Arterial pulse measurement using electret condenser microphone requires
the standard to validate the value of the measurement. This standard
requires the test device to reproducing the mechanical vibration to emulate
the arterial pulse vibration. The main objective of this paper is to discuss
the test device of electret condenser microphone using class A amplifiers and
low-frequency loudspeaker. To validate this pulse measurement, this class A
amplifier is examined under an experimental setup. The experiments showed
that the device can be used as an alternative solution to generate the mechanical
signal source to simulate the human arterial pulse.
Performance Analysis of Constant-K Low-Pass and Band-Pass Filters in a Uni-Po...paperpublications3
Abstract: Power system is designed to operate at a frequency of 50 or 60 Hz. However, certain types of non-linear loads produce current and voltages with frequency that are integer multiple of fundamental frequency. These frequency components known as harmonic pollution and is having adverse effect on the power system network. Harmonics generates serious problem to the quality of power supply of transmission and distribution network.. In today’s scenario, power system has not only to become reliable one, but also has to ensure about the quality of power. Due to few of the load side equipment only, the quality of power supply worsens. It affects not only the whole power system as well as many consumer side appliances and some sensitive equipment which cannot be afforded to be malfunctioned leading to even loss of life.
The output voltage waveform of ideal inverter should be sinusoidal. However, the waveforms of practical inverters are non sinusoidal and contain certain harmonics. For low and medium power applications, square-wave or quasi-square wave voltages may be acceptable; and for high-power applications, low distorted sinusoidal waveforms are required. With the availability of high-speed power semiconductor devices, the harmonic content of output voltage can be minimised or reduced significantly by switching techniques.
Keywords: SPWM inverter. low-pass, band-pass, carrier frequency, cut-off frequency, characteristic impedance, THD.
Title: Performance Analysis of Constant-K Low-Pass and Band-Pass Filters in a Uni-Polar SPWM Single Phase Inverter for Resistive Load
Author: Rashmi Vaishya, Ashish Choubey
ISSN 2349-7815
International Journal of Recent Research in Electrical and Electronics Engineering (IJRREEE)
Paper Publications
Accurate Evaluation of Interharmonics of a Six Pulse, Full Wave - Three Phase...idescitation
Interharmonics are the non-integral multiples of
the system’s fundamental frequency. The interharmonic
components can be apprehended as the intermodulation of
the fundamental and harmonic components of the system with
any other frequency components introduced by the load. These
loads include static frequency converters, cyclo-converters,
induction motors, arc furnaces and all the loads not pulsating
synchronously with the fundamental frequency of the system.
The harmonic and interharmonic components inflict common
damage to the system and apart from these damages the
interharmonics also cause light flickering, sideband torques
on motor/generator and adverse effects on transformer and
motor components. To
filter/compensate the interharmonic
components, their accurate evaluation is essential and to
achieve the same the Iterative algorithm has been proposed.
The main cause of spectral leakage errors is the truncation of
the time-domain signal. The proposed adaptive approach
calculates the immaculate window width, eliminating the
spectral leakage errors in the frequency domain and thereby
the interharmonics/harmonics can be calculated accurately.
The algorithm does not require any inputs regarding the
system frequency and interharmonic constituents of the
system. The only parameter required is the signal sequence
obtained by sampling the analog signal at equidistant sampling
interval.
Performance Analysis of Constant-K Low-Pass and Band-Pass Filters in a Uni-Po...paperpublications3
Abstract: Power system is designed to operate at a frequency of 50 or 60 Hz. However, certain types of non-linear loads produce current and voltages with frequency that are integer multiple of fundamental frequency. These frequency components known as harmonic pollution and is having adverse effect on the power system network. Harmonics generates serious problem to the quality of power supply of transmission and distribution network.. In today’s scenario, power system has not only to become reliable one, but also has to ensure about the quality of power. Due to few of the load side equipment only, the quality of power supply worsens. It affects not only the whole power system as well as many consumer side appliances and some sensitive equipment which cannot be afforded to be malfunctioned leading to even loss of life.
