101results about How to "High tuning accuracy" patented technology

The invention relates to a high / intermediate-frequency front-end circuit of a digital short-wave receiver, which mainly comprises a PIN diode electric control attenuator, digital control electric tuning preselected tracking filter groups, a gain control low-noise amplifier, a direct digital frequency synthesizer, a plurality of frequency mixers, an intermediate-frequency amplifier, an amplitude detection and grain control circuit and a preselected controller, wherein a weak signal sensed by an antenna is subjected to tracking frequency selection by the first digital control electric tuning preselected tracking filter group after passing through the PIN diode electric control attenuator and then is subjected to frequency selection by the second digital control electric tuning preselected tracking filter group after being amplified by the gain control low-noise amplifier, the signal after being subjected to frequency selection is subjected to frequency mixing three times with the plurality of frequency mixers by three local oscillators formed by the frequency synthesizer and is transmitted to a demodulator for demodulation after being subjected to multistep intermediate-frequency amplification and gain control processing. The high / intermediate-frequency front-end circuit of the digital short-wave receiver can meet the requirement of high sensitivity, strong anti-interference performance and wide dynamic range for the short-wave receiver, is suitable for a frequency-hopping receiving machine with rapid frequency change and has the effects of low insertion loss, low in-band ripple and high selectivity.

There is provided a semiconductor device which can maintain a high tuning accuracy while suppressing a cost increase and suppress an increase in the time required for tuning. There are included, in addition to variable resistors configuring a level shift circuit, an additional resistor coupled between the output node of a VBGR voltage of a BGR circuit and one of the variable resistors and an additional resistor coupled between the other of the variable resistors and a reference voltage. N-channel MOS transistors are coupled in parallel with the additional resistors, respectively.

The three-port polarizing offset tunable optical filter based on TFF comprises a set or more tunable filter unit with one composed of optical ring connected to the multi channel optical signal input end, a thin film filter, the polarized beam divider A & B on the same light path on the back and forth of the thin film filter plate, featuring in the polarized beam divider A dividing input signal light dividing into P and S parallel lights, with P having half wave plate C rotating P into P-S, two parallel S lights reaching thin film filter plate whose normal line slants on the two parallel S light paths, half wave plate D rotating S into S-P, polarized beam divider B synthesizing P and S into ordinary light signal to output, reflective mirror E paralleling laid with thin film filter plate with reflective mirror F setting behind reflective mirror E with F vertically set with two parallel light paths. It is simple in structure, easy for realization, being able to eliminate polarized relative consumption and polarized light dividing.

The invention provides an adaptive tuning device and tuning method of emission end of a wireless electric power transmission device. An alternating current power supply, a rectification filtering circuit, a high-frequency inversion circuit, a voltage detection device, an LC adjustable network, a compensation capacitor CP, an emission coil LP, an emission end impedance RP and a current detection device are successively connected together. A controller receives current and output of the current detection device and calculates and controls the high-frequency inversion circuit and the LC adjustable network. Two full-controlled devices M1 and M2 are serially connected with diodes D1 and D2, then are reversely parallelly connected with each, then are serially connected with a fixed inductor LT and then are parallelly connected with a power common capacitor CT, so a phase-controlled inductor capacitor parallel circuit is formed. S1 and S2 are square waves for the LC control circuit to controlon and off the M1 and M2. According to the invention, stability of the energy transmission system can be improved; and defects that the current wireless energy transmission system is easily detuned and an emission device fails to transmit energy to various kinds of receiving ends are solved.

A resistor tuning network is disclosed that comprises a first resistor connected in parallel with a second variable resistor and a third resistor coupled in series with the first resistor and the second variable resistor. The second variable resistor comprises an R-2R ladder network having an input and first and second output terminals, with a first line having a plurality of first arms connected in series with the input and first output terminal and nodes between each pair of arms, each arm having an identical resistor R. A series of shunt arms, each with a 2R resistor and a switch, are selectively connected between the respective nodes and the first or second output terminal. The resistance of the resistor tuning network is tuned by varying the switch positions in the shunt arms in the R-2R ladder network.

