120results about How to "Resolution frequency" patented technology

The invention discloses a dispatching end grid fault diagnosis method based on wide-area fault recording information. The method comprises the following steps that when a grid breaks down, fault data of a primary system of the grid are recorded according to a certain sampling frequency mode and are sent to a dispatching main station end through a fault recording networking system; the mapping relation between a basic data platform of grid equipment and a fault recording system is established through CT identification; different sampling frequencies of a fault recorder are unified to be the same sampling frequency according to an interpolation method; a differential-current out-of-limit value is set and independent grid equipment serves as a calculation unit to carry out differential-current calculation; whether the differential-current value is out of limit is confirmed to position fault places and confirm protection actions. The dispatching end grid fault diagnosis method has the advantages of solving the key problems that sampling frequency of the fault recorder is different and data are hard to synchronize, and achieves fault diagnosis application functions such as system operation state monitoring, protection behavior analyzing and accurate fault positioning through the fault recording information only.

The invention discloses an inverter output filter with a set of series resonance subcircuits. The inverter output filter comprises a traditional LCL output filter body and further comprises a series resonance subcircuit set formed by the N series resonance subcircuits mutually connected in parallel. The N series resonance subcircuits mutually connected in parallel are all connected with a capacitor in the LCL output filter body in parallel. An inverter is connected with a power grid through the inverter output filter. According to the inverter output filter with a set of series resonance subcircuits, the N series resonance subcircuits can respectively filter first N-time switching frequency harmonic components in the output current of the inverter, and therefore the total cost and the total size of the inverter output filter can be reduced.

The invention discloses a capturing and tracking system based on a relay terminal and an automatic target tracking method. The system comprises a Ka relay antenna, a filter module, a low noise amplifier module, a single-channel modulation module, a Ka/C frequency conversion module, a capturing and tracking module and a servo control module. Due to the adoption of the automatic target tracking method, a relay satellite beacon antenna forward single-beacon signal can be captured and tracked by a low-track satellite relay terminal. Compared with the technology that TM01 is adopted as a difference mode and an analog processing method is adopted in the prior relay satellite technology, the automatic target tracking method has the advantages that a TE11 sum mode and TE21 difference mode higher-order mode error generation method meets the requirements that any polarization signal can be tracked by the relay terminal and azimuth and pitching error cross coupling is small; due to the utilization of a method for capturing and tracking a beacon signal large in frequency offset and low in signal to noise ratio, large-frequency-offset frequency compensation and dynamic tracking are achieved, and system sensitivity is high; due to the utilization of a digital azimuth error delta A and pitching error delta E extraction, separation and filter method, requirements for high-precision target orientation and tracking are met.

The invention discloses a mini three-dimensional scanning confocal microscope. The double-comb linear scanning comprises an actor, two X linear drivers using as stator, Z linear driver, the second microlens is set on the actor, the light from the point-source become to the collimated light laser beam after passing the fist microlens, the beam goes through the mini optical spectroscope, reflected by the micro-scanning reflector, and focalize on the sample by the second microlens, the reflected or fluorescence light passes the second microlens and the micro-scanning reflector along the original path and returns to the mini optical spectroscope, the reflected light shines in the micro-light detector through the third microlens and the pinhole, the controlling device is used to collect and process the data and control said linear scanning on the focus of the direction X and Y.

The invention provides a POE switch testing device and a detection method thereof. The POE switch testing device comprises a temperature and humidity adjusting box; a POE switch system disposed in the temperature and humidity adjusting box; a POE system detection tool module connected with the POE switch system, arranged outside the temperature and humidity adjusting box, and used for detecting the power supply function of the POE switch system; an IP network camera connected with the POE switch system and arranged outside the temperature and humidity adjusting box; a temperature acquisition module connected with the POE switch system and used for detecting the temperature rise state of the POE switch system; and a PC arranged outside the temperature and humidity adjusting box, connected with the POE system detection tool module and used for detecting the data packet transmitting and receiving function of the POE switch system. The POE switch testing device solves the defects and the abuses of a conventional detection system using single AC voltage and power frequency by using different AC voltage and power frequency according to users at different regions.

