Showing papers on "Spectrum analyzer published in 2010"
TL;DR: A mass spectrometer interface for planar geometries is constructed that takes advantage of atmospheric pressure gas dynamic principles, rather than ion focusing, to minimize ion losses from diffusion in the analyzer and to maximize total ion transport into the mass spectromaeter.
166 citations
TL;DR: It is shown that the ellipsometric data obtained with the novel terahertz ellipsometer can be well described within the classical Drude model, which at the same time is in perfect agreement with midinfrared ellipsometry data obtained from the same sample for comparison.
Abstract: We report an experimental setup for wavelength-tunable frequency-domain ellipsometric measurements in the terahertz spectral range from 0.2 to 1.5 THz employing a desktop-based backward wave oscillator source. The instrument allows for variable angles of incidence between 30° and 90° and operates in a polarizer-sample-rotating analyzer scheme. The backward wave oscillator source has a tunable base frequency of 107–177 GHz and is augmented with a set of Schottky diode frequency multipliers in order to extend the spectral range to 1.5 THz. We use an odd-bounce image rotation system in combination with a wire grid polarizer to prepare the input polarization state. A highly phosphorous-doped Si substrate serves as a first sample model system. We show that the ellipsometric data obtained with our novel terahertz ellipsometer can be well described within the classical Drude model, which at the same time is in perfect agreement with midinfrared ellipsometry data obtained from the same sample for comparison. The ...
90 citations
TL;DR: A silicon nanowire based radio-frequency spectrum analyzer capable of characterizing ultrahigh speed optical data is demonstrated and it is shown that although nonlinear loss affects device efficiency, free-carrier dispersion is negligible.
Abstract: We demonstrate a terahertz bandwidth silicon nanowire based radio-frequency spectrum analyzer using cross-phase modulation. We show that the device provides accurate characterization of 640Gbaud on-off-keyed data stream and demonstrate its potential for optical time-division multiplexing optimization and optical performance monitoring of ultrahigh speed signals on a silicon chip. We analyze the impact of free carrier effects on our device, and find that the efficiency of the device is not reduced by two-photon or free-carrier absorption, nor its accuracy compromised by free-carrier cross-chirp.
81 citations
Patent•
02 Jun 2010TL;DR: In this article, a spectrum detector/analyzer is provided with a spectrum manager/planner capable of understanding a plurality of air interface standards, reserving and providing the right amount of white space spectrum to each application, based on the respective standard requirements.
Abstract: TV white space spectrum sensors and methods for detecting and managing the white space are provided. The sensor is provided with a spectrum detector/analyzer, which senses and analyzes the wireless signals present in a spectrum of interest, identifies white space, and assigns the white space to secondary services. For reducing the white space detection time, the sensor uses a group detection method whereby multiple channels are sensed simultaneously. For reducing the sensor cost, the dynamic range of the sensor is reduced by operating the sensor in saturation for signals with the energy higher than a threshold. The sensor is also provided with a spectrum manager/planner capable of understanding a plurality of air interface standards, reserving and providing the right amount of white space spectrum to each application, based on the respective standard requirements. The particular architectures used by the sensor result in an affordable addition to any wireless device.
81 citations
TL;DR: The novelty of this work is the development of a low-cost FPGA based on a multichannel vibration analyzer, capable of providing an automatic diagnosis of the motor state carrying out online continuous monitoring.
Abstract: Early detection of failures in equipment is one of the most important concerns to industry. Many techniques have been developed for early failure detection in induction motors. There is the necessity of low-cost instrumentation for online multichannel measurement and analysis of vibration in the frequency domain, and this could be fixed to the machine for continuous monitoring to provide a reliable continuous diagnosis without needing trained staff. Field-programmable gate arrays (FPGAs) are distinguished by being very fast and highly reconfigurable devices, allowing the development of scalable parallel architectures for multichannel analysis without changing the internal hardware. The novelty of this work is the development of a low-cost FPGA based on a multichannel vibration analyzer; this is capable of providing an automatic diagnosis of the motor state carrying out online continuous monitoring. To test the functionality of the proposed vibration analyzer, three experiments on 746-W (1-hp) induction motors were carried out. Such experiments are intended to detect motor failures such as broken bars, unbalance, and looseness. The obtained results show the overall system performance.
