202 results about "Four-frequency" patented technology

A medical ultrasound image denoising method based on wavelet transform and quick bilateral filtering comprises the following steps of the first step of establishing a medical ultrasound image model, the second step of carrying out wavelet transform on an image obtained in the first step after logarithm transformation to obtain four frequency domains (LL1, LH1, HL1and HH1), continuously carrying out wavelet transform on the low frequency domain LL1 to obtain four frequency domains (LL2, LH2, HL2 and HH2) again and then repeating the step until resolving the maximum layer number, the third step of carrying out quick bilateral filtering on the low frequency portion (LLJ) at the last layer, the fourth step of carrying out threshold value method shrinkage on wavelet coefficients of the high frequency portions (LHj, HLj and HHj) of all layers and the fifth step of carrying out wavelet inverse transformation to obtain the denoised medical ultrasound image. In addition, the J is 1, 2, ..., J. If denoised ultrasound envelope signals are wanted, exponential transformation is carried out on the ultrasound image obtained in the fifth step.

The invention provides an electric transmission control method of tilting of a rotating furnace, comprising the following steps that: 1) a network is configured, and then a control system is operated; 2) a PLC controller sends a torque instruction value to frequency converters which then adjust motors corresponding thereto according to the instruction; 3) a tilting speed encoder detects actual speed values of all the motors and feedbacks the actual speed values to the frequency converters; 4) the frequency converters send the actual rotating speed and the torque values of all the motors by the network to the PLC controller, and the PLC controller judges that all the frequency converters are in normal state according to data; and 5) the PLC controller obtains a speed feedback value of the current system after analysis and operation, and then the PLC controller sends the torque instrument value to four frequency converters after calculation of a speed regulator of the PLC controller. The electric transmission control method leads transmission equipment to be in good working state, thus being capable of prolonging the service life of machines.

The present invention relates to a multiband antenna specifically adapted for use with a Base Station Antenna (“BSA”). The present invention provides narrow azimuth or horizontal beamwidth (“HBW”) having 45 degrees and operational over four frequency bands. The composite antenna topology and associated circuitry described in embodiments achieves reduced antenna installation requirements and allows for ease of network deployment or reconfiguration at reduced cost. Embodiments employ an array of low band radiating elements and two sets of high band radiating elements. The first set is co-located within an array of low band radiating elements. The second set of is offset and outside the low band radiating elements. An RF feed network energizes the first and second set of high band radiating elements to compensate for interference between the high and low band elements.

The invention discloses an impulse type grain mass flow sensor calibrating and testing device, which relates to the field of grain mass flow sensor calibrating and test machines. The impulse type grain mass flow sensor calibrating and testing device comprises a machine frame (1), a net rice elevator (3), a hopper A (2), a hopper B (19), a rotating speed sensor (4), a vibration sensor (7), a tilt angle sensor (9), a hopper scale (18), a grain flow sensor mounting position adjusting device, a grain mass sensor mounting position adjusting device, three vibration motors, a three-phase asynchronous motor (26), four frequency converters, a high-speed camera acquisition system (6), a monitoring storage system and four wheels. The impulse type grain mass flow sensor calibrating and testing device is simple in mounting and is convenient to detach and move. After an impulse type grain flow sensor is calibrated on the testing device, the impulse type grain flow sensor can be directly arranged on a combine harvester to operate.

The invention discloses an image super-resolution reconstruction method based on wavelet transformation and a convolutional neural network. The method comprises the following steps: at a training stage, carrying out Gaussian filtering and downsampling processing on a high-definition image Ih in a training data set to generate a low-definition image Il; carrying out single-scale two-dimensional discrete wavelet transform on the Ih to extract four frequency components thereof, such as a low frequency component FLL, a horizontal low-frequency vertical high-frequency component FLH, a horizontal high-frequency vertical low-frequency component FHL and a diagonal direction high-frequency component FHH; and with the Il serving as input data and the four frequency components of the Ih serving as labels, training four convolution neural network models; and in a super-resolution reconstruction stage, inputting the low-definition image Il into the four trained convolution neural network models to generate four frequency components of the high-definition image and carrying out single-scale two-dimensional discrete wavelet inverse transformation to generate a high-definition image Ih. The method carries out super-resolution reconstruction on the image at different frequencies, can make full use of learning capacity of the convolutional neural network, and substantially enhances the super-resolution reconstruction effect.

