358 results about "Pulse modulator" patented technology

A millimeter-wave transmitter-receiver uses an NRD guide as a fundamental configuration and includes a millimeter-wave signal oscillator, a pulse modulator, a circulator, an antenna and a mixer. In the millimeter-wave transmitter-receiver, a line length of a third dielectric guide is set so that δ=±π in which δ is a phase difference at a center frequency between a portion of a transmission millimeter-wave signal, which is reflected via a third dielectric guide on the leading end portion of the third dielectric guide and returned to leak to a third connecting portion of the circulator, and another portion of the millimeter-wave signal, which leaks from a first connecting portion to the third connecting portion of the circulator. It is possible to reduce the change in the mixer output and enhance the millimeter-wave transmission/reception performance.

A pulse modulator generates a pulse-modulated signal by pulse-modulating and amplifying the amplitude component of an input signal. A low-pass filter filters the pulse-modulated signal from the pulse modulator, and generates an amplified amplitude signal which is obtained by amplifying the amplitude component. An error corrector generates a corrected amplitude signal by correcting an error of the amplified amplitude signal from the low-pass filter by using the amplitude component of the input signal. A mixing unit generates the output signal by mixing the corrected amplitude signal from the error corrector and the phase component of the input signal.

The invention relates to a switching amplifier comprising at least one pulse modulator arranged for modulating at least one input utility signal into at least one pulse modulated signal and at least one switching power stage arranged to establish at least one amplified utility signal on the basis of said at least one pulse modulated signal and a power signal, said power signal being delivered by a tracking power supply at least partly controlled by said at least one input utility signal, characterized in that said switching amplifier is arranged to process said at least one input utility signal according to a correction signal established by a correction signal estimator on the basis of a supply information signal derived from said tracking power supply.

According to the present invention an advantageous switching amplifier enabling use of a tracking power supply is provided. Thereby the many benefits of switching amplifiers can now be obtained together with the benefits of utilizing a tracking power supply. Among many things, this reduces power consumption, reduces EMI noise and enables using more of the dynamic range available for the utility signal during the pulse modulation. The last advantage further renders noise introduced by the power supply and the switching output stage less significant, as the signal-to-noise ratio in the power stage is greatly improved due to the utilization of the full dynamic range enabled by using a tracking power supply.

The invention discloses a COTDR (coherent detection based optical time-domain reflectometry) fused long-distance coherent detection brilouin optical time-domain analyzer which comprises a narrow-linewidth laser, two couplings, a microwave signal source, an electro-optic modulator, an isolator, a long-distance sensing optical fiber, an optical circulator, a 3 db coupling, a pulse modulator, an Er-doped fiber amplifier, a scrambler, a pulse signal generator, a balancing photoelectric detector, an electrical frequency spectrum analyzer, a data processing module and an acousto-optic modulator. According to the invention, the signal-to-noise ratio of BOTDA (brilouin optical time domain analysis) is improved by using a coherent detection method, a non-local effect of a BOTDA system is reduced in a double-sideband detection mode, and the sensing distance is more than 70 km under the condition of no light amplification such as raman; and according to the invention, the COTDR is fused to a coherent detection based BOTDA system, and the system can run in a breakpoint testing mode, so that the defect that the traditional BOTDA can not run when a sensing fiber has breakpoints and can not carry out positioning on breakpoints is effectively overcome, thereby enhancing the adaptability and practicability of the sensing system.

A circuit for controlling the discharging of stored energy in an electrosurgical generator includes a pulse modulator which controls an output of a power supply. At least one comparator is configured to provide an error signal to the pulse modulator based on a comparison between an output signal generated by the power supply and a feedback signal generated in response to the application of energy to tissue. A discharge circuit is configured to control the discharge of the output of the power supply to an inductive load disposed in parallel with the output of the power supply based on the comparison between the output signal and the feedback signal. The discharge circuit provides a rapid response and time rate control of the delivered electrosurgical energy by controlling the power supply and delivered RF energy in real time, based on a feedback signal generated in response to the application of energy to tissue.