The output voltage waveform of ideal inverter should be sinusoidal. However, the waveforms of practical inverters are non sinusoidal and contain certain harmonics. For low and medium power applications, square-wave or quasi-square wave voltages may be acceptable; and for high-power applications, low distorted sinusoidal waveforms are required. With the availability of high-speed power semiconductor devices, the harmonic content of output voltage can be minimised or reduced significantly by switching techniques.
Keywords: SPWM inverter. low-pass, band-pass, carrier frequency, cut-off frequency, characteristic impedance, THD.
Title: Performance Analysis of Constant-K Low-Pass and Band-Pass Filters in a Uni-Polar SPWM Single Phase Inverter for Resistive Load
Author: Rashmi Vaishya, Ashish Choubey
ISSN 2349-7815
International Journal of Recent Research in Electrical and Electronics Engineering (IJRREEE)
Paper Publications
Accurate Evaluation of Interharmonics of a Six Pulse, Full Wave - Three Phase...idescitation
Interharmonics are the non-integral multiples of
the system’s fundamental frequency. The interharmonic
components can be apprehended as the intermodulation of
the fundamental and harmonic components of the system with
any other frequency components introduced by the load. These
loads include static frequency converters, cyclo-converters,
induction motors, arc furnaces and all the loads not pulsating
synchronously with the fundamental frequency of the system.
The harmonic and interharmonic components inflict common
damage to the system and apart from these damages the
interharmonics also cause light flickering, sideband torques
on motor/generator and adverse effects on transformer and
motor components. To
filter/compensate the interharmonic
components, their accurate evaluation is essential and to
achieve the same the Iterative algorithm has been proposed.
The main cause of spectral leakage errors is the truncation of
the time-domain signal. The proposed adaptive approach
calculates the immaculate window width, eliminating the
spectral leakage errors in the frequency domain and thereby
the interharmonics/harmonics can be calculated accurately.
The algorithm does not require any inputs regarding the
system frequency and interharmonic constituents of the
system. The only parameter required is the signal sequence
obtained by sampling the analog signal at equidistant sampling
interval.
An Overview of Different PWM Techniques to Reduce Total Harmonic Distortion o...paperpublications3
Abstract: There are three types of DC/AC inverters available on the market, which are classified by their output types: (1) in practice, DC/AC conversion is done with topologies of varying precision. It can be as simple as applying voltages of equal magnitude in opposite directions across a load to generate a square wave. It is a square wave inverter. (2) A more precise method of DC/AC conversion is the modified sine wave, which introduces a dead time in a normal square wave output so that higher peak voltage can be used to produce the same average voltage as a sinusoidal wall-outlet output. This method produces fewer harmonics than square wave generation, but it still is not quite the same as the AC power that comes from AC outlet. The harmonics that are still present in a modified sine wave makes this type of inverter unsuitable for use while electrical noise is a concern, such as in medical devices which monitor the vital signs of a human.(3)Pure sine wave DC/AC conversion will introduce the least amount of harmonics into an electrical device, but are also most expensive method. Since the AC sine wave must come from a DC source, switching must still take place. However, switching takes place with logic so that the energy delivered to a load approaches that of a pure sine wave. This means that extra components and design considerations are involved in the control circuitry of a pure sine wave inverter, driving up cost.
In this paper an overview is presented of different PWM techniques to control the output voltage as well as to reduce the total harmonic distortion of output voltage in an H-bridge inverter.
