85 results about "Eigen frequency" patented technology

A system for detecting the eigen frequency of a sensing coil in a fiber optic gyro (FOG) that includes a fiber coupler connected to the light source, an integrated optics chip (IOC) capable of modulating light received from the light source via the fiber coupler, a sensing coil in communication with the IOC, a first modulation generator for imparting a first modulation signal to the light, and a photodetector for receiving light returning from the sensing coil that is representative of a rotation rate of the sensing coil. Along with the foregoing there is provided a second modulation generator for imparting a second, preferably sinusoidal, modulation signal to the light, a high-frequency demodulator in communication with a signal produced, at least indirectly, by the photodector, and a low-frequency demodulator in communication with the high-frequency demodulator. The high-frequency demodulator receives the first modulation signal as a reference frequency and the low-frequency demodulator receives the second modulation signal as a reference frequency. An output of the low-frequency demodulator represents a magnitude and sign of a frequency difference between a frequency of the second modulation signal and an even-harmonic of the eigen frequency.

The invention discloses a frequency-preset distributed frequency-hopping synchronizing method. The method comprises two basic steps, namely synchronous establishment and synchronous maintenance of a hopping system. The step of synchronous establishment comprises three stages, namely initiation, primary network entry and final primary network entry of the frequency-hopping system. The step of synchronous maintenance comprises two operation rules, namely the way of determining and then stopping, and the way of presetting frequency, namely a given secret key determines a frequency-hopping table and determines a frequency-hopping sequence and an eigenfrequency sequence through a chaotic sequence; and the hopping system hops frequency according to the given frequency sequence, a frequency-hopping radio station hops frequency according to the eigenfrequency sequence, and synchronization information is issued through service frequency. The method has adaptive frequency-hopping function, is applied to a local area network frequency-hopping communication system consisting of N frequency-hopping radio stations, wherein N is more than or equal to 3. The frequency-hopping radio stations are required to have a full duplex working mode. Compared with the traditional frequency-hopping synchronizing method, the method has higher anti-jamming capability and anti-interception capability, and can realize information seamless connection and signal relay transmission.

The invention discloses a multimode multifrequency transceiver, which comprises a radio frequency front-end module, an analog baseband module and a frequency synthesizer module. The frequency front-end module comprises a plurality of radio frequency links used for receiving and dispatching signals in different frequency ranges; the analog baseband module comprises an analog baseband signal receiving link and an analog baseband signal emission link, and is used for carrying out filter and amplification on signals sent by the radio frequency links, converting the signals into digital signals, carrying out digital to analog conversion and filtering amplification processing on signals transmitted by a digital baseband, and outputting the signals to the radio frequency links, and the multimode multifrequency transceiver shares the analog baseband signal receiving link and the analog baseband signal emission link; and the frequency synthesizer module is utilized to provide different eigenfrequencies for the plurality of radio frequency links. The working frequency bandwidth of the ultrawideband multimode multifrequency transceiver provided by the invention can cover 0.3GHz to 6GHz, so that the ultrawideband multimode multifrequency transceiver is suitable for a plurality of different wireless communication standards.

A method for measuring the quantity of fluid in a tank may include the steps of selecting a match between a measured set of electromagnetic eigenfrequencies and a simulated plurality of sets of electromagnetic eigenfrequencies using a matching algorithm, wherein the match is one simulated set of electromagnetic eigenfrequencies from the simulated plurality of sets of electromagnetic eigenfrequencies, and determining the fill level of the tank based upon the match.

The invention discloses an online automatic tracking method for an eigen frequency of a fiber optic gyroscope, and belongs to the technical field of fiber optic gyroscopes. Based on an eigen frequencymeasurement in an open-loop offline state, a relation model of an error amount of the online extracted gyro modulation signal frequency deviating from the eigen frequency and the eigen frequency is established, and a scheme that carries out seamless switching and adjusting double clocks of time division multiplexing modulation and modulation signal frequency on a closed-loop fiber optic gyroscopeare designed on a premise of not influencing normal angular velocity demodulation of the closed-loop gyroscope. According to the online automatic tracking method for the eigen frequency of the fiberoptic gyroscope, the error amount of the modulation frequency deviating from the eigen frequency is extracted, fed back and adjusted under the premise of not influencing the angular velocity demodulation of a main closed-loop circuit. Moreover, jitter that can be caused in a switching process can be eliminated, compensation for a scale factor of fiber optic gyroscope with high precision is provided.

