293 results about "Passband filter" patented technology

A system and method for broadband communications over power lines has a low-voltage transformer for the house connection unit and / or the electricity distribution inside the house. The system method allow for several parallel asynchronous data communications in different sub-channels with individual transmit power in each sub-channel. Sub-channel separation uses pass-band filters with high stop-band attenuation. High data rate in each sub-channel is achieved through the use of discrete wavelet multi-tone modulation. Coarse synchronization in each sub-channel and the optimization of the coefficients of the time-domain equalizer are carried out using a training sequence.

A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant tank circuit which provides a notch filter in addition to a band pass filter. A additional band pass filter provided in the resonant tank circuit achieves increased power transfer to a load and reduced circulating resonant currents and conduction losses. The inductances of the preferred LCLCL tank circuit or other tank circuit with two pass band filters and a notch filter may be integrated into a single electrical component.

Methods and apparatus are described herein that make use of complex tuning, the inherently repetitive nature of sampled signals, and programmable digital filtering to create a flexible digital up-conversion system that utilizes a digital-to-analog converter (DAC) with a fixed effective sample rate while still being adapted for tunability over a wide frequency range. With a knowledge of the fixed effective sample rate of the DAC and a desired frequency of up-conversion and combining complex tuning at baseband and up-sampling by a factor of N with a programmable passband filter configured to select one of a plurality of signal images resulting from the up-sampling, it is possible to translate a baseband input signal to a wide range of frequencies above or below Fs, without changing the sampling rate of the fixed rate DAC used in the up-conversion process.

A resonant switched power converter having switching frequency controlled in response to an output voltage thereof achieves over-current protection such as at start-up or under short circuit conditions using a resonant tank circuit which provides a notch filter in addition to a band pass filter. A additional band pass filter provided in the resonant tank circuit achieves increased power transfer to a load and reduced circulating resonant currents and conduction losses. The inductances of the preferred LCLCL tank circuit or other tank circuit with two pass band filters and a notch filter may be integrated into a single electrical component.

A circuit is disclosed with an external coupling port for coupling to an external antenna, for example. The circuit has an FDD receive path including a narrowband passband filter. The circuit has a TDD receive path bypassing the narrowband passband filter but relying on a same amplifier. The circuit also has an FDD transmit path including a narrowband passband filter. The circuit has a TDD transmit path bypassing the narrowband passband filter of the FDD transmit path but relying on a same transmit amplifier. A switching configuration allows the circuit to operate in TDD mode, alternating between the TDD receive path and the TDD transmit path and in the FDD mode wherein the FDD transmit and receive paths are simultaneously coupled to the external coupling port.

A system and a method are proposed for broadband communications over power lines comprising the area of the low-voltage transformer to the house connection unit and / or the electricity distribution inside the house. The new method allows for several parallel asynchronous data communications in different sub-channels with individual transmit power in each sub-channel. Sub-channel separation uses pass-band filters with high stop-band attenuation. High data rate in each sub-channel is achieved through the use of discrete wavelet multi-tone modulation. Coarse synchronization in each sub-channel and the optimization of the coefficients of the time-domain equalizer are carried out using a training sequence.

The invention relates to a method and an apparatus for agile RF spectrum monitoring in a radio system with dynamic frequency access. It provides a spectrum monitor based on non-coherent heterodyne detection that utilizes a DDS signal generator to digitally generate a reference signal at a variable reference frequency for mixing with an input RF signal received from an RF antenna, a pass-band filter and a log amplifier for obtaining energy estimates at a monitored transmission frequency corresponding to the reference frequency. A processor is provided for adaptively selecting sets of monitored transmission frequencies, for controlling the DDS signal generator, and for processing obtained spectral energy estimates to assess spectral usage data.

A switchable diplexer includes a plurality of bandpass filters having passbands for the frequency bands in which communication across a communication channel is desired. The bandpass filters can be arranged in groups of bandpass filters located adjacent to one another physically. Further, a group of bandpass filters can include a plurality of bandpass filters having a stop band in a common frequency range of interest. A plurality of switches can be provided to switch the desired bandpass filter into the circuit to allow communication on its corresponding band. The switches can therefore be electrically coupled to the passband filters and configured to select one of the plurality of bandpass filters for signal communication on the communication channel.