74 citations
69 citations
Patent•
12 Mar 2010
TL;DR: In this article, a distance to PIM measurement circuit is made using a device such as an AWS transceiver that has separate transmit and receive bands, where a desired harmonic of a test PIM harmonic signal is selected outside the band of the band reject filter.
Abstract: A distance to PIM measurement circuit is made using a device such as an AWS transceiver that has separate transmit and receive bands. With a typical AWS transceiver placed in close proximity to a PCS transceiver, the AWS device will include a band reject filter to eliminate interference from the PCS signals. The PIM measurement circuit includes two frequency sources F 1 and F 2 that are provided through a combiner for characterization of the PIM circuit. To enable distance determination, an FM measurement is created by using an offset sweep generator attached to one of the two frequency sources. To avoid frequencies blocked by the band reject filter, a desired harmonic of a test PIM harmonic signal is selected outside the band of the band reject filter.
59 citations
TL;DR: The relationship between the retrieved autocorrelation trace and signal impairments is exploited to simultaneously monitor dispersion, in-band optical signal to noise ratio (OSNR) and timing jitter from a single measurement.
Abstract: We report the first demonstration of simultaneous multi-impairment monitoring at ultrahigh bitrates using a THz bandwidth photonic-chip-based radio-frequency (RF) spectrum analyzer. Our approach employs a 7 cm long, highly nonlinear (gamma approximately 9900 /W/km), dispersion engineered chalcogenide planar waveguide to capture the RF spectrum of an ultrafast 640 Gb/s signal, based on cross-phase modulation, from which we numerically retrieve the autocorrelation waveform. The relationship between the retrieved autocorrelation trace and signal impairments is exploited to simultaneously monitor dispersion, in-band optical signal to noise ratio (OSNR) and timing jitter from a single measurement. This novel approach also offers very high OSNR measurement dynamic range (> 30 dB) and is scalable to terabit data rates.
52 citations
TL;DR: An embedded frequency response analyzer for fuel cells (FCs) based on a robust measurement technique with simple implementation and the lock-in amplification technique, which allows very accurate and precise measurements even in the presence of high noise levels is presented.
Abstract: This paper presents an embedded frequency response analyzer for fuel cells (FCs) based on a robust measurement technique with simple implementation. A frequency response analysis technique provides valuable information of different electrochemical processes that occur inside the FC. The measurement system is implemented on a low-cost digital signal processor to perform frequency response and impedance tracking. The small-size and low-power consumption allows this special device to be embedded into the FC controller or power conditioning stage. The system is capable of measuring automatically the frequency response of the FC at different operating points, even when the FC is operating with a load. These measurements can be used to characterize the FC at the design stage and to perform online monitoring of the FC state during a continuous operation. The proposed instrument uses the lock-in amplification technique, which allows very accurate and precise measurements even in the presence of high noise levels. The proposed hardware and signal processing technique are described in this paper, including the experimental result of a 1.2-kW proton exchange membrane FC system.
47 citations
TL;DR: A heterodyne measurement of the spectral amplitude and phase of periodic optical signals requires no optical modulation of either the signal or the local oscillator, places much relaxed tunability requirements on the optical local oscillators, and requires no electronic clock to be passed to the receiver.
Abstract: We present a heterodyne measurement of the spectral amplitude and phase of periodic optical signals. In contrast to previous techniques this measurement requires no optical modulation of either the signal or the local oscillator, places much relaxed tunability requirements on the optical local oscillator, and requires no electronic clock to be passed to the receiver. We present measurements of the spectral amplitude and phase of 20 GHz 33% return-to-zero, and 66% carrier-suppressed return-to-zero optical signals, as well as a passively modelocked optical source with in excess of 100 modes.