A drive signal generating unit generates a drive signal having a cyclic waveform containing a zero period in a vibration mode. A driver unit generates the drive current in response to the drive signal generated by the drive signal generating unit so as to supply the drive current to a voice coil. An induced voltage detector detects the induced voltage occurring in the voice coil during a nonconducting period. A zero-cross detector detects the zero cross of the induced voltage detected by the induced voltage detector. The drive signal generating unit estimates the eigen-frequency of a vibration speaker from a detected position of the zero cross and brings the frequency of the drive signal close to the estimated eigen-frequency.

The invention discloses an optical fiber ring eigen frequency measurement device and method based on sine wave modulation and second harmonic detection. According to the optical fiber ring eigen frequency measurement device and method, modulation is applied to by adopting a sine wave, and a second harmonic amplitude in an output signal is interfered through detecting an optical fiber ring, thus an eigen frequency is measured. The optical fiber ring eigen frequency measurement device has the technical effect that the modulation is applied by using the sine wave instead of a square wave, multiple defects caused by modulation of the square wave are overcome, the amplitude of the second harmonic of the output signal is detected, and high signal to noise ratio can be obtained by adopting a correlation detection technology.

The invention discloses a method of nondestructive elasticity measurement by photoacoustic eigen spectrum analysis. The method provided by the invention utilizes laser pulse to irradiate an elastomer to make it radiate sound wave under the action of photoacoustic effect, and through analysis of the photoacoubtic signal radiated by the elastomer, a photoacoustic eigen spectrum of the elastomer can be obtained, the eigen frequency of the elastomer can be extracted from the photoacoustic eigen spectrum, on the basis of the eigen frequency, inversion algorithm is also utilized to evaluate the elastic properties of the elastomer. The method of nondestructive elasticity measurement by photoacoustic eigen spectrum analysis provided by the invention has no need for mutual contact of an acoustic transducer and the elastomer during measurement, and also has no need for any dissection treatment on the elastomer. The method can realize non-contact and nondestructive evaluation of elastic parameters, and has high safety and usability.

The invention discloses an optical fiber loop eigen frequency measurement device and an optical fiber loop eigen frequency measurement method based on sine wave modulation and first harmonic detection. According to the device and the method, the eigen frequency is measured by applying modulation through a sine wave and detecting the amplitude of the first harmonic in an interference output signal of an optical fiber ring. The technical effects are that the sine wave instead of a square wave is used for applying modulation, so that various shortcomings caused by the square wave modulation are overcome; furthermore, the amplitude of the first harmonic of the output signal is detected, so that a high signal-to-noise ratio can be obtained by a relevant detection technology.

The invention relates to an active acoustic metamaterial based on local resonance. According to the metamaterial, a hard sheet metal material is used as a substrate plate; a plurality of magnetic massblock units are embedded in the substrate plate; each magnetic mass block unit is composed of a magnetic mass block and a circular thin film fixed to the magnetic mass block, the magnetic mass blockunits are periodically arranged on the substrate plate in a lattice form, an electromagnet with adjustable current magnitude and positive and negative currents is further arranged above each magneticmass block unit, the vertical distance between each electromagnet and the corresponding magnetic mass block is 2-3 cm, and the electromagnets are used for applying adjustable reverse restoring force to the magnetic mass block units. According to the acoustic metamaterial provided by the invention, the electromagnets with adjustable current are introduced, and the intrinsic frequency of the thin film type acoustic metamaterial unit is actively adjusted, so that the sound insulation peak frequency is adjusted, the metamaterial has negative mass density, the sound insulation quantity far higher than the mass law can be realized, and the low-frequency line spectrum sound insulation is realized.

The invention belongs to the technical field of automatic identification and in particular relates to a radio frequency identification system. The radio frequency identification system consists of a PC (Personal Computer) terminal, a reader, a reader antenna, a label antenna and a label chip, wherein the eigenfrequencies of a receiving module and a transmitting module of the reader are different, the transmitting carrier frequency of the reader is set as f0, and the backscatter carrier frequency of a label is set as F(sum0), wherein F indicates a certain function relationship. The transmitting carrier of the reader is subjected to simple transformation by using the label to obtain carriers with different frequencies so as to carry out backscatter modulation. According to the harmonic radio frequency identification system, self-interference and multipath interference of the radio frequency identification system can be greatly reduced, and therefore the sensitivity of the reader and the radio frequency identification system is improved.

The related relay amplification device in TD-SCDMA system comprises: a couple of correlative RF transceivers orientated BS and coverage respectively, a frequency and clock structure unit to provide Eigen frequency and timing-enable control for two transceivers and feed back work unit working state to BS, a TD-SCDMA terminal baseband circuit unit to use the BS-orientated transceiver to complete initiation and build communication with BS to get network synchronism time and emission power parameter and computer needed up-down gain for work state monitor.

