Signal Analyzer Research Articles

A low level liquid scintillation spectrometer with five counting modules for 14C, 222Rn and delayed coincidence measurements

This paper presents a low-level liquid scintillation counting spectrometer with five identical counting units that allow simultaneous measurements to be performed. The counting chambers are enclosed in high purity copper and lead shielding which significantly decreases the background count rate. Each of the five counting chambers is equipped with a high stability software-controllable power supply, and each counting module contains a signal analyzer that measures the pulse height, pulse shape and the time between subsequent pulses, returning all the data as a time-stamped sequence which enables the identification of pulse pairs. Such pulse pairs, arising from the decay of 214Bi/214Po, provides a sensitive tool for 222Rn contamination determination in low-level 14C measurements. This enables radiocarbon dating or bio-component determination to be performed directly after liquid scintillator production without the risk of 222Rn interfering with the measurement of 14C.

Characterization of a 300-GHz Transmission System for Digital Communications

The paper presents the characterization of a 300-GHz transmission system for modern digital communications. The quality of the modulated signal at the output of the system (error vector magnitude, EVM) is measured using a vector signal analyzer. A method using a digital real-time oscilloscope and consecutive mathematical processing in a computer is shown for analysis of signals with bandwidths exceeding that of state-of-the-art vector signal analyzers. The uncertainty of EVM measured using the real-time oscilloscope is open to analysis. Behaviour of the 300-GHz transmission system is studied with respect to various modulation schemes and different signal symbol rates.

Numerical Model of an Injection-Locked Wideband Frequency Modulator for Polar Transmitters

We present a numerical model of a wideband injection-locked frequency modulator used in a polar transmitter for 3G cellular radio application. At the heart of the system is a self-injection-locked oscillator with a programmable linear tuning range of up to 200 MHz at 4-GHz oscillation frequency. The oscillator is injection locked to a time-delayed version of its resonating voltage, and its frequency is modulated by manipulating the phase and amplitude of the injected current. The model is used to study the feasibility of the proposed system by analyzing the impact of various impairments in the auxiliary injection loop on the system performance. The model is written in MATLAB/SIMULINK, and the simulation output is analyzed by a vector signal analyzer in terms of 3GPP specifications. Based on the simulation results, key specifications for individual blocks in the system are determined. The key benefits of the presented modeling methodology are simplicity, efficiency, and portability.

Modal Analysis of a Vertically Tapered Frame

The paper delineates the procedure to assess probable failure sections through the dynamic conditions of a vertically tapered frame using the experimental modal analysis (EMA), which is validated through the finite element analysis (FEA). The modal parameters are experimentally determined by the frequency response functions (FRFs) using the accelerometer, force transducer, electro-dynamic shaker, dynamic signal analyzer (DSA) and post processed by the ME’Scope software. The ANSYS Workbench 14 was used for finding the modal parameters through the FEA. The FEA model was also tested by convergence study. The boundary conditions of the vertically tapered frame in the FEA is kept similar to the EMA. The values obtained by the two methods have been compared for their proximity.

Condition monitoring of power components in electric grid using electromagnetic stray fields

Monitoring and fault detection of the power components in power grid through radiated fields are proposed in this paper. The frequency response of electromagnetic radiated fields from the components was measured through low-frequency antennas and signal analyzer. Proper algorithms are developed for the identification of the components as well as the detection of faults and failures. These algorithms are designed based on the active performance of the components including induction, DC and synchronous machines as well as power converters. More than 150 tests of various combinations of the components and their conditions were implemented to fulfill this identification. The results show that the proposed technique demonstrates reliable monitoring of the components. Since there is no need to dismantle the components to detect the faults in this method, it can be considered as nonintrusive for industry. Moreover, this method can be used for applications in which it may be impossible to access the parameters of the components for online monitoring.

Very High Cycle Fatigue of Butt-Welded High-Strength Steel Plate

Welded parts fabricated from high-strength steel (HSS) require an almost infinite lifetime, i.e., a gigacycle (109). Therefore, it is necessary to test its high-cycle fatigue behavior. In this paper, an accelerated fatigue test method using ultrasonic resonance is proposed. This method reduces the experimental time required in comparison with a conventional fatigue test setup. The operating principle of the accelerated ultrasonic fatigue test involved the use of a 20-kHz resonant frequency. Therefore, it was necessary to design a specimen specifically for the test setup. In the study, ultrasonic fatigue testing equipment was used to test butt-welded 590- and 780-MPa ferrite–bainite steel plates. In order to design the specimen, a dynamic Young’s modulus was measured using piezoelectric element, a laser Doppler vibrometer, and a digital signal analyzer. The S–N curves of fatigue behavior of the original and butt-welded specimens were compared. The fatigue test results showed that the infinite (i.e., gigacycle) fatigue strengths of the welded specimens were approximately 8% less than those of the original specimen.

