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104 results about "Very high frequency" patented technology

In the US and Canada, the VHF television band occupies frequencies between 54 and 216 MHz and the UHF band between 470 and 890 MHz. In general, VHF channels are numbered 2 to 13 and UHF channels 14 to 51. However, the channel’s physical broadcast frequency is not always reflected by the channel number you see.

Intelligent detection and fault early warning method and system for ring main unit

The invention relates to a ring main unit intelligent detection and fault early warning method and system. The method comprises the following steps: deploying an ultrahigh frequency sensor, an infrared thermal imager, an ultraviolet sensor and a high-frequency current transformer, and synchronously acquiring multi-modal data such as partial discharge, temperature distribution, corona discharge and grounding current of the ring main unit; carrying out feature extraction on the collected data, wherein the feature extraction comprises a time-frequency statistical feature and a temperature-load correlation feature of the partial discharge signal; the Dempster-Shafer evidence theory is utilized to carry out fusion calculation on the multi-source feature evidence, and confidence coefficients for insulation degradation, poor contact, arc faults and other fault types are obtained; arc fault prediction is carried out in combination with a long-short-term memory network model; and finally executing a grading early warning strategy according to the fault confidence. The problems of low detection reliability and fault early warning lag of a single sensor are solved, early accurate diagnosis and predictive maintenance of the insulation fault of the ring main unit are realized, and the operation safety and reliability of power equipment are remarkably improved.
Owner:ZHEJIANG SHUOWEI POWER TECH CO LTD

Low-altitude target identification system and method combined with multi-band signal processing

The invention relates to the technical field of target detection and identification, and discloses a low-altitude target identification system and method combined with multi-band signal processing. Comprising the steps of establishing a cross-frequency implicit vector model and constraining a geometric scale, a scattering center and rotor harmonic waves through synchronous acquisition of an L-band radar, a Ku-band radar and a millimeter-wave radar, and realizing unified characterization of multi-frequency signals; receiving a global satellite navigation system reflection signal, communication channel state information or a very high frequency / ultrahigh frequency passive radar signal to form prior discrimination, and triggering high-frequency radar short-time imaging; carrying out propagation correction on millimeter wave, terahertz and infrared signals in combination with a meteorological profile and generating an environment label; determining a sampling window by using the region of interest and rotor phase prediction, and optimizing a residence strategy; harmonic waves are extracted from radar and acoustic signals, robust pairing is carried out, and a cross-domain consistency score output category is calculated. The method realizes multi-frequency multi-source cooperative processing, has environment self-adaption and closed-loop feedback capabilities, and can improve the precision and stability of low-altitude target identification.
Owner:BEIJING RUIDAEN TECH CO LTD

Intelligent operation and maintenance early warning management system for coal mine substation based on multi-source information fusion

The invention discloses a coal mine substation intelligent operation and maintenance early warning management system based on multi-source information fusion, and belongs to the technical field of coal mine substation operation and maintenance early warning. The multi-source sensing layer comprises an environment sensor arranged in a substation switch cabinet, an ultrahigh frequency partial discharge sensor array embedded in the root part of a switch cabinet insulating sleeve and the periphery of a GIS basin-type insulator, and vibration sensors mounted on a transformer shell and a circuit breaker operating mechanism mounting surface, and the environment sensor is used for detecting humidity and dust concentration; the ultrahigh-frequency partial discharge sensor array is used for capturing ns-level partial discharge pulses in real time and dynamically predicting the growth trend of the insulator surface contamination degree through the partial discharge amount, and the vibration sensor recognizes mechanical looseness through vibration spectrum features. According to the method, the pollution degree is associated with the partial discharge amount, so that early warning is changed from passive fault response to active risk pre-judgment, an accurate triggering condition and a decision basis are provided for operation and maintenance, and a changing curve of the insulator pollution degree along with the environment or the operation time is analyzed through data accumulation.
Owner:HUAIBEI MINING CO LTD

Long Deployable Helix Antenna

A helix antenna and methods of making and using helix antenna to concurrently or independently radiate pulses in a very high frequency (VHF) band in a range of about 240 MHz to about 270 MHz and / or in an ultrahigh frequency (UHF) band in a range of about 360 MHz to about 380 MHz which can be useful in space to ground data transmissions, subsurface radar, and measurement of ice and snow pack.
Owner:TENDEG LLC

