133 results about "Low frequency band" patented technology

An image blur correction device acquires a blur detection signal, and separates it into a high frequency band signal component and a low frequency band signal component using an HPF and an LPF. A high frequency side prediction processing unit acquires an output of the HPF, and a low frequency side prediction processing unit acquires an output of the LPF via a down-sampler. A prediction processing unit updates a filter coefficient of a prediction filter using an adaptive algorithm, and performs linear prediction on the blur detection signal. An adder adds an output of the high frequency side prediction processing unit to an output of the low frequency side prediction processing unit via a up-sampler, and outputs a superimposed output signal. Image blur correction control is performed on the basis of a superimposed output signal.

A discharge detection unit 1 that can detect noise superimposed on a voltage or current of an electric circuit to which the load is connected by being electrically connected to an electric circuit to which a load is connected, the discharge detection unit includes a filter unit 11 that can output a waveform of passed noise in a high frequency band without passing noise at a commercial frequency band and in a low frequency band by cutting noise of a predetermined frequency or lower superimposed on the voltage or current of the electric circuit, a counting unit 12 that can calculate the number of waveform detections in a predetermined time from a waveform passed through the filter unit, and an arithmetic processing unit 13 that can determine presence or absence of noise caused by discharge in the electric circuit using the number of times detected calculated by the counting unit.

The application belongs to the technical field of zinc powder purification, and provides a condensation and sedimentation system for zinc powder purification, which comprises the following steps: collecting a time sequence of original radiation intensity of a condensation chamber, performing frequency spectrum analysis through fast Fourier transform, calculating energy values of high and low frequency band frequency domain signals, solving a signal coherence factor and calculating a transmittance attenuation coefficient, constructing a metal thin film radiation compensation model based on a long short-term memory network, inputting the attenuation coefficient and the time sequence of original radiation intensity to output a corrected real temperature of the condensation chamber, expanding an inference layer of a full connection neural network structure, outputting a calibrated attenuation coefficient through the inference layer, selecting an effective attenuation coefficient input model by comparing a deviation threshold value, dynamically responding to temperature measurement nonlinear attenuation caused by zinc film deposition, guaranteeing production continuity and product quality of zinc powder purification, adapting to industrial multi-working condition operation requirements, being convenient to operate and controllable in cost.

The application belongs to the technical field of test and measurement, and particularly relates to a tight-field reflecting surface realized by building cement. The tight-field reflecting surface is used for low-frequency tight-field measurement and mainly comprises a cement support, a cement parabolic reflecting surface arranged on the cement support, a surface geometry of the cement parabolic reflecting surface being a parabolic surface with periodic side teeth, and a metal plating layer formed on the surface of the cement parabolic reflecting surface and used for providing a metal boundary condition for electromagnetic reflection. The application can greatly reduce manufacturing cost and effectively form a high-quality quiet zone in a low-frequency band.

This disclosure relates to an antenna module and an electronic device. The antenna module includes: a first radiating stub, a second radiating stub, a third radiating stub, and a feed terminal; the second radiating stub is disposed between the first and third radiating stubs; a first gap is formed between the second and first radiating stubs; a second gap is formed between the second and third radiating stubs; the feed terminal is connected to a first upper frame point of the second radiating stub and is used to output a feed signal to the second radiating stub, enabling the antenna module to operate in a first frequency band, a second frequency band, and a third frequency band; wherein the first frequency band includes a low-frequency band; the second frequency band includes a mid-frequency band; and the third frequency band includes a high-frequency band. Embodiments of this disclosure can cover more frequency bands while reducing the space occupied.