The invention discloses a double frequency band filter of a SIR coaxial cavity. The double frequency band filter of the SIR coaxial cavity comprises a CQ-type topological structure formed by coupling of a coaxial SIR in magnetic and galvanic modes. The coaxial SIR is composed of a rod-shaped inner layer metal transmission line, an outer layer barrel-shaped metal wall and a middle medium layer, wherein the outer layer barrel-shaped metal wall shares the same axis with the inner layer metal transmission line which is formed by connecting of two coaxial transmission lines with different diameters. A terminal opening end coaxial borehole is formed at the top end of a terminal opening end of the metal transmission line, and a tuning screw is placed at the top end of the terminal opening end of the metal transmission line to tune. The double frequency band filter is provided with the CQ-type topological structure of 8 cavities, two transmission zeroes are generated on the outside of a double frequency band, so that out-of-band suppression performances are greatly improved. Compared with a traditional duplexer, the double frequency band filter is improved on the aspects of size miniaturization and design complexity in quality mode. The double frequency band filter has the advantages of being small, low in insertion loss, high in double frequency selection properties and the like. The demands on filter performances by a modern communication system are met, and the double frequency band filter can be widely applied in double frequency band mobile communication systems.

The invention discloses a multi-passband filtering method of railroad bed disease detection ground penetrating radar signals. The filtering method comprises steps of automatically acquiring roadbed original radar data through a vehicle-mounted roadbed detection radar; extracting radar reflection signals at joints of all scanning channel sleepers so as to form a digital sequence, and obtaining frequency spectrum features of the sleepers and the rail strong reflection interference signals by carrying out frequency spectrum analysis on the digital sequence; designing a multi-passband filter used for inhibiting strong interference of the sleepers and the rails; and using the filter to successively filter the radar signals according to sampling points so as to remove interference signal. According to the invention, by analyzing the strong reflection interference signals of the rails and the sleepers in the railroad bed disease detection ground penetrating radar signals for the first time, sleeper identification device is not required, radar signal acquisition is carried out without avoiding the rails, and the multi-passband filter designed on the basis of strong interference frequency spectrum features of the rails and the sleepers is used for removing strong reflection interference of the sleepers and the rails, the signal to noise ratio of reflection radar signals of the roadbed medium is improved.

A dual-band semi-active laser (SAL) sensing system incorporating a dual-passband filter. According to one example, a semi-active laser sensing system includes a detector assembly and an aperture lens. The SAL sensing system further comprises a dual-passband filter having a stopband, a first passband and a second passband, the first and second passbands being distinct and non-overlapping and spectrally separated from one another by a portion of the stopband, the filter being configured to receive the electromagnetic radiation from the aperture lens and to filter the electromagnetic radiation to pass a first wavelength range within the first passband and a second wavelength range within the second passband. The SAL sensing system further includes a lens assembly configured to receive the first and second wavelength ranges from the filter and to focus the first and second wavelength ranges onto the detector assembly.

The invention discloses a method for manufacturing a novel terahertz ultra-wide pass band filter. The method includes cleaning a substrate, coating a polyimide film on the substrate, coating a photoresist lift off resist (LOR) on the polyimide film and drying, coating a photoresist AZ1500 on the photoresist LOR and drying, exposing the photoresist, subjecting the exposed photoresist to development and drying, vaporizing a first layer of metal on the photoresist AZ1500 and the exposed polyimide film, soaking the substrate which is subjected to vaporizing the first layer of metal in an acetone solution for lift-off, coating the polyimide film on the substrate and curing, vaporizing a second layer of metal on the photoresist AZ1500 and the exposed polyimide film, soaking the substrate which is subjected to vaporizing the second layer of metal in the acetone solution for lift-off, coating the polyimide film on the substrate and curing, removing the substrate, and lifting off the substrate and the polyimide film. The method for manufacturing the novel terahertz ultra-wide pass band filter has the advantage that the expansion of frequency bands is achieved.