The invention discloses a closed-loop fiber gyro signal modulation method, and relates to the technical field of fiber gyro signal modulation and demodulation. According to the modulation method, themodulation frequency of a fiber gyro is dynamically adjusted via a four-mode square wave modulation signal plus a sawtooth step modulation signal, an error is resolved and real-time fed back within each tau/2 period, new modulation frequency is generated on such basis, the modulation frequency is dynamically adjusted in a next tau period, and the intrinsic frequency is tracked and the modulation frequency is rapidly and dynamically adjusted in the next tau period. The modulation frequency is dynamically adjusted via existing circuits and optical paths, intrinsic frequency tracking data is completely synchronized with fiber gyro signal processing data, there is no problems in delay and data synchronization among the signals, the instantaneity is high, use is simple and convenient, the dynamic tracking performance is higher, and extra parts are not needed.

The invention belongs to the field of pentamode metamaterial, and discloses a method for improving the binding force of two-phase materials of pentamode metamaterial in additive manufacturing. The method comprises the step (a) of regulating the size and wall thickness of hexagonal micro-units of the pentamode metamaterial, so that the actual density and modulus parameters of a honeycomb structureare approximate to set values, thereby obtaining a new size and wall thickness of the hexagonal micro-units; the step (b) of forming slots in interfaces between metallic phases and nonmetallic phasesat the connection position between the adjacent edges of each hexagonal micro-unit; the step (c) of calculating the sizes of the slots by making the compression wave velocity and shear wave velocity of eigen frequency in a curve equal to the set values; and the step (d) of establishing a three-dimensional structural model of the pentamode metamaterial, and forming and obtaining required pentamodemetamaterial parts through additive manufacturing. Through the method, the structural stability at the interface position between the metallic phases and the nonmetallic phases of the pentamode metamaterial is improved, and mechanical members of the pentamode metamaterial are improved; and strategies are provided for practical application of multiphase metamaterial in additive manufacturing.

The invention discloses a temperature self-compensation in-plane biaxial acceleration sensor and a temperature compensation method. The sensor comprises a mass block, a plurality of groups of resonance sensitive elements are uniformly arranged around the mass block in a central symmetry manner, when acceleration in any direction and any magnitude in a plane is applied to the device, the mass blockapplies stress to the plurality of groups of resonance sensitive elements at the same time, the intrinsic frequency of the resonance sensitive elements is changed, and the resonance frequency is readout by corresponding real-time frequency reading circuits respectively. Compared with a traditional differential single-axis acceleration sensor, the sensor has unique advantages in the aspects of measurement precision, sensitivity, measurement range and the like. According to the temperature compensation method provided by the invention, the system error caused by the temperature is eliminated,and the current temperature value information can be additionally provided.

In a brushless motor, the rotational frequency N (Hz) of the hub satisfies N<F₀/(3*P+2), where F₀ (Hz) is an Eigen frequency of the second order rocking-mode resonance when not rotating in the situation where the recording disk is mounted on the hub. The recording disk is mounted on the hub. A base plate rotatably supports the hub. A laminated core is fixed to the base. The core has a ring portion and a plurality of teeth that extend radially from the ring portion. Coils are wound around the plurality of teeth. The coils are three-phase driven. A cylindrical magnet is fixed to the hub. The cylindrical magnet are magnetized for driving with P (P is a natural number) poles along the circumferential direction and are arranged to radially face the plurality of teeth.

The invention discloses a bridge cable monitoring method based on an optimized tensioning string model and a bridge cable monitoring system thereof. The method comprises the steps that a steel cable having the same specification with the actually measured bridge cable is selected to construct the residual function of the Gauss-Newton method, then iterative solving is performed on the residual function of the Gauss-Newton method and the optimal eigen-frequency order number and the optimal steel cable flexural rigidity of the residual function of the Gauss-Newton method are obtained, and finally the tensioning string model is optimized according to the result of iterative solving; the theoretical eigen-frequency is solved; the vibration spectrum of the bridge cable is obtained, and then the frequency meeting the optimal eigen-frequency order number is selected from the obtained vibration spectrum to act as the actually measured eigen-frequency through screening; and an acceleration sensor node determines transmitting of acquisition data and sampling frequency for adjusting the acceleration sensor to an upper computer monitoring center according to the size of the ratio of the difference value of the actually measured eigen-frequency and the theoretical eigen-frequency to the theoretical eigen-frequency. The bridge cable monitoring method is low in error and considers analysis of both accuracy and power consumption so that the bridge cable monitoring method can be widely applied to the field of bridge monitoring.