The application relates to the field of wireless communication technology and provides a power amplifier, a power amplification module and a multi-mode multi-frequency power amplifier. The power amplifier comprises a first-stage low-frequency power amplifier, a second-stage low-frequency power amplifier, a harmonic suppression circuit, a first output matching circuit, a first filter circuit and a second filter circuit; the first-stage low-frequency power amplifier and the second-stage low-frequency power amplifier are used for amplifying low-frequency signals; the harmonic suppression circuit is used for suppressing the harmonics output by the first-stage low-frequency power amplifier and the second-stage low-frequency power amplifier; and the output end of the first output matching circuit is used for outputting signals. The first output end of the first filter circuit and the output end of the second filter circuit respectively provide filtered power supply voltages for the first-stage low-frequency power amplifier and the second-stage low-frequency power amplifier. The application can optimize the harmonic leakage of the multi-mode multi-frequency power amplifier.

A multiband antenna has an array face with closely spaced dipoles of multiple frequency bands in the low band, the mid band, and C-band or CBRS (Citizens Broadband Radio Service). The low band dipole has four dipole arms formed in a plurality of loops from a single piece of metal. In one embodiment, the loops successively decrease in dimension, resulting in a tapered dipole arm shape and has a bend that bends the dipole arms downward to accommodate radome curvature. In a second embodiment, the outermost loop of each dipole arm is larger in volume and has its lateral loop features bent downward.

A computer implemented method for controlling call capacity in a mobile network. The method includes: activating a mass event mode in a first cell of a first base station, wherein the first cell is a high frequency band cell, and wherein operating in the mass event mode comprises: checking if any low frequency band cells are available in a first sector served by the first cell; and responsive to detecting that one or more low frequency band cells are available, switching, at least some, voice call connections of the users of the first cell to at least some of the available low frequency band cells.

The application discloses a kind of fusions ultrasonic wave, short wave low frequency band radio safety penetration device, comprising: ultrasonic wave radio signal transceiver link module, short wave / ultra-short wave radio signal transceiver link module and power module;The power module is respectively with the circuit connection between ultrasonic wave radio signal transceiver link module and short wave / ultra-short wave radio signal transceiver link module;The ultrasonic wave radio signal transceiver link module includes ultrasonic wave radio signal receiving link module and ultrasonic wave radio signal transmitting link module;The short wave / ultra-short wave radio signal transceiver link module includes short wave / ultra-short wave radio signal receiving link module and short wave / ultra-short wave radio signal transmitting link module.The application solves the deficiency of existing radio bottom layer safety depth scanning penetration tool.

The application discloses a kind of wideband sandwich radome based on double-band super surface, it includes sequentially arranged first impedance matching layer, radome frequency selective surface layer, second impedance matching layer, the radome frequency selective surface layer includes several periodic frequency selective surface units, radome frequency selective surface layer is formed by multilayer metal structure and dielectric substrate A space filter, so that corresponding wideband sandwich radome has wave band selectivity;When electromagnetic wave irradiates to the surface of wideband sandwich radome based on double-band super surface, two transmission poles are generated in low frequency band to form second-order band-pass filter response, and three transmission poles are generated in high frequency band to form third-order band-pass filter response.The advantages are: the wideband sandwich radome has the excellent characteristics of double-band wideband wave transmission, large-angle stability, out-of-band steep cutoff, adjustable frequency ratio of wave transmission band center frequency, polarization insensitivity and the like by the above structure, and the overall structure is simple and easy to process.

This utility model discloses a bladeless fan light, including a lamp body with a fan section and an illumination section. The fan section includes an upper housing, a motor, and a fan wheel. The rotating shaft of the motor is fixedly connected to the center of the fan wheel. The fan wheel has several blades, and the tips of the blades have a serrated structure. The illumination section includes a lower housing and a light source plate. The light source plate is located in the center of the lower housing, and the edge of the lower housing has several air outlets that communicate with the air duct of the fan wheel. The serrated structure divides the smooth, large edge into many small, discontinuous edges. When the airflow passes through these small serrations, the size of the generated vortices becomes smaller, the frequency of vortex shedding increases, and the randomness of vortex shedding increases. This disperses the "roaring" noise, which was originally concentrated in the lower frequency band and is relatively sensitive to the human ear, to a wider and higher frequency spectrum, significantly reducing the overall perceived noise level and making the sound smoother, quieter, or softer.