41 citations
Patent•
23 Feb 2010TL;DR: A particle analyzer that includes optical waveguides, a support, and a detector can be coupled to the core stream sample system as mentioned in this paper, and the coupling can use an optical waveguide device configured to convey optical radiation arising from sample interaction to the detector.
Abstract: A particle analyzer that includes optical waveguides, a support, and a detector. The optical waveguides direct spatially separated beams from a source of radiation to produce measuring beams in a sample flow measuring area. The support maintains each of the optical waveguides in a fixed relative position with respect to each other and maintains the positioning of the measuring beams within the measuring area. The detector senses light produced from the measuring beams interacting with a particle flowing through the measuring area. At least one of the support and the detector can be coupled to the core stream sample system. The coupling can use an optical waveguide device configured to convey optical radiation arising from sample interaction to the detector. In another example, a particle analyzer comprises an optical system configured to be fixedly coupled to a sample system and configured to direct beams along independent beam paths from a source of radiation to produce measuring beam spots in a sample flow measuring area of the sample system and a detection system configured to sense radiation delivered from the sample flow measuring area.
TL;DR: In this article, a single-tone cancellation formula is developed requiring only the power of the probing signal and the combined probe and cancellation signal so that the phase shift required for cancellation can be predicted.
Abstract: This paper presents an intermodulation distortion measurement system based on automated feedforward cancellation that achieves 113 dB of broadband spurious-free dynamic range for discrete tone separations down to 100 Hz. For 1-Hz tone separation, the dynamic range is 106 dB, limited by carrier phase noise. A single-tone cancellation formula is developed requiring only the power of the probing signal and the power of the combined probe and cancellation signal so that the phase shift required for cancellation can be predicted. The technique is applied to a two-path feedforward cancellation system in a bridge configuration. The effects of reflected signals and of group delay on system performance is discussed. Spurious frequency content and interchannel coupling are analyzed with respect to system linearity. Feedforward cancellation and consideration of electromagnetic radiation coupling and reverse-wave isolation effects extends the dynamic range of spectrum and vector analyzers by at least 40 dB. Application of the technique to the measurement of correlated and uncorrelated nonlinear distortion of an amplified wideband code-division multiple-access signal is presented.
TL;DR: The first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL) is proposed, promising better repeatability, speed, and reliability.
Abstract: To the best of our knowledge, we propose the first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL). Unlike prior analyzers that require profiling the beam at multiple locations along the light propagation axis, the proposed analyzer profiles the beam at the same plane for multiple values of the ECVFL focal length, thus eliminating beam profiler assembly motion. In addition to measuring standard Gaussian beam parameters, the analyzer can also be used to measure the M2 beam propagation parameter of a multimode beam. Proof-of-concept beam parameter measurements with the proposed analyzer are successfully conducted for a 633 nm laser beam. Given the all-digital nature of the DMD-based profiling and all-analog motion-free nature of the ECVFL beam focus control, the proposed analyzer versus prior art promises better repeatability, speed, and reliability.
TL;DR: This paper presents a method for properly measuring the loop gain frequency response of digitally controlled power converters by means of an analog frequency response analyzer (FRA).
Abstract: The study of the loop gain frequency response in a power converter is a powerful tool commonly used for the design of the controllers used in the control stage. As the control of medium- and high-power electronic converters is usually performed digitally, it is useful to find a method to measure the digital loop gains. The purpose of this paper is to present a method for properly measuring the loop gain frequency response of digitally controlled power converters by means of an analog frequency response analyzer (FRA). An analog sinusoidal reference signal generated by the FRA is injected through an analog-to-digital converter into the digital controller, and added to the discrete feedback signal. To obtain the frequency response of the open-loop gain, both feedback and disturbed feedback signals are sent back to the FRA by using the pulsewidth modulation peripherals of the controller.