The invention discloses a digital pulse width modulator based on a digital delayed-locked loop (DLL). The digital pulse width modulator comprises: a frequency division circuit, a DLL oscillation loop circuit, a reset signal generation circuit and a PWM output logic circuit. By using inputting a high frequency clock signal fs, the DLL oscillation loop triggers a oscillation loop to perform concussion outputting a 2 channel signal and then the signal is sent to the reset signal generation circuit. The reset signal generation circuit combines the input fs and a duty ratio command signal of mbits so as to generate a pulse signal PWM_clr. Under an effect of post-stage PWM output logic circuit, the PWM signal is generated so as to be taken as the output of the system. The DLL oscillation loop circuit uses a programmable delay unit (PDU) to real-timely track the input signal so that the effect of outputting a good pulse width modulation wave under different process corners and differentworking environments can be achieved. By using the digital pulse width modulator of the invention, areas needed by a chip can be minimized to a larger degree and costs of chip development can be saved.

The invention provides an anti-collision electronic device control box, which relates to the field of electronic devices. The anti-collision electronic device control box includes a fixing plate, four corners of the bottom of the fixing plate are fixedly installed with connecting blocks, and the bottom of the connecting blocks is fixedly connected with the top of the first pressure rod. The bottom end penetrates the first shock absorber and extends to the inside of the first shock absorber and is fixedly connected with the top of the first pressing block. The anti-collision electronic device control box drives the second splint to clamp and fix the front and back of the box through the second shock absorber, and drives the first splint to clamp and fix the left and right sides of the box through the screw, so that the box is clamped and fixed. Reliably fixed, through the first shock absorber and the buffer shock absorption, the fixed plate drives the box body to move along the surface of the guide rod, so as to effectively buffer the box body and make it difficult for the box body to separate from the base. The electronic devices inside the protection box are not easily damaged, and the use cost is effectively reduced.

The invention provides a motorcade autonomous car following system, a portable device and a method; the system comprises the following parts: a GPS module in a data acquisition unit is used for gathering vehicle positioning information, and an inertial navigation module in the data acquisition unit is used for gathering vehicle acceleration information and angular velocity information; a fusion positioning module in a data processing unit is used for fusing the GPS information and inertial navigation information in real time, thus obtaining a self-vehicle absolute pose; a car following controlcalculation module is used for planning an absolute route according to the self-vehicle absolute pose information, front vehicle absolute pose information and a head vehicle history route, updating an absolute route table, and calculating to obtain a vehicle target velocity and direction turning angle for vehicle control. The system and method can realize combined positioning via the GPS module and the INS module, are high in positioning precision, high in data refreshing frequency, and cannot be affected by illumination and weather environment factors, thus effectively improving the autonomous car following system precision and reliability. The device is portable and easy to construct, and low in cost.

The invention provides a method and a system for testing high-order modal frequency and high-order modal damping of a thin wall member. The method comprises steps that theoretical modal frequency and modal shape calculation for the thin wall member is carried out, and the high-order modal frequency quantity and corresponding nodes, corresponding to nodel lines, the corresponding to pitch circle position and distribution of the modal shape can be acquired; the constraint boundary condition for testing the high-order modal frequency and the high-order modal damping of the thin wall member are determined; the high-order modal frequency of the thin wall member is tested; the high-order modal damping of the thin wall member is tested. According to the method, a piezoelectric ceramic vibration exciter is employed to realize high frequency excitation for the thin wall member, and a problem that traditional excitation equipment can not effectively excite the high-order modal of the thin wall member is solved. The frequency domain bandwidth method can be utilized to effectively acquire high-order modal damping of same-type structures, and problems of a traditional frequency domain damping test method existing in thin wall structure application can be solved. The method and the system are advantaged in that the test system is easy to establish, the test method is concise, simple and clear, and good repeatability and relatively high test precision are realized.