High-frequency cable coupler

The invention relates to a high frequency cable coupler. Compact cable couplers connect cables with different wire gauges and do not interfere with electrical performance up to very high frequencies. Each cable coupler has a pair of conductive elements having first and second contact portions on opposite ends that terminate the wires of the first and second cables. A housing surrounds the conductive element, including a cable attachment. The conductive layer extends from the first cable to the second cable and is conformal with the underlying surface. The housing has a region having a lower dielectric constant adjacent the cable attachment. A parameter of the cable coupler in each of the plurality of portions may be selected to provide a matched impedance through the coupler. Such couplers enable dense connection of small diameter cables with connectors while large diameter cables provide low loss routing to remote locations to achieve high density signal connections with high signal integrity at frequencies sufficiently high to support 224 Gbp.
Owner:AMPHENOL CORP

Very high frequency broadband radiation source positioning method based on energy weighted subspace fitting

The invention discloses a very high frequency broadband radiation source positioning method based on energy weighted subspace fitting, and relates to the technical field of signal processing and radiation source imaging, and the method comprises the steps: carrying out the DFT processing of a lightning very high frequency broadband signal collected by an array, and obtaining any narrowband component; then characteristic decomposition is carried out on covariance matrixes of X-axis and Y-axis sub-arrays according to array receiving signals, main characteristic vectors are taken as signal sub-spaces, in order to emphasize the signal sub-spaces with higher energy, characteristic values are used for weighting, weighted signal sub-spaces are constructed, then the signal sub-spaces are fitted by using a least square method, and the signal sub-spaces with higher energy are obtained; the method comprises the following steps: further constructing a sub-band energy weighted spatial spectrum adapted to a very high frequency broadband signal, then carrying out spectrum peak search on the weighted spatial spectrum to obtain a spatial angle of a spectrum peak, and finally calculating the direction of arrival of a radiation source according to a spatial angle relation to obtain an azimuth angle and an elevation angle. According to the invention, aiming at a lightning very-high-frequency weak radiation source positioning problem, a lightning channel can be inverted more clearly.
Owner:HEFEI UNIV OF TECH +2

Block chain-based power data tamper-proofing integrity protection method, system and device, and storage medium

The invention relates to the technical field of block chain data security, in particular to a power data tamper-proofing integrity protection method, system and device based on a block chain and a storage medium. Receiving a multi-source data stream from a power system, and classifying the multi-source data stream according to the sensitivity level and the sampling frequency of the data; representing each data record as a node in a directed acyclic graph, establishing a directed edge carrying a digital signature between the nodes to represent a data reference relationship, and calculating the confirmation degree of the current node through the confirmation degree of the precursor node and the dynamic weight of the edge; adopting Markov chain Monte Carlo sampling to select an evidence storage path with the highest confirmation degree from the candidate paths, and calculating the confidence coefficient of the transaction node based on the quoted historical transaction quantity; and for extremely high frequency data or low sensitive data, the legality of the power transaction is converted into a verification circuit defined by a constraint coefficient, a certification key and a verification key are generated, and the data source equipment generates zero knowledge certification for data meeting constraint conditions by using the certification key.
Owner:GUANGXI POWER GRID CORP

Low latency wireless messaging

Technology for wireless transmission of messages to remote receiving devices is disclosed. The technology includes receiving a message for transmission, determining transmission parameters for transmission of the message, and transmitting the message to a remote receiving device according to the determined transmission parameters. The technology may also include encoding the message to effect message latency and may be employed for message transmission via the ionosphere or other atmospheric layer at frequencies in the Medium Frequency (MF), High Frequency (HF), or Very High Frequency (VHF) spectrum. Further, the disclosed technology may be employed for message transmission to effect low latency financial transaction execution, such as high speed high frequency trading.
Owner:SPECTRANET TECHNOLOGIES LLC

Plasma processing apparatus and plasma processing method

In an example of an embodiment, a plasma processing apparatus includes a processing container, a stage, an upper electrode, an inlet, and a waveguide device. The stage is provided within the processing container. The upper electrode is provided above the stage, to interpose a space within the processing container. The inlet is configured to introduce high-frequency waves. The high-frequency waves are VHF waves or UHF waves. The inlet is provided at an end of the space in the lateral direction, and extends in a circumferential direction around a central axis of the processing container. The waveguide device is configured to supply high-frequency waves to the inlet. The waveguide device includes a resonator that provides a waveguide. The waveguide of the resonator extends in the circumferential direction around the central axis and extends in the direction in which the central axis extends to be connected to the inlet.
Owner:TOKYO ELECTRON LTD +1