This application relates to the field of terahertz emission, specifically providing a low-frequency terahertz emitting device and its fabrication and usage methods. The device includes an excitation material, which is a heterojunction formed by a perovskite layer and a high-resistivity silicon layer. It also includes a first metal layer disposed outside the perovskite layer and a second metal layer disposed outside the high-resistivity silicon layer. During fabrication, a perovskite solution is first spin-coated onto the high-resistivity silicon to form a perovskite layer, and finally, the metal layers are deposited by vapor deposition. During use, a femtosecond laser is incident from one side of the perovskite layer, and a voltage is applied between the first and second metal layers. The applied electric field of this application enhances the interfacial band bending and widens the depletion layer, while simultaneously forming a stable potential gradient in the thickness direction. This makes the transient current change smoother, increases the time constant, and reduces the rate of change of the transient current over time, thereby increasing the proportion of the low-frequency terahertz component and achieving enhanced low-frequency radiation.

This invention discloses a GaN power amplifier system and control method based on envelope tracking and thermal feedback. The system includes a system control module, and an audio signal conditioning module, a programmable power supply module, a thermal feedback module, and a GaN power output module, all communicatively connected to the control module. The system control module executes dual closed-loop control logic: the first closed loop dynamically adjusts the output voltage of the programmable power supply module using envelope tracking technology, ensuring it closely follows changes in the amplitude of the audio signal, thus reducing power consumption and heat generation at the source; the second closed loop, based on real-time temperature data collected by the thermal feedback module, prioritizes dynamic compression of the low-frequency band of the audio signal or smoothly reduces the overall main volume when overheating occurs, achieving intelligent thermal derating protection without interrupting playback. This invention significantly improves the energy efficiency and reliability of the power amplifier system.

The application discloses a C-band tuning-free duplexer and belongs to the technical field of microwave filters. The tuning-free duplexer comprises an upper conductor and a lower conductor, and the upper conductor and the lower conductor are buckled one above the other to form a waveguide cavity. The upper conductor is provided with a combining port in the middle of the top, and the lower conductor is provided with a low-frequency input / output port and a high-frequency input / output port at the bottom. The waveguide cavity from the low-frequency input / output port to the combining port constitutes a low-end filter, and the waveguide cavity from the high-frequency input / output port to the combining port constitutes a high-end filter. The main bodies of the high-end filter and the low-end filter are both a plurality of waveguide resonant cavities arranged along a straight line, the middle positions of each waveguide resonant cavity are provided with cavity loading, and adjacent waveguide resonant cavities are connected through inter-cavity coupling. The tuning-free duplexer adopts a symmetrical structure and a center loading mode, realizes tuning-free assembly, has the characteristics of high power bearing capacity, low transmission loss and excellent signal isolation, and is suitable for a C-band communication system.

This invention provides a comparator circuit with latching function and its control method. The comparator circuit with latching function uses an initial voltage provided by a pre-comparison module. The initial voltage is dynamically adjusted based on the input comparison voltage to generate a first current variable. This first current variable is converted into a control voltage, and a first comparison result is output based on the control voltage. The first comparison result is compared and positive feedback latched by the latching module to obtain a second comparison result. This comparator circuit with latching function, designed for low-to-medium precision and low-frequency applications, replaces the redundant design and related bias circuits of multi-stage operational amplifier cascades with a pre-comparison module. The common-mode voltage bias is integrated into the structure of the pre-comparison module, simplifying the circuit structure. This comparator circuit does not interfere with the preceding or following circuits, reducing process sensitivity.

Adaptive tunable antenna system includes a first radiating element having an elongated length and a second radiating element extending from a distal end of the first radiating element. The first radiating element is for a high band of operation and the second radiating element is for a low-band of operation. The second radiating element is a helical member including a plurality of turns. A low-band circuit selectively bypasses one or more of the turns of the second radiating element in response to a control signal.