06 Apr 2010
TL;DR: In this paper, an existing RF front-end in CMOS-technology with IIP3=+11dBm and NF<6.5dB is duplicated and attenuators are put in front to increase linearity.
Abstract: Spectrum sensing for cognitive radio requires a high linearity to handle strong signals, and at the same time a low noise figure (NF) to enable detection of much weaker signals. Often there is a trade-off between linearity and noise: improving one of them degrades performance of the other. Cross-correlation can break this trade-off by reducing noise at the cost of measurement time. An existing RF front-end in CMOS-technology with IIP3=+11dBm and NF<6.5dB is duplicated and attenuators are put in front to increase linearity (IIP3=+24dBm). The attenuation degrades NF, but by using cross-correlation of the outputs of the two front-ends, the NF is reduced to below 4dB. In total this results in a spurious-free dynamic range (SFDR) of 89dB in 1MHz resolution bandwidth (RBW).
Patent•
13 Dec 2010TL;DR: In this article, the authors proposed a ratio of an integral of a particular portion of an electrical pulse to a combination of a decay portion and a rise portion of the electrical pulse, where each of the integrals can be integrated over time.
Abstract: A radiation detection system can include a photosensor to receive light from a scintillator via an input and to send an electrical pulse at an output in response to receiving the light. The radiation detection system can also include a pulse analyzer that can determine whether the electrical pulse corresponds to a neutron-induced pulse, based on a ratio of an integral of a particular portion of the electrical pulse to an integral of a combination of a decay portion and a rise portion of the electrical pulse. Each of the integrals can be integrated over time. In a particular embodiment, the pulse analyzer can be configured to compare the ratio with a predetermined value and to identify the electrical pulse as a neutron-induced pulse when the ratio is at least the predetermined value.
TL;DR: The analyzer capabilities, in terms of energy resolution and transmission, are shown by using an electron gun, an ultraviolet-discharge lamp, and hard x-ray synchrotron radiation as excitation sources.
Abstract: We have developed an energy analyzer, High Voltage-Cylinder Sector Analyzer 300/15, for electron kinetic energies up to 15 keV. It is especially suited for hard x-ray photoelectron spectroscopy, but also for ultraviolet and soft x-ray photoelectron spectroscopy (ultraviolet photoemission spectroscopy, x-ray photoemission spectroscopy), Auger electron spectroscopy, and reflection high energy electron spectroscopy. The analyzer is based on a cylinder sector with 90 degrees deflection, 300 mm slit-to-slit distance, and a four-element pre-retarding lens system with 50 mm sample-to-lens distance. The result is a very compact design of the analyzer that is easily integrated into a multipurpose experiment with different techniques. A low noise/low drift electronics is capable of continuous energy scans from 0 to 15 keV using nonlinear lens curves. The first analyzer is allocated at the Spanish CRG SpLine beamline at the ESRF at an end station where simultaneous surface x-ray diffraction is possible. The analyzer is operated routinely since 2006 up to 15 keV electron kinetic energy, expanding the achievable electron kinetic energy range compared to other commercial analyzers. In this work we present a detailed description of the developed electron analyzer. The analyzer capabilities, in terms of energy resolution and transmission, are shown by using an electron gun, an ultraviolet-discharge lamp, and hard x-ray synchrotron radiation as excitation sources.
TL;DR: In this article, a lock-in analyzer for nonlinear systems is proposed for intermodulation atomic force microscopy, which is implemented on a field-programmable gate array, providing speed in analysis, real-time feedback and stability in operation.
Abstract: Nonlinear systems can be probed by driving them with two or more pure tones while measuring the intermodulation products of the drive tones in the response. We describe a digital lock-in analyzer which is designed explicitly for this purpose. The analyzer is implemented on a field-programmable gate array, providing speed in analysis, real-time feedback and stability in operation. The use of the analyzer is demonstrated for Intermodulation Atomic Force Microscopy. A generalization of the intermodulation spectral technique to arbitrary drive waveforms is discussed.