Antenna providing window mountable semitransparent sunshade

An antenna mountable to a window to provide non-destructive installation and removal therefrom. The antenna has a substrate of dielectric material having a first surface with patterned conductive material providing a main radiator and ground plane, and a back surface of patterned conductive material providing a feeding circuit, which capacitively conveys and receives, via the substrate, RF signals with the main radiator and ground plane. The main radiator and ground plane, and preferably the feeding circuit, are each radiating structures to achieve different frequency ranges, such as over VHF, UHF, and cellular bands, with wideband performance. The antenna is configured to resemble a semitransparent sunshade by the antenna body being perforated, through the front and back thereof, with holes enabling a majority of the antenna body to appear semitransparent for screening sunlight. One or more fixtures are utilized for detachably mounting the antenna along a surface of a window.
Owner:STI CO IND INC

Plasma processing method and plasma processing device

There is provided a plasma processing method comprising: continuously introducing electromagnetic waves into a chamber of a plasma processing apparatus, the electromagnetic waves being VHF waves or UHF waves, the electromagnetic waves being introduced into the chamber so as to form standing waves within the chamber along a lower surface of an upper electrode of the plasma processing apparatus; periodically applying a negative voltage to the upper electrode while performing said continuously introducing the electromagnetic waves; and supplying a processing gas into the chamber only during a period in which the negative voltage is applied to the upper electrode.
Owner:TOKYO ELECTRON LTD

Nickel zinc copper ferrite for VUHF antenna applications

The present invention relates to a nickel zinc copper ferrite for VUHF antenna applications. In particular to a composition and solid material particularly suitable for the manufacture of antennas suitable for operation in the very high frequency (VHF) band and the ultra high frequency (UHF) band or V / UHF, and to a method of manufacture and use thereof. The composition has the formula Ni a Zn b Cu c Co d Fe 2‑δ O4, wherein: 2(a+b+c+d)+3(2-δ)=80.05
Owner:EXXELIA

Lightning very high frequency interferometric positioning method based on irregular array

The application discloses a lightning VHF interference positioning method based on an irregular array, relates to the lightning positioning field, and comprises the following steps: S1, acquiring the antenna positions of N station interferometers and calculating the time difference τ of a radiation source reaching all baselines ij ; S2, judging whether all the antennas are on the same plane, if yes, entering S3, otherwise, entering S4; S3, calculating the positioning direction of the radiation source by using M groups of baselines and entering S6; S4, combining any three stations to form a selection; S5, calculating the direction of the radiation source under each selection and determining the positioning direction of the radiation source; S6, calculating the elevation angle and the azimuth angle of the radiation source according to the positioning direction of the radiation source; when the interference positioning is performed, the non-coplanar characteristics of the antenna array and the increase of the number of antennas can obviously improve the positioning result of the interferometer, and the method can be applied to any irregular array, that is, the antenna array can be randomly arranged, the coplanar of the antenna array is not required, and the baselines formed by the antenna array are not required to be orthogonal to each other, so that the installation difficulty of the antenna is effectively reduced.
Owner:INST OF ATMOSPHERIC PHYSICS CHINESE ACADEMY SCI

Beidou-based integrated positioning, navigation and communication apparatus for engineering ship in deep and sensitive sea area

Embodiments of the present application disclose a Beidou-based integrated positioning, navigation and communication apparatus for an engineering ship in a deep and sensitive sea area. The apparatus comprises: a route switching module, an ad hoc network communication module, a very high frequency communication module, a basic communication module and a Beidou communication module. The route switching module is configured to acquire communication scenario data of a current ship, determine, on the basis of the communication scenario data, a target communication module among the ad hoc network communication module, the very high frequency communication module, the basic communication module and the Beidou communication module, and establish a connection with an external communication device by means of the target communication module.
Owner:NAT ENG RES CENT OF DREDGING TECH & EQUIP +1

