81 results about "Double frequency" patented technology

The invention discloses an MMC sub-module fault processing method, device and equipment and a storage medium, and the method comprises the steps: obtaining the capacitor voltage value of a sub-module of an MMC and the bridge arm current value of the sub-module, the MMC comprises six bridge arms of three phases, each bridge arm comprises a plurality of sub-modules, the capacitor of each sub-module is connected with an equivalent series resistor in series, and further, the equivalent series resistor is connected with the capacitor voltage value of the sub-module of the MMC; the resistance value of an equivalent series resistor in the sub-module is monitored through the capacitor voltage value and the bridge arm current value, if the resistance value of the equivalent series resistor is higher than a preset resistance value, it is determined that the capacitor of the sub-module fails, fault-tolerant control is carried out on the sub-module through a voltage-sharing and circulating current suppression algorithm, a three-phase switching signal is output, and the three-phase switching signal acts on the MMC. Therefore, the circulating current fundamental frequency component and the double frequency component caused by fault-tolerant control after the fault can be eliminated through the circulating current suppression strategy, the effect of circulating current suppression is achieved, and the stability of system fault operation is improved.

The invention relates to the technical field of converter control, and provides a loss optimization control method for a modular multilevel converter and related equipment, and the method comprises the steps: solving an expression of the average conduction loss and an expression of the average switching loss of a target modular multilevel converter; according to the expression, the positive correlation between the loss and the absolute average value of the bridge arm current is obtained through analysis, and the expression of the absolute average value of the bridge arm current is obtained; according to the positive correlation, loss optimization is equivalent to optimization of the absolute average value of the bridge arm current, and the optimal value range of the initial phase angle when the absolute average value of the bridge arm current is minimized is analyzed; according to the optimal value range of the initial phase angle, calculating an optimal initial phase angle and an optimal double frequency circulation component when the absolute average value of the bridge arm current is minimized; and controlling the target modular multi-level converter according to the optimal double-frequency circulation component and the optimal initial phase angle. According to the method, the optimization precision can be improved while loss optimization is realized.

The invention relates to the technical field of satellite navigation and wireless communication, and discloses an indoor positioning method and system based on feeder multiplexing Beidou double-frequency, and the method comprises the steps: receiving outdoor B1I and B2a signals through a high-gain Beidou double-frequency receiving antenna, carrying out the frequency separation and signal conditioning through a double-frequency separation filter, and carrying out the positioning of the B1I and B2a signals; and transmitting the B1I signal to an indoor distributed antenna for broadcasting through the existing communication feeder network, and transmitting the B2a signal to a central directional antenna to establish a time synchronization reference. A mobile terminal receives a dual-frequency signal, capturing and tracking are carried out through digital signal processing, and pseudo-range and carrier phase observation values are extracted. And performing pairing processing on observation data of the same antenna, calculating a dual-frequency pseudo-range difference value, eliminating system errors, and performing position calculation by adopting a weighted least square method and Kalman filtering. The method solves the problem that the traditional GPS signal cannot cover the indoor environment, and has a good application prospect in the scenes of underground commercial complexes, tunnels, parking lots and the like.

The invention relates to a double-ridge waveguide antenna array applied to satellite communication, and relates to the technical field of antennas. The antenna comprises a horn radiation layer, a waveguide transmission layer, a low-frequency feed layer and a high-frequency feed layer which are sequentially arranged in the stacking direction. The low-frequency feed layer and the high-frequency feed layer are connected with the horn radiation layer through the waveguide transmission layer and the stepped impedance conversion waveguide; the horn radiation layer comprises dual-band horn common-caliber radiation units, metal blocks and metal strips, the metal blocks and the metal strips are used for constructing ridge waveguide structures, the adjacent dual-band horn common-caliber radiation units are separated by the metal strips, and the ridge waveguide structures constructed by the metal blocks are used for loading and expanding bandwidth; according to the invention, the design complexity of double frequency bands with a large frequency ratio is effectively simplified, and the design compactness of the antenna array is improved.

