Showing papers on "Spectrum analyzer published in 2020"
TL;DR: In this article, an atomic radio-frequency (RF) receiver and spectrum analyzer based on thermal Rydberg atoms coupled to a planar microwave waveguide is presented, which achieves an intrinsic sensitivity of up to -120(2) dBm/Hz, DC coupling, 4 MHz instantaneous bandwidth, and over 80 dB of linear dynamic range.
Abstract: We demonstrate an atomic radio-frequency (RF) receiver and spectrum analyzer based on thermal Rydberg atoms coupled to a planar microwave waveguide. We use an off-resonant RF heterodyne technique to achieve continuous operation for carrier frequencies ranging from DC to 20 GHz. The system achieves an intrinsic sensitivity of up to -120(2) dBm/Hz, DC coupling, 4 MHz instantaneous bandwidth, and over 80 dB of linear dynamic range. By connecting through a low-noise preamplifier, we demonstrate high-performance spectrum analysis with peak sensitivity of better than -145 dBm/Hz. Attaching a standard rabbit-ears antenna, the spectrum analyzer detects weak ambient signals including FM radio, AM radio, Wi-Fi, and Bluetooth. We also demonstrate waveguide-readout of the thermal Rydberg ensemble by non-destructively probing waveguide-atom interactions. The system opens the door for small, room-temperature, ensemble-based Rydberg sensors that surpass the sensitivity, bandwidth, and precision limitations of standard RF sensors, receivers, and analyzers.
65 citations
TL;DR: A technique to quickly and accurately predict and analyze the EMI spectrum from time-domain waveforms is proposed and the predicted peak, quasi-peak, and average EMI matches the measured EMI in whole conductive frequency range.
Abstract: EMC spectrum analyzers are popularly used for electromagnetic interference (EMI) measurement in power electronics systems. Depending on the specifications of EMI standards, the EMI measurement could be very time consuming. Conventionally, the fast Fourier transform is used to derive the EMI spectrum from the measured time-domain waveforms. However, these results may not agree with the measurement results from spectrum analyzers, and sometimes the difference could be significant. In this paper, a technique to quickly and accurately predict and analyze the EMI spectrum from time-domain waveforms is proposed. The technique is developed based on the spectrum analyzer's operating principle and the requirements of EMI standards. The EMI spectra of three modulation schemes are also analyzed. Theoretical analysis, simulations, and experiments were all conducted. The predicted peak, quasi-peak, and average EMI matches the measured EMI in whole conductive frequency range. The developed technique can accurately predict EMI using much shorter time than conventional EMC spectrum analyzers and it saves cost of expensive spectrum analyzers.
40 citations
TL;DR: It is shown that this STNO-based spectrum analyzer can perform analysis of frequency-agile signals, having multiple rapidly changing frequency components with temporal resolution in a μs time scale and frequency resolution limited only by the "bandwidth" theorem.
Abstract: We demonstrate that a spin-torque nano-oscillator (STNO) rapidly sweep-tuned by a bias voltage can be used to perform an ultrafast time-resolved spectral analysis of frequency-manipulated microwave signals. The critical reduction in the time of the spectral analysis comes from the naturally small-time constants of a nanosized STNO (1-100 ns). The demonstration is performed on a vortex-state STNO generating in a frequency range around 300 MHz, when frequency down-conversion and matched filtering is used for signal processing. It is shown that this STNO-based spectrum analyzer can perform analysis of frequency-agile signals, having multiple rapidly changing frequency components with temporal resolution in a μs time scale and frequency resolution limited only by the "bandwidth" theorem. Our calculations show that using uniform magnetization state STNOs it would be possible to increase the operating frequency of a spectrum analyzer to tens of GHz.
37 citations
TL;DR: In this paper, a high performance high speed silicon photonics carrier-depletion Mach-Zehnder modulation with commercial foundry by co-optimization of doping and device design assisted with an accurate electro-optical (EO) model was achieved.