The invention provides a continuously tunable single-frequency Ti sapphire laser device. The continuously tunable single-frequency Ti sapphire laser device comprises a pump source (3), a Ti sapphire crystal (2), a laser resonant cavity, an isolator, a double-refraction filter (4), an etalon (5) and piezoelectric ceramic (14), wherein a nonlinear crystal (1) is inserted between a third flat concave mirror (11) and a fourth flat concave mirror (12) forming the laser resonant cavity, the nonlinear crystal (1) is an optical crystal machined to be provided with two unparallel light through surfaces or an optical crystal placed in a light path at a Brewster angle; moreover, the nonlinear crystal (1) is used for realizing generation of second harmonics of the base-frequency light of the laser device in a mode of critical phase matching or noncritical phase matching. According to the continuously tunable single-frequency Ti sapphire laser device provided by the invention, the nonlinear loss stressed by the main oscillation mode of the base-frequency light is one half of a non-oscillation mode, thus the oscillation starting of the non-oscillation mode of the base-frequency light is effectively suppressed, and the laser device realizes continuously tunable property for the frequency in a valid gain bandwidth. The laser device is compact in structure and convenient to operate.

This invention relates to single frequency attuning laser, which comprises laser gaining medium, laser resonance chamber, pump source, laser single frequency operation device and laser resonance device and is characterized by the following: the said laser resonance device is composed of one super standard electricity crystal and other micro resonance long electricity crystal. The electrical crystal relative two sides are covered electrode. This invention uses two blocks crystal with wide range, non-continuous adjusting laser frequency and takes place of mechanic adjusting and uses optical element to take place active optical elements.

The invention discloses an automatic frequency tuning circuit of an active RC filter. The automatic frequency tuning circuit comprises comparators, a constant current source, a reference voltage generating circuit, a switched capacitor circuit and a digital logic control circuit. The automatic frequency tuning circuit is characterized in that the reference voltage generating circuit generates first reference voltage, second reference voltage and third reference voltage which are input to the first comparator, an operational amplifier and the second comparator respectively, voltage generated by the constant current source on the switched capacitor circuit is input to the operational amplifier, and the digital logic control circuit receives signals output by the first comparator and the second comparator, conducts operation treatment, outputs control codes to the switched capacitor circuit and adjusts the equivalent capacitance of the switched capacitor circuit. The automatic frequency tuning circuit is simple in implementation method, low in cost, small in volume, low in power consumption, high in tuning precision, good in application prospect and capable of being widely used in fields such as electronics and communication.

The invention provides a wavelength division-time division hybrid passive optical network system, which comprises a central office, a plurality of optical network units and a remote node, wherein the remote node is positioned between the central office and the plurality of optical network units; the central office is provided with a plurality of light sources for emitting downlink signal light of various wavelengths, a plurality of receivers for receiving uplink signal light emitted by the plurality of optical network units and transmitted by the remote node respectively, and a plurality of multiplexer / demultiplexers for multiplexing and demultiplexing the downlink signal light and the uplink signal light; the remote end node is used for multiplexing the downlink signal light from the central office and demultiplexing the uplink signal light from the optical network units; and each optical network unit is provided with an internal annular coupler, a light separating unit for separating downlink signal light into signal light and injection light, a downlink data receiver for receiving separated signal light, and an MEMS (Micro Electro Mechanical System) tunable laser for receiving injection light and generating uplink signal light.

The invention discloses a transmitting end dynamic tuning device and method based on a double inverter. A transmitting end mainly comprises a DC / DC converter DA, a full bridge inverter NA, a transmitting end compensating network TC and a transmitting coil Lp; a receiving end mainly comprises a receiving coil Ls, a receiving end compensating network RC, a rectifier bridge Z, a load R and a direct current filter capacitor Cd; the transmitting end dynamic tuning device mainly comprises a full bridge inverter NB and a transformer; and the input end of the full bridge inverter NB is connected to the output end or the input end of the DC / DC converter DA in parallel. The transmitting end dynamic tuning device has the beneficial effects that the resonant state of a primary side is judged by directly measuring the phases of output voltages and currents of the inverters, so that the device is simple, effective and high in real-time performance; the dynamic tuning device is simple in structure, the full bridge inverter NB is in a soft switching state all the time, so that the switching loss of the inverters is reduced; real-time tuning is realized by adjusting the phase difference of controlsignals of the two inverters, so that the device is high in regulation speed and high in tuning precision; and a closed-loop control is formed by output voltage by using the DC / DC converter so as to maintain constant output voltage.