Compensation of impedance modulation in a plasma generator by frequency sweep

A plasma processing system is disclosed. A very high frequency (VHF) generator delivers power to a plasma chamber, and a mid-frequency (MF) generator delivers power to the plasma chamber. The VHF generator includes a sensor configured to provide a signal indicative of an impedance of a plasma load that is presented to the VHF generator. The VHF generator further includes a frequency tuner configured to adjust a frequency of the VHF generator within a cycle of the MF generator based on the signal to mitigate impedance modulation caused by the MF generator. Impedance modulation may also be mitigated by a sync line between the VHF and MF generators that allows presetting the VHF generator frequency in synchronization with a cycle of the MF generator.
Owner:ADVANCED ENERGY IND INC

Very high frequency omnidirectional antenna array blind area optimization method based on directional antenna supplement

The invention relates to the technical field of wireless communication, in particular to a very high frequency omnidirectional antenna array blind area optimization method based on directional antenna supplement, which comprises the following steps of: establishing a very high frequency omnidirectional antenna unit model, and executing free space simulation; constructing at least one directional antenna precise model; constructing a very high frequency reference omnidirectional antenna array model based on an erected base; and simulating the reference model, obtaining an initial radiation pattern, and identifying and recording the orientation and range of the communication blind area. According to the invention, the number and spacing of the directional antennas are optimized through parameterized scanning, the communication blind area of the very high frequency omnidirectional antenna array is accurately eliminated, and the communication reliability is improved; a complete reusable design process is established, the erection of a base model is simplified, and the simulation time and the engineering cost are reduced; a parameter interval in a limited space is defined, and the engineering operability is enhanced; a single / double directional antenna supplement scheme library is formed, different blind areas and resource scenes are adapted, and the practicability is high.
Owner:CIVIL AVIATION UNIV OF CHINA

Heat dissipation structure of very high frequency data exchange system equipment

The utility model provides a heat dissipation structure of very high frequency data exchange system equipment. The heat dissipation structure comprises a case shell, a heat dissipation module and a circuit board, heat dissipation holes are formed in the side walls of the two ends of the case shell; a dustproof net is arranged on the heat dissipation holes; a fan is fixed in the heat dissipation hole in one end of the case shell through a fan bracket; a system power switch is arranged on the front side shell of the case shell; a heat dissipation module is arranged on an inner bottom shell of the case shell; the heat dissipation module is composed of a heat dissipation plate, a radio frequency power supply radiator, a baseband power supply radiator, a multi-step heat dissipation fin and a heat pipe. The heat dissipation plate is fixed on an inner bottom shell of the case shell; the heat pipe is fixed to the bottom of the heat dissipation plate, and the multi-step heat dissipation fins are fixed to the lower portion of the fan. Heat generated by the chip is transmitted to the fan end through the heat dissipation plate, the heat pipe and the multi-step heat dissipation fins which are arranged in the case shell, the heat is discharged out of a product through the fan, and the problem that the outward transmission efficiency of internal temperature is low is solved.
Owner:遨海科技有限公司

Partial discharge signal generation method and system, computer device and storage medium

The application discloses a partial discharge signal generation method and system, computer equipment and a storage medium, comprising: generating a PRPS atlas, converting the PRPS atlas into a pulse sequence, importing the pulse sequence into a partial discharge signal generation device and saving it locally, obtaining the pulse sequence, analyzing the pulse sequence to convert it into a PRPS atlas, selecting the PRPS atlas, setting output parameters according to the phase coordinates, amplitude coordinates and real-time power frequency information of the PRPS atlas, and outputting corresponding signals. The application can obtain a power frequency in real time, output any very high frequency or high frequency partial discharge signal, has two independent output channels, can simultaneously output very high frequency or high frequency partial discharge signals respectively, the signal type, amplitude, pulse number, carrier frequency and other parameters can be adjusted, and the function test, calibration, sensitivity test, time difference positioning test and partial discharge type identification test of a partial discharge detection device can be realized. The application has multiple function applications such as remote control, cluster work and competition mode.
Owner:ELECTRIC POWER RESEARCH INSTITUTE OF STATE GRID SHANDONG ELECTRIC POWER COMPANY

Film forming method and film forming apparatus

A film forming method includes: a supply operation of supplying a processing gas into a processing container in which a substrate is accommodated, the processing gas including a silicon-containing gas, a nitrogen-containing gas, and a diluent gas; and a film forming operation of plasmarizing the processing gas by supplying, into the processing container, power obtained by phase-controlling and superimposing first power with a first frequency in a VHF band and second power with a second frequency different from the first frequency in the VHF band, and forming a silicon nitride film on the substrate by the plasmarized processing gas.
Owner:TOKYO ELECTRON LTD