TL;DR: A vector Brillouin optical time-domain analyzer that has a high immunity level to noise, and it features a phase spectrogram capability, well suited for complex situations involving several acoustic resonances, such as high-order longitudinal modes.
Abstract: Thanks to a double-frequency phase modulation scheme, we report a vector Brillouin optical time-domain analyzer (BOTDA). This BOTDA has a high immunity level to noise, and it features a phase spectrogram capability. It is well suited for complex situations involving several acoustic resonances, such as high-order longitudinal modes. It has notably been used to characterize a dispersion-shifted fiber, allowing us to report spectrograms with multiple acoustic resonances. A very high 57dB dynamic range is also reported for 100-ns-long pulses simultaneously with a 16cm numerical resolution.
TL;DR: This paper presents a prototype of an automatic digital modulation classifier based on a real-time spectrum analyzer (RTSA) architecture that is suitable for efficient spectrum monitoring to identify the signals present in a certain frequency band, without the need of knowing any parameter about them.
Abstract: This paper presents a prototype of an automatic digital modulation classifier based on a real-time spectrum analyzer (RTSA) architecture. The modulation classifier is suitable for efficient spectrum monitoring to identify the signals present in a certain frequency band, without the need of knowing any parameter about them. The realized prototype is able to recognize classical single-carrier modulations such as M-ary phase-shift keying (PSK), M-ary frequency-shift keying (FSK), M-ary amplitude-shift keying (ASK), and M-ary quadrature amplitude modulation (QAM), as well as orthogonal frequency-division multiplexing (OFDM) modulations such as the discrete multitone (DMT). To evaluate the performance of the prototype, several experiments with actual signals have been carried out in different operating conditions by varying the values of both the main modulation parameters and the signal-to-noise ratio.
01 Nov 2010
TL;DR: A practical measurement setup using two types of spectrum sensing equipment: a high precision spectrum analyzer and a medium precision USRP2 software defined radio and results are compared in terms of duty cycle of the occupancy in the measured bands.
Abstract: Spectrum sensing is an important consideration in the future cognitive radio networks. In order to protect communicating users, it is essential to make a reliable and correct occupancy decision. A possible way in providing a more accurate sensing measurement is to adapt measurement parameters to the inspected band and inspected signal. Parameters settings for resolution bandwidth and sweep time are technology dependent and should be different for detecting various signal types in the frequency domain. This paper presents a practical measurement setup using two types of spectrum sensing equipment: a high precision spectrum analyzer and a medium precision USRP2 software defined radio. Different parameter sets are used for the both devices, and results are compared in terms of duty cycle of the occupancy in the measured bands. All the measurements are performed in the Industrial Scientific and Medical (ISM) band.
Patent•
25 May 2010
TL;DR: In this paper, an apparatus for generating high frequency audio signal that comprises an analyzer (12) for analyzing an input signal to determine a transient information adaptively, and a spectral converter (14) is provided for converting the input signal into an input spectral representation.
Abstract: An apparatus for generating a high frequency audio signal that comprises an analyzer (12) for analyzing an input signal to determine a transient information adaptively Additionally a spectral converter (14) is provided for converting the input signal into an input spectral representation A spectral processor (13) processes the input spectral representation to generate a processed spectral representation comprising values for higher frequencies than the input spectral representation A time converter (17) is configured for converting the processed spectral representation to a time representation, wherein the spectral converter or the time converter are controllable to perform a frequency domain oversampling for the first portion of the input signal having the transient information associated and to not perform the frequency domain oversampling for the second portion of the input signal not having the associated transient information
TL;DR: In this paper, the automatic detection of whistler traces from the raw broadband VLF signal was achieved. But the full potential of whistlers for monitoring plasmaspheric electron density variations has not yet been realized.