The invention provides a frequency tuning method for a TeraHertz parameter oscillator, which can realize high precision continuous tuning output of coherent narrow band TeraHertz by continuously changing pumping wavelength of the TeraHertz parameter oscillator without changing the incident angle of the pumping light. The invention has high frequency tuning precision (in particular in the long wavelength part), can overcome the change of characteristic of TeraHertz parameter oscillator caused by the change in the action area of the triple waves, can obviously expand frequency tuning scope of the TeraHertz parameter oscillator together with the angle tuning technology, and is hopeful to reach the low frequency area far smaller than 1THz which is hard to reach by singly using the angle tuning technology. Based on the tuning technology, the TeraHertz parameter oscillator can be widely used in TeraHertz optoelectronic technical fields such as medical diagnosis, fine spectrum analysis, bio-medical imaging, TeraHertz communication and the like.

The present invention discloses a dynamically tuning device and a tuning method for the sending terminal of a wireless electric energy transmission device, and relates to the technical field of wireless electric energy transmission. The primary side of the dynamically tuning device is provided with a phase detection device PD, a BUCK circuit, a control unit CU and a rectifier bridge. According to the detected phase difference state, the resonant state is judged. Meanwhile, the real-time tuning is realized through adjusting the equivalent output resistance of the BUCK circuit. As a result, the primary side can be maintained to run at a minimum voltage phase difference and a minimum current phase difference. That means, a primary side circuit is closer to the completely resonant state, so that the active power of the sending terminal is improved. Furthermore, the transmission power and the transmission efficiency of the wireless electric energy transmission device are improved.

The invention discloses a tunable true time delay test device and method based on discrete chirped fiber gratings. Light emitted by a tunable laser and a fixed wavelength laser at the same time enters a discrete chirped fiber grating time delay unit composed of uniform fiber gratings and linear discrete chirped fiber gratings successively in two times after microwave signal modulation so as to complete two-stage time delay, and four paths of electric signals with equal time delay difference are output at last; and meanwhile, the output wavelength of the tunable laser and the tunable linear fiber gratings are synchronously tuned to realize the change of the time delay difference. By adoption of the tunable true time delay test device and method disclosed by the invention, the output of four paths of signals with equal time delay difference and fine tuning can be realized, the instantaneity is good, although a path of error sources is imported, the system can neglect the error sources by means of smart combination of the linear chirped fiber gratings, meanwhile the test device is simplified, and the cost is reduced.

The invention relates to a method and a system for improving tuning precision and signal-to-noise ratio of a proton precession sensor. The method comprises the steps of outputting a first FID signal by an excitation sensor; waiting by a preset time period after excitation, acquiring the first FID signal and generating discrete data; constructing a spatial matrix according to the discrete data, performing singular value decomposition on the spatial matrix according to an SVD algorithm for eliminating noises and obtaining reconstructed data; processing the reconstructed data according to an FFT algorithm, and acquiring a first frequency value which corresponds with a maximal peak voltage in a first FID signal frequency spectrum; introducing the capacitance and the first frequency value of the sensor into an LC resonance formula for solving a first capacitance, and switching the capacitance of a tuning capacitor which is parallelly connected with the sensor from zero to the first capacitance. The method in which the SVD algorithm and the FFT algorithm are combined realizes tuning of the proton precession sensor and effectively overcomes defects such as low tuning speed, low tuning precision in an interference environment and easy imbalance phenomenon in an existing tuning algorithm.