A pulse modulator generates a first pulse signal having a duty ratio which is adjusted such that a detection voltage which indicates the electrical state of an LED string to be driven matches a predetermined reference voltage. A first pulse signal is applied to a primary coil of a pulse transformer. A DC/DC converter includes a switching element the ON/OFF operation of which is controlled according to a signal that originates at a secondary coil of the pulse transformer. The DC/DC converter stabilizes an input voltage Vdc, and supplies the input voltage Vdc thus stabilized to the anode of the LED string.

A circuit for controlling the discharging of stored energy in an electrosurgical generator includes a pulse modulator which controls an output of a power supply. At least one comparator is configured to provide an error signal to the pulse modulator based on a comparison between an output signal generated by the power supply and a feedback signal generated in response to the application of energy to tissue. A discharge circuit is configured to control the discharge of the output of the power supply to an inductive load disposed in parallel with the output of the power supply based on the comparison between the output signal and the feedback signal. The discharge circuit provides a rapid response and time rate control of the delivered electrosurgical energy by controlling the power supply and delivered RF energy in real time, based on a feedback signal generated in response to the application of energy to tissue.

The invention discloses a long-distance distributed optical fiber vibration sensing system and a method thereof. The system comprises an induction system for inducting outside vibration events and a detecting and controlling system for detecting and controlling vibration signals; the induction system is connected with the detecting and controlling system. The induction system comprises a light source, a pulse modulator, an optical fiber circulator, a first optical fiber amplifier, and a light switch of a first optical fiber filter. The detecting and controlling system comprises a plurality of optical-electrical converters and a system control unit; the system control unit collects output light of the converters, analyzing the collected signals and judges whether the alarm is needed according to the analysis result. The invention adopts the optical switch technology to adopt time-division processing on backward Rayleigh scattering light which is reflected back, the dynamic range of the system is large, and the sensible distance can be tens of kilometers as high as possible, even hundreds of kilometers; and the invention adopts phase detecting technology and optical time domain reflection technology and can greatly improve detecting sensibility of the system and positioning precision.

Disclosed is an optical time domain reflectometer simultaneously sensing temperature and stress. The system is based on parallel detection of Rayleigh and Brillouin scattered light and includes devices such as a multi-wavelength laser source, a light-pulse modulator, a balance detector, a microwave amplifier, a high-speed data acquisition card, a coupler and a circulator and the like. In the optical time domain reflectometer, the frequency interval of wavelengths of the multi-wavelength laser source is arranged to be in a range of 9-12 GHz, which is equivalent to a frequency shift quantity of Brillouin scattered light in a fiber. A heterodyne coherent detection method is used to carry out parallel detection on Rayleigh and Brillouin scattered spectra and temperature and stress information is demodulated through a Landau-Placzek ratio (LPR) and Brillouin frequency shift distribution; and at the same time, coherent Rayleigh noises are reduced and superposition of the scattered spectra improves the signal-to-noise ratio of the scattered light. The optical time domain reflectometer is capable of realizing simultaneous temperature and stress sensing of a distributed fiber sensing system, improving the signal-to-noise ratio of the scattered light and improving the sensing precision and distance.

An output monitoring comparator outputs an ON signal when an output voltage becomes lower than a reference voltage. A pulse modulator generates a pulse signal at a predetermined level, an ON time-period from when the ON signal is outputted. A driver circuit alternately turns ON, after a dead time, a switching transistor and a synchronous rectification transistor, based on the pulse signal. A light load mode detector compares a switching voltage at a connection point of the switching transistor and the synchronous rectification transistor, and ground potential, and at timing at which the ON signal is outputted from the output monitoring comparator, when the switching voltage is higher than the ground potential, nullifies the ON signal.