Many modern Global navigational satellite systems (GNSS) utilize signaling that includes a primary pseudorandom number (PRN) code and a secondary low rate PRN code, the latter of which is modulo-2 added to the first. In some GNSS acquisition receivers in which precise a priori synchronization information is unavailable, the acquisition process performs a set of correlation operations that begin at a time that is not aligned with the epoch of the secondary PRN code. This epoch misalignment results in loss of system performance. This disclosure provides new methods for dealing with such epoch misalignments and minimizes system performance loss. In one embodiment, a method combines a first and a second correlation operation, each using a different correlation epoch, to reduce the effect of epoch misalignments. This disclosure also provides methods for advantageously processing a characteristic double frequency peak that may appear in the acquisition process as a result of the correlation misalignment with the epoch of the secondary code.

The utility model belongs to the technical field of fiber lasers, and particularly relates to a high-efficiency frequency doubling system for a laser. The high-efficiency frequency doubling system for the laser comprises a first lens, a first frequency doubling crystal, a 4f system and a second frequency doubling crystal which are arranged in sequence. According to the high-efficiency frequency doubling system for the laser, the two frequency doubling crystals are used, phase matching is adopted, S polarization light and P polarization light of fundamental frequency light are subjected to frequency doubling in sequence to form P polarization frequency doubling light and S polarization frequency doubling light, two times of frequency doubling of the non-polarization-maintaining fiber laser are achieved through two times of frequency doubling, and high-power green light in the mixed polarization direction is obtained. And under the condition that the infrared fundamental frequency power is kept unchanged, the proportion of S polarization component light to P polarization component light is changed due to the change of the polarization state, but two generated green light beams are complementary, so that the power output is more stable than that of one crystal.

The invention relates to an antenna assembly and a vehicle. The antenna assembly comprises a dielectric body, a first antenna structure, a second antenna structure and a metal frame body. The projections of the plurality of second antenna structures on the dielectric body along the thickness direction of the dielectric body are arranged around the circumferential direction of the first antenna structure, the plurality of second antenna structures are rotationally symmetrical about the center of the first antenna structure, and each second antenna structure is coupled with the first antenna structure. The metal frame body is arranged around the periphery of the first antenna structure, and the metal frame body is connected with the dielectric body. The low-profile antenna structure is realized, the influence caused by the surface wave effect of the dielectric body is improved, the mutual coupling interference between double frequencies is reduced, and the antenna gain and the antenna bandwidth are improved. Besides, the metal frame body can restrain back lobe level energy, capacitance coupling is formed between the first antenna structure and the metal frame body, capacitance coupling is formed between the second antenna structure and the metal frame body, the antenna miniaturization design is further achieved, the overall size is reduced, and the installation space can be prevented from being limited.

The application discloses a high-energy and few-cycle blue light laser generation method and device, and belongs to the technical field of ultrafast laser, wherein the method comprises the following steps: adopting a nonlinear crystal to double frequency of a base frequency pulse after compression, and performing at least twice pulse width compression on the obtained double frequency pulse to obtain high-energy and few-cycle blue light laser; wherein, the double frequency process and the pulse width compression process are both performed in a cavity filled with helium; the pulse width compression process is performed through spectral broadening of a solid sheet; since the helium has extremely low linear dispersion and nonlinear coefficient and extremely high ionization energy, not only the solid sheet damage can be avoided, and a part of spectral broadening is contributed, but also an environment close to vacuum can be provided in terms of dispersion and laser-induced ionization, so that the dispersion compensation of the double frequency pulse is easier, and the energy loss caused by gas ionization and the input energy limitation are avoided, and higher output energy is allowed; the problem that the high-energy and ultra-short pulse width blue light pulse is difficult to be realized simultaneously at present is effectively solved.

1. The name of the design product: full transparent vertical double frequency anti-theft access control. 2. The use of the design product: the design product is used for attendance management, identity recognition and access control management. 3. The design points of the design product: in shape. 4. The picture or photo that best indicates the design points: perspective view 1.