The invention discloses a small differential tee band-pass filter and solves the problems of multi-frequency operation of a differential band-pass filter and common-mode noise suppression. The filter comprises a micro band structure, a micro band medium substrate, a metal grounding plate and a defective ground structure; the micro band structure is transversely symmetric about the longitudinal central axis of a filter body; two side U-type differential input and output ports in the same structures are provided and are located on the upper surface of the micro band medium substrate; the defective ground structure is arranged on the metal grounding plate in an etched manner, and the defective ground structure is transversely symmetric about the longitudinal central axis of the filter body and comprises three complementary opened resonant rings, an input clearance line and an output clearance line; the complementary opened resonant rings are embedded mutually in a surrounded manner corresponding to the center of the metal grounding plate from interior to exterior, the input and output clearance lines are in stepped impedance types, and the defective ground structure is reduced accordingly. The differential filter miniaturization is realized, the central frequency and bandwidth of three differential mode pass bands are controlled independently, and the fine broadband common mode suppression features are provided.

The invention discloses an electrically tunable four-passband filter based on a double layered resonator, and mainly solves the problems that the number of passbands of a traditional electrically tunable filter is small, adjustable passband bandwidth is not constant, the out-of-band rejection degree is poor and the volume is large. The electrically tunable four-passband filter based on the double layered resonator includes a pair of parallel coupling feeder lines (1) and a pair of adjustable stepped impedance resonators (2, 3) which are arranged on an upper microstrip medium substrate (7), and a branch loading resonator (4) and two direct current biasing circuits (5, 6) which are arranged on a lower microstrip medium substrate (8), wherein the two direct current biasing circuits (5, 6) are connected to two ends of the adjustable stepped impedance resonators (2) and (3), thereby realizing continuously adjustability of a third passband and a fourth passband, and the branch loading resonator (4) realizes fixing of a first passband and a second passband. The electrically tunable four-passband filter based on the double layered resonator is small in size and high in out-of-band rejection degree, can realize four passbands, realizes continuous adjustability of the third passband and the fourth passband under the condition that the bandwidth is basically maintained unchanged, and can be used for a wireless communication system.

The invention discloses a single-band and three-band switchable filter based on a vanadium dioxide phase change metamaterial. The filter comprises an outer open resonance ring, an inner long branch open U-shaped ring, a first vanadium dioxide gap block body, a second vanadium dioxide gap block body, an inner short branch open U-shaped ring and a dielectric layer. The outer open resonance ring, theinner long branch open U-shaped ring, a first vanadium dioxide gap, a second vanadium dioxide gap and the inner short branch open U-shaped ring are located on the top layer, and the dielectric layeris located below a resonance ring pattern and the vanadium dioxide gaps. By changing the temperature, the vanadium dioxide material is subjected to phase change to form a metal state, the resonance characteristic of the structural unit is changed, and the switching from a three-passband filter before the phase change of vanadium dioxide to a single-passband filter after the phase change of vanadium dioxide is realized. The single-band and three-band switchable filter based on a vanadium dioxide phase change metamaterial has the advantages of compact structure, low cost, excellent performance and the like, and meets the application requirements of terahertz imaging and terahertz communication systems.

The invention discloses a plane compact type three-passband filter, which is realized by a centrally loaded resonator and an embedded half-wavelength resonator. The centrally loaded resonator consists of a microstrip line and a centrally loaded T-shaped structure and is used to generate a first passband and a third passband; the half-wavelength resonator is embedded into the centrally loaded resonator and is used to generate a second passband; and an interdigital coupling structure is used to realize interstage electromagnetic coupling. For the second passband, the structure can realize source-load coupling, so as to generate a pair of transmission zero point near the second passband and increase the roll-off property. The whole filter adopts a planar structure, is centrosymmetric and can realize the screening of signals at three different frequency bands. Both sides of each passband of the filter are provided with at least one transmission zero point, so high skirt selectivity is achieved. Meanwhile, the filter has the characteristics of small size, high space utilization rate, easy processing and the like.

