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 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.

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 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 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.

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.