The invention discloses a distributed ultrahigh-speed disturbance quantitative detection method. Ultrahigh-speed disturbance detection can be realized through a time division multiplexing method; and phase demodulation is carried out through phase demodulation methods such as Hilbert transformation and orthogonal transformation so as to be able to realize real-time detection on the disturbance position, frequency and amplitude. The invention further discloses a distributed ultrahigh-speed disturbance quantitative detection device, which comprises a pulse generator, a laser, a first coupler, a pulse modulator, an erbium-doped optical fiber amplifier, a circulator, an optical fiber sensing unit, a second coupler, a balance detector, a band-pass filter, a power amplifier and a data acquisition card. According to the invention, the repetition frequency of detecting light pulses is improved through a time division multiplexing technology, so that a reflecting grating based phi-OTDR system is enabled to realize ultrahigh-speed disturbance detection; and real-time detection for the disturbance position, frequency and amplitude is realized through the phase demodulation method by using a coherent detection structure and combining a phase unwrapping algorithm.

The invention discloses an optical fiber Brillouin optical time domain analyzer, which is made based on optical fiber broadband nonlinear light amplification effect and strain, temperature effect and optical light domain analysis principle of coherent amplified Brillouin scattering. The optical fiber Brillouin optical time domain analyzer comprises a narrowband single-frequency fiber laser, a fiber beam splitter, a pulse modulator, two optical fiber circulators, a heterodyne receiver, a digital signal processor, a fiber-grating filter, a monomode fiber and a continuous-operating fiber Raman pump laser. The continuous-operating high-power fiber Raman pump laser is used as the pump light source of the Brillouin optical time domain analyzer, which can overcome the difficulty in strictly locking the frequency of a detection laser and the pump laser of the Brillouin optical time domain analyzer; and boardband fiber nonlinear scattering amplification is used for substituting for narrowband Brillouin amplification to increase the gain of stimulated Brillouin scattering with back amplification, thus improving the S/N ratio of the system, increasing the measurement length, and improving the accuracy for simultaneous measurement of stain and temperature.

The invention discloses a compliant and coordinated control method for the in-orbit capturing process of a space robot. The compliant and coordinated control method includes the steps that a space robot model oriented to control is established according to dynamics and kinematics equations; a mechanical arm compliant capturing control rule is established according to the space robot model oriented to control; a base posture control rule based on a base gas spraying device is determined; a mechanical arm compliant control loop is established according to the mechanical arm compliant capturing control rule; a base posture control loop is established according to the base posture control rule and a PSR pulse modulator; the control amounts calculated by the mechanical arm compliant control loop and the base posture control loop serve as the control input of a mechanical arm of a space robot system and the control input of the base gas spraying device of the space robot system correspondingly; and meanwhile control force of the base serves as a feed-forward item and is input into the mechanical arm control rule to offset the interference of base control to mechanical arm tail end compliant control. By means of the compliant and coordinated control method, stability of the base is ensured while a target is stably captured.

A current driving circuit is connected to an LED terminal LED_i, and generates an intermittent driving current I_LEDi that corresponds to a dimming pulse signal PWM_i. An error amplifier generates a feedback voltage V_FB that corresponds to the difference between a detection voltage V_LEDi and a predetermined reference voltage V_REF. A pulse modulator generates a pulse signal having a duty ratio that corresponds to the feedback voltage V_FB. A fault detection comparator COMP_OPEN_i generates a fault detection signal OPEN_DET which is asserted when the detection voltage V_LEDi is lower than a predetermined threshold voltage V_{OPEN<sub2>—</sub2>DET}. A forced turn-off circuit instructs the current driving circuit to suspend the generation of the driving current I_LEDi during a predetermined period after a switching power supply starts to operate. The fault detection circuit detects whether or not the fault detection signal OPEN_DET_i has been asserted in a predetermined period.

A control IC controls a switching power supply configured to supply a driving voltage Vout to one terminal of an LED string to be intermittently driven. In the on period of the LED string, a pulse modulator generates a pulse signal having a duty ratio adjusted such that a detection voltage V_LED that corresponds to the output voltage Vout of the switching power supply matches a predetermined reference voltage Vref. A driver drives a switching transistor included in the switching power supply according to the pulse signal. After transition from the on period to the off period, the pulse modulator reduces the duty ratio of the pulse signal over time.