Abstract: We achieved high performance high speed silicon photonics carrier-depletion Mach-Zehnder modulation with commercial foundry by co-optimization of doping and device design assisted with an accurate electro-optical (EO) model. We demonstrated high performance IQ modulators operating at 85 Gbaud 16 QAM and 64 Gbaud 64 QAM with extinction ratio of over 25 dB. For the design of the high performance all-silicon carrier depletion modulator, we developed modeling and design tools to provide not only accuracy, but also efficiency in the simulation of distributed optical and electronic characteristics of travelling waveguides with different designs of optical and microwave waveguides under various doping conditions, which allow the co-design of velocity phase match between optical and microwave waveguides and the impedance match between microwave travelling waveguide and terminal impedance. Our experimental characterization test data agreed well with the model simulation data. More recently, with practical Nyquist filter and linear compensation in commercial arbitrary wave generator (AWG) and optical modulation analyzer (OMA), we demonstrated 100 Gbaud 32 QAM with an all-silicon IQ modulator, which has 6 dB electro-optical bandwidth of 50 GHz and BER achieving FEC threshold with a modern FEC, showing the potential for Tb/s applications.
33 citations
TL;DR: A new ion composition and three-dimensional velocity analyzer, 3-Dimensional ion velocity and mass Imager (3DI), measures 3D velocity distribution functions (VDFs) for each major ion species in Earth’s topside ionosphere.
Abstract: A new ion composition and three-dimensional velocity analyzer, 3-Dimensional ion velocity and mass Imager (3DI), measures 3D velocity distribution functions (VDFs) for each major ion species in Earth’s topside ionosphere. The 3DI instrument is composed of a miniaturized electrostatic analyzer (ESA) and a deflector, backed by a static, magnet-based, mass spectrometer. We have developed a micro-pixel read-out anode technique that significantly saves power in the particle detection system, and integrated it into an imaging microchannel plate (MCP). We tested the ESA and deflector, magnet-based mass spectrometer, and anode in the laboratory to demonstrate the 3DI prototype’s performance. We have applied numerical calculations to evaluate and discuss 3DI’s performance and dynamic range. Due to complexities associated with imaging 3D distribution functions during fast spacecraft motion, we also discuss the operation strategy for 3DI to capture and resolve the VDF within the field of view. Once applied to flight investigations, the 3DI observations will be extremely useful in identifying ionosphere composition, mass-dependent ion transport such as upflows, and mass-dependent ion heating. Furthermore, the precise measurement of non-thermal plasma VDFs provides information to improve ionospheric environment modeling and ground-based radar observations.
32 citations
TL;DR: A novel photonic approach for simultaneously measuring both the Doppler frequency shift (DFS) and the angle of arrival (AOA) of a microwave signal in a radar system is presented.
Abstract: A novel photonic approach for simultaneously measuring both the Doppler frequency shift (DFS) and the angle of arrival (AOA) of a microwave signal in a radar system is presented. It has the same structure as a fiber optic link consisting of a laser, an optical modulator and a photodetector. The incoming microwave signal and a reference signal are applied to the optical modulator. Beating of the echo and reference signal sidebands at the photodetector generates a low-frequency electrical signal. The DFS and the AOA can be determined from the frequency and the power of the low-frequency electrical signal measured on an electrical spectrum analyzer. The system has a very simple structure and is low-cost. It has a wide operating frequency range and a robust performance. Experimental results demonstrate a DFS measurement at around 15 GHz with errors of less than ±0.2 Hz, and a 0° to 90° AOA measurement with less than ±1° errors.
27 citations
TL;DR: An overview of all the basic types of approaches used for the realization of optical vector analyzers, including the advanced ones with the best performances are provided.
