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93 results about "Bipolar signal" patented technology

In telecommunication, a bipolar signal is a signal that may assume either of two polarities, neither of which is zero. A bipolar signal may have a two-state non-return-to-zero (NRZ) or a three-state return-to-zero (RZ) binary coding scheme.

Methods and apparatus for optical transmission of digital signals

A method of communicating digital information over a dispersive optical channel includes encoding the digital information into a plurality of data blocks, each of which includes a number of bits of the information. A time-varying electrical signal is generated which corresponds with each of said data blocks. The time-varying electrical signal is applied to an optical transmitter (122) to generate an optical signal which includes an asymmetrically amplitude limited transmitted signal modulated onto an optical carrier. The optical signal is then transmitted over the dispersive optical channel (106). At a receiving apparatus (104) the optical signal is detected to produce an electrical signal which corresponds with the asymmetrically amplitude limited transmitted signal. A frequency domain equalisation of the electrical signal mitigates the effect of dispersion of the optical channel (106) on the transmitted optical signal, and the equalised signal is decoded to recover the encoded data blocks and the corresponding transmitted digital information. The method enables bipolar signals to be transmitted over a dispersive unipolar optical channel, and reduces or eliminates the need to apply a high optical bias level at the transmitter, thereby improving optical power efficiency and enabling output power levels to be maintained below applicable safe levels, while simultaneously enabling the effects of channel dispersion to be substantially mitigated.
Owner:MONASH UNIV

Sheet material thickness online detection and adjustment system based on laser ultrasonic

A sheet material thickness online detection and adjustment system based on laser ultrasonic comprises a sheet material rolling mechanism and a sheet material thickness online detection mechanism. The sheet material rolling mechanism comprises an upper roller, a lower roller, an upper-lower roller interval adjust mechanism and a PLC control system, the sheet material thickness online detection mechanism comprises an optics system assembly, a high temperature testing meter, a data collection system assembly and a data process system assembly, the data process system assembly transforms bipolar signals which are aliased in peak values and complex in background noise into unipolar signals which are clear in peak values and low in background noise, so that the time that longitudinal wave and transverse wave reach the center of the bottom surface of the sheet material for the first two times is obtained, and thereby the sheet material thickness value is calculated, the measured sheet material thickness value is compared with a preset sheet material thickness value in the PLC control system, the PLC control system transmits forward rotating/backward rotation movement commands to a servo motor, so that the interval between the upper roller and the lower roller is adjusted, and the sheet material thickness value is made to be consistent with the preset sheet material thickness value.
Owner:ZHEJIANG UNIV

Target detecting and identifying method and target detecting and identifying system based on sound vibration signal

The invention discloses a target detecting and identifying method and a target detecting and identifying system based on a sound vibration signal. The method comprises the steps of acquiring a vibration signal at a preset node position in a preset time period and storing the vibration signal into a vibration data matrix by means of M fiber sensors or equivalent M fiber sensors; performing preprocessing on the vibration data matrix by means of a pre-emphasis method, and selecting a bipolar data frame which comprises a target signal; extracting a speed characteristic, an energy distribution characteristic and a spectrum estimation characteristic of each row of each kind of signal from the bipolar data frame, acquiring a relatively long characteristic vector matrix according to each characteristic and a corresponding weighted value and performing dimension reduction on the relatively long characteristic vector matrix; and identifying the vibration signal kind of the bipolar signal data, the bipolar signal data frame and the relatively long characteristic vector after dimension reduction by means of a long-and-short-period selection memory neural network model. According to the target detecting and identifying method and the target detecting and identifying system, sound vibration signal identification is determined according to combined action of information in different steps, thereby improving target identification accuracy.
Owner:北京知觉科技有限公司

Methods and apparatus for optical transmission of digital signals

A method of communicating digital information over a dispersive optical channel includes encoding the digital information into a plurality of data blocks, each of which includes a number of bits of the information. A time-varying electrical signal is generated which corresponds with each of said data blocks. The time-varying electrical signal is applied to an optical transmitter (122) to generate an optical signal which includes an asymmetrically amplitude limited transmitted signal modulated onto an optical carrier. The optical signal is then transmitted over the dispersive optical channel (106). At a receiving apparatus (104) the optical signal is detected to produce an electrical signal which corresponds with the asymmetrically amplitude limited transmitted signal. A frequency domain equalization of the electrical signal mitigates the effect of dispersion of the optical channel (106) on the transmitted optical signal, and the equalized signal is decoded to recover the encoded data blocks and the corresponding transmitted digital information. The method enables bipolar signals to be transmitted over a dispersive unipolar optical channel, and reduces or eliminates the need to apply a high optical bias level at the transmitter, thereby improving optical power efficiency and enabling output power levels to be maintained below applicable safe levels, while simultaneously enabling the effects of channel dispersion to be substantially mitigated.
Owner:MONASH UNIV