Very high speed, high density electrical interconnection system with broadside subassemblies

A modular electrical connector with broad-side coupled signal conductors in a right angle intermediate portion. Broadside coupling provides balanced pairs for very high frequency operation. The connector may be assembled with multiple subassemblies, each of which may have multiple pairs of signal conductors. The subassemblies may be formed from an insulative portion having grooves in opposite sides into which the intermediate portions of signal conductors. Covers, holding the signal conductors in the grooves, may establish the position of the signal conductors relative to reference conductors at the exterior of subassembly, so as to provide a controlled impedance. Lossy material may be positioned between the pairs in a subassembly and / or may contact the reference conductors of the subassemblies, and the lossy material of the subassemblies may in turn be connected with a conductive structure.
Owner:AMPHENOL CORP

A switch cabinet partial discharge on-line intelligent detection system

The present application relates to the technical field of switch cabinet partial discharge detection, and particularly relates to a switch cabinet partial discharge online intelligent detection system; the system comprises a preliminary screening module, an environment monitoring module, a first diagnosis module, a second diagnosis module and a feedback adjustment module. According to the present application, the diagnosis path is adaptively selected according to the real-time environmental noise level; in a low-noise environment, ultrasonic waves and very high frequency signals are synchronously fused, and through double consistency analysis of intensity distribution and phase spectrum, accurate judgment and positioning of the discharge type are realized; in a high-noise environment, the very high frequency detection with strong anti-interference ability is mainly used, combined with the synchronicity verification of ultrasonic wave signals and the concentration trend analysis of SF6 decomposition products, and the final quantitative confirmation and accurate positioning are carried out by using the pulse current method; the noise judgment threshold is dynamically optimized, the continuous self-optimization of the detection strategy is realized; the insulation abnormalities are accurately warned through online real-time monitoring, and the safety and reliability of the operation of the key electrical equipment are improved.
Owner:YICHUN POWER SUPPLY COMPANY OF STATE GRID HEILONGJIANG ELECTRIC POWER COMPANY

A centralized monitoring system for air traffic control equipment

The present invention provides an air traffic control equipment centralized monitoring system, comprising: an air traffic control equipment cabinet, a centralized monitoring cabinet, a local navigation data acquisition component, a local radar station, a very high frequency communication device, and a relay. The air traffic control equipment cabinet includes a centralized monitoring equipment network, a centralized monitoring server, and a centralized monitoring terminal. The centralized monitoring equipment network is connected to the centralized monitoring server and the centralized monitoring terminal respectively. The centralized monitoring cabinet includes an air traffic control equipment data acquisition unit, a navigation data acquisition unit, a radar data acquisition unit, a very high frequency data acquisition unit, and a relay data acquisition unit. The navigation data acquisition unit, the radar data acquisition unit, the very high frequency data acquisition unit, and the relay data acquisition unit are connected to the centralized monitoring server respectively through the air traffic control equipment data acquisition unit, and the collected data is transmitted to the centralized monitoring terminal via the centralized monitoring server and the centralized monitoring equipment network. Therefore, air traffic control equipment can be centrally monitored and managed.
Owner:CIVIL AVIATON ZHONGNAN ATC EQUIP ENG CO

Non-position-aware downlink channel estimation and positioning method assisted by reconfigurable intelligent surface

Reconfigurable intelligent surface is considered as one of the key technologies to improve the performance of the system in multiple-input multiple-output communication systems. When the system works at very high frequencies (such as terahertz), the sparsity of channel parameters becomes a significant feature. In order to effectively recover these channel parameters, we introduce an optimization method based on the atomic norm, which uses the sparsity in the angular domain to accurately estimate the channel state information. In the mixed reconfigurable intelligent surface scenario, the selection of randomly activated elements aims to reduce the cost of reconfigurable intelligent surface deployment while maintaining the performance of channel estimation and positioning. Simulation experiments show that this method can achieve super-resolution channel estimation and outperform the existing orthogonal matching pursuit method. Comparison of various performance indicators shows that the proposed method has obvious advantages. This advantage is crucial for achieving accurate positioning services in complex environments.
Owner:NANJING UNIV OF POSTS & TELECOMM