Abstract: [1] The full potential of whistlers for monitoring plasmaspheric electron density variations has not yet been realized. The primary reason is the vast human effort required for the analysis of whistler traces. Recently, the first part of a complete whistler analysis procedure was successfully automated, i.e., the automatic detection of whistler traces from the raw broadband VLF signal was achieved. This study describes a new algorithm developed to determine plasmaspheric electron density measurements from whistler traces, based on a Virtual (Whistler) Trace Transformation, using a 2-D fast Fourier transform transformation. This algorithm can be automated and can thus form the final step to complete an Automatic Whistler Detector and Analyzer (AWDA) system. In this second AWDA paper, the practical implementation of the Automatic Whistler Analyzer (AWA) algorithm is discussed and a feasible solution is presented. The practical implementation of the algorithm is able to track the variations of plasmasphere in quasi real time on a PC cluster with 100 CPU cores. The electron densities obtained by the AWA method can be used in investigations such as plasmasphere dynamics, ionosphere-plasmasphere coupling, or in space weather models.
TL;DR: In this paper, a scheme for multi-impairment performance monitoring at ultrahigh bit rates based on cross-phase modulation (XPM) in a nonlinear waveguide is presented.
Abstract: We introduce a scheme for multi-impairment performance monitoring at ultrahigh bit rates based on cross-phase modulation (XPM) in a nonlinear waveguide. We demonstrate that we can simultaneously monitor in-band optical signal-to-noise ratio and group velocity dispersion at bit rates of 320 Gb/s (return-to-zero format) from a single measurement. Our approach retrieves the autocorrelation of the signal via the radio-frequency (RF) spectrum, which is captured with an XPM-based RF spectrum analyzer in a highly nonlinear fiber.
TL;DR: A terahertz spectrum analyzer based on frequency and power measurement that has a frequency precision of 1x10(-11), a frequency resolution of 1Hz, a frequency band up to 1.7THz, and an optical noise equivalent power of approximately 1 pW/Hz(1/2).
Abstract: We demonstrate a terahertz (THz) spectrum analyzer based on frequency and power measurement. A power spectrum of a continuous THz wave is measured through optical heterodyne detection using an electromagnetic THz frequency comb and a bolometer and power measurement using a bolometer with a calibrated responsivity. The THz spectrum analyzer has a frequency precision of 1×10−11, a frequency resolution of 1Hz, a frequency band up to 1.7THz, and an optical noise equivalent power of ~1 pW/Hz1/2.
Patent•
07 Oct 2010TL;DR: In this article, a communications receiver includes a noise analyzer to characterize the composition of the interference and/or distortion impressed onto a transmitted communications signal in the presence of one or more time-varying conditions.
Abstract: A communications receiver includes a noise analyzer to characterize the composition of the interference and/or distortion impressed onto a transmitted communications signal in the presence of one or more time-varying conditions. The noise analyzer may provide a selection signal indicating the composition of the interference and/or distortion impressed onto a transmitted communications signal in the presence of one or more time-varying conditions to be used by the communications receiver. In an exemplary embodiment, the communications receiver selects at least one set of filter coefficients to compensate for the interference and/or distortion impressed onto a transmitted communications signal in the presence of a particular time-varying interference and/or distortion condition. In another exemplary embodiment, the communications receiver selects a corresponding interference cancellation filter bank to compensate for the interference and/or distortion impressed onto a transmitted communications signal in the presence of the particular time-varying interference and/or distortion condition.