The application discloses a kind of lithium battery charge-discharge intelligent early warning method and system, belong to computer technology field.The method includes: when battery charges and discharges, actively injects multiple-frequency ac disturbance signal;Response signal is collected and is parsed to obtain dynamic electrochemical impedance spectroscopy containing charge transfer impedance and low-frequency phase angle;Based on the preset multidimensional health impedance mapping table, the reference impedance and reference phase angle corresponding to the current temperature and state of charge are inquired;Impedance relative deviation and phase angle offset are calculated;At least based on the deviation and offset, the internal micro-short circuit of battery is identified and early warning operation is executed;Through multidimensional mapping table and dynamic threshold mechanism, effectively eliminate working condition and aging interference, with high sensitivity and low false alarm rate;And supplemented by hierarchical early warning, standing verification and multi-cell collaborative calibration, the safety and usability of battery system are significantly improved.

This invention provides a visually evoked brain-computer interface system and method based on high-frequency time-division multiplexing coding, relating to the field of brain-computer interfaces. The system includes: a visual stimulation module comprising multiple visual stimulation units; a high-frequency time-division multiplexing coding module pre-stored with multiple baseband symbols and coding rules; a signal acquisition and processing module located in the user's brain, which acquires the user's EEG signals after stimulation by the visual stimulation module and preprocesses the acquired EEG signals; a classification module connected to the signal acquisition and processing module, which predicts the coding pattern of the preprocessed EEG signals after passing through a classification model module; and an application control module with a pre-set instruction mapping table for converting the coding pattern output by the classification module into control instructions for external devices or software. The technical solution of this invention overcomes the problems of visual fatigue, excessive coding capacity, and low recognition accuracy caused by low-frequency coding in existing brain-computer interfaces.

The utility model provides a kind of road noise barrier based on sound-absorbing material, including barrier support assembly and barrier body, barrier support assembly includes the barrier support post of pair arrangement, and the sliding slot upper end of barrier support post is connected with buffer sliding block, and one barrier hanging pole is connected between buffer sliding block, barrier hanging pole is connected with barrier assembly support by hinged link, and barrier assembly support is connected with barrier body by bolt.The utility model in barrier body is converted into heat energy dissipation by the sound hole hole of sound hole board body, and the sound-absorbing micropore on microporous attraction cloth layer is based on micro-perforated plate theory, and the sound-absorbing coefficient is excellent in full frequency band, especially in low frequency part, further improve sound-absorbing effect, significantly improve the sound-absorbing performance of low frequency band by sound-absorbing cotton layer, and the porous structure of sound-absorbing cotton layer effectively insulates internal air convection and heat radiation, significantly reduce heat loss, while large aperture area absorbs and reflects sound wave, effectively reduce noise.

The application relates to a voiceprint recognition method and device. The method comprises the following steps: obtaining a spectrogram of a speech signal, and dividing the spectrogram into a plurality of sub-spectrograms of different frequency bands; using feature extraction networks with different time resolutions to extract feature information of the plurality of sub-spectrograms, wherein the time resolution of a first feature extraction network used for extracting feature information of a high-frequency sub-spectrogram is greater than the time resolution of a second feature extraction network used for extracting feature information of a low-frequency sub-spectrogram; and fusing the feature information extracted by the feature extraction networks with different time resolutions into a voiceprint of the speech signal.

This disclosure relates to an antenna assembly and a terminal device. The antenna assembly includes: a first radiating arm to a third radiating arm and a first matching circuit. A first gap is provided between the first radiating arm and the second radiating arm, and a second gap is provided between the second radiating arm and the third radiating arm. A first terminal of the first matching circuit is connected to the end of the second radiating arm near the first gap, and a second terminal of the first matching circuit is grounded. The first matching circuit has a first state and a second state. When the first radiating arm transmits and receives signals in various low-frequency bands, the first matching circuit is in the first state, so that the second radiating arm has the effect of loading the physical length of the low-frequency signal path, thereby improving the performance and efficiency of the low-frequency band antenna. When the third radiating arm transmits and receives signals in various mid-to-high-frequency bands, the first matching circuit is in the second state, so that the second radiating arm excites a parasitic current mode at the high-frequency signal position, thereby widening the bandwidth of the high-frequency signal and improving the efficiency of the mid-to-high-frequency antenna.