The invention belongs to a multi-band bandstop filter comprising N resonant cavity groups. N is a the number of bands and is in a closed interval from 2 to 4; the N resonant cavity groups are stacked and aligned to acquire the response of the multi-band bandstop filter; each resonant cavity group comprises n resonant cavities arranged in a line, and n is in a closed interval from 3 to 5; distance among the n resonant cavities belonging to the same resonant cavity group is odd times of a 1 / 4 wavelength; a rectangular waveguide is in a 3 / 4 waveguide wavelength; and the N resonant cavity groups share the same main passage, are parallel to the main passage and are arranged at one side of the main passage or at both sides of the main passage by being arranged in an overlapping way while less than two resonant cavity groups are arranged at either side. The stopbands of the multi-band bandstop filter have good rejection characteristics and inter-stopband passband characteristics so that the multi-band bandpass filter can be designed by applying the structure of the multi-band bandstop filter based on a design idea that a bandpass filter and an N-band bandpass filter are integrated into an N+1-band multi-band bandpass filter.

In a splitter, a first band pass filter is connected between an antenna terminal and a first terminal, a high pass filter and a second band pass filter are connected between the antenna terminal and a second terminal, a pass band of the second band pass filter is higher than a pass band of the first band pass filter, a cut off frequency of the high pass filter is located closer to the high-frequency side than the pass band of the first band pass filter, the pass band of the second band pass filter is located closer to the high-frequency side than the cut off frequency, and the high pass filter also functions as a notch filter having an anti-resonant frequency in a transition region such that the steepness of the transition region between the pass band of the second band pass filter and the attenuated band is high.

The invention discloses a multi-bandpass filter based on a multimode resonator and mainly solves the problem of large size and poor performance of the multi-bandpass filter. The multi-bandpass filter based on the multimode resonator comprises a micro-strip dielectric substrate (1), a metal earth plate (2), a resonator (3) and an input-output feeder line (4). The resonator (3) is composed of two identical five-mode resonators which are staggered, each five-mode resonator is composed of a short-circuit branch (31), an open-circuit branch (32), a U-shaped microstrip line (33), a bulged loop (34) and L-shaped open-circuit branches (35 and 36). The symmetric center of the bulged loop (34) is superposed with that of the U-shaped microstrip line, and the top end of the bulged loop is connected with the bottom end of the U-shaped microstrip line. The L-shaped open-circuit branches are connected at the bottom end of the U-shaped microstrip line. The input-output feeder line (4) is composed of a pair of quasi fork-finger type coupled feeder lines. The size of the multi-bandpass filter can be reduced, design complexity is reduced, bandpass selectivity is improved, and the multi-bandpass filter can be used for a wireless communication system.

A filter circuit is provided having multipath interference mitigation. The filter includes a signal path extending from an input to an output. The signal path includes a conductive path and a ground. A pass band filter is disposed along the signal path between the input and the output. The pass band filter passes a first frequency spectrum in a provider bandwidth, and attenuates a second frequency spectrum in a home network bandwidth. The filter circuit further includes a multipath interference mitigation leg operatively branched from the signal path. The multipath interference mitigation leg increases a return loss of the home network bandwidth. A frequency response of the filter circuit is characterized by an insertion loss characteristic between the input and the output being less than 3 dB in the provider bandwidth, and more than 20 dB in the home network bandwidth. The frequency response is further characterized by a return loss characteristic at the output being more than 10 dB in the provider bandwidth and home network bandwidth.

The invention provides a triple-band band-pass filter based on an openstub loaded resonator, and mainly solves the problems in the design of the multi-passband filter that the size of the filter is large, the internal insertion loss of the passband is high and the echo loss is low. The triple-band band-pass filter comprises a microstrip dielectric substrate (1), a metal grounding plate (2), resonators (3), input and output feed lines (4) and a grounding through hole (5). The metal grounding plate (2) is arranged on the lower surface of the dielectric substrate (1). The resonators (3) are connected in series between the input feed line (41) and the output feed line (42). The resonators (3) and the input feed line (41) and the output feed line (42) are arranged on the upper surface of the dielectric substrate (1). According to the filter, the overall size of the filter can be reduced, the extremely low insertion loss can be acuqired and each passband can be independently controlled so that stop-band suppression can be increased, the passband selectivity can be enhanced and the triple-band band-pass filter can be used for the WLAN and WIMAX wireless communication system.