The invention relates to a space voltage vector modulation method achieving common mode voltage minimization. Combined with the principle of a traditional space voltage vector modulation method, in each control period, on the basis of choosing two non-zero valid vectors, two reverse non-zero vectors are adopted fixedly for forming a zero vector. The two reverse non-zero vectors are inserted into the head and tail and the middle of the control period symmetrically. Through adjusting the acting sequence of the valid vectors, a switch tube can switch on and off once in each control period. According to the invention, the modulation complexity is not increased and only the minimal change on the basis of the traditional space voltage vector modulation method, NZ-SVPWM can be realized. An advantage of constant frequency of a traditional SVPWM switch is kept and harmonic current is reduced. The algorithm is simple and digitization implementation is easy. At the same time, the common mode voltage is limited within 1/6 of DC bus voltage. Therefore, reliable and safe system operation can be ensured when the method is applied to fields of three-phase motor driving, photovoltaic power generation and the like.

The invention relates to a controllable temperature water body total dissolved gas supersaturation generation and an experimental device for studying the influence thereof on fish. The device comprises an autoclave, an air inlet, an adjusting air valve, a safe air valve, an air gauge, a water inlet, a water outlet, a water pool provided with a temperature controller, a water pump, a first ball valve, a first flowmeter and a water inlet, wherein, the autoclave, the air inlet, the adjusting air valve, the safe air valve, the air gauge, the water inlet and the water outlet are arranged on the autoclave, and the water pump, the first ball valve, the first flowmeter and the water inlet are sequentially connected with the water pool; an air compressor is connected with the air inlet; the water outlet is sequentially connected with a second ball valve, a second flowmeter and a water channel; a total dissolved gas tester and a water quality monitor are arranged outside the water channel; and the water channel is communicated with the water pool via a latex tube. The invention generates water body featuring total dissolved gas supersaturation by autoclave sealing pressurization, and the whole device adopts circulating water and controls water temperature thereof to be constant. The invention can realize the control on measurement of major physical parameters, such as water temperature,water body pressure, airation content, flow and the like, which affects total dissolved gas supersaturation generation so as to quantificationally analyze the generation principle of total dissolved gas supersaturation and study the influence thereof on fish.

An MT29F series NAND FLASH test aging system with a customizable process comprises an upper computer, a program control power source, a high temperature test box, a USB-to-UART bridge, and a lower computer. The lower computer comprises N motherboards with a same structure, M signal boards with a same structure, and K DUT boards with a same structure. Multiple signal boards are mounted on each motherboard in the lower computer, and one DUT board is mounted on each signal board. The motherboard comprises a power source interface, a UART interface, multiple connectors docking with the signal board, and multiple signal board identity setting circuit docking with the signal board. The signal board comprises an FPGA used as a test controller and an auxiliary circuit thereof, and also comprises a connector docking with the motherboard and a connector docking with the DUT board. The DUT board comprises multiple high-temperature resistant test clippers and a connector docking with the signal board.

The invention discloses a method of considering different real-time frequency modulation capabilities of wind turbine generators for a wind farm for participating in system coordination. The method comprises the contents as follows: (1) a wind turbine generator unit detects a current wind speed and operation control information in real time and the wind turbine generators are dynamically classified according to the wind speed and the operation control information; (2) the wind turbine generators are matched with corresponding frequency modulation control strategies and frequency modulation parameters in real time according to current categories; and (3) a system detects a current frequency. According to the method, the wind turbine generators are dynamically classified according to the real-time wind speed, rotating speeds and unit control information and are matched with corresponding frequency modulation strategies and different frequency modulation threshold parameters in real timeaccording to different categories, the frequency modulation thresholds of the wind turbine generators under different working conditions are set from the wind farm and the system level, so that frequency modulation priorities of different power supplies and coordination are achieved through coordination of various frequency modulation control frequency setting values, the frequency stability of the system is improved at relatively low control and economic cost, and the problem that wind power participates in primary frequency modulation of a power grid and is matched with a traditional unit and DC frequency modulation is solved.