Abstract: The optical vector analyzer is a device used to measure the magnitude, phase responses, and other parameters of optical devices. There have been increasingly higher demands placed on optical vector analyzers during the development of optical technologies, which are satisfied by the creation of new devices and their operating principles. For further development in this area, it is necessary to generalize the experience gained during the development of optical vector analyzers. Thus, in this report, we provide an overview of all the basic types of approaches used for the realization of optical vector analyzers, including the advanced ones with the best performances. The principles of their working, as well as their associated advantages, disadvantages, and existing solutions to the identified problems, are examined in detail. The presented approaches could be of value and interest to those working in the field of laser dynamics and optical devices, as we propose one use of the optical vector analyzer as being the characterization of Fano resonance structures.
20 citations
TL;DR: In this paper, an inverter impedance measurement method in stationary frame using the off-shelf frequency response analyzer (FRA) was proposed, which can be represented by the equivalent admittance, which enables accurate representation of the inverter frequency response.
Abstract: When the impedance-based stability criterion is used to analyze the stability of a three-phase inverter-grid system, the impedance of the grid-connected inverter has to be known. This article proposes an inverter impedance measurement method in stationary frame using the off-shelf frequency response analyzer (FRA). In small-signal representation, inverter impedance can be represented by the equivalent admittance, which enables accurate representation of the inverter frequency response. The admittance expression in the stationary frame contains frequency coupling components. These components include the response current or voltage at frequency different from the perturbation frequency. But, the existing FRA only measures the response current and voltage having the same frequency as the perturbation frequency. The proposed method constructs three intermediate variables to overcome this limitation. These variables can be obtained by the measured data from FRA. Then the equivalent admittance under different grid impedances can be expressed by them. Since the equivalent admittance considers the frequency coupling effect, accurate stability analysis of the inverter-grid system can be guaranteed. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed impedance measurement method.
18 citations
TL;DR: An all-optical photoacoustic (PA) multigas analyzer is presented by using a digital fiber-optic acoustic detector, which consists of a spectrum demodulation based fiber Fabry–Perot (F–P) pressure sensor and a digital virtual lock-in amplifier.
Abstract: We present an all-optical photoacoustic (PA) multigas analyzer by using a digital fiber-optic acoustic detector, which consists of a spectrum demodulation based fiber Fabry–Perot (F–P) pressure sensor and a digital virtual lock-in amplifier. The concentration of multigas is quantified by using an intensity-modulated infrared thermal source and two wavelength-modulated laser diodes. Light beams from the three sources are coupled to a single nonresonant PA cell. The generated PA pressure is detected by the fiber F-P pressure sensor, which is demodulated by a near-infrared spectrometer. A lock-in white-light interferometer is developed for detecting first-harmonic ( $1f$ ) and second-harmonic ( $2f$ ) signals. The noise equivalent detection limits with a 100-s averaging time are 37, 9, 6, 17, 4, and 60 ppb for CH4, C2H2, C2H4, C2H6, CO, and CO2, respectively.
18 citations
TL;DR: The technical feasibility of radar waveforms capable of ensuring spectral coexistence with overlaid emitters via a modern digital arbitrary waveform generator is explored.
Abstract: Radar operation in a spectrally dense environment is nowadays a very challenging problem due to the increasing demand of spectral resources for defence/surveillance applications, remote sensing capabilities, and civilian wireless services. This article explores the technical feasibility of radar waveforms capable of ensuring spectral coexistence with overlaid emitters via a modern digital arbitrary waveform generator. To this end, a specific hardware-in-the-loop test bed is designed to mimic the perception-action cycle necessary for the agile management of the radio spectrum. Then, a spectrum analyzer (SA) and a digital oscilloscope (DO) are used to demonstrate the compliance of the synthesized waveforms with the theoretical counterparts. In particular, the SA is used to establish if the synthesized waveforms fulfil the spectral requirements forced at the design stage. The DO, instead, is used to assess the adherence of synthesized signals ambiguity function (AF) with the theoretical one. For the considered case studies, results highlight that the synthesized waveforms enable spectral compatibility between radar and communication systems and exhibit desirable AF properties.