A circuit is disclosed with an external coupling port for coupling to an external antenna, for example. The circuit has an FDD receive path including a narrowband passband filter. The circuit has a TDD receive path bypassing the narrowband passband filter but relying on a same amplifier. The circuit also has an FDD transmit path including a narrowband passband filter. The circuit has a TDD transmit path bypassing the narrowband passband filter of the FDD transmit path but relying on a same transmit amplifier. A switching configuration allows the circuit to operate in TDD mode, alternating between the TDD receive path and the TDD transmit path and in the FDD mode wherein the FDD transmit and receive paths are simultaneously coupled to the external coupling port.

The invention discloses a multi-target micro-vibration video amplification method based on a multi-passband filter, and the method comprises the following steps: S1, photographing a multi-target vibration video through a camera, carrying out the YIQ color space conversion of the video, and extracting the video data of a Y channel; S2, in the Y video, manually selecting an ROI (region of interest)region containing the edge of the first vibration target, extracting brightness signals at N pixel positions in the region, and calculating an average frequency spectrum of the signals; similarly, obtaining the average frequency spectrum of other M-1 vibration targets; and then, detecting vibration frequencies and frequency peak values of the M targets to obtain a frequency vector and a frequencypeak value vector; S3, designing a multi-passband filter according to the sum of the frequency vectors; S4, replacing a band-pass filter in the PVM method with a filter to realize amplification of theM target micro-vibration videos. The multi-target micro-vibration video amplification method provided by the invention has the advantages of realizing multi-target micro-vibration visual display andthe like.

The invention provides an electromagnetic band gap (EBG) substrate-based resonator / filter. A top layer metal plate, a bottom layer metal plate, a middle dielectric layer, periodical metal columns and an external control network which consists of a series of resonator / filter working frequency control elements are included, wherein the periodically-arranged metal columns are embedded in the dielectric layer to form the periodical EBG substrate; an energy coupling structure designed on the top layer metal plate consists of coplanar waveguide and groove lines; and the frequency control elements can be built in or externally connected with a capacitor, and are connected with a central metal column to jointly form a resonant network to realize frequency tuning. On the basis, a dual-passband filter is also provided; the dual-passband filter comprises two or more EBG substrate-based single-band filters, and the external control network which consists of a series of frequency control elements. The single-band filters share the EBG substrate, so that miniaturization and high performance of the filter are realized.

Concentrations of N gas species can be detected from a single beam NDIR gas sensor having a differential infrared source and an (N+1)-passband filter (having a neutral passband and N absorption passbands for N gases) mounted at a single infrared detector by driving the infrared source with N input power levels to render the source into emitting at N distinct temperatures whose radiation outputs are characterized by N corresponding Planck curves which are dependent only upon the respective source temperatures and which link a Spectral Radiant Emittance MsubLamba with wavelength, measuring N detector outputs at the single infrared detector and detecting the concentrations of N different gas species, each of the N gas species having its own unique infrared absorption passband, by (a) setting up N causality relationship equations linking outputs of the detector respectively for N different source temperatures and a set of relevant parameters of the sensor components, (b) determining the values of all of the parameters for the N equations utilizing appropriate boundary conditions except the N concentrations for the respective N gas species, and (c) solving for the N gas concentrations with the measured N detector outputs, there being N equations and N unknowns, when N is an integer of 2 or more.