The application discloses a kind of based on decoupling surface and isolation plate's dual polarization and double frequency base station antenna and array, the base station antenna includes low frequency antenna array, high frequency antenna array, antenna floor and multiple first isolation plate being arranged in antenna floor, multiple second isolation plate being arranged in the middle of adjacent two first isolation plate;High frequency antenna array includes multiple columns of high frequency antenna unit column being installed in the middle of adjacent first isolation plate and second isolation plate;Low frequency antenna array includes multiple columns of low frequency antenna unit column being installed in the middle of adjacent two first isolation plate;Each column of low frequency antenna unit column includes multiple low frequency antenna units printed with decoupling surface, decoupling surface includes 8 several Chinese character shape metal strip, 180 square metal patch and 40 rectangular metal patch.Not only solve the problem of low frequency antenna to high frequency antenna's shelter, repair high frequency antenna pattern, but also can effectively improve low frequency antenna and high frequency antenna's same frequency isolation, improve decoupling effect.

The present invention discloses an optical ranging method of a coherent phase-pushing system, which uses a single-frequency microwave signal to perform double-sideband modulation on an optical carrier signal. After the generated modulated optical signal passes through the optical link to be measured, it is polarized and split into two beams of detection optical signals in the horizontal and vertical polarization directions, and the local oscillator optical signal is polarized and split into two beams of local oscillator optical signals in the horizontal and vertical polarization directions; the local oscillator optical signal in the horizontal polarization direction and the detection optical signal, and the local oscillator optical signal in the vertical polarization direction and the detection optical signal are respectively combined, photoelectrically detected, and envelope detected, and then the two obtained electrical signals are combined to generate the electrical signal to be measured; the phase difference between the doubled frequency signal of the single-frequency microwave signal and the corresponding frequency component in the electrical signal to be measured is detected, and the distance of the optical link to be measured is calculated based on the phase difference. The present invention also discloses an optical ranging device of a coherent phase-pushing system. The present invention can effectively improve the optical ranging accuracy of the coherent phase-pushing system.

The application discloses a polarization converter using terminated filter circuit to control frequency characteristics, comprising: a dual-polarized antenna array and a filter circuit arranged on the back of the antenna array floor, the dual-polarized antenna array is used for transmitting the received electromagnetic wave signal to the filter circuit arranged on the back of the antenna array floor, and transmitting the signal output through the filter circuit to the free space; the filter circuit is used for realizing the control on the frequency characteristics of the polarization converter. By arranging different filter circuits on the back of the antenna array floor, the polarization converter with different frequency characteristics can be obtained. The application designs a reflection type polarization converter with super wideband and double frequency band. When linear x-polarized or y-polarized electromagnetic wave irradiates to the surface of the polarization converter, the reflected wave is the orthogonal polarization thereof. The application can be used for antenna design, radar cross section (RCS) reduction and wireless communication technology.

The application discloses a kind of triaxial SERF atom magnetometer quadrature double frequency modulation system and method, the system utilizes signal generation module to generate frequency f m The sine quadrature modulation signal of cosine is respectively driven SERF atom magnetometer X and Y axis magnetic field generating coil, and 2nf m Frequency sine signal of driving Z axis coil, through the integral filter of 3 groups of integral period integration, the open-loop magnetic field signal of X axis, Y axis and Z axis magnetic field component is obtained, and through control module, the driving current of three-axis magnetic field coil is controlled to generate compensation magnetic field, so that the open-loop magnetic field signal of X axis, Y axis and Z axis magnetic field component is zero, at this time, the magnetic field intensity of atom chamber is zero, and the compensation current output by control module is the X, Y and Z axis magnetic field intensity signal measured by triaxial SERF atom magnetometer.The system can directly extract triaxial magnetic field calculation signal from a laser signal, and eliminate the cross-coupling effect when triaxial magnetic field is calculated, improve the measurement range and quadrature of SERF atom magnetometer, with very high engineering application value.