17 citations
TL;DR: In this article, a microwave photonic system that can measure the angle of arrival (AOA) of multiple microwave signals with improved measurement accuracy is presented, which is based on a photonic mixer approach to down convert the incoming microwave signals into IF signals.
Abstract: The objective of this paper is to present a microwave photonic system that can measure the angle of arrival (AOA) of multiple microwave signals with improved measurement accuracy. It is based on a photonic mixer approach to down convert the incoming microwave signals into IF signals, which enables a low-frequency electrical spectrum analyser to be used for measuring the power of the IF signals to determine the incoming microwave signal AOAs. AOA measurement errors can be reduced by operating the optical modulator at a different transmission point for a different range of microwave signal AOA. The system also has the ability to remove the incoming microwave signal amplitude dependence in the AOA measurement. Measured results demonstrate 0°−81.5° AOA measurement with less than ±2° errors over the 0°−30° and 30°−81.5° AOA measurement range when the optical modulator is biased at the minimum and maximum transmission point respectively. The errors remain below ±2° even when there is a ±0.1 dB change in the output IF signal power. AOA measurement of two microwave signals is also demonstrated.
TL;DR: In this paper, the design, fabrication and use of the open-source arc analyzer is described, which is a multi-sensor monitoring system for quantifying the processing during wire arc additive manufacturing (WAAM), including voltage, current, sound, light intensity, radio frequency, and temperature data outputs.
TL;DR: The 2 mm $\times \,\,1$ mm die has been validated in vivo in real-time multisite potassium sensing in the rodent brain using gold microelectordes implemented on a polyimide substrate.
Abstract: A fully integrated 130-nm CMOS 12-channel biofouling-resistant potassium-selective brain neurochemistry impedance spectrum analyzer is presented. Each 0.004 mm2 channel is an amperometric readout circuit composed of an opamp-less delta-sigma-modulated analog-to-digital converter (ADC) that consumes only 50 nW of power from a 0.6-V supply. The latter is analytically proven to be approximately equivalent to the former under conditions that are typical for the biochemical microsensors. The circuit also includes a low-power multiplierless frequency response analysis (FRA) unit that performs bioimpedance extraction. The channel achieves 1 pA current sensitivity and attains 50.3-dB signal-to-noise-and-distortion ratio (SNDR). The impedance analyzer achieves a dynamic range of 1 pA to 20 nA and a 5-kHz frequency scan range. The 2 mm $\times \,\,1$ mm die has been validated in vivo in real-time multisite potassium sensing in the rodent brain using gold microelectordes implemented on a polyimide substrate.
TL;DR: A method of expanding the sensing component of acoustic detectors by connecting acoustic sensors through a digital communication system using the 3G/4G networks to a monitoring center with an acoustic spectrum analyzer, which provides offline detection of leakages in the underground water pipelines remotely without deforming the surrounding environment or adjusting the acoustic detector’s analyzing system.
Abstract: Water leaks in the distribution network produce significant losses and cause serious economic inconvenience especially in areas with water shortage. In this paper, the operational aspects of the most popular offline detection technologies, ground penetrating radars (GPR’s), infrared (IR) cameras, and acoustic detectors, were compared. The authors also studied the potential of using the recent Terahertz imaging technology for the same application. Acoustic detectors were found the most suitable technology for the atmosphere in UAE, where the levels of humidity and, consequently, soil moisture are high, because both of GPRs and IR cameras operational capability to detect leaks tend to decrease sharply as soil moisture increases. On the other side, a conventional acoustic detector has very limited scope of detection. This paper presents a method of expanding the sensing component of acoustic detectors by connecting acoustic sensors through a digital communication system using the 3G/4G networks to a monitoring center with an acoustic spectrum analyzer. The novelty of this system is its ability to provide offline detection of leakages in the underground water pipelines remotely without deforming the surrounding environment or adjusting the acoustic detector’s analyzing system. Simulation results proves the ability of the system to reconstruct the input noise signal at the end of the proposed network which is to be connected to the acoustic analyzer.