The invention discloses a method and device for demodulating a distributed optical fiber vibration sensing system. The method comprises that two continuous ultra-narrow linewidth lasers with the sameoptical power are subjected to acousto-optic modulation and electro-optic modulation to be converted into two pulsed light signals; the two pulsed light signals are input into a sensing fiber at an interval of set pulse width; the backward Rayleigh scattered light of the two pulsed light signals generate a set frequency difference such that the returned Rayleigh light signals exhibit sinusoidal interference fringes; when a disturbance signal has an effect on the sensing fiber, the phase difference of the returned Rayleigh light signals changes, and the vibration waveform and position sensed bythe sensing fiber are obtained according to the phase difference. When the disturbance signal appears, a detector can quickly obtain the position of the disturbance signal and the intensity of the disturbance signal, which solves the problem that the demodulation algorithm of a [phi]-OTDR system is complex and a laser frequency drifts, and guarantees that the positioning error of the system is within +/-1m.

The invention provides a simulation configuration method for constant-value parameters of frequency control devices in weak interconnection power grids. According to the characteristics that the frequency changes quickly and the amplitude is large after an isolated grid runs due to a reason that the weak interconnection power grids are serially faulted, acting characteristics of frequency control devices such as a primary frequency modulation control device of a steam turbine generator set, a primary frequency modulation control device of a water turbine generator set, a steam turbine overspeed protection control device, a high-frequency generator tripping safety automatic device, a low-frequency load shedding safety automatic device and a low-voltage load shedding safety automatic device are comprehensively considered from two aspects, i.e. isolated grid frequency decrease and increase. A scientific and reasonable simulation configuration method for the constant-value parameters of the frequency control devices in the weak interconnection power grids is made and has the advantages of high applicability, comprehensive considered factors, reasonable scheme and the like.

The invention discloses a system and a method for extracting a global LFP (Late Follicular Phase) Parkinsonism feature value. The system comprises a signal transceiving module, a feature extraction module, a comprehensive processing module and an output module, wherein the signal transceiving module is used for generating stimulation pulses and measuring LFP signals at the same time; the feature extraction module is used for performing energy analysis on the LFP signals measured by the signal transceiving module, and extracting the feature value of each band; the comprehensive processing module is used for calculating correlation coefficients of bands and energy baseline spectra according to the difference between the feature value of each band and each corresponding point on the energy baseline spectra; and the output module is used for adding the products of the feature values and correlation coefficients of the bands to obtain a global LFP Parkinsonism feature value. The LFP signals are preprocessed into a low frequency band, an intermediate frequency band and a high frequency band; the preprocessed signals are converted from a time domain to a frequency domain for analyzing, an autoregressive model and a neural network model are established using the feature value of each band as a parameter and using the correlation coefficient of each band as a weight, and a global feature value which is objective and accurate and does not depend on doctor experience is obtained.

The invention discloses a method for up-conversion energy feeding of a tuned mass of a magnetorheological damper and the damper. The damper mainly comprises a piston rod, a piston and a cylinder block; a main vibrating structure and the piston are connected through the piston rod; an induction coil is arranged on the piston; and the cylinder block is filled with magnetorheological elastomers. A controllable electromagnetic field is produced through control on the current of the induction coil, so that the rigidity and the damping of the damper are adjusted. The cylinder block used as the tunedmass produce the inertia force reacting on the main vibrating structure, so that the purpose of reducing and even eliminating vibration of the main vibrating structure is achieved. An impact head isarranged at the tail end of the piston rod, an annular elastic membrane is fixed to the cylinder block, a piezoelectric material sheet is arranged on the elastic membrane, when the piston rod moves relative to the cylinder block, the impact head collides with the elastic membrane to produce high-frequency self-excited vibration, the piezoelectric material is subjected to high-frequency pulling andcompression, and efficient conversion of vibration energy is realized. The method and the damper have the advantages as follows: 1, targeted delivery of energy is realized; 2, the structure is compact and reliable; 3, the energy feeding efficiency is relatively high.