Theoretical and experimental investigation of spindle axial drift and its effect on surface topography in ultra-precision diamond turning

In ultra-precision diamond turning (UPDT), the spindle axial drift directly affects the machining accuracy. Due to the difficulty of measuring the spindle drift during the machining process, the spindle axial drift was rarely studied. In this paper, an experimental method is used to prove and measure the existence of the spindle axial drift at the machining process, and the influence of spindle drift error on the machined surface is further studied. A mechanical model of the spindle system is considering the mass eccentricity, and the dynamic behavior of the spindle in working conditions are simulated with the mathematical model. Periodicity whirl of the spindle is found in the simulation, which is verified by the end face turning experiments. Then, the influence of the spindle vibration on surface topography is discussed, considering the spindle rotation speed and its dynamic balance. Meanwhile, the vibration frequencies induced by the spindle rotation are detected by the signal analyzer, and the detected frequency has been found to agree well with the experimental wave period of the workpiece surface (WS). This study is quite meaningful for deeply understanding the influence rule of spindle unbalanced error from the viewpoint of machined surface and vibration frequency. The research results are useful for the spindle error control and machined surface error prediction.

Study of Indoor Path Loss Computational Models for Femtocell Based Mobile Network

Path loss minimization in next generation mobile network is a challenging research area. The signal transmitted by a base station degrades due to various obstacles in the environment. The received signal level at the mobile station is less than the transmitted signal level of the base station. This loss in the signal level is referred as path loss in mobile network. In this paper different path loss models are discussed for indoor environment covered by femtocell. It is assumed that the mobile users in that region exclusively access the services of femtocell. As only indoor area is considered, non-line of sight propagation is examined. Signal-to-interference-plus-noise-ratio for a femtocell base station is calculated. The performance of the path loss models are analyzed using vector signal generator and vector signal analyzer. A comparative analysis is carried out between the models. Based on the comparative analysis, a case study is performed to demonstrate how an appropriate path loss model will be selected depending on the frequency range, building type, walls and floors.

Adaptive Optimization of Control Parameters for Feed-Forward Software Defined Equalization

In this paper we briefly describe the design, implementation, and evaluation of a novel adaptive optimization approach for the feed-forward software defined equalization (FFSDE) method using the least mean squared (LMS) algorithm. In our design, we adaptively change the filter length (N) and step size (\(\mu\)) to achieve the optimal bit error rate value. We used a vector signal generator RF PXI-5670 and a vector signal analyzer (VSA) RF PXI-5660 to test the validity of our approach. We implemented our method for the M-ary quadrature amplitude modulation (M-QAM) scheme in the VSA (which served as a receiver). The experimental results showed that we achieved high convergence speed and accuracy for rapidly changing transmitter channel characteristics. The automatic optimal setting feature of the LMS Algorithm parameters N and \(\mu\), enabled us to solve the hardware configuration problem for the FFSDE method. Determination of the LMS Algorithm training sequence size for the particular M-QAM allowed us to eliminate redundant data of the training sequence and increase the throughput.

Diagnostics of a common rail system using a signal analyser

Diagnostics of a common rail system using a signal analyser

An Adaptive Bitrate Clock and Data Recovery Circuit for Communication Signal Analyzers

Many measurement instruments require an external timing reference to perform an accurate measurement. In equivalent-time oscilloscopes, for example, a trigger signal properly aligned to the data is essential, since they base their operation on a very accurate delay of the trigger, which is obtained by a clock and data recovery (CDR) circuit. In this paper, an adaptive bitrate CDR circuit for instrumentation applications is presented. It is designed in a standard 0.18- $\mu \text{m}$ CMOS technology with a single supply voltage of 1.8 V and operates from 312.5 Mb/s to 2.5 Gb/s with a maximum power consumption of 140 mW and occupies an area of 1.5 mm $\times $ 0.6 mm.