The aim of this paper is illustrating and exposing the performance of a Series Active Power Filter (SAPF) with PI controller and Fuzzy controller within simulation and experimental validations. This performance is best manifested in compensating the sags and the swells voltages and in eliminating the harmonic voltage and regulate the terminal voltage of the load by injecting a voltage component in series with source voltage which is increased or decreased from the source voltage, hence, maintaining the load side waveforms as pure sinusoidal. The control method used in this work is not so complex and it is based on a phase locked loop (PLL) that is used to control the active filter. It is valid only in the phase system. The efficiency of the method I suggested is affirmed through simulation results by MATLAB\Simulink® and some prototypes experiments. These results shows the capability of the proposed prototypes.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
DESIGN AND ANALYSIS OF PHASE-LOCKED LOOP AND PERFORMANCE PARAMETERSIJMEJournal1
In this paper, we are present design and analysis of PLL, which is simulated in CMOS 0.18μm technology.The digital phase locked loop achieves locking within about 100 reference clock cycles. The pure digital
phase locked loop is attractive because it is less sensitive to noise and operating conditions than its analog
counterpart.In this PLL circuit successfully achieved 1.55GHz frequency. Jitter is 1.09ns achieved is very
less. Also achieve low phase noise -98.5827 at 1MHz Frequency
Nonlinearity compensation of low-frequency loudspeaker response using interna...TELKOMNIKA JOURNAL
This paper presents the nonlinearity compensation of low-frequency loudspeaker response. The loudspeaker is dedicated to measuring the response of Electret Condenser Microphone which operated in the arterial pulse region. The nonlinearity of loudspeaker has several problems which cause the nonlinearity behaviour consists of the back electromagnetic field, spring, mass of cone and inductance. Nonlinearity compensation is done using the Internal Model Controller with voltage feedback linearization. Several signal tests consist of step, impulse and sine wave signal are examined on different frequencies to validate the effectiveness of the design. The result showed that the Internal Mode Controller can achieve the high-speed response with a small error value.
An antenna is an electrical device which converts electric energy into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver.
An antenna is a device for sending or receiving electromagnetic waves.
A device that converts sound,
light, or electrical signals
into radio, microwave, or
other electrical signals .
An antenna used to convert electromagnetic waves in to electrical energy.
LOG – PERIODIC ANTENNA
YAGI – UDA ANTENNA
HELIX ANTENNA
PARABOLIC ANTENNA
LOOP ANTENNA
A unidirectional antenna in which the length and spacing of the elements increase logarithmically from one end to the other.
It is frequency-independent antenna.
Frequency range – VHF and UHF band.
It is broadband antenna.
It is unidirectional antenna.
It is frequency independent antenna.
A directional-type antenna consisting of one or more complete turns of a conductor.
It determine the direction of arrival of radio signals.
Frequency range – 500-1600KHz.
Direction finding of signal propagation.
Radio(AM/FM)reception.
Long distance point to point communication.
All the antenna are very useful in all the application such as transmitter and receiver.
Antenna are used to convert electrical energy to electromagnetic energy
TOTAL HARMONIC DISTORTION POWER METER BY EMBUILT TECHNOLOGIESEmbuilt Technologies
THDPM-1 is THD analyzer which measures upto 51st harmonic.It provides Voltage and Current THD.It shows the net effect on THD due to load.
It also shows following parameters-
Voltage
Current
Watt
Frequency
Power Factor
It is useful for testing of LED Drivers, SMPS, CFL, CHOKES etc.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Study of single pulse width modulated inverter and sinusoidal pulse width mod...IJLT EMAS
This paper highlights the problems associated with
single pulse width modulation, the most important being high
harmonic content in output voltage. A comparative study with
Sinusoidal Pulse Width Modulation Technique is done
highlighting the reduction in Total Harmonic Distortion of the
output voltage waveform.