The application provides a time-frequency offset estimation method and device of an LTE system, and relates to the technical field of communication. The method comprises the following steps: a plurality of decimal multiple frequency offsets are used to compensate the initial received signal to obtain a first target signal; after PSS detection and screening of the first target signal, the first m first correlation peak values in descending order, N-ID-2 corresponding to the first correlation peak values, the first timing position and the first frequency offset value are obtained; a plurality of integer multiple frequency offsets are preset and the second correlation peak values corresponding to each first correlation peak value are calculated; the time domain position of each second correlation peak value is located and frequency offset compensation is performed to obtain a second target signal; after SSS detection and screening of the second target signal, the first n second correlation peak values in descending order, N-ID-1 corresponding to the second correlation peak values, the second timing position and the second frequency offset value are obtained, and the cell ID is obtained by combining N-ID-1 and N-ID-2. The application separates the decimal multiple frequency estimation and the integer multiple frequency offset estimation, and the double frequency offset estimation improves the accuracy.

The application relates to the technical field of signal processing, and provides a signal processing method and system of a rubidium atomic frequency standard, a main frequency standard adopts a double-threshold amplitude comparison circuit, a standby frequency standard adopts a single-threshold amplitude comparison circuit, and the existence of a signal, the validity of an amplitude and a locking state are synchronously monitored; double-threshold detection of the main frequency standard ensures reliability, single-threshold detection of the standby frequency standard ensures readiness for quick switching, and the reliability and switching efficiency are balanced; through preset logic rule fusion analysis, the validity is comprehensively judged in combination with a frequency standard locking signal. A control signal is generated based on a priority rule, the main frequency standard is kept when the main frequency standard is valid, a high-level pulse synchronized with a 10MHz signal zero-crossing point is generated when the main frequency standard is invalid and the standby is ready, an abnormal alarm is triggered when the double frequency standards fail, and the control signal is transmitted to a frequency standard switching circuit through a level conversion subunit, so that the trigger timing requirement of a high-speed switching module is met, quick response switching is ensured, the stability in the switching process is ensured, and the whole is reliable and stable.

The invention discloses a three-phase current source inverter fault diagnosis and positioning method based on phase angle signal characteristics, and belongs to the technical field of new energy converter fault diagnosis and positioning. Firstly, a three-phase load current signal of a system is measured, and a three-phase current fitting degree is calculated according to the three-phase load current signal for fault judgment; secondly, converting three-phase load current in an abc coordinate system into an alpha-beta coordinate system according to Clark coordinate conversion, dynamically calculating a module value of a space current vector in real time, performing normalization processing on current signals in a two-phase static coordinate system, and calculating the processed signals through a frequency doubling phase angle feature classification method; next, a fault phase angle is judged through a three-phase current fitting degree and frequency doubling phase angle feature classification method, sampling is carried out, and coding is carried out according to a sampling result to carry out fault positioning. A real-time processing and judging process is adopted in the fault judging and positioning process, and the dynamic performance and the anti-jamming capability of the system are improved.

This invention discloses an adaptive dual-mode direction backtracking system based on double frequency conversion, comprising a radio frequency (RF) circuit, a control circuit, a local oscillator (LOO), and an antenna array. The RF circuit amplifies, filters, and mixes the RF signals received by the antenna array to form signal transmission links in mixed-mode and Van Atta array modes. The control circuit provides unified control over the RF switches and the transmit / receive delays of each channel, and outputs control signals according to the operating mode switching requirements. The LEO generates and distributes a fixed LEO signal and an adaptive LEO signal to achieve frequency matching under different incoming wave frequencies. The antenna array receives external incoming wave signals and transmits direction backtracking signals, employing an adjacent transceiver unit interconnection method in mixed-mode and a centrally symmetrical array element interconnection method in Van Atta array mode. This invention enables stable direction backtracking under different incoming wave frequencies and different application scenarios.