The invention relates to an optical signal detection technology, in particular to a device and a method for eliminating a back light signal by utilizing a dual-optical switch. The invention solves the problem that the existing back light restraining technology can not eliminate the back light signal which is synchronous with a pulse laser signal and has the same frequency with the pulse laser signal. The device for eliminating the back light signal by utilizing the dual-optical switch comprises a pulse laser, a practice target, the dual-optical switch, a single photon detector and a computer, wherein the dual-optical switch comprises a first acoustic optical modulator and a second acoustic optical modulator; the external trigger input end of the pulse laser is connected with a pulse signal generator; and the external trigger input end of the pulse signal generator is connected with a function signal generator, and the output end of the pulse signal generator is connected with a time-to-amplitude converter. The invention solves the problem that the existing back light restraining technology can not eliminate the back light which is synchronous with the pulse laser signal and has the same frequency with the pulse laser signal, and is suitable for weak pulse laser signal detection in the fields of precision measurement, communication, information processing, military and the like.

The invention relates to a method for implementing master-slave control for a microgrid under an islanding condition, which realizes master-slave operations of a plurality of parallelly connected DGs (distributed generations) in the microgrid, wherein each DG adopts a segmented novel droop control method which comprises improved droop control and traditional droop control, the DG acting as a master control unit stays at an improved droop control state, and the DGs acting as slave control units stay at a traditional droop control state. In the improved droop control, P-f control adopts a method of automatically adjusting a droop factor of a P-f curve so as to realize maintenance for system frequency f, and Q-V control adopts a method of parallelly changing droop external characteristics so as to realize maintenance for system voltage V. Compared with the prior art, the method provided by the invention is used for solving substantial changes in frequency and voltage caused by load or mode conversion in the operating process of the microgrid, thereby improving the quality of electric energy of the microgrid.

The invention discloses a servo control system applied to precise numerical-control machine tool processing equipment. The servo control system comprises a programmable control unit with a CAN (controller area network) open communication interface and a servo driving unit with a CAN open communication interface, and the programmable control unit is in communication with the servo driving unit via a CAN open bus. A positioning module of a programmable controller is omitted, the CAN open bus replaces a pulse signal wire and a control wire, consumption of wires is reduced by two-third, cost is saved, and simultaneously, failure rate of circuits is greatly reduced. Digital signals transmitted by the CAN open bus replace pulse signals of the prior art, problems that speed is limited due to over high pulse frequency and individual pulse signals cannot be identified by servo drivers in the prior art are resolved, the speed can be 1.5 times faster than the original speed, processing efficiency is improved, and precision is increased to 0.3mm from 0.5mm of the original precision.

The invention discloses a storage battery wireless charging minimum connecting device. The device comprises a high-frequency inverter power supply, an energy transmitting system, an energy receiving system, an energy coupling coil, a load side, a power detection circuit and a battery energy management system, wherein the energy transmitting system and the energy receiving system are coupled in a resonant mode, and the load side comprises a rectification voltage stabilizing system, a storage battery and a power variation load; and the high-frequency inverter power supply adjusts the energy output power according to the real-time power of the power variation load, starts energy output according to a relationship between the real-time resistance value of the storage battery and a set charging frequency and provides power for the energy transmitting system. The storage battery wireless charging minimum connecting device provided by the invention is simple in principle and convenient to adjust, can be popularized to a minimum regulation method after various types of loads are connected with a wireless energy transmission system, and a related minimum connecting technological problem of the wireless energy transmission system is basically solved.

The invention discloses a parallel-serial capillary tube varying system inherent frequency vehicle shock absorber running method. A capillary tube parallel damping association segment and a capillary tube serial system inherent frequency association segment are sequentially connected to a pipeline between an upper oil bin oil conveying opening and a lower oil bin oil conveying opening from top to bottom; the capillary tube parallel damping association segment comprises four parallel capillary tubes, and each capillary tube is in serial connection with an electromagnetic valve and controls the electromagnetic valve to work; the capillary tube serial system inherent frequency association segment comprises four serial capillary tubes; the four capillary tubes are all in parallel connection with an electromagnetic valve and controls the valve to work. The diameter of the minimum capillary tube of the frequency adjusting segment is far larger than the diameter of the capillary tube of the resistance adjusting segment; in the matrix type work state table, according to the condition, the configuration value Smn of the electromagnetic valve in the frequency adjusting segment is selected, and through the manner of changing the mass, the problem that the inherent frequency of an automobile hydraulic shock absorber system cannot be adjusted or the adjustable range is very small is solved.