Provided in the present invention is a method for accurately solving for wideband Q-factor and C-value curves of a capacitor, the method comprising frequency segmentation, low-frequency band and high-frequency band processing, transition region setting, curve splicing and smoothing processing. The specific steps comprise: dividing a frequency range into a low-frequency band of 0-5 GHz and a high-frequency band of above 5 GHz; in the low-frequency band, using an equivalent circuit model method to calculate a Q factor and a C value within the frequency range of 0-5 GHz; in the high-frequency band, using an S parameter fitting method to calculate a Q factor and a C value; setting a transition region at 4-6 GHz; and splicing curves of the low-frequency band and the high-frequency band and then performing smoothing processing on the curves in the transition region, so as to obtain final Q-factor and C-value curves. The present invention can accurately solve for the wideband Q-factor and C-value curves of the capacitor, thereby improving the accuracy and reliability of capacitor performance analysis.

This invention discloses a high-resistivity fault location method for distribution networks based on feeder segment model mismatch identification. First, the zero-sequence voltage of the bus and the zero-sequence current at each measuring point are collected, and the derivative of the zero-sequence voltage and the segment zero-sequence current difference of each feeder segment are calculated. Then, the data from the first power frequency cycle after the fault is selected, and the effective value of a selected low-frequency band is used as a scaling factor to normalize the segment zero-sequence current difference and the derivative of the zero-sequence voltage, achieving accurate alignment of the effective signals. Next, a first-order accumulation generator is used to enhance the signal, suppressing random noise and amplifying fault characteristics. The model mismatch degree of each feeder segment is calculated and multiplied with the fault intensity index to construct a comprehensive mismatch index as the location criterion. Finally, the fault segment is determined based on the maximum value of the comprehensive mismatch index. This invention fully utilizes the essential differences between healthy and faulty segments in the zero-sequence equivalent model, and combines the fault current intensity to construct a comprehensive criterion, possessing advantages such as strong anti-interference capability, good physical interpretability, and wide engineering applicability.

This invention discloses a gimbal vibration damping device based on a high-damping honeycomb core composite structure, relating to the field of unmanned aerial vehicle (UAV) technology. It includes an upper damping plate, a lower damping plate, a honeycomb damping unit, and a damping connection unit. The upper damping plate is used to connect to the UAV body; the lower damping plate is used to mount airborne equipment; the damping connection unit is disposed between the upper and lower damping plates, with both ends connected to the upper and lower damping plates respectively; the honeycomb damping unit is disposed between the upper and lower damping plates, arranged side-by-side with the damping connection unit, and located within the entire... The centroid region of the gimbal vibration damping device based on a high-damping honeycomb core composite structure; the two ends of the honeycomb vibration damping unit are connected to the upper and lower vibration damping plates respectively. The honeycomb vibration damping unit is made of a material used to provide damping loss factor in the low frequency band, and honeycomb cells are densely arranged on the honeycomb vibration damping unit. The honeycomb cells are used for elastic deformation in the high frequency band. The gimbal vibration damping device based on the high-damping honeycomb core composite structure can significantly improve the overall structure's broadband vibration damping effect through a dual-path coupling damping mechanism of honeycomb vibration damping unit and vibration damping connection unit.

The invention discloses low-frequency electromagnetic shielding concrete and a preparation method thereof, and belongs to the technical field of electromagnetic shielding concrete preparation. The low-frequency electromagnetic shielding concrete is prepared from a wet material and a dry material, wherein the wet material is prepared from water, a nano carbon black dispersing agent and a defoaming agent; the dry material is prepared from the following components: cement, an admixture, nano carbon black, steel fibers, magnetic aggregate and a water reducing agent; the mass ratio of the water to the cement is 0.4 to 0.68. A multi-scale and multi-dimensional developed electric conduction and magnetic conduction network is built in a three-dimensional space in the concrete, a tiny electromagnetic leakage area in the concrete is made up from different scales, the situation that an electric conduction and magnetic conduction path is disconnected in the electromagnetic concrete is avoided, effective shielding protection can be formed for 14 kHz-950 MHz low-frequency-band electromagnetic waves, and the electromagnetic shielding effect is good. And low-frequency electromagnetic wave shielding effectiveness-mechanical bearing capacity integrated construction in special engineering can be realized.