The invention provides a medical ultrasonic image denoising method based on wavelet transform and a trilateral filter. The medical ultrasonic image denoising method comprises the following steps that step 1) a medical ultrasonic image model is established; and step 2) wavelet decomposition is performed on an image obtained in the step 1 after logarithmic transform so that four frequency domains (LL1, LH1, HL1 and HH1) are obtained. Wavelet decomposition is continuously performed on the low frequency domain LL1 so that four frequency domains (LL2, LH2, HL2 and HH2) are obtained again; then the step is repeated until the maximum number J of layers of decomposition; step 3) threshold method contraction processing is performed on the wavelet coefficient of the high frequency part (LHj, HLj and HHj, j=1,2,...,J) of each layer; step 4) filtering processing is performed on the wavelet coefficient of the low frequency part (LLJ) of the last layer by utilizing the trilateral filter; and step 5) inverse wavelet transform processing is performed so that a denoised medical ultrasonic image is obtained.

Quad band antenna interface modules include a diplexer that is configured to connect to an antenna port, a switching core that is connected to the diplexer, and filters that are connected to the switching core and are configured to provide transmit and receive ports for four frequency bands. At least one matching network port is connected between the switching core and at least one of the filters and is configured to connect a matching network thereto. Three filters and three matching network ports may be provided. A switched impedance matching network and/or a singly compensated dual diode switch also may be provided.

When a four-frequency laser gyro adopts light intensity difference for frequency stabilization, accuracy thereof is easily influenced by parameter variation in light combination, photoelectric conversion and amplification processes. The invention discloses a novel frequency stabilization mode, small jitter modulation is carried out on path length of the four-frequency laser gyro, and then frequency stabilization is carried out according to the modulation condition of four-frequency laser gyro intracavity travelling wave mode amplitude, so that the four-frequency laser gyro operates under the condition that homonymous travelling wave mode beat-wave amplitude is maximum. The invention can solve problems which are caused when light intensity difference is adopted for frequency stabilization, and performance of four-frequency laser gyro is improved while the four-frequency laser gyro operates in unique uninterrupted state.

The invention discloses a method for de-noising a medical ultrasonic image based on wavelet transformation and a guide filter, and the method comprises the following steps of: step 1) creating a medical ultrasonic image model; step 2) performing wavelet decomposition to the logarithm transformation image in the step 1) to obtain four frequency domains (LL1, LH1, HL1 and HH1); performing wavelet decomposition to LL1 in the low frequency domain so as to obtain four frequency domains (LL2, LH2, HL2 and HH2); repeating the step until to decompose the maximum layer J; step 3) performing filter processing to a wavelet coefficient in the final-layer low-frequency part (LLJ) by the guide filter; step 4) performing threshold valve method contraction treatment to the wavelet coefficient in each-layer high-frequency part (LHj, HLj and HHj, j=1, 2, ......, J); step 5) performing wavelet inverse transformation treatment to gain the de-noised medical ultrasonic image; performing exponential transformation to the medical ultrasonic image obtained in the step 5) to obtain de-noised ultrasonic envelope signals.

The invention belongs to the technology of high-precision angle measurement and relates to a device and method for improving the measurement precision of a rotary table dynamic angular position error. The device comprises an angle measurement sensor, a highly-stable external synchronous clock, a servo motor control system, and a servo motor. The angle measurement sensor is formed by a spatial four-frequency differential laser gyroscope and a control circuit thereof. The angle measurement sensor and the servo motor control system of a detected rotary table are synchronized by a highly-stable clock signal. The servo motor control system and the high-precision angle measurement sensor transmit high-speed angular increment information thereof to a PXI measurement and control system. The PXI measurement and control system outputs dynamic angular position error information. By means of a manner that the PXI measurement and control system and a motor control system are deeply coupled, a dozens of MHz synchronizing clock between the PXI measurement and control system and the motor control system, and high-speed phase-locked loop technology, the device and the method control the clock misalignment and clock jitter of the PXI measurement and control system and the motor control system to be a magnitude of nanoseconds, and achieve super-speed and high-precision synchronous measurement of rotating angle dynamic errors.

A high frequency switch having a plurality of signal paths for four frequency bands, the high frequency switch, has

• • branching means,
  • first and second transmission reception changeover means connected to the branching means, and
  • a plurality of filters placed in the plurality of signal paths,
  • the first transmission reception changeover means has a first common transmitting end for transmission signals of the first frequency band and the second frequency band, a first receiving end for a reception signal of the first frequency band, and a second receiving end for a reception signal of the second frequency band, and
  • the second transmission reception changeover means has a second common transmitting end for transmission signals of the third frequency band and the fourth frequency band, a third receiving end for a reception signal of the third frequency band, and a fourth receiving end for a reception signal of the fourth frequency band.