The invention discloses a sound insulation and noise reduction type motor. The motor comprises a base, a motor shell is fixedly connected to the upper surface of the base, a heat dissipation plate isfixedly connected to the outer surface of the motor shell, a mounting bottom plate is fixedly connected to the outer surface of the heat dissipation plate, a noise reduction layer is fixedly connectedto the outer surface of the mounting bottom plate, a noise reduction layer is fixedly connected to the outer surface of the noise reduction layer, and a protection plate is fixedly connected to the outer surface of the noise reduction layer. According to the sound insulation and noise reduction type motor, the effect of carrying out multi-stage filtering and noise reduction on the noise generatedby the motor is achieved, the noise reduction layer firstly performs primary noise reduction on the noise generated by the motor, a part of noise is absorbed in advance by the sound-absorbing spongein the sound-absorbing device, and then secondary noise reduction is carried out under the blocking of inert gas in the sound insulation layer, finally, repeated refraction is carried out under the refraction effect of a refraction plate in the sound insulation layer, and finally noise reduction is carried out to the maximum extent, so that the problems that the loss frequency and the maintenancecost of a motor used in a forging workshop are very high are solved.

The invention discloses a cutting machine for inductive elements capable of cutting legs in batches, which comprises a base, a placing platform is fixedly installed on the top of the base, a placing groove is opened on the top of the placing platform, a fixing plate is placed inside the placing groove, and a fixing plate is placed inside the fixing plate. There are blind holes on the top, and the top of the base and both sides of the placing table are fixedly installed with slide rails, the top of the slide rails is slidably installed with support rods, the top of the support rods is fixedly connected with the bottom of the top plate, and the top of the top plate is fixedly installed There is an electric box, and the inside of the electric box is fixedly equipped with a motor. In the present invention, by setting the cooperation between the driving wheel and the driven wheel, when the driving wheel rotates, it will drive the driven wheel to rotate, and when the driven wheel rotates, it will drive the rotating rod to rotate, so that the gear rod and the rack are matched, so that the motor The chassis is moved to batch cut the inductance components on one line, which saves time and effort by cutting corners in batches.

The invention discloses a broadband fine-step frequency synthesis circuit and method, and relates to the technical field of frequency synthesis, and the broadband fine-step frequency synthesis circuit comprises a reference unit, an intermediate frequency unit, a local oscillator unit and a spread spectrum unit. The reference unit generates low-noise reference signals, and the output end is connected with the signal input end of the intermediate frequency unit and the signal input end of the local oscillator unit. The intermediate frequency unit generates fine-stepping broadband intermediate frequency signals, and the output end of the intermediate frequency unit is connected with the signal input end of the spread spectrum unit. The local oscillator unit generates low-phase noise local oscillator signals, and the output end of the local oscillator unit is connected with the signal input end of the spread spectrum unit. The local oscillator signals and the intermediate frequency signals are mixed in the spread spectrum unit, and the output of the spread spectrum unit is the output of the frequency synthesis circuit. According to the invention, comb line cascade connection and direct combination are adopted to realize low-phase noise local oscillation; a DDS + phase-locked loop is adopted to realize fine stepping broadband intermediate frequency; the working bandwidth is efficiently expanded by means of frequency mixing shift, interpolation filling, frequency band splicing and the like, and cross-octave broadband fine-step frequency synthesis is realized.

