a frequency-modulated save subjected to the amplitude limiting; and taking the absolute value of the modulation signal, responding the changes of the amplitude of the modulation signal to an envelope line, and acquiring a low-frequency modulation signal through a down-sampling low-pass filter. The device comprises an AD converter, at least two large-capacity high-speed caches FIFO (first in first out), a DSP digital signal processor), and an FPGA (field programmable gate array). According to the invention, the wide frequency band scanning and the full-depth scanning can be realized, the timeliness and signal-to-noise ratio (SNR) of the system are improved, a blood flow dynamic parameter is accurately extracted, the SNR of a detecting signal is improved, and the quality of a frequency spectrum image is improved.

An optical network including multiple nodes is subject to intermittent faults that may raise alarms in the system. The invention focuses on an optical network based on the Any rate architecture. A single fault such as a client failure at a node in such a network can give rise to a loss of client signal leading to multiple alarms detected at multiple points. To alleviate this problem this invention provides switching in a special Signature signal in place of the lost client signal. By detecting the Signature signal containing a specific code, the fault on the any rate-based architecture can be uniquely identified. In addition to fault identification, the Signature signal on the network makes it possible to maintain Clock and Data Recovery Locks at downstream nodes. The Signature signal serves also as a vehicle for carrying a special optical tag called Wavekey provided by the Wavelength Tracker technology developed by the Applicant. This optical tag includes a low frequency modulation of one or more dither tones onto an optical channel, which is uniquely identified by the tag. Maintaining the Wavekey is important for tracing the end-to-end path and power level of the signal on each wavelength. A method and a Field Programmable Gate Array-based system for the generation and identification of such a Signature signal that not only identifies the fault that has occurred on the optical network but also provides for the maintenance of the Wavekey, are described.

Described herein is a device and system and method for the detection of naturally occurring gas bubbles in the bloodstream; in one embodiment, a wireless optical device may be placed on various parts of the body including a finger or earlobe or is coupled with the SCUBA mouthpiece and detects certain vital signs such as heart rate, blood oxygen saturation (SpO2) and respiration rate by analyzing the photoplethysmogram (PPG) from a miniature sensor. There is also a method and apparatus for real-time non-invasive optical monitoring of actual state of decompression sickness are presented. The method is based on simultaneous measurements of PPG signals in different locations of human body and analysis of such a factor as phase shifts between various locations, change the shape of PPG signal between different locations, existence and modification of slow trends and low frequency modulations and angular distributions of the out-coming light.

The invention discloses a self-measurement-control mosquito expelling and killing device which comprises a mosquito sound positioning assembly, an ultrasonic expelling assembly, a mosquito sucking and killing assembly and an assembly control module. The assembly control module is connected with the mosquito sound positioning assembly, the ultrasonic expelling assembly and the mosquito sucking and killing assembly. The mosquito sound positioning assembly comprises audio sensors, an operational amplifier module and an AD module which are sequentially connected. The assembly control module calculates the sound source position and the frequency and phase of a sound source through the different linear distances between at least two audio sensors in the mosquito sound positioning assembly and the sound source and drives the ultrasonic expelling assembly or the mosquito sucking and killing assembly to work according to the distance, frequency and phase information. When the ultrasonic expelling assembly works, the ultrasonic expelling assembly gives out same-phase or reverse-phase low-frequency modulation ultrasound wave signals or low-frequency signals with the same frequency as that of the sound source of mosquitoes. The self-measurement-control mosquito expelling and killing device can react on mosquitoes of different types and genders in different regions and reach the mosquitoes intelligently to achieve the optimal culling effect; the mosquitoes can be expelled or killed intelligently, efficiently and quickly through sound-light alarm.