TL;DR: A simple and practical method to estimate the PSD based on the Welch algorithm for spectrum monitoring, which can be easily implemented in most of software-based systems or low-level Field-Programmable Gate Arrays (FPGAs) and yields a smooth overview of the spectrum.
Abstract: Power Spectral Density (PSD) is an essential representation of the signal spectrum that depicts the power measurement content versus frequency. PSD is typically used to characterize broadband random signals and has a variety of usages in many fields like physics, engineering, biomedical, etc. This paper proposes a simple and practical method to estimate the PSD based on the Welch algorithm for spectrum monitoring. The proposed method can be easily implemented in most of software-based systems or low-level Field-Programmable Gate Arrays (FPGAs) and yields a smooth overview of the spectrum. The original Welch method utilizes the average of the amplitude squared of the previous Fast Fourier Transform (FFT) samples for better estimation of frequency components and noise reduction. Replacing the simple moving average with a weighted moving average can significantly reduce the complexity of the Welch’s method. In this way, the amount of required Random Access Memory (RAM) is reduced from K (where K is the number of FFT packets in averaging) to one. This new method allows users to adjust the dependency of the PSD on the previous observed FFTs and its smoothness by setting only one feedback parameter without any hardware change. The obtained results show that the algorithm gives a clear spectrum, even in the noisy situation because of the significant Signal to Noise Ratio (SNR) enhancement. The trade-off between spectrum accuracy and time convergence of the modified algorithm is also fully analysed. In addition, a simple solution based on Xilinx Intellectual Property (IP), which converts the proposed method to a practical spectrum analyzer device, is presented. This modified algorithm is validated by comparing it with two standard and reliable spectrum analyzers, Rohde & Schwarz (R&S) and Tektronix RSA600. The modified design can track any signal type as the other spectrum analyzers, and it has better performance in situations where the power of the desired signal is weak or where the signal is mixed with the background noise. It can display the spectrum when the input signal power is 5 dB lower than the visible threshold level of R&S and Tektronix. In both narrowband and wideband scenarios, the new implemented design can still display frequency components 5 dB higher than the noise, while the output spectrum of other analyzers is completely covered by noise.
TL;DR: A method to overcome challenges of determination of size and composition of fast-flowing cells, with diameters in the range of 2- 15 μ m, by using a hydrodynamic flow-based microfluidic platform coupled with on-chip integrated fiber optics is reported.
Abstract: Rapid optical interrogation of flowing cells or particles is a powerful tool in the field of biomedical diagnostics. Determination of size and composition of fast-flowing cells, with diameters in the range of 2– 15 μ m, often require complex open-space optics and expensive high-speed cameras. In this work, a method to overcome these challenges by using a hydrodynamic flow-based microfluidic platform coupled with on-chip integrated fiber optics is reported. The lab-scale portable device developed uses a combination of on-chip lensed and non-lensed optical fibers for precision illumination. The narrow light beam produced by the lensed fiber ( f = 150 μ m ) enables precise optical analysis with high sensitivity. A planar arrangement of optical fibers at various angles facilitates multi-parametric analysis from a single point of interrogation. As proof of concept, the laboratory-scale portable bench-top prototype is used to measure fluorescence signals from CD4 immunostained cells and human blood samples. The performance of microfluidic flow analyzer is also compared to the conventional Guava® easyCyte 8HT flow cytometer.
11 Oct 2020
TL;DR: In this article, a real-time condition monitoring of photovoltaic (PV) cells by implementing electrical impedance spectroscopy (EIS) using a boost converter is presented.