Patent•
03 Feb 2010
TL;DR: In this article, a vibration monitoring structure based on optical fiber polarized light time domain reflection sense, comprising a laser (1), a first coupler (2), a second coupler, a third coupler and a fourth coupler), an acoustic optical modulator (3), a polarizer (4), a circulator (5), a sensing optical fiber, a first analyzer, a second analyzer and a detector (6), a detector, a low-pass filter, an analog-to-digital converter, anFPGA, and a microprocessor MCU,
Abstract: The invention relates to a vibration monitoring structure based on optical fiber polarized light time domain reflection sense, comprising a laser (1), a first coupler (2), a second coupler (7), a third coupler (8), a fourth coupler (11), a fifth coupler (13), an acoustic optical modulator (3), a polarizer (4), a circulator (5), a sensing optical fiber (6), a first analyzer (9), a second analyzer (10), a first detector (12), a second detector (14), a first low-pass filter (15), a second low-pass filter (16), a first analog-to-digital converter (17), a second analog-to-digital converter (18), anFPGA (19) and a microprocessor MCU (20); the method comprises the following steps: measuring the changes of the polarization state of each optical fiber section with time according to a plurality ofmeasurements, combining Fourier transformation technology to obtain frequency spectrum information, and analyzing the frequency spectrum information to obtain vibration information. Compared with theprevious method which is adopted by a POTDR system and carries out iteration operation on polarization state, the method has the advantages of simple algorithm and small data operation and greatly reduces monitoring time and cost of the system.
TL;DR: In this article, a photoacoustic (PA) system based on a completely open cylindrical acoustic resonator was proposed for water vapor concentration measurements, in which it was operated in parallel with a fast water vapor analyzer with a response time of 0.5 seconds.
Abstract: This paper describes a fast response gas concentration measuring photoacoustic (PA) system based on a completely open cylindrical acoustic resonator. Contrary to conventional PA systems, the operation of the resonator presented here does not require the use of gas sampling unit. Thus adverse effects of adsorption/desorption processes that always occur on the walls of sampling units (longer response time and lower measurement accuracy) can be avoided completely. High sensitivity is ensured by efficient PA signal generation in resonant operation (through modulated laser excitation of a specially selected high-frequency combination acoustic mode of the resonator) and external noise suppression (through dual microphone configuration based differential detection scheme). The developed PA system was tested in water vapor concentration measurements, in which it was operated in parallel with a fast water vapor analyzer (LI-COR 840 with a response time of 0.5 s). Results of test measurements prove that the minimum detectable water vapor concentration with the proposed photoacoustic system is approximately 80 ppm and its response time is shorter than that of the reference instrument; which makes it a promising candidate for being used in highly demanding applications such eddy covariance flux measurements.
18 Nov 2010
TL;DR: In this paper, a 6×6 ultrasonic transducer array based on SOI-Si bonding and PZT-coated membrane structures has been designed for real-time 3D medical imaging.
Abstract: Piezoelectric micromachined ultrasonic transducer (pMUT) is a new approach to form high frequency arrays for real-time 3-D medical imaging. pMUT arrays based on SOI-Si bonding and PZT-coated membrane structures have been designed in this paper. After simulation, the 6×6 ultrasonic transducer array was fabricated and characterized. The total array area is approximately 2.0 mm by 2.0 mm. The micrograph of the device shows that the physical parameters are consistent with the designed value. The impedance-frequency spectrum of the pMUT was measured by HP 4194A impedance phase analyzer. Resonance frequency and effective electro-mechanical coupling coefficient can be deduced from it. The resonance frequency is 980 KHz, and the effective electro-mechanical coupling coefficient is about 4.64%. Due to its performance, it is promising for medical ultrasonic imaging applications.
Patent•
15 Jan 2010TL;DR: In this paper, a system for visually assisted audio mixing using a spectral analyzer is described, which allows a user to visually mix an audio arrangement by imputing a desired spectral result and having the program make the changes necessary to achieve it.
Abstract: Processor-implemented methods and systems for visually-assisted mixing of audio using a spectral analyzer are disclosed. The system calculates and displays a spectral view for each track in an arrangement in a multi-track view. A user can then request modification of the spectral view. In response to this request for modification, the system automatically adjusts associated mixing parameters for the modified track so that the spectral output of the track substantially matches the user-requested modified spectral view. This allows a user to visually mix an arrangement by imputing a desired spectral result and having the program make the changes necessary to achieve it.