The invention discloses an audio signal processing method. The method comprises the following steps: acquiring a stride parameter of a user in the movement process; acquiring a to-be-processed audio signal from a terminal; modifying the beat frequency of the audio signal according to the stride parameter so that the difference between the modified beat frequency of the audio signal and the stride parameter is less than a preset threshold; outputting the modified audio signal. The invention further provides a terminal capable of realizing the above audio signal processing method. The consistency of the music beat frequency and the user movement stride can be maintained through the adoption of the method disclosed by the invention.

An OFDM (Orthogonal Frequency Division Multiplexing) is a key technology in the field of wireless communication, and a phase deviation is generated easily to cause restoration distortion of a carrier signal in a time-varying excitation environment, but FFT (Fast Fourier Transform) adopting an all phase signal preprocessing technology has phase invariability, and a research shows that an OFDM system utilizing the technology can reduce a phase error effectively, and can reduce the noise power significantly. According to the system, an all phase FFT processing unit for signal processing in the OFDM system can be achieved by adopting an FPGA (Field Programmable Gate Array) technology; an all phase processing module of the system is achieved by selecting a windowless all phase preprocessing method; an all phase OFDM baseband transmission system is achieved; the processing efficiency and the expense of an APOFDM (All Phase Orthogonal Frequency Division Multiplexing) system are simulated very well on hardware due to the parallelism and the dynamic reconstruction performance of an FPGA; the system has significant performance advantages, and is low in power consumption, high in integration level and good in stability; and therefore, the system has a better theoretical value and practical significance in further improvement of the OFDM system.

The invention discloses a system and method of digital single frequency network broadcast frequency and system time synchronization. Said ground supplement transponder adds synchronization module which can resume system clock, system time, carrier wave frequency. Main station adds picking up and packaging module of secondary planet frequency-difference information. Said method includes steps as following: main station modulates the information source data and frequency expanding data according to system clock, and modulates the system time to the frequency expanding information; ground supplement transponder sends the same digital broadcast signal according to the system clock which is resumed from the information source data, system time and secondary planet frequency-difference information which are get from the frequency expanding information and the same carrier wave and time as the secondary planet transmit digital broadcast signal. The invention resolves the problems of frequency synchronization and time synchronization which are the most pivotal in single frequency net system synchronization, and it possesses very important utility value.

The invention discloses a low-complexity anti-frequency offset synchronization method based on a CAZAC sequence in a multi-carrier OFDM system, which mainly solves the problems of poor synchronizationperformance and high complexity of the existing algorithm, and adopts the implementation scheme by comprising the following steps of creating a training sequence based on the CAZAC sequence at a sending end; constructing a timing metric function at a receiving end, searching the maximum value of the timing metric function, and finishing timing synchronization; and estimating rough decimal frequency offset, then estimating fine decimal frequency offset and finally estimating integral multiple frequency offset by utilizing a timing synchronization result to finish frequency synchronization. Thesynchronization performance of the OFDM system is improved, the timing metric function is simplified, the calculation complexity is reduced, and the method can be applied to a wireless communicationscene of burst transmission or continuous transmission.

The invention discloses a cell phone 4G double-LOOP structure antenna belonging to the cell phone antenna technology field. The cell phone 4G double-LOOP structure antenna comprising a signal feed point, a first feed grounding point, a second feed grounding point, a first antenna wiring, a second antenna wiring, a first high frequency arm, a high frequency coupling arm, a second high frequency arm, and a low frequency arm. The first antenna wiring, the signal feed point, and the first feed grounding point are used to form a first LOOP structure. One end of the first antenna wiring is connected with the signal feed point, and the other end is connected with the first feed grounding point. The second antenna wiring, the signal feed point, and the second feed grounding point can be used to form a second LOOP structure, and one end of the second antenna wiring is connected with the signal feed point, and the other end is connected with the second feed grounding point. The first high frequency arm and the high frequency coupling arm are respectively connected with the first LOOP structure, the second high frequency arm and the low frequency arm are respectively connected with the second LOOP structure. The cell phone 4G double-LOOP structure antenna is advantageous in that the good performance of the antenna can be provided in the severe radiation environment, and the SAR risks can be reduced greatly.