The invention discloses a Brillouin optical time domain reflectometer for single-photon detection based on an edged filter method, which comprises a narrow linewidth laser (1), a pulse modulator (2), a circulator (3), a sensing optical fiber (4), an optical fiber module (5), 3dB coupler (6), a linear edged filter (7), an InGaAs/InP SPAD (single-photon avalanche diode) detector group (8), a signal generator (9), a data processing module (10) and a pulse signal generator (11), wherein the InGaAs/InP SPAD detector group (8) includes two or three InGaAs/InP SPAD detectors. The InGaAs/InP SPAD detector group with a high counting rate and high sensitivity is used as a detection unit, Brillouin frequency shift information is acquired by the edged filter method, time correlation single-photon counting technology is adopted by the data processing module (10), limitations on the bandwidth and sensitivity of a traditional detector are broken through, spatial resolution and measuring precision of the reflectometer can be simultaneously improved, and temperature and strain are simultaneously sensed.

The invention discloses a sensing signal detecting device and a sensing signal detecting method based on a fiber Brillouin ring laser. The device comprises a narrow linewidth DFB (distributed feedback) laser, three optical fiber couplers, a pulse modulator, two erbium-doped fiber amplifiers, two optical fiber circulators, two single-mode fibers, an optical isolator, a polarization controller and a photoelectric detector, wherein the fiber Brillouin ring laser is composed of the second optical fiber circulator, the second single mode fiber, the optical isolator, the second optical fiber coupler and the polarization controller. Light emitted from the laser is divided into two beams of light via the optical fiber couplers, wherein the probe light is modulated into pulsed light which enters into sensing optical fiber after passing through the erbium-doped fiber amplifiers to ensure that back spontaneous Brillouin scattered signals are generated; the reference light passes through the center frequency of the fiber Brillouin ring laser to ensure that a Brillouin frequency shift is generated; and the coherent detection is carried out on the two Brillouin scattered signals which are scattered back to ensure that the advantages of rapid high-accuracy detection and simple structure are realized by utilizing low-cost devices.

The invention relates to the aerospace field, and provides a rendezvous docking method and device of a space non-cooperative target. The method comprises the steps of guiding the space non-cooperative target to a system capture range through ground guideness; determining measurement angle of sight, relative distance and azimuthal angle respectively according to the simplest combination of measurement components capable of determining relative parameters of the space non-cooperative target; carrying out relative navigation by using an extended Kalman filter algorithm, according to the capture measurement results; tracking track the target by executing CW reference trajectory guidance and linear reference trajectory guidance respectively to according to navigation results and giving out a relative position and relative speed equation of an ideal trajectory; and carrying out thrust control by adopting a PID control law and a pseudo rate pulse modulator during an approaching process. Through capturing, tracking and approaching of the space non-cooperative target, autonomous capturing, continuous tracking and stable approaching of the space non-cooperative target can be finished after a spacecraft enters a work range of capturing the non-cooperative target, thereby realizing rendezvous docking of the space non-cooperative target.

The invention relates to a digital power factor converter with a fast transient response function. The digital power factor converter is provided with an EMI (electro magnetic interference) filter, a rectifying circuit, a Boost type converter power stage main topology structure, two voltage dividing units, three A/D (analog to digital) sampling converting units, a prediction control unit, a PID (proportion integration differentiation) control unit, a duty ratio correction unit and a digital pulse modulator, wherein the alternating current voltage AC is connected with the input end of the EMI filter, the output end of the EMI filter is connected with the input end of the rectifying circuit, the input end of the second voltage dividing unit is connected with the output end of the rectifying circuit, i.e. the input end of the main topology structure, the input end of the first voltage dividing unit is connected with the output end of the main topology, the output ends of the three A/D sampling converting units are respectively connected with the prediction control unit, after output signals and reference voltage signals Vref are compared, voltage error signals and voltage error deviation signals are output to the PID control unit, output signals of the duty ratio correction unit and output signals of the PID control unit are multiplied and are then connected with the digital pulse modulator, and the output end of the digital pulse modulator is connected with a grid electrode of an MOS (metal oxide semiconductor) transistor Q in the main topology structure.