The invention discloses a double-passband filter with a left-hand performance, comprising a grounding plate, a central transmission line, a hollow-out split resonant ring and split-ring resonators, wherein, the hollow-out split resonant ring is etched on the grounding plate; the grounding plate is equipped with a medium plate; the central transmission line is arranged on the medium plate, two ends thereof are respectively connected with an external signal input cable and an external signal output cable, two sides thereof are symmetrically equipped with two split-ring resonators, and the central position thereof is etched with a slit; and the central transmission line at two sides of the slit is etched with a plurality of through holes on the grounding plate. The double-passband filter helps a signal passing the same have the left-hand performance and small structural physical dimensions.

The invention discloses a dual-passband power amplifier integrated with a filter. One end of an inductor L1 is connected with a negative voltage, while the other end of the inductor L1 is connected with one end of a microstrip line R1 and one end of a capacitor C1; the other end of the microstrip line R1 is connected with the grid of a transistor M, and the other end of the capacitor C1 is earthed; one end of an inductor L2 is connected with a positive voltage, while the other end of the inductor L2 is connected with one end of a microstrip line R2 and one end of a capacitor C2; the other endof the microstrip line R2 is connected with the source of the transistor M; the other end of the capacitor C2 is earthed. One end of an input matching network is connected with the grid of the transistor M; the other end of the input matching network is connected with one end of a capacitor C3; the other end of the capacitor C3 is connected with a 50-Ohm port impedance Z1 to serve as a signal input end. According to the dual-passband power amplifier integrated with the filter, a dual-passband filter is integrated at the output stage of the transistor via an integrating thought, so that a dual-passband output circuit integrated with matching and filtering functions is acquired, meanwhile, the matching circuit can be omitted, so that the amplifier can be directly connected with the filter, and meanwhile the matching function is completed.

The invention discloses a three-passband micro-band filter with low loss, based on a wedged SIR (Signal to Interference Ratio) structure. The three-passband micro-band filter adopts a coupling feedback structure on a micro-band transmission line with matched 50ohm resistance, and a rectangular defective geo-structure (DGS) is additionally arranged under the lower side of the three-passband micro-band filter; and a resonator adopts an interdigital wedged SIR (Signal to Interference Ratio) structure. The wedged SIR structure adopts a transition line for improving the resistance mutation of the SIR to achieve the smooth effect, and can be equivalent to a limiting form of a multi-order SIR at the same time, and the coupling effect is stronger. The rectangular defective geo-structure (DGS) additionally arranged under 50ohm of a coupling feeder line is equivalent to that one low-pass filter is cascaded at the front end of a post-stage band-pass filter, thereby the performance of the filter under the condition of not increasing the volume of the filter is further optimized. The invention discloses the three-passband micro-band filter with the low loss on the basis of the wedged SIR structure, the structure of the which is smaller than that of a single filter, and the three-passband micro-band filter can better meet the requirement on modern communication of miniaturized three-passband.

The invention discloses a dielectric cavity dual-bandpass filter, belonging to the field of filters. A cavity resonator (dielectric cavity resonator) loaded with a high dielectric constant cylindrical dielectric is adopted, two filter pass bands are realized by three of the modes, one filter pass band (signle-die filter) is realized by the TE01 delta resonance mode, and the other filter pass band (double-die filter) is realized by the HEH11 degenerate dual-mode resonant mode. A crotch-shaped probe structure is adopted to realize coupling of the input / output ports to the first and last resonators. A double-probe coupling structure realizes the coupling between two cavities. The coupling between the HEH11 degenerate dual-mode in each cavity is realized by adjusting screws on the cavity diagonal line. The tuning of the modes can be realized by the plurality of adjusting screws arranged on a cover plate. The filter takes full advantage of the lowest three modes of the dielectric cavity resonator to achieve a dual passband filter, thereby being capable of freely setting the center frequency and bandwidth of the two pass bands, and having the advantages of low loss, small size and large power capacity.

A realization method of a multiple passband filter that equalizes a group delay without using an external equalizer is disclosed. The realization method includes the steps of: a) calculating a transfer function based on poles and zeros; b) extracting an input / output coupling coefficient and a coupling matrix from the calculated transfer function as a network parameter; and c) physically designing and realizing elements of the filter to have the extracted network parameter.