The invention provides a high-precision and wide-tunability single-frequency optical fiber laser. The high-precision and wide-tunability single-frequency optical fiber laser includes a multi-component glass optical fiber, a broadband optical fiber grating or a dual-color mirror, a narrow-band optical fiber grating, a wavelength division multiplexer, an optical isolator, a pump source, a laser frequency tuning device and a heat sink, wherein the laser frequency tuning device is composed of a PZT piezoelectric ceramic assembly and a precise temperature controller. According to the high-precision and wide-tunability single-frequency optical fiber laser of the invention, the laser can be made to be in single longitudinal mode operation based on a short straight F-P linear resonant cavity structure of the multi-component glass optical fiber; a precise temperature control technology and a piezoelectric ceramic assembly stretching technique are combined with each other so as to adjust a laser resonant cavity, and therefore, the frequency of the high-precision, wide-range and continuous-tuning laser can be improved; and an all-optical fiber link structure is used in cooperation, and therefore, high-tuning precision, wide-tuning range and high-stability frequency-tunable single-frequency optical fiber laser output can be realized. The frequency tuning precision of the high-precision and wide-tenability single-frequency optical fiber laser of the invention is smaller than 1MHz, and the tunable range of the optical fiber laser of the invention can achieve 800pm, and the output power of the optical fiber laser is larger than 100mW, and the linewidth of the optical fiber laser is smaller than 10kHz.

A digitally controlled filter tuning method and corresponding WLAN (Wireless Local Area Network) communication devices and integrated circuit chips are provided. A WLAN communication signal is filtered by a tunable filter. A cut-off frequency of the tunable filter is tuned by a feedback loop. Tuning the cut-off frequency includes comparing by a comparator an output signal emitted by the tunable filter to a reference signal and emitting by the comparator a comparator signal indicative of the difference between the output signal and the reference signal. Further, tuning the cut-off frequency comprises receiving the comparator signal by a tuning controller and setting by the tuning controller the cut-off frequency of the tunable filter based on the comparator signal by applying a digital tuning word to the tunable filter. The described filter tuning technique may reduce product and manufacturing costs while providing enhanced tuning accuracy.

A system for heating hydrocarbon resources in a subterranean formation having a wellbore therein includes a coaxial transmission line, a balun, and a radio frequency (RF) antenna coupled together in series and configured to be positioned in the wellbore so that the RF antenna heats the hydrocarbon resources in the subterranean formation. The coaxial transmission line includes an inner conductor and an outer conductor surrounding the inner conductor. The balun includes an outer conductive sleeve having a proximal end coupled to the outer conductor of the coaxial transmission line and a medial portion coupled to the inner conductor of the coaxial transmission line. An inner tubular conductor extends longitudinally within the outer conductive sleeve between the outer conductor of the coaxial transmission line and the RF antenna. The balun also includes a ferrite body surrounding the inner tubular conductor at the proximal end.

A precision adjusting device for large-sized gratings comprises a grating mounting frame, grating positioning jackscrews, a grating pitching adjustment platform, a mounting base, a displacement fine-adjustment knob, a displacement fine-adjustment knob positioning jackscrew, an ejector disc, a tension spring, a tension spring support rod, a gear set, a transmission screw, bearings, a guide, keys, an angular fine-adjustment knob, a driving gear positioning block, and a level. The precision adjusting device for large-sized gratings has the advantages of simple structure, convenience in operation and high adjustment precision, and is applicable to optical systems with large-sized gratings requiring precision tuning.

The invention discloses a tunable true-time-delay experiment device and method based on wavelength division multiplexing, and the method comprises the steps: building the tunable true-time-delay experiment device based on the wavelength division multiplexing: building two groups of delay lines which are formed by the series connection of uniform fiber bragg gratings and chirp fiber bragg gratings and one group of delay lines which are formed by the series connection of two chirp fiber bragg gratings, respectively connecting two ports of three optical circulators, enabling the three groups of delay lines to three arms of a 1*2 optical splitter so as to achieve the two-stage time delay, adding a delay compensation module to one delay channel, and finally connecting the remaining delay devices; carrying out the synchronous tuning of the wavelength of a laser with the tunable wavelength and the chirp fiber bragg gratings at one position, and achieving the real-time tuning of a tunable true-time-delay system. The deice achieves the independent tuning of the delay time of one signal of a multiplexing signal, reduces an error source, is high in tuning precision, is large in tuning range, is simple in structure, and is low in manufacturing difficulty.