Abstract: This work focuses on the real-time condition monitoring of Photovoltaic (PV) cells by implementing electrical impedance spectroscopy (EIS) using a boost converter. In residential or industry PV applications with storage, solar panels are connected to a battery through a charge controller with a dcdc converter. This set-up makes using a dc-dc converter for condition monitoring ideal for PV cells. The bandwidth of a PV cell is greater than 100kHz, as such, to obtain the impedance information of the cells, the dc-dc converter would need a switching frequency of at least ten times this bandwidth – which will be achieved by using Silicon Carbide (SiC) MOSFETS. The nonlinear relationship between the EIS duty cycle and the EIS control voltage signal, was characterized for signal injection. A QFT control law that treats the EIS frequency and PV’s capacitive parameters as structured uncertainties, was designed to ensure robust signal injection. The simulation results show that the online system adequately performs EIS and gives good impedance results comparable to a Frequency Response Analyzer (FRA).
TL;DR: In this article, the simulation of fiber bragg grating (FBG) as a temperature sensor is conducted, and the FBG temperature sensor was designed based on Optical Frequency Domain Reflectometer (OFDR) concept.
Abstract: In this paper, the simulation of Fiber Bragg Grating (FBG) as a temperature sensor is conducted. The FBG temperature sensor is designed based on Optical Frequency Domain Reflectometer (OFDR) concept. A continuous wave (CW) laser is used as the optical source and it is transmitted to two FBGs. The two FBGs reflection spectra will produce a beat frequency that can be detected using a Radio Frequency (RF) Spectrum Analyzer. Any temperature change will shift Bragg wavelength, thus produce a shift for the beat frequency. In this work, an FBG with temperature sensitivity 10 pm/˚C is employed. It is found that by using this technique, a high-resolution temperature sensor can be designed with temperature resolution of 0.1˚C.
TL;DR: It is shown that the SDR instrument is capable of performing an urban propagation study in VHF and UHF short range devices bands in a fast and low-cost manner and to a high degree of agreement with a commercial spectrum analyzer, thus validating the approach.
Abstract: Software-defined radio (SDR) instruments can be used to replace bulky and expensive spectrum analyzers for RF field measurements. Using the commercial off-the-shelf (COTS) equipment, a low-cost, portable SDR instrument for measuring RF propagation has been created and tested. In the U.K., parts of the very high-frequency (VHF) spectrum have been repurposed for the use of Internet-of-Things devices; the instrument developed here is designed to meet the use case of performing an urban propagation study in VHF and UHF short range devices bands in a fast and low-cost manner. Design of the hardware and software is discussed, as well as the calibration of the instrument. The results of a test propagation study are given for the completed instrument. It is shown that the SDR instrument is capable of performing the study to a high degree of agreement with a commercial spectrum analyzer, thus validating the approach. The readings of the received power taken by the instrument are shown to agree with the readings taken at the same locations with a commercial spectrum analyzer to within an average of 1.4 dB at 71 MHz and 1.1 dB at 869.525 MHz. From the measurements taken, log-distance models were able to be produced with a path-loss exponent of 2.44 and a log-normal shadowing standard deviation of 8.5 dB at 71 MHz, and a path-loss exponent of 4.06 and a log-normal shadowing standard deviation of 8.8 dB at 869.525 MHz.
TL;DR: In this paper, the characterization of the fiber based laser sensor by means of relative intensity noise (RIN) has been done by an electrical based measurement system, which has been accomplished by the implementation of an optical receiver setup.
Abstract: This work is concerned with the characterization of the fiber based laser sensor by means of relative intensity noise (RIN). The characterization has been done by an electrical based measurement system, which has been accomplished by the implementation of an optical receiver setup. The optical receiver setup has been built by using commercially available low noise amplifier (LNA), Bias Tee, and fast photodiode (FPD). Besides the optical receiver setup designing, software in Labview has been built and implemented to enable easy and fast measurement of data from measurement instruments. Using the self assembled optical receiver and an electrical spectrum analyzer (ESA), optical fluctuation 'noise' of the fiber based laser sensor has been measured. We have found good agreement between the measurement results taken by our measurement setup and costly Agilent RIN measurement setup. Also, average RIN over wide frequency range has been calculated and discussed for different operating states of the laser sensor. The results are applicable in the field of an optical sensor.