Frequency response of late-season ‘Valencia’ orange to selective harvesting by vibration for juice industry

Citrus mechanical harvesting has been investigated since the 1960's. Even though mechanical harvesting could significantly lower production costs, the implementation by the private sector has been slow. The current harvesting technologies detach the fruits with trunk, canopy or branch vibration. For late-season sweet orange varieties which simultaneously bear mature fruit, immature fruitlets and flowers, shaker harvesting decreases the subsequent year's yield. This study, investigated the frequency response of mature fruits and immature fruitlets to determine the optimum frequency range for an efficient and selective harvest. Laboratory vibration transmission tests were conducted with 14 branches bearing 76 mature fruits and 151 immature ‘Valencia’ fruitlets. The fruit and branch response to the forced vibration was measured by several sets of five triaxial accelerometers with a dynamic signal analyser. Three frequency ranges with the highest vibration transmission values were identified for mechanical harvesting lower than 10 Hz. The first frequency range (1.5–2.5 Hz) corresponded best with the most efficient vibration transmission, involving more than 90% of fruit. The second frequency range (4.5–5 Hz) successfully discriminated between mature fruit and immature fruitlets. In this frequency range, 53.4% of mature fruit amplified the acceleration a mean value of 2.2 times, while only 7.3% of immature fruitlets amplified the acceleration with a mean value of 4.4 times. The third frequency range (7–8 Hz) had the lowest vibration transmission value. The frequency response of mature citrus fruits, and their markedly higher fruit mass, were significant factors in efficient selective mechanical harvesting.

Focus on test, measurement, and analytical equipment

Focus on test, measurement, and analytical equipment

Characterization for Multiharmonic Intermodulation Nonlinearity of RF Power Amplifiers Using a Calibrated Nonlinear Vector Network Analyzer

This paper presents a novel realization of nonlinear vector network analyzer (NVNA) test-bed with a new phase calibration technique, in order to characterize the multiharmonic intermodulation nonlinearity of a radio frequency (RF) power amplifier (PA) under a large-signal modulated input. The NVNA test-bed uses a step recovery diode comb generator as the phase reference, which is driven by a pulsed-RF signal with a high duty cycle of over 99%. Hence all the multiharmonic intermodulation tones of interest can be measured at once. A multisine phase standard provided by a vector signal analyzer is used to calibrate the intermodulation tones at each harmonic on a dense spectral grid. Two harmonic phase standards with different fundamental frequencies are used to synchronize the phase calibration results at different harmonics. The validity of this paper is verified by comparing NVNA measurements with oscilloscope measurements of the same PA under test. This paper can be used to inspect the nonlinearity of RF amplifiers under large-signal modulated excitations in both the frequency and time domains.

Extending the Characterization Bandwidth of Dynamic Nonlinear Transmitters With Application to Digital Predistortion

This paper reports a new measurement method for wideband radiofrequency power amplifier (PA) characterization and digital predistortion. The proposed measurement procedure significantly relaxes the sampling rate requirement on the analog-to-digital converters of the feedback path. Successful PA linearizations were achieved in the presence of 20, 40, and 60-MHz LTE-A signals using a vector signal analyzer with sampling speeds equal to only 24, 40.96, and 61.44 Ms/s, respectively. Despite these very low sampling rates, a quasiperfect cancellation of the PA distortions was achieved (more than 50 dBc in terms of ACLR), in all tests, over bandwidths including up to fifth-order intermodulation distortions. Such a correction bandwidth is much wider than the observation bandwidths associated with the receiver sampling rates.

Signal monitoring and performance stability evaluation tool in a high speed optical communication network

The diverse communication systems in South Africa have changed drastically over the last few years and are envisioned to continue to improve as evidenced by the deployment of high speed optical fibre networks, in both access and metro networks. The key task in the design of any communication network is to come up with a tool that monitors and evaluates the performance stability of the entire communication link. A cost effective, reliable and reconfigurable bit error ratio (BER) signal analyzer was designed and implemented to monitor and evaluate the overall performance stability of a high speed optical communication link. The reconfigurable digital signal processing (DSP) assisted optical receiver is an alternative technology to the expensive and complex hardware receivers, based on its ability to be repurposed to adapt to different modulation formats. BER is a figure of merit that allows different optical communication systems to be evaluated in a fair and consistent manner. In this experimental work, a reconfigurable DSP signal analyzer tool was developed and implemented to evaluate the performance stability of an unamplified transmission through a 25km G. 655 fibre at 1550nm. The developed DSP algorithm was authenticated and validated by comparing its performance with results obtained from a commercial BER tester. A transmission penalty of 2dB was attained on comparing the back-to-back to a transmission over 25km of fibre. The cost effective DSP assisted receiver is a valuable tool to monitor and evaluate the performance fidelity of a high speed optical communication link.