This paper proposes a design method for a frequency- and phase-reconfigurable broadband low-RCS metasurface antenna. Based on the low-RCS frequency band requirement of the antenna, a reconfigurable metasurface element with four reflection frequency bands for the incident wave is designed, with adjacent reflection phase curves having an effective phase difference of 180°±37°. Combined with feeding technology, a portion of the metasurface structure is effectively excited, quickly obtaining a frequency- and reflection phase-reconfigurable metasurface antenna. The resulting metasurface antenna is constructed into an n×n array. By controlling the active modulation devices of each metasurface antenna element and arranging them according to a phase-cancellation coding scheme, the array antenna can exhibit low RCS characteristics in any of the three frequency bands, resulting in a broadband low-RCS array. This invention integrates the reconfigurable metasurface element and the antenna design, accelerating the design process of broadband low-RCS antennas. It also extends the stealth bandwidth of low-RCS antennas through frequency reconfiguration. The reconfigurable broadband stealth antenna has a simple structure, light weight, low cost, and broad application prospects.

The application discloses a double-frequency double-mode wearable filtering antenna with independently controllable radiation zero points, adopts an air gap structure of superposition of a first dielectric substrate and a second dielectric substrate, and integrates structures such as a rectangular patch, a parasitic patch, a circular patch, a U-shaped slot and double short-circuit columns.The application generates two omnidirectional mode resonance points and two radiation zero points in a low-frequency band through the design of the top layer and the bottom layer circular patch and the double short-circuit columns; three directional mode resonance points and two radiation zero points in a high-frequency band through the rectangular patch loaded with the U-shaped slot, the rectangular slot and the parasitic patch. The independent regulation and control of the four radiation zero points can be realized by adjusting the circular patch radius, the short-circuit column length, the U-shaped slot and the parasitic patch length. The application adopts PDMS flexible material and conductive nylon cloth, has the characteristics of flexible wearable, double-frequency double-mode radiation and filtering, and is suitable for wireless scenes such as 2.45GHz ISM and 3.5GHz 5G communication.

An apparatus may include: a common input terminal; a first inductor and a second inductor, each coupled to the common input terminal, wherein the first inductor and the second inductor are disposed in an electromagnetic coupling configuration; a lower frequency band output terminal coupled to the first inductor; a higher frequency band output terminal coupled to the second inductor; wherein the first inductor and the second inductor are to separate signals received from the common input terminal into the lower and the higher frequency band output terminals based on frequencies of the received signals. An apparatus may include: a first transformer magnetically couple a signal within a first frequency band and generate a first magnetic field with a first orientation; and a second transformer configured to magnetically couple a signal within a second frequency band that is different from the first frequency band.

The application discloses a kind of railway bed moisture content quantitative detection methods based on low high-frequency energy ratio, comprising: setting multiple transverse detection channels to collect ground penetrating radar signal;The radar signal of each transverse detection channel is continuously wavelet transformed, and the frequency axis in the time-frequency transform result is divided into low frequency band and high frequency band according to preset boundary frequency, and the low high-frequency energy ratio is calculated;The low high-frequency energy ratio mean of each transverse detection channel is calculated in each test area, and the low high-frequency energy ratio mean of multiple transverse detection channels in multiple test areas forms joint sample;According to joint sample, regression model for representing the nonlinear mapping relationship between water content severity index and low high-frequency energy ratio is constructed;The digital determination threshold of different water content grades is calculated according to regression model using interclass geometric midpoint method, establishes bed moisture state grading standard, and outputs moisture state grade.The application can realize accurate quantitative detection and grading of railway bed moisture content.