The invention discloses a master-slave control method for a converter tilting frequency conversion system, which is used for controlling a frequency conversion system of a motor in a converter tilting system. According to the method, four AC asynchronous motors in the converter tilting system are respectively connected with a first frequency converter, a second frequency converter, a third frequency converter and a fourth frequency converter; the four frequency converters are Siemens S120-series frequency converters; The four frequency converters perform isochronal synchronous communication through SINAMICS Link network; one of the four frequency converters is used for main control, and at least one of the other frequency converters is used for slave control. The invention adopts Siemens S120-series frequency converters, performs communication through the SINAMICS Link isochronal synchronous network, and limits the communication delay to be within 3 ms. In addition, with the logical operation function of the S120-series frequency converter itself, the data can be collected and processed directly and accurately, which greatly improves the control precision.

The invention relates to an implementation method of a multi-frequency-band UC-EBG (Uniplanar Compact Electromagnetic Band Gap) structure and belongs to the technical field of electromagnetic propagation and reception. According to the method provided by the invention, an H-type groove is arranged on a unit paster, so as to design a four-frequency-band H-type groove UC-EBG structure within a frequency range of less than 60GHz; the invention also provides a method for realizing the miniaturization of the structure by increasing the groove length w of the H-type groove, decreasing the groove width a and increasing the dielectric constant epsilon of a dielectric substrate and the like. In addition, the method provided by the invention can be used for further realizing the miniaturization of the EBG structure by introducing an H-type groove primary fractal structure, and designing the four-frequency-band H-type groove UC-EBG structure within a frequency range of less than 3 GHz by enlarging the structure through the period unit size SF (Scale Factor). The implementation method provided by the invention can be used for solving the problem that the EBG structure has less possibility of realizing multiple frequency bands in a lower frequency because of the size restriction and providing guidance for the specific design of a multi-frequency-band miniaturized electromagnetic band-gap structure.

The invention relates to a four-frequency-band printed antenna applied to wireless communications. The four-frequency-band printed antenna applied to the wireless communications is characterized by comprising a substrate unit, a feeder line unit, a first antenna unit, a second antenna unit, a third antenna unit and a dielectric slab unit. The feeder line unit, the first antenna unit, the second antenna unit and the third antenna unit are respectively located on the same face of the dielectric slab unit. The substrate unit is located on the other face of the dielectric slab unit. The first antenna unit, the second antenna unit and the third antenna unit are connected with a conductor of the feeder line unit. The feeder line unit is connected with a conductor of an applied device. When the four-frequency-band printed antenna operates, the first antenna unit arouses a first resonant mode and a third resonant mode, and the second antenna unit and the third antenna unit arouse a second resonant mode and a fourth resonant mode respectively. The four-frequency-band printed antenna is a multi-frequency-band antenna and has the advantages of being easy to obtain, low in cost, high in system integration degree and the like.

Four frequency components (f1 to f4) (where, f1<f2<f3<f4) are input into a port (10) of a first demultiplexing filter circuit (1), and demultiplexed into low frequency components (f1 and f2) and high frequency components (f3 and f4), and input in a port (20) of a second demultiplexing filter circuit (2) and a port (30) of a third demultiplexing filter circuit (3), respectively. The frequency components (f1 and f2) are demultiplexed into the component (f1) and the component (f2) by the second demultiplexing filter circuit (2), and output from a port (23) and a port (24), respectively. The frequency components (f3 and f4) are demultiplexed into the component (f3) and the component (f4) by the third demultiplexing filter circuit (3), and output from a port (33) and a port (34), respectively. The first demultiplexing filter circuit (1) comprises a low-pass filter (11) and a high-pass filter (12), the second demultiplexing filter circuit (2) comprises a low-pass filter (21) and a combined filter (22) of a combination of a low-pass filter and a band elimination filter, and the third demultiplexing filter circuit (3) comprises a combined filter (31) of a combination of a high-pass filter and a band elimination filter and a high-pass filter (32). These demultiplexing filter circuits are formed of a stacked structure.

The invention relates to a WSN gateway supporting multiple frequency bands and multiple communication modes, and belongs to the technical field of wireless communication. The gateway comprises an extranet access unit, a master control unit, a WSN radio frequency access unit and a power supply management unit. The extranet access unit comprises 3G, WiFi and the ethernet and is used for uploading data of a wireless sensing network to an upper computer through three different transmission paths so that remote monitoring of internal nodes of the wireless sensing network can be realized, and the upper computer can also directly access and control the internal nodes of the wireless sensing network. The master control unit is used for processing data packages of various protocol types in the gateway so that system scheduling, management and control can be completed. The WSN radio frequency access unit is composed of wireless radio frequency modules of 433MHz, 470MHz, 780MHz and 2.4GHz frequency bands and responsible for networking of four frequency bands and management and data interaction of node equipment. The power supply management unit is responsible for supplying working power for the whole gateway system. According to the gateway, various types of network equipment can stably access to the internet so that centralized control and management of various network systems can be realized.