The latest trend in nano-bio sensor signal analysis

Purpose This paper aims to discuss a nanoscale biosensor and its signal analysis algorithms. Design/methodology/approach In this work, five nanoscale biosensors are reviewed, namely, silicon nanowire field-effect-transistor biosensors, polysilicon nanogap capacitive biosensors, nanotube amperometric biosensors, gold nanoparticle-based electrochemical biosensors and quantum dot-based electrochemical biosensors. Findings Each biosensor produces a different output signal depending on its electrical characteristics. Five signal analysers are studied, with most of the existing signal analyser analyses based on the amplitude of the signal. Based on the analysis, auto-threshold peak detection is proposed for further work. Originality/value Suitability of the signal processing algorithm to be applied to nano-biosensors was reported.

Green Spectrum Sharing: Genetic Algorithm Based SDR Implementation

Green spectrum sharing techniques share the spectrum with minimum interference to the primary user with reduced transmit power at secondary. Usually, the green spectrum sharing is achieved by operating the cognitive radio in underlay mode by power control mechanism or MIMO cognitive radio based antenna selection mechanism. But the above approaches will not guarantee the Quality of Service (QoS) requirement of the secondary user. Interference Minimization and meeting the QoS requirement of secondary user is modeled as a multi objectives optimization problem and solved using genetic algorithm (GA) in this paper. MIMO cognitive radio system with the GA based power control, antenna selection, and link adaptation is proposed to share the spectrum with minimum interference to primary receiver and QoS assurance of the secondary user. QoS parameter considered under the works are the secondary user bit error rate, band efficiency, and data rate. The GA optimizes the parameters of antenna selection matrix, transmitter power, modulation type, modulation order, the roll-off factor of pulse shaping filter and symbol rate to achieve target QOS. The earlier convergence of the GA is another issue addressed in this work. The earlier convergence of GA results in a local optimum value of parameters, therefore, this work used the hybrid transform for the fitness of individual chromosome. The proposed work is carried out in real time using software defined radio (SDR) platform 6 GHz Vector Signal Generator 5673 configured as a secondary transmitter, Vector Signal Analyzer 5663 as the secondary receiver and two 2 × 2 MIMO USRP RIO SDR 2943R as a primary transmitter and receiver.

Contact-free monitoring of vessel graft stiffness - proof of concept as a tool for vascular tissue engineering.

Tissue-engineered vessel grafts have to mimic the biomechanical properties of native blood vessels. Manufacturing processes often condition grafts to adapt them to the target flow conditions. Graft stiffness is influenced by material properties and dimensions and determines graft compliance. This proof-of-concept study evaluated a contact-free method to monitor biomechanical properties without compromising sterility. Forced vibration response analysis was performed on human umbilical vein (HUV) segments mounted in a buffer-filled tubing system. A linear motor and a dynamic signal analyser were used to excite the fluid by white noise (0-200Hz). Vein responses were read out by laser triangulation and analysed by fast Fourier transformation. Modal analysis was performed by monitoring multiple positions of the vessel surface. As an inverse model of graft stiffening during conditioning, HUV were digested proteolytically, and the course of natural frequencies (NFs) was monitored over 120min. Human umbilical vein showed up to five modes with NFs in the range of 5-100Hz. The first natural frequencies of HUV did not alter over time while incubated in buffer (p=0.555), whereas both collagenase (-35%, p=0.0061) and elastase (-45%, p<0.001) treatments caused significant decreases of NF within 120min. Decellularized HUV showed similar results, indicating that changes of the extracellular matrix were responsible for the observed shift in NF. Performing vibration response analysis on vessel grafts is feasible without compromising sterility or integrity of the samples. This technique allows direct measurement of stiffness as an important biomechanical property, obviating the need to monitor surrogate parameters. Copyright © 2016 John Wiley & Sons, Ltd.

Realization of 4G Downlink Channel

Today’s era people have grown in every field, such that their needs are also growing linearly with their advancement. This rapid development of broadband wireless access technologies in recent years was the result of growing demand for mobile Internet and wireless multimedia applications. Now it is becoming difficult to meet the demands of these data hungry people. So, the wireless network is advancing after 3G and providing better coverage, higher data rate and by reducing Latency. It uses the frame structure as Time Division Duplexing (TDD) and Frequency Division Duplexing (FDD).LTE technology uses different channels in both uplink and downlink. This paper mainly focuses on the Downlink channels named as PDCCH, PBCH, PCFICH, PHICH and downlink Signals i.e., PSS and S-SS. The individual Downlink Channels are analyzed using Agilent SystemVue platform further it is synchronized with the Agilent Vector Signal Analyzer (VSA) to the check the Output Response of the individual downlink channels.