The invention discloses an optical detection system for measuring concentrations of different gases. A microprocessor controls a signal source to generate a voltage drive signal and controls the signal source to output a low-frequency sinusoidal modulating signal and a frequency-doubling square wave reference signal, the low-frequency sinusoidal modulating signal is used for carrying out wavelength regulation on output light of an adjustable optical filter, the frequency-doubling square wave reference signal is used for locking the reference input of an amplifier so as to control the output wavelength of the adjustable optical filter for completing the selection of a measuring gas, and a low-frequency modulation and locking amplification technology is selected according to the characteristic of a device for achieving the demodulation of the concentrations of the gases. Compared with a traditional method for measuring the concentrations of different gases, the optical detection system is capable of selectively measuring different gases, achieves concentration modulation by adopting a hardware circuit, and particularly relates to the absorption characteristic of the gas in a near-infrared band and a wavelength-modulation-based locking and amplifying technology. The optical detection system for measuring the concentrations of different gases has the advantages of high integration degree, strong anti-electromagnetic interference capacity, high measuring degree, stable and reliable performance and long service life and the like.

The invention discloses an electronic drive mosquito-killer comprising a shell. A mosquito acoustic location component, a low-frequency modulation ultrasonic/low-frequency transmitting dispelling component, a suction-killing component and a component control module are mounted within the shell. The mosquito acoustic location component comprises a microphone, an operational amplifier module and an AD (analog/digital) module connected in order. The mosquito acoustic location component, the low-frequency modulation ultrasonic/low-frequency transmitting dispelling component and the suction-killing component are connected with the component control module. The component control module receives information transmitted by the mosquito acoustic location component, calculates the information of an acoustic source, drives the low-frequency modulation ultrasonic/low-frequency transmitting dispelling component or the suction-killing component to operate according to the information; the low-frequency modulation ultrasonic/low-frequency transmitting dispelling component sends out low-frequency modulation ultrasonic signals or low-frequency signals under the same frequency as, the same phase as or the opposite phase to a mosquito acoustic source. The electronic drive mosquito-killer is capable of responding to mosquitoes of different types and from different areas, making prompts on existence of the mosquitoes, and automatically dispelling or killing the mosquitoes in an intelligent, efficient and fast way.

The invention provides a control system and a control method of welding equipment. The welding equipment comprises a welding power source and a wire feeding device, wherein the communication is carried out between the welding power source and the wire feeding device by a method of loading high-frequency carriers on a power line. The control method comprises the following steps of inputting information of welding conditions at the wire feeding device side; generating a baseband signal according to the information of the welding conditions; demodulating multiple paths of high-frequency carriers with different frequency according to the generated baseband signal; sending the multiple paths of high-frequency carriers with different frequencies; at the welding power source side, receiving the multiple paths of high-frequency carriers with different frequency sent from the wire feeding device side; demodulating the received high-frequency carriers into a low-frequency modulation signal; shaping and filtering the demodulated low-frequency modulation signal, and outputting; and determining a signal for controlling the output of the welding power source, and controlling the output of the welding power source according to the determined signal. The control system and the control method have the advantages that the anti-jamming capability is realized, and the stable welding is ensured.

The invention discloses a new method for performing digital phase-locking processing on a passive atomic clock. The new method comprises the steps of performing high-precision digital processing on an excited low-frequency modulation signal and an error feedback signal of a physical portion in the passive atomic clock respectively to realize capturing of the maximum energy level transition probability points (such as the lowest optical detection signal point in the passive rubidium atomic clock) and the zero frequency modulation point of a low-frequency modulation signal, and further to obtain a time difference between the two points; then obtaining a frequency difference of VCOCXO based on a relationship between time and frequency deviation; measuring a time interval tau between the two maximum energy level transition probability points to obtain phase difference change information deltaT; and after accumulated phase difference change is obtained, realizing the high-precision digital phase-locking technology of the passive atomic clock. The new method for performing digital phase-locking processing on the passive atomic clock not only simplifies the internal circuits of the passive atomic clock to a great extent, but also can change the change rule of the frequency stability of the passive atomic clock along with the time in principle, and accordingly can greatly improve the frequency stability and related technical indexes.