The invention belongs to the technical field of detection, and discloses a method and device for obtaining frequency offset by utilizing a pre-fitting phase-locked frequency difference value. The method comprises the steps of segmenting a pre-fitting signal; carrying out frequency mixing calculation on the pre-fitting signal and two paths of phase-locked reference signals to obtain superposed signals of a difference frequency term and a sum frequency term, and carrying out low-pass filtering on the two paths of superposed signals; acquiring the amplitude ratio of the output signal to the phaselocking result of an original state signal of a probe to determine the position of a phase locking convergence point, and fitting a corresponding convergence site-frequency offset curve; dividing theacquired probe signal into N sections, and performing phase-locked filtering processing on each section and the pre-fitting signal to obtain a phase-locked convergence point position in the section;and obtaining the frequency offset corresponding to each convergence site according to the convergence site-frequency offset curve and the phase-locked convergence point position. According to the method, the micro-frequency offset of the AFM probe fluctuating on a high intrinsic frequency level in a strong noise environment can be accurately and quickly measured and calculated.

The invention provides a fiber-optic gyroscope main control panel crystal oscillator selecting method based on anti-fuse FPGA. The method comprises the following steps: (1) by virtue of an FPGA with a DDS (Direct Digital Synthesizer) module serving as a fiber-optic gyroscope control panel of a control chip, controlling the DDS module to generate the initial modulation frequency A; (2) observing the signal waveform of an output voltage of a photoelectric detector to determine whether the signal is a sharp comb periodic signal; (3) if not, controlling the DDS to generate modulation frequency B close to the modulation frequency A by the FPGA, repeating the above steps until the peak width reaches the dozens of ns magnitudes, considering to be equal to the eigen frequency of the gyroscope; and (4) amplifying the eigen frequency of the gyroscope by integer multiples of 2n to be used as the frequency of a selected crystal oscillator. The method can accurately measure the eigen frequency of the gyroscope, solves the problem of large zero offset of the gyroscope, caused by inaccurate eigen frequency design, and can provide reference for the anti-fuse-based FPGA crystal oscillator selection of a fiber-optic gyroscope main control panel.

The invention belongs to the technical field of vibrating gyroscopes, and discloses a chemical trimming method for a second harmonic error of a quartz cylindrical harmonic oscillator. The method comprises the following steps of A, obtaining the intrinsic frequency, frequency splitting and inherent rigid axis orientation of the harmonic oscillator through a frequency sweeping method; B, calculatinga second harmonic error value of the harmonic oscillator according to the intrinsic frequency, the mass and the amplitude ratio of the harmonic oscillator; C, calculating the chemical trimming time according to the immersion depth and the inclination angle of chemical trimming, the second harmonic error value of the harmonic oscillator and the etching rate of the chemical etching liquid; and D, according to the chemical trimming time, etching the harmonic oscillator at two positions at an interval of 180 degrees along the low-frequency axis direction by using a chemical etching solution. According to the present invention, the second harmonic error value is reduced by removing the specific mass from the low-frequency axis orientation of the harmonic oscillator n = 1 mode, the consistencyand symmetry of the harmonic oscillator can be further improved, the noise in the output signal is reduced, and the precision of a cylindrical vibrating gyro is improved.

The invention provides a modulation method and system of a magnetoelectric mechanical antenna, a computer device and a readable storage medium thereof. The modulation method of the magnetoelectric mechanical antenna comprises the step of applying a bias magnetic field to the heterojunction antenna to be modulated; detecting the ferromagnetic resonance frequency of the heterojunction antenna to be modulated, and comparing the ferromagnetic resonance frequency with the mechanical resonance eigenfrequency of the heterojunction antenna; and if the ferromagnetic resonance frequency and the mechanical resonance eigenfrequency are not equal in an error range, adjusting the size of the bias magnetic field, so that the resonance eigenfrequency and the ferromagnetic resonance frequency are equal in the error range. By the adoption of the method, BFSK modulation communication of the mechanical antenna can be directly achieved, BFSK modulation achieved by changing the mechanical resonant frequency of a system through an additional circuit is avoided, and therefore the BFSK modulation scheme is simplified, and the integration of the mechanical antenna is facilitated.

A drive signal generating unit generates a drive signal used to alternately deliver a positive current and a negative current to a coil with a nonconducting period inserted between conducting periods. A driver unit generates a drive current in response to the drive signal generated by the drive signal generating unit and supplies the drive current to a coil. The drive signal generating unit estimates the eigen frequency of a linear vibration motor based on a detected position of the zero cross occurring in the coil during the nonconduting period, and the frequency of the drive signal is brought close to the estimated eigen frequency. The zero-cross detecting unit sets a detection window for avoiding the detection of zero cross of voltages other than the induced voltage. The zero-cross detecting unit enables a zero cross detected within the detection window and disables a zero cross detected outside the detection window.