An Overview of Different PWM Techniques to Reduce Total Harmonic Distortion o...paperpublications3
Abstract: There are three types of DC/AC inverters available on the market, which are classified by their output types: (1) in practice, DC/AC conversion is done with topologies of varying precision. It can be as simple as applying voltages of equal magnitude in opposite directions across a load to generate a square wave. It is a square wave inverter. (2) A more precise method of DC/AC conversion is the modified sine wave, which introduces a dead time in a normal square wave output so that higher peak voltage can be used to produce the same average voltage as a sinusoidal wall-outlet output. This method produces fewer harmonics than square wave generation, but it still is not quite the same as the AC power that comes from AC outlet. The harmonics that are still present in a modified sine wave makes this type of inverter unsuitable for use while electrical noise is a concern, such as in medical devices which monitor the vital signs of a human.(3)Pure sine wave DC/AC conversion will introduce the least amount of harmonics into an electrical device, but are also most expensive method. Since the AC sine wave must come from a DC source, switching must still take place. However, switching takes place with logic so that the energy delivered to a load approaches that of a pure sine wave. This means that extra components and design considerations are involved in the control circuitry of a pure sine wave inverter, driving up cost.
In this paper an overview is presented of different PWM techniques to control the output voltage as well as to reduce the total harmonic distortion of output voltage in an H-bridge inverter.
The aim of this paper is illustrating and exposing the performance of a Series Active Power Filter (SAPF) with PI controller and Fuzzy controller within simulation and experimental validations. This performance is best manifested in compensating the sags and the swells voltages and in eliminating the harmonic voltage and regulate the terminal voltage of the load by injecting a voltage component in series with source voltage which is increased or decreased from the source voltage, hence, maintaining the load side waveforms as pure sinusoidal. The control method used in this work is not so complex and it is based on a phase locked loop (PLL) that is used to control the active filter. It is valid only in the phase system. The efficiency of the method I suggested is affirmed through simulation results by MATLAB\Simulink® and some prototypes experiments. These results shows the capability of the proposed prototypes.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
DESIGN AND ANALYSIS OF PHASE-LOCKED LOOP AND PERFORMANCE PARAMETERSIJMEJournal1
In this paper, we are present design and analysis of PLL, which is simulated in CMOS 0.18μm technology.The digital phase locked loop achieves locking within about 100 reference clock cycles. The pure digital
phase locked loop is attractive because it is less sensitive to noise and operating conditions than its analog
counterpart.In this PLL circuit successfully achieved 1.55GHz frequency. Jitter is 1.09ns achieved is very
less. Also achieve low phase noise -98.5827 at 1MHz Frequency
Nonlinearity compensation of low-frequency loudspeaker response using interna...TELKOMNIKA JOURNAL
This paper presents the nonlinearity compensation of low-frequency loudspeaker response. The loudspeaker is dedicated to measuring the response of Electret Condenser Microphone which operated in the arterial pulse region. The nonlinearity of loudspeaker has several problems which cause the nonlinearity behaviour consists of the back electromagnetic field, spring, mass of cone and inductance. Nonlinearity compensation is done using the Internal Model Controller with voltage feedback linearization. Several signal tests consist of step, impulse and sine wave signal are examined on different frequencies to validate the effectiveness of the design. The result showed that the Internal Mode Controller can achieve the high-speed response with a small error value.
An antenna is an electrical device which converts electric energy into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver.
An antenna is a device for sending or receiving electromagnetic waves.
A device that converts sound,
light, or electrical signals
into radio, microwave, or
other electrical signals .
An antenna used to convert electromagnetic waves in to electrical energy.
LOG – PERIODIC ANTENNA
YAGI – UDA ANTENNA
HELIX ANTENNA
PARABOLIC ANTENNA
LOOP ANTENNA
A unidirectional antenna in which the length and spacing of the elements increase logarithmically from one end to the other.
It is frequency-independent antenna.
Frequency range – VHF and UHF band.
It is broadband antenna.
It is unidirectional antenna.
It is frequency independent antenna.
A directional-type antenna consisting of one or more complete turns of a conductor.
It determine the direction of arrival of radio signals.
Frequency range – 500-1600KHz.
Direction finding of signal propagation.
Radio(AM/FM)reception.
Long distance point to point communication.
All the antenna are very useful in all the application such as transmitter and receiver.