The invention discloses a multi-wavelength external cavity laser for a non-fluorescence raman spectrometer. More than two laser diodes with equal central wavelengths in an array are driven to be independently opened and closed through a power supply switching circuit; output light beams are calibrated into parallel collimated laser beams through a collimating laser calibration optical element; a special design is adopted by a grating; different grating periods are set for incident point regions, corresponding to the collimated laser beams, of the grating; the collimated laser beams form zero-order reflected beams and first-order diffracted beams after being diffracted by the grating; the zero-order reflected beams are output in the same direction and have a wavelength difference; the first-order diffracted beams return to the inside of the corresponding laser diodes along the original path to participate in internal mode competition of a resonant cavity; and the zero-order reflected beams are converged into an optical fiber combiner through an optical fiber coupling lens for wavelength output. The wavelength output is switched by the circuit, so that the unreliability and the possible error of conventional mechanical adjustment are eliminated; a tuning structure is relatively simple and stable; high stability of output wavelengths is ensured; the wavelength output repeatability in actual operation is high; and the tuning accuracy is relatively high.

The invention discloses an external cavity tuning laser, comprising a laser gaining chip for performing wavelength gaining on laser, a collimating lens for collimating a laser beam, a grating for generating first level diffraction light and zero level diffraction light by the collimated laser beam, a focusing lens for condensation transmission on the first level diffraction light, a reflection lens for performing selective reflection on the first level diffraction light subject to condensation transmission and a motor for driving the reflection lens to rotate, wherein the reflection lens is also provided with a metallizing fine line region pattern. According to the metallizing fine line region pattern, a micromachining process comprises photoetching and thin film depositing to realize manufacturing of the patterns, different pattern designs can realize an adjusting function of different wavelengths, such as a mono-wavelength linear tuning laser, a dual wavelength tuning laser, and a multi-wavelength tuning laser, and further meets application requirements of the tuning lasers in different occasions.

The invention relates to a tunable optical filter irrelevant to a polarization state of incident light. The tunable optical filter is characterized by comprising a tunable Fabry-Perot filter, a tunable acousto-optic filter, a polarized light synthetizing device and a system control circuit; the incident light firstly penetrates through the tunable Fabry-Perot filter, an output light beam penetrates through the tunable acousto-optic filter, polarization states of two output line polarization light beams are vertical with each other and the line polarization light beams have a certain separated included angle, and the two line polarization light beams are synthetized to a single light beam by the polarized light synthetizing device and then output; and the system control circuit can be respectively connected with the tunable Fabry-Perot filter and the tunable acousto-optic filter to realize a tunable output control function on a laser. The tunable optical filter is reasonable in design, stable and reliable in performance, small size, easy for installation and production, and the like, and can be widely applied to the fields of the lasers, optical test, optical fiber communication, organisms, medical equipment, optical fiber sensor networks, and the like.

The invention discloses a transmitting-end dynamic tuning device and method based on double DC-DC converters. A transmitting end comprises a DC power supply E, a DC-DC converter DA, a full-bridge inverter NA, a transmitting-end compensation network TC and a transmitting coil Lp, wherein the DC power supply E, the DC-DC converter DA, the full-bridge inverter NA, the transmitting-end compensation network TC and the transmitting coil Lp are connected sequentially. A receiving end comprises a receiving coil Ls, a receiving end compensation network RC, a rectifier bridge Z, a load Z and a DC filtering capacitor Cd, wherein the receiving coil Ls, the receiving end compensation network RC, the rectifier bridge Z, the load Z and the DC filtering capacitor Cd are connected sequentially, and the DCfiltering capacitor Cd is connected to two ends of the load RZ in a parallel manner. The dynamic tuning device comprises a DC / DC converter DB, a full-bridge inverter NB, and a transformer. The beneficial effects of the invention are that the phases of the output voltage and current of the inverter are directly measured, so as to judge the resonant state of the transmitting end, so the device is simple and effective, and is good in real-time performance; the tuning device enables the output of the full-bridge inverter NB to remain resistive, reduces the reactive power of a system, can reduce the capacity of a power supply through resonance adjustment, can achieve real-time tuning, is high in tuning precision, and enables the transmitting end to be closer to an ideal resonant state; the device enables the output voltage to achieve the closed-loop control and maintains the constant-voltage output through the DC / DC converter.