The invention relates to an energy storage converter harmonic wave and double frequency suppression method. By sampling the inductive current output by the DC / AC converter, dead time compensation is carried out, low-order harmonics in the output voltage can be reduced, and the quality of output electric energy is improved. Band elimination filtering is performed on voltage sampling feedback of the DC / DC converter, so that the output DC capacitor of the DC / DC converter bears frequency doubling power, the power fluctuation of an energy storage element is reduced, the service life of the energy storage element can be prolonged, the loss of the energy storage converter is reduced, and the performance and the power density of the energy storage converter are improved.

The present application relates to a kind of large specification 86CrMoV7 steel kind embossing roller processing technology, roller body processing method: roller body quenching and tempering piece-frame position-rough boring inner hole-half precision turning-outer circle grinding-magnetic exploration-double frequency quenching+tempering-precision turning frame position-precision boring inner hole-precision turning and shaft head hot mounting;Shaft head processing method: shaft head quenching and tempering piece-precision turning and roller body hot mounting.Processing method is adopted after roller body hollow double frequency quenching and then hot mounting, selects reasonable process parameter, solves the precision control problem of fit length and total length, avoids the quality problems such as quenching crack, deformation, uneven hardness easily appeared in hollow double frequency quenching process, effectively guarantees product quality, satisfies user demand.

The application relates to a group velocity mismatch-based closed defect reference-free positioning method and system, which comprises the following steps: acquiring attribute information of a sample to be tested, determining ultrasonic excitation parameters based on the attribute information; generating an ultrasonic signal based on the ultrasonic excitation parameters, and propagating into one end of the sample to be tested; receiving a receiving signal generated at the other end of the sample to be tested; performing time-frequency analysis on the receiving signal to determine whether a fundamental frequency signal and a double frequency signal exist simultaneously, if yes, extracting peak times of the fundamental frequency signal and the double frequency signal, and if no, determining that there is no closed defect; and determining the position of the closed defect in the sample to be tested based on the peak times and a group velocity curve of the sample to be tested. Compared with the prior art, the application can reference-free identify and position the closed defect by using the contact acoustic nonlinear effect of the closed defect without damaging the sample to be tested, and has the advantages of fast detection, high defect positioning accuracy and the like.

The embodiment of the invention provides a single-point time service method and device for a receiver, the receiver and a storage medium thereof, and relates to the technical field of satellite positioning time service. The method comprises the following steps: acquiring historical parameter value vectors and historical covariance vectors of a plurality of undetermined parameters in non-difference and non-combination PPP model linearization observation equations of a plurality of satellites and receivers, the plurality of undetermined parameters comprise receiver clock errors of different types of satellites, troposphere time delays of the satellites, receiver orientations and space signal ranging errors; acquiring satellite observed quantities of a plurality of satellites at double frequency points in a standard single-point mode; obtaining a current parameter value vector and a current covariance vector through a Kalman filtering algorithm according to the satellite observed quantity, the historical parameter value vector and the historical covariance vector; and determining and determining a target clock error for time service according to the satellite observed quantity of the target satellite, the troposphere time delay of the target satellite in the current parameter value vector and the current position of the receiver, thereby realizing precise time service.

The application relates to the technical field of signal processing, and provides a signal processing method and system of a rubidium atomic frequency standard, a main frequency standard adopts a double-threshold amplitude comparison circuit, a standby frequency standard adopts a single-threshold amplitude comparison circuit, and the existence of a signal, the validity of an amplitude and a locking state are synchronously monitored; double-threshold detection of the main frequency standard ensures reliability, single-threshold detection of the standby frequency standard ensures readiness for quick switching, and the reliability and switching efficiency are balanced; through preset logic rule fusion analysis, the validity is comprehensively judged in combination with a frequency standard locking signal. A control signal is generated based on a priority rule, the main frequency standard is kept when the main frequency standard is valid, a high-level pulse synchronized with a 10MHz signal zero-crossing point is generated when the main frequency standard is invalid and the standby is ready, an abnormal alarm is triggered when the double frequency standards fail, and the control signal is transmitted to a frequency standard switching circuit through a level conversion subunit, so that the trigger timing requirement of a high-speed switching module is met, quick response switching is ensured, the stability in the switching process is ensured, and the whole is reliable and stable.