Sheet thickness online measurement system based on laser ultrasound

A sheet thickness online measurement system based on laser ultrasound comprises a light path system integration, a high-temperature detection meter, a data acquisition system integration and a data processing system integration, wherein the light path system integration comprises a U-shaped grounding frame, a three-dimensional mobile platform and a control cabinet integrating with a laser transmitter and a light path regulating system; the data acquisition system integration comprises a capacitive displacement sensor, a pre-amplifier and a high-speed data acquisition card, the capacitive displacement sensor is arranged at the first distance position below the alignment position of the bottom surface of a sheet, the data processing system integration converts bipolar signals having aliasing peak values and complex background noise into unipolar signals having clear peak values and low background noise, and therefore the time when longitudinal waves and transverse waves reach the alignment position of the bottom surface of the sheet first two times is accurately obtained, and the thickness of the sheet is calculated. The sheet thickness online measurement system has the advantages that the sheet thickness online measurement system is suitable for online measuring the thickness of the sheet under extreme environments such as high temperature, strong corrosion and high radiation, thickness measurement is accurate, and errors are small.
Owner:ZHEJIANG UNIV

Online plate thickness measuring system based on laser ultrasonics

An online plate thickness measuring system based on laser ultrasonics comprises a light path system integration module, a high-temperature detector, a data collection system integration module and a data processing system integration module. The light path system integration module comprises a U-shaped grounding frame, a vertical moving platform and a control cabinet, a laser transmitter, a light path adjusting system and a scanning galvanometer are integrated in the control cabinet, the data collection system integration module comprises a capacitive displacement sensor, a preposed amplifier and a high-speed data collection card, the capacitive displacement sensor is arranged at a first distance position above the upper surface of a plate, and the data processing system integration module converts bipolar signals with aliasing peak value and complex background noise into unipolar signals with clear peak value and low background noise so as to accurately acquire time when longitudinal wave and transverse wave reach an O point on the upper surface of the plate in two previous times to calculate thickness of the plate. The online plate thickness measuring system has the advantages that the system utilizes a laser ultrasonics principle to measure thickness and is suitable for online measuring of thickness of the plate in extreme environment with high temperature, high corrosion and high radiation, accurate in thickness measuring and few in thickness measuring error.
Owner:ZHEJIANG UNIV

Digital-analog hybrid chaotic circuit containing mathematical operation circuit and operation method thereof

The invention discloses a digital-analog hybrid chaotic circuit containing a mathematical operation circuit and an operation method thereof. According to the digital-analog hybrid chaotic circuit disclosed by the invention, the chaotic circuit composed of a difference equation and a symbolic function is realized in such a manner that the difference equation is realized by an analog circuit and the symbolic function is realized by the mathematical operation circuit. The analog circuit is composed of a resistor, a capacitor, an operational amplifier and other conventional analog devices. A digital circuit is composed of a signal forming module, a mathematical operation module and a unipolar-bipolar signal conversion module, wherein the mathematical operation module is composed of an adder, a multiplier and other conventional digital circuits. According to the digital-analog hybrid chaotic circuit disclosed by the invention, the digital devices are embedded in the traditional analog chaotic circuit to complete symbolic computation, and different chaotic systems can be realized by switching different mathematical operation modules in the same circuit, so the precision is very high, and the universality and the adaptability are relatively strong.
Owner:NANJING UNIV OF SCI & TECH

Voltage monitoring instrument of single pile piece of fuel cell

The invention discloses a voltage monitoring instrument of a single pile piece of a fuel cell. The voltage monitoring instrument is composed of a signal interface circuit board and a signal processingcircuit board that are in connection by direct plugging between pins and a pin base. The signal interface circuit board consists of a power conversion circuit, a signal isolation conversion circuit,an analog channel selection circuit, a decoding circuit and an impedance conversion circuit. The signal processing circuit board includes a DSP minimum system, an externally expanded RAM circuit, an externally extended AD sampling circuit, a reference voltage circuit, and a CAN communication circuit. According to the invention, with a bipolar signal isolation converter on the signal interface circuit board, one-to-one isolation conversion of the single cell voltages of the pile is carried out. The voltage monitoring instrument has characteristics of large isolation voltage, high measurement accuracy, short measurement period, strong anti-electromagnetic interference capability, wide operating temperature range, long service life, and high reliability and the like; and modularization and miniaturization of the monitoring instrument are realized.
Owner:WUHAN MARINE ELECTRIC PROPULSION RES INST CHINA SHIPBUILDING IND CORP NO 712 INST
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