The invention discloses a medium-long baseline ambiguity resolution method based on a BeiDou four-frequency signal. The method comprises the following steps of: S1, working out two wide-lane ambiguities by utilizing a four-frequency combination pseudorange and a four-frequency combination carrier; S2, working out the pseudorange of a deionized layer and the delay of a double-difference ionized layer with a frequency point B1 by utilizing the double-difference observed quantities and the corresponding ambiguities of two wide-lane carrier phases; S3, working out two ambiguities related to a fourth frequency according to the pseudorange of the deionized layer and the delay of the double-difference ionized layer with the frequency point B1; and S4, working out the independent ambiguity of a BeiDou four-frequency carrier according to the four ambiguities worked out in the S1-S3. According to the medium-long baseline ambiguity resolution method based on the BeiDou four-frequency signal, under the condition of a medium-long baseline, the independent ambiguity of the four-frequency carrier is rapidly and reliably resolved by adopting the four-frequency combination pseudorange and the four-frequency combination carrier. Compared with a three-frequency method, the ambiguity resolution time is greatly shortened and the ambiguity fixed success rate is effectively increased by the medium-long baseline ambiguity resolution method based on the BeiDou four-frequency signal.

The invention discloses a Beidou precise time service technology. According to the technology, the Beidou second-generation satellite navigation system is used for carrying out high-precision dual-machine common-view time service, thereby solving a problem of poor accuracy of time and frequency transmission in the communication field and the national defence building of our country. On the basis of utilization of the Beidou second-generation machine, GPS, and a dual-satellite four-frequency special-purpose time service receiver as well as a pseudo-range difference and a synchronous pseudo-range difference of a mobile radio station, a precise clock difference between two receives can be calculated, wherein the precision can achieve the nanosecond level; and the clock difference is used for fulfill the following tasks: (1), precise determination of deviation between the user clock and the standard time; and (2), realization of precise synchronization of the user clocks at different places.

The invention belongs to a laser gyroscope technology, and relates to a frequency stabilization system and method for a four-frequency laser gyroscope. The frequency stabilization system for the four-frequency laser gyroscope comprises a four-frequency laser gyroscope and an alternating-current frequency stabilization circuit, wherein the four-frequency laser gyroscope comprises two planar mirrors and two groups of spherical mirror for controlling a cavity length; the alternating-current frequency stabilization circuit comprises a photoelectric converter, a band-pass filter, a phase-sensitive detector, a rectifier, a PID (Proportion Integration Differentiation) controller, a summator and a voltage amplifier; and the voltage amplifier is connected with frequency stabilization piezoelectric ceramics of the two spherical mirrors. In the invention, the cavity length of the four-frequency laser gyroscope is modulated by applying an alternating-current voltage signal to the frequency stabilization piezoelectric ceramics, a frequency stabilization error signal is obtained by performing band-pass filtering and phase-sensitive demodulation and rectification, and the error signal is stabilized at a zero value through closed loop control, so that frequency stabilization of the four-frequency laser gyroscope is realized. Due to the adoption of the system and the method, frequency stabilization control of the four-frequency laser gyroscope is simplified greatly, and the frequency stabilization accuracy is increased greatly.

The invention provides a medical ultrasonic image denoising method based on a statistical model. The medical ultrasonic image denoising method comprises the following steps that step 1) a medical ultrasonic image model is established; step 2) wavelet decomposition is performed on an image after logarithmic transformation obtained in the first step so that four frequency domains (LL1, LH1, HL1 and HH1) are obtained; wavelet decomposition is continuously performed on the low frequency domain LL1 and then four frequency domains (LL2, LH2, HL2 and HH2) are obtained; and then the step is repeated until the maximum number J of layers of decomposition; step 3) threshold method contraction processing is performed on the wavelet coefficient of the high frequency part (LHj, HLj and HHj, j=1,2,...,J) of each layer; step 4) filtering processing is performed on the wavelet coefficient in the low frequency part (LLJ) of the last layer by utilizing a guidance filter; and step 5) wavelet inverse transformation processing is performed so that a denoised medical ultrasonic image is obtained.

A frequency reuse method in an OFDM mobile communication system is provided. Frequency resources available to each BS are divided into at least four frequency groups and a different or the same frequency reuse distance is set for each of the frequency groups. The frequency groups are sequentially assigned to cell areas of each BS such that lower frequency groups are available to a near cell area and higher frequency resource groups are available to a remote cell area.