The invention discloses a double-frequency phased array composite pulse histotripsy system and a double-frequency phased array composite pulse histotripsy method. Comprising a double-frequency phased array transducer, a driving control module, a focus control module and a real-time monitoring module, wherein the double-frequency phased array transducer is a double-frequency hundreds of array element phased array transducer or a double-frequency split array transducer; the double frequency multiplication phased array transducer comprises a fundamental frequency array element group and a frequency multiplication array element group, the driving control module is used for outputting driving signals with corresponding frequencies to two groups of array elements, the focus control module is used for regulating and controlling the positions and the number of focuses, and the real-time monitoring module is used for tracking the effect; the double-frequency phased array composite pulse histotripsy system adopts a four-stage composite pulse time sequence to cooperatively control the working states of a fundamental frequency array element group and a frequency multiplication array element group, and is realized in combination with a multi-focus control strategy; according to the method, the defect of fogging zone front cavitation shielding possibly caused by double-frequency millisecond long-pulse tissue damage and the defect that instant B-ultrasonic monitoring is affected by slow bubble dissipation after treatment are overcome.

The present application discloses a laser signal modulation system and a CPT Maser atomic clock, which are applied to the field of atomic frequency standards. The system includes an optical signal emission module, a double-pass frequency shift module, an amplitude noise suppression module, and an optical signal modulation module; the double-pass frequency shift module is configured to divide the original optical signal emitted by the optical signal emission module into a first light beam and a second light beam for generating the CPT effect, and perform a double frequency shift operation on the second light beam to obtain a frequency-shifted light beam. The amplitude noise suppression module is configured to obtain the electrical signal corresponding to the combined optical signal of the optical beam modulated by the optical signal modulation module and the frequency-shifted light beam, and obtain an error signal of the double-sideband amplitude value through demodulation processing and differential amplification processing of the electrical signal, and at the same time, based on the error signal, feedback control the modulation depth of the optical signal modulation module at the current moment. The optical signal modulation module performs real-time modulation on the first light beam based on the adjusted depth, thereby effectively reducing the double-sideband amplitude difference.

An underground buried object detection sensor based on metamaterial resonance is mainly composed of three layers which are a metal grounding layer, a dielectric layer and a metal patch layer from bottom to top. Two complementary slotted metal rings (CSRR) are etched on a metal grounding layer, and a metal patch layer is formed by combining a circular ring and two microstrip lines. The sensor can achieve the purpose of detecting the dielectric constant of the dielectric plate in different detection modes in double frequency bands. In other words, the detection of the dielectric constant is realized by monitoring the amplitude change in the frequency band of 1.25-2.00 GHz, and the detection sensitivity is 2.10 dB / permittivity unit; the detection of the dielectric constant is realized by monitoring the frequency change in the frequency band of 2.00 to 3.00 GHz, and the detection sensitivity of the dielectric constant sensor is 39.8 MHz / permittivity unit. The method has the characteristics of high sensitivity, dual-band detection and dual detection modes, and has potential application prospects in buried target detection.

The invention provides a DC bus frequency doubling current harmonic suppression method and system for an AC-DC interconnected power grid, and the method comprises the steps: 1, analyzing the influence of the introduction of a two-phase VPCR technology on the grid-connected current of an inverter system, and building a DC side power fluctuation theoretical model after the introduction of the two-phase VPCR technology under the condition that the DC side harmonic is not considered; and step 2, based on the proposed two-phase VPCR technical parameter design method, solving the binary equation set through a particle swarm optimization algorithm, obtaining a first virtual phase current gain and a second virtual phase current gain, and realizing complete suppression of power fluctuation on the DC bus. The VPCR technology which is only used for alternating current side power fluctuation treatment originally is popularized to the direct current side, and one phase of virtual phase current gain is additionally introduced on the basis of the VPCR technology which only has single-phase virtual phase current gain, so that the degree of freedom of the VPCR technology is increased, and the power fluctuation treatment capability of the VPCR technology is improved.