Antenna are used to convert electrical energy to electromagnetic energy
TOTAL HARMONIC DISTORTION POWER METER BY EMBUILT TECHNOLOGIESEmbuilt Technologies
THDPM-1 is THD analyzer which measures upto 51st harmonic.It provides Voltage and Current THD.It shows the net effect on THD due to load.
It also shows following parameters-
Voltage
Current
Watt
Frequency
Power Factor
It is useful for testing of LED Drivers, SMPS, CFL, CHOKES etc.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
Study of single pulse width modulated inverter and sinusoidal pulse width mod...IJLT EMAS
This paper highlights the problems associated with
single pulse width modulation, the most important being high
harmonic content in output voltage. A comparative study with
Sinusoidal Pulse Width Modulation Technique is done
highlighting the reduction in Total Harmonic Distortion of the
output voltage waveform.
Design of Microcontroller Based Multi-Frequency Ultrasonic Pulser ReceiverIJERA Editor
Ultrasonic technique is widely accepted as a characterizing tool because of its non destructive nature. Great
technical advancement in ultrasonic apparatuses over the last few years has permitted their increased use. In the
present work, an attempt has been made to develop an ultrasonic pulser receiver for pulse echo technique which
gives pulsed RF of desired frequency on selection from PC without shifting to another oscillator. A
microcontroller (ATMega16) controlled oscillator generates required frequencies on receiving a command. A
pulse repetition frequency (PRF) is generated by microcontroller in such a way to give fixed number of RF
cycles for each selected frequency. The receiver section receives the echoes from the same transducer, rectifies
and amplifies it and is projected to oscilloscope for further study. The designed multi frequency ultrasonic pulser
receiver system has been tested in standard liquids for velocity measurements.
As a communication engineer our princple interest is signal and their measuring instrument; Thus Spectrum Analyzer is an instrument which graphically provides the energy distribution of a signal as a function of the frequency on its CRT.
The spectrum analyzer provides information about all these things, by displaying the signal in the frequency domain.
The measurement of dominant frequencies and their responses.
The component levels and energy strength
Frequency stability
Bandwidth and Spectral purity
Modulation index and attenuation
Harmonic and intermodulation distortion
Various signal generation and so on
Which is not easy to measure at time domain
Ultrasonic transducers are a key element that governs the performances of both generating and receiving ultrasound in an ultrasonic measurement system. Electrical impedance is a parameter sensitive to the environment of the transducer; it contains information about the transducer but also on the medium in which it is immersed. Several practical applications exploit this property. For this study, the model is implemented with the VHDL-AMS behavioral language. The simulations approaches presented in this work are based on the electrical Redwood model and its parameters are deduced from the transducer electroacoustic characteristics.
Design of Negative Resistance Oscillator with Rocord Low Phase NoiseTELKOMNIKA JOURNAL
The aim of this paper is to use a new design of a negative resistance microwave oscillator in order to fabricate oscillator with very good performance in terms of output power, efficiency, stability and phase noise. In this study the new concept of oscillator using distributed resonator and micro-strip circuit elements improve performances of our structure. A micro-strip microwave oscillator with low phase noise based on an NPN silicon planar epitaxial transistor has been designed, fabricated, and characterized. In this design, each step has been conducted by using Advanced Design System (ADS) and following a theoretical study which enable to optimize the different performances of the whole circuit. The oscillator produce a sinusoidal signal with spectrum power of 12.25 dBm at 2.45 GHz into 50 Ω load when polarized at Vcc=15V with DC to RF efficiency of 16. The obtained phase noise of -120 dBc/Hz at 100 Hz offset is the result of the use of high Q factor resonator and the depth study of the parameters of the oscillator. Simulation and measurement results are in good agreement.