The invention relates to a filtering device with adjustable central wavelengths. The filtering device is composed of a narrow bandpass filter, a clamp, a pressing ring, a heat preservation cover, a heat preservation cover cap, a thermistor, a first heat preservation lens, a second heat preservation lens, a servo turntable, a heating resistor, a light splitter mirror, a wavelength meter and a controller. The filtering device is high in adaptive capacity to the environment, can normally work under the condition that temperature fluctuation is large, has the advantages of being simple in structure, convenient to operate and high in central wavelength tuning accuracy, and can be applied to an optical system with strict requirements for the spectrum central wavelengths under the temperature alternating condition.

A system for heating hydrocarbon resources in a subterranean formation having a wellbore therein includes a coaxial transmission line, a balun, and a radio frequency (RF) antenna coupled together in series and configured to be positioned in the wellbore so that the RF antenna heats the hydrocarbon resources in the subterranean formation. The coaxial transmission line includes an inner conductor and an outer conductor surrounding the inner conductor. The balun includes an outer conductive sleeve having a proximal end coupled to the outer conductor of the coaxial transmission line and a medial portion coupled to the inner conductor of the coaxial transmission line. The balun also includes an inner tubular conductor extending longitudinally within the outer conductive sleeve between the outer conductor of the coaxial transmission line and the RF antenna.

The invention belongs to the technical field of integrated circuit design and discloses a frequency self-tuning method and a frequency self-tuning circuit for a filter. The self-tuning circuit comprises a magnitude-locked loop (MLL) and a phase-locked loop (PLL). The self-tuning method and the self-tuning circuit correct the cut-off frequency of the filter by a coarse and fine tuning combined process. The self-tuning method comprises the following steps of: firstly, adopting the MLL to coarsely tune the cut-off frequency of the filter by regulating a control bit of a digital control capacitor array, wherein an error is a least significant bit (LSB) of the digital control capacitor array at the moment; secondly, regulating a capacitance value of a varactor by using the PLL and by VTUNE generated by a phase identifier and a charge pump; and finally, precisely matching the cut-off frequency of the filter with a reference frequency. The method has a wide tuning range and high tuning precision, only regulates capacitance and has no influences on the performance of the filter and therefore has a great practical value.

The invention discloses a digital tuning circuit for an RC (resistor-capacitor) filter and relates to the technical field of impedance networks. The digital tuning circuit comprises an integrator circuit and a window comparator circuit; the integrator circuit for producing a periodic digital waveform comprises PMOS (P-channel metal oxide semiconductor) transistors M1-M4, an NMOS (N-channel metal oxide semiconductor) transistor M5, NMOS transistors M7 and M8, a capacitor C, a programmable switch resistor array Rref and an error amplifier U1. The window comparator circuit comprises comparators U2 and U3. Compared with the prior art, the digital tuning circuit is simple in structure, easy to implement, low in power consumption and high in tuning precision; especially for low-frequency and multimode filters, chip area is greatly reduced, and cost is greatly reduced accordingly; the digital tuning circuit is widely applicable to on-chip active filters in the fields such as electronics and communication.

The invention provides a digital tuning method for a radar receiver front-end, comprising the following steps: emitting pulse signals, wherein the pulse signals include a first pulse signal; converting the first pulse signal into a medium-frequency pulse signal; preprocessing the medium-frequency pulse signal; and adjusting the frequency offset of the frequency value of the preprocessed medium-frequency pulse signal in a predetermined tuning mode to acquire a tuning control signal in accordance with the electrical characteristics of the radar receiver front-end. According to the digital tuning method, a digital tuning system and a digital tuning device for a radar receiver front-end provided by the invention, the digital tuning method has advantages such as strong anti-jamming capability, quick closed-loop control response and high tuning precision compared with an analog tuning method, a radar receiver front-end can output an ideal medium-frequency signal stably, the echo image is clear and full, the target and the clutter are distinct, and the target identification rate is improved effectively.