TL;DR: A vector optical-chirp-chain Brillouin optical time-domain analyzer (BOTDA) based on complex principal component analysis (CPCA) is proposed and experimentally demonstrated by employing a four-tone OCC probe with two orthogonal polarization states.
Abstract: A vector optical-chirp-chain (OCC) Brillouin optical time-domain analyzer (BOTDA) based on complex principal component analysis (CPCA) is proposed and experimentally demonstrated by employing a four-tone OCC probe with two orthogonal polarization states. The polarization-fading-free complex Brillouin spectrum (CBS) of the vector OCC-BOTDA is obtained by combining the amplitude and phase response spectra of the probe wave at both Brillouin gain and loss region. We utilize the CPCA method to determine the Brillouin frequency shift (BFS) directly using the measured CBS, and the sensing accuracy is improved by a factor of up to 1.4. The distributed temperature sensing is demonstrated over a 20 km standard single-mode fiber with a 6 m spatial resolution and less than 1 MHz frequency uncertainty under 10 times of trace averaging.
01 May 2020
TL;DR: This audio signal analyzer is based on a microcontroller and a field programmable gate array and consists of a controllable gain amplifier circuit, an active filter circuit, A / D conversion and D / A feedback circuits, and a main control circuit and liquid crystal display module.
Abstract: This audio signal analyzer is based on a microcontroller (MCU) and a field programmable gate array (FPGA). It consists of a controllable gain amplifier circuit, an active filter circuit, A / D conversion and D / A feedback circuits, and a main control circuit and liquid crystal display module. Through AD conversion, the audio signal is sampled, the continuous signal is discretized, and then the FFT fast Fourier transform operation is performed to analyze and process each frequency component and power of the audio signal in the time and frequency domain. By controlling the gain of the amplifier to expand the dynamic range of the input signal and improve the sensitivity, it can also complete the corresponding human-computer interaction control based on the PS2 keyboard input, while using the high-resolution LCD to display the signal spectrum. The audio signal frequency range that this system can accurately measure is 20Hz-10KHz, its amplitude range is 5mVpp-5Vpp, and the resolution is divided into 20Hz and 100Hz. The measured power accuracy is as high as 1%, and the period of the periodic signal can be accurately measured, which is the ideal solution for audio signal analyzers.
TL;DR: This article proposes a method for the measurement of phase noise (PN, or PM noise) and amplitude noise (AN, or AM noise) of digital-to-analog converters (DACs) and direct digital synthesizers (DDSs) based on the modulation-index amplification.
Abstract: This article proposes a method for the measurement of phase noise (PN, or PM noise) and amplitude noise (AN, or AM noise) of digital-to-analog converters (DACs) and direct digital synthesizers (DDSs) based on the modulation-index amplification. The carrier is first reduced by a controlled amount (30–40 dB) by adding a reference signal of nearly equal amplitude and opposite in phase. Then, residual carrier and noise sidebands are amplified and sent to a conventional PN analyzer. The main virtues of our method are: 1) the noise specs of the PN analyzer are relaxed by a factor equal to the carrier suppression ratio and 2) the capability to measure the AN using a PN analyzer with no need for the analyzer to feature AN measurement. An obvious variant enables AN and PN measurements using an AN analyzer with no PN measurement capability. Such an instrument is extremely simple and easy to implement with a power-detector diode followed by an FFT analyzer. Unlike the classical bridge (interferometric) method, there is no need for external line stretcher and variable attenuators because phase and amplitude controls are implemented in the device under test. In one case (AD9144), we could measure the noise over 10 decades of frequency. The flicker noise matches the exact $1/f$ law with a maximum discrepancy of ±1 dB over 7.5 decades. Due to the simplicity, reliability, and low background noise, this method has the potential to become the standard method for the AN and PN measurements of DACs and DDSs.