Qualitative analysis of Fruits and Vegetables using Earth’s Field Nuclear Mag...IJERA Editor
Among the imaging techniques, magnetic resonance imaging (MRI) is a non-contact and a non-invasive technique to obtain images of the objects rich in water content and provides an excellent tool to study variation of contrast among the soft issues. It often utilizes a linear magnetic field gradient to obtain an image that combines the visualization of molecular structure and dynamics. It measures the characteristics of hydrogen nuclei of water and nuclei with similar chemical shifts, modified by chemical environment across the object. In the present work, MRI of fresh tomatoes has been recorded using Terranova-MRI for qualitative analysis. The technique is effective, powerful and reliable as an investigative tool in the quality analysis and diagnosis of infections in fruits and vegetables.
A Plasma Tweeter is an audio device which uses a pair of electrodes as a source of sound. It has a clear reproduction and Omni directional radiation pattern. A plasma tweeter has a better frequency response than a conventional speaker and does not involve any moving part (diaphragm) and thus has less reverberation and no wear and tear. Plasma tweeters invented earlier were very expensive. This paper presents a plasma audio system which is making the regular audio system more efficient because of the use of the latest plasma tweeter. Here the objective is to create a low cost and more efficient version of the most speakers invented till now with the complete audio system.
Design of Low Power, High PSRR Error Amplifier for Low Drop-Out CMOS Voltage...IJEEE
This paper presents design of an improved Error amplifier (EA) for Low Drop-Out Voltage Regulator. The proposed circuit shows good behaviour as compared to the previous Error Amplifier. The Gain, Unity Gain Bandwidth, Phase Margin, CMRR and PSRR of an Error Amplifier is analysed. The proposed circuit is designed on UMC 180nm CMOS technology with supply voltage of 1.8Volts. All the simulation results are calculated through SPECTRE Simulator of cadence.
Performance Comparison of Power Quality Evaluation Using Advanced High Resolu...IOSRJEEE
Most of the conventional methods of power quality assesment in power systems are almost exclusively based on Fourier Transform that suffer from various inherent limitations. First limitation of an FFT based method is that of frequency resolution, whereas the second limitation is due to no coherent signal sampling of the data which proves itself as a leakage in spectrum domain. These two performance limitations of FFT or similar methods are particularly troublesome when analyzing short data records. To overcome from this problem, high regulation spectrum estimation methods can be used where resolution problem is not found. In this thesis, high resolution methods, such as MUSIC, root MUSIC and ESPRIT are discussed that use a different approach to spectral estimation; instead of trying to estimate the power spectral density (PSD) directly from the data, they model the data as the output of a linear system driven by white noise, and then attempt to estimate the parameters of that linear system. Detail Matlab simulations are carried out in order to investigate the performance of MUSIC, Root MUSIC and ESPRIT methods in estimating amplitude, power (squared amplitude) and frequency estimation of synthetic power signal both in clean and noisy conditions. Using mean square error (MSE) as the evaluation criterion, the variation of amplitude, power (squared amplitude) and frequency estimation are shown with respect to data sequence length and SNR and their influences on MSE are compared for the different methods as mentioned above.
A Status Data Transmitting System for Vessel MonitoringIJECEIAES
This paper presents a status data transmitting system suitable for vessel monitoring. The system consists of four main parts, which are a frequency synthesizer, a horn antenna, a status data module and a power amplifier. The proposed frequency synthesizer can flexibly change the frequency in a wide range (from 600 MHz to 4.2 GHz) and the output power (from -6 dBm to -3 dBm). By using the phase-locked loop, the synthesizer’s stability over temperature and tolerance are comparable to temperature compensated crystal oscillators (TCXO) that is about +/- 3 ppm. Moreover, phase noise performance of the synthesizer is less than -90 dBc/Hz at 1 KHz and -100 dBc/Hz at 100 KHz. The impedance bandwidth of the horn antenna can be controlled by using the beveling technique. The status data module packs information of the identification, longitude, latitude, and state of the vessel into data frames. FSK/MSK/GMSK schemes were used to modulate the data. The power amplifier provides 130 W output power at S-band. The fundamental characteristics of the implemented transmitter have been measured and verified.