Multi-band ultrahigh frequency detection device and method and computer readable storage medium

The embodiment of the invention discloses a multi-band ultrahigh frequency detection device, a multi-band ultrahigh frequency detection method and a computer readable storage medium. The multi-band ultrahigh frequency detection device comprises an ultrahigh frequency sensor, a front-end processing module and an acquisition module. The ultrahigh frequency sensor is used for collecting an electric signal sent by a measured object. The front-end processing module comprises a band-pass filter circuit and a detection filter circuit, and the band-pass filter circuit is used for separating the electric signal into multiple sub-band signals of different wavebands; the detection filter circuit is used for collecting effective content in each sub-band signal to obtain a detection signal. And the acquisition module is used for converting the multiple paths of detection signals into ultrahigh-frequency acquisition information and uploading the ultrahigh-frequency acquisition information, and the ultrahigh-frequency acquisition information is used for representing the working condition state of the detected object. Therefore, the ultrahigh frequency acquisition information under different frequency bands can be effectively acquired, and synchronous acquisition of the ultrahigh frequency acquisition information of multiple independent frequency bands can be realized.
Owner:YUNNAN POWER GRID CO LTD ELECTRIC POWER RES INST

Dynamic and static encryption key technology and method applied to encryption ship automatic identification system

The invention relates to the technical field of communication, in particular to a dynamic and static secret key encryption technology and method applied to an encryption ship automatic identification system. Comprising a ship name, a call number, a ship length, a ship width, a ship type, a ship native place port and positioning antenna position information, and the ship AIS terminal module is configured to collect ship static data, dynamic data and navigation related data and broadcast the data through a very high frequency channel; the dynamic data comprises longitude and latitude coordinates of the ship, the speed to the ground, the course to the ground, the bow direction, the navigation state and the steering rate, and the navigation related data comprises the draft of the ship, the dangerous cargo type, the destination and the estimated arrival time; the core problem that a traditional AIS system is insufficient in data protection capacity in a dynamic threat environment can be solved.
Owner:GUANGZHOU ZHONGKE LAISI TECHNOLOGY DEVELOPMENT CO LTD

Remote power control box

An apparatus comprises: a case enclosing a space; a power connector, extending through the case, to be connected to an external device; a power switch, retained in the space, and configured to be controlled responsive to commands in a UHF / VHF radio signal received by the power switch; a battery, retained in the space, having battery terminals connected to the power connector such that at least one of the battery terminals is connected to the power connector through the power switch; and an antenna, mounted to the case, to receive, and deliver to the power switch, the UHF / VHF radio signal, wherein the commands include a first command to close the power switch to connect the battery to the external device, and a second command to open the power switch to disconnect the battery from the external device.
Owner:L3HARRIS TECH INC

Frequency modulated continuous wave (FMCW) waveform generator / decoder

The present disclosure is directed to the transmission and reception of sets of very high frequency electromagnetic (EM) signals in ways that allow a sensing apparatus to discriminate between different sets of transmitted EM signals. Here a sensing apparatus may sequentially transmit different sets of EM signals. Each of these different sets of signals may include an encoded identifier that uniquely identifies each respective signal set of the different sets of signals. Each of these signal sets may include several pulses of a particular frequency with a same relative phase relationship followed by pulses that have a different phase relationship. These changes in phase may be used to encode the unique identifiers into the different sets of transmitted EM energy and these identifiers may be used by a sensing apparatus to associate specific received sets of EM energy with specific sets of transmitted EM energy.
Owner:GM CRUISE HOLDINGS LLC

Compensation of impedance modulation in a plasma generator by frequency sweep

A plasma processing system is disclosed. A very high frequency (VHF) generator delivers power to a plasma chamber, and a mid-frequency (MF) generator delivers power to the plasma chamber. The VHF generator includes a sensor configured to provide a signal indicative of an impedance of a plasma load that is presented to the VHF generator. The VHF generator further includes a frequency tuner configured to adjust a frequency of the VHF generator within a cycle of the MF generator based on the signal to mitigate impedance modulation caused by the MF generator. Impedance modulation may also be mitigated by a sync line between the VHF and MF generators that allows presetting the VHF generator frequency in synchronization with a cycle of the MF generator.
Owner:ADVANCED ENERGY IND INC