The invention discloses a training method of a neural network model, a washing machine and a control method. The training method of the neural network model comprises the following steps: converting current in a data set into q-axis current and d-axis current; respectively carrying out FFT (Fast Fourier Transform) to obtain a current frequency spectrum; determining the rotating speed of the motor, calculating the mechanical rotating frequency of the motor, and extracting harmonic amplitudes of a double frequency and a double frequency in a current spectrum; taking the extracted harmonic amplitude and the motor rotating speed as the input of a neural network model, wherein the output of the neural network model comprises weight, eccentricity and diagonal eccentricity; and training the model according to the eccentricity, diagonal eccentricity and weight output by the neural network model and corresponding actual values. The model is trained through harmonic amplitudes of one time and two times of frequencies in a current spectrum, and the obtained model can predict eccentricity and diagonal eccentricity. Meanwhile, the change characteristic of the extracted harmonic amplitude is more obvious than that of the direct use of the current, the model is easier to train, and the accuracy of model output is improved.

The utility model relates to a high-integration-level KuKa double-frequency time-sharing up-conversion power amplifier device, which comprises a common intermediate frequency input and switching module used for time-sharing switching of intermediate frequency signals of Ku / Ka channels; the time-sharing frequency conversion processing module is used for realizing Ku single frequency conversion and Ka double frequency conversion; the high-power GaN amplification module is used for supporting Ku and Ka frequency band power amplification respectively; and the deep sharing subsystem comprises a shared local oscillation source generation unit, an intelligent power distribution module for time-sharing power supply, an integrated radiator and an MCU (Microprogrammed Control Unit) control unit. High integration of a double-frequency function is realized by sharing an intermediate-frequency link, time-sharing frequency conversion and sharing a subsystem. Through time-sharing power supply and intermediate-frequency switching, dual-band multiplexing of an intermediate-frequency link, a reference source and a heat dissipation system is realized, a subverted split structure is adopted, a single device realizes a dual-frequency function, and compared with a traditional split scheme, the device size is reduced by 40%, the weight is reduced by 35%, and the hardware cost is reduced by 30%. The spectrum expansibility is high, and the design of twice frequency conversion and LO3 adjustability supports three-segment seamless coverage of the Ka frequency band.

A high precision magnetic compass based on a stationary Hall probe and a spinning two-poles mu-metal field concentrator. The spinning poles lead to an oscillating magnetic field at the location of the Hall probe. The Hall probe sensitivity direction is oriented at an angle of 90 degrees to the rotation axis of the device. A second harmonic of oscillating component, or double frequency, of the signal from the probe, synchronized with the device rotation, is used to align the axis of rotation to be parallel to the magnetic field. The device does not require prior calibration. It is insensitive to drift of the probe parameters and can provide an angle with precision equal to or better than a 0.05 degree.

The invention belongs to the technical field of ship medium-voltage power grid parameter measurement, and discloses a ship medium-voltage power grid ground capacitance measurement method based on a high and low frequency method, which comprises the following steps: constructing a ship medium-voltage power distribution network model with a neutral point high-resistance grounding, and analyzing component parameters under the condition that high and low frequencies are injected into a power grid by utilizing a circuit theory; and deducing a related parameter expression. A high-frequency and low-frequency frequency selection scheme of an improved double-frequency method is researched in a simulation comparison mode, and low-frequency and high-frequency signals for signal injection are determined by analyzing amplitude-frequency characteristics corresponding to parameters of each device according to signals with different injection frequencies. Based on a simulation model, a scaling experiment platform is constructed, signals with different frequencies are injected by using a signal generator, sampling and analysis of parameters are realized by using an oscilloscope, and measurement of the ground capacitance of the power grid is realized. According to the invention, on-line measurement of the ground capacitance of the system can be realized more accurately under the condition that the capacitance value of the medium-voltage power system of the large ship is large.