TL;DR: In this article, a dispersion compensation system for an ultrafast 256 Tbps waveform using multilevel 8-ary amplitude and 32-ary phase modulation was proposed and demonstrated by a 200 GHz optical frequency comb (OFC) synthesizer with a 64 THz bandwidth.
07 Sep 2020
TL;DR: In this paper, the use of standard periodic non-harmonic signals instead of the traditionally used set of harmonic signals when calibrating by a total harmonic distortion of power quality analyzers is considered.
Abstract: The possibility of using standard periodic non-harmonic signals is considered instead of the traditionally used set of harmonic signals when calibrating by a total harmonic distortion of power quality analyzers. The use of squarewave, triangular, sawtooth signals and a truncated sine wave signal is proposed, which presented in Fourier order contain specific harmonic components. Thus, by selecting a specific standard periodic signal, a corresponding specific reference value of the total harmonic distortion is set. Results of calibration of Fluke 435 power quality analyzer using Metrix CX1651 calibrator are presented, which give an experimental estimate of the ability to calibrate by a total harmonic distortion using standard periodic non-harmonic signals.
TL;DR: A compact electrostatic energy bandpass filter based on a laminated analyzer design has been developed to measure charged particle fluxes at energies ranging from 0 to 5 keV and has demonstrated the ability to accurately measure negative spacecraft frame charging using a low Earth orbit plasma simulator.
Abstract: A compact electrostatic energy bandpass filter based on a laminated analyzer design has been developed to measure charged particle fluxes at energies ranging from 0 to 5 keV. The sensor head has been successfully tested against a low energy magnetically filtered plasma source and an ion beam source capable of producing energetic ions in the range of 100–1250 eV. Additionally, the instrument has demonstrated the ability to accurately measure negative spacecraft frame charging using a low Earth orbit plasma simulator. The effects of the spacecraft frame charging on the measured energy distribution measurements and the impact regarding the derived charged particle density and temperature parameters are also examined.A compact electrostatic energy bandpass filter based on a laminated analyzer design has been developed to measure charged particle fluxes at energies ranging from 0 to 5 keV. The sensor head has been successfully tested against a low energy magnetically filtered plasma source and an ion beam source capable of producing energetic ions in the range of 100–1250 eV. Additionally, the instrument has demonstrated the ability to accurately measure negative spacecraft frame charging using a low Earth orbit plasma simulator. The effects of the spacecraft frame charging on the measured energy distribution measurements and the impact regarding the derived charged particle density and temperature parameters are also examined.
TL;DR: In this paper, a cascade structure of a dual-polarization Mach-Zehnder modulator (DPol-MZM) and a phase modulator was proposed to simultaneously identify the value and direction of Doppler frequency shift (DFS).
TL;DR: A compact, open-path CO2 and H2O sensor based on the newly introduced scanned-wavelength modulation spectroscopy with the first harmonic phase angle (scanned-WMS-θ1f) method for high-sensitivity, high temporal resolution, ground-based measurements.
Abstract: We report here the development of a compact, open-path CO2 and H2O sensor based on the newly introduced scanned-wavelength modulation spectroscopy with the first harmonic phase angle (scanned-WMS-θ1f) method for high-sensitivity, high temporal resolution, ground-based measurements. The considerable advantage of the sensor, compared with existing commercial ones, lies in its fast response of 500 Hz that makes this instrument ideal for resolving details of high-frequency turbulent motion in exceptionally dynamic coastal regions. The good agreement with a commercial nondispersive infrared analyzer supports the utility and accuracy of the sensor. Allan variance analysis shows that the concentration measurement sensitivities can reach 62 ppb CO2 in 0.06 s and 0.89 ppm H2O vapor in 0.26 s averaging time. Autonomous field operation for 15-day continuous measurements of greenhouse gases (CO2/H2O) was performed on a shore-based monitoring tower in Daya Bay, demonstrating the sensor's long-term performance. The capability for high-quality fast turbulent atmospheric gas observations allow the potential for better characterization of oceanographic processes.