Noise uncertainty effect on multi-channel cognitive radio networks IJECEIAES
Achieving high throughput is the most important goal of cognitive radio networks. The main process in cognitive radio is spectrum sensing that targets getting vacant channels. There are many sensing methods like matched filter, feature detection, interference temperature and energy detection which is employed in the proposed system; however, energy detection suffers from noise uncertainty. In this paper a study of throughput under noise fluctuation effect is introduced. The work in this paper proposes multi-channel system; the overall multi-channel throughput is studied under noise fluctuation effect. In addition, the proficiency of the network has been examined under different number of channels and sensing time with noise uncertainty.
Bio-medical (EMG) Signal Analysis and Feature Extraction Using Wavelet TransformIJERA Editor
In this paper, the multi-channel electromyogram acquisition system is being developed using programmable
system on chip (PSOC) microcontroller to obtain the surface of EMG signal. The two pairs of single-channel
surface electrodes are utilized to measure the EMG signal obtained from forearm muscles. Then different levels
of Wavelet family are used to analyze the EMG signal. Later features in terms of root mean square, logarithm of
root mean square, centroid of frequency, as well as standard deviation were used to extract the EMG signal. The
proposed method of feature extraction for extracting EMG signal states that root means square feature extraction
method gives better performance as compared to the other features. In the near future, this method can be used to
control a mechanical arm as well as robotic arm in field of real-time processing.
Similar to Low-frequency response test device of electret condenser microphone (20)
Amazon products reviews classification based on machine learning, deep learni...TELKOMNIKA JOURNAL
In recent times, the trend of online shopping through e-commerce stores and websites has grown to a huge extent. Whenever a product is purchased on an e-commerce platform, people leave their reviews about the product. These reviews are very helpful for the store owners and the product’s manufacturers for the betterment of their work process as well as product quality. An automated system is proposed in this work that operates on two datasets D1 and D2 obtained from Amazon. After certain preprocessing steps, N-gram and word embedding-based features are extracted using term frequency-inverse document frequency (TF-IDF), bag of words (BoW) and global vectors (GloVe), and Word2vec, respectively. Four machine learning (ML) models support vector machines (SVM), logistic regression (RF), logistic regression (LR), multinomial Naïve Bayes (MNB), two deep learning (DL) models convolutional neural network (CNN), long-short term memory (LSTM), and standalone bidirectional encoder representations (BERT) are used to classify reviews as either positive or negative. The results obtained by the standard ML, DL models and BERT are evaluated using certain performance evaluation measures. BERT turns out to be the best-performing model in the case of D1 with an accuracy of 90% on features derived by word embedding models while the CNN provides the best accuracy of 97% upon word embedding features in the case of D2. The proposed model shows better overall performance on D2 as compared to D1.
Design, simulation, and analysis of microstrip patch antenna for wireless app...TELKOMNIKA JOURNAL
In this study, a microstrip patch antenna that works at 3.6 GHz was built and tested to see how well it works. In this work, Rogers RT/Duroid 5880 has been used as the substrate material, with a dielectric permittivity of 2.2 and a thickness of 0.3451 mm; it serves as the base for the examined antenna. The computer simulation technology (CST) studio suite is utilized to show the recommended antenna design. The goal of this study was to get a more extensive transmission capacity, a lower voltage standing wave ratio (VSWR), and a lower return loss, but the main goal was to get a higher gain, directivity, and efficiency. After simulation, the return loss, gain, directivity, bandwidth, and efficiency of the supplied antenna are found to be -17.626 dB, 9.671 dBi, 9.924 dBi, 0.2 GHz, and 97.45%, respectively. Besides, the recreation uncovered that the transfer speed side-lobe level at phi was much better than those of the earlier works, at -28.8 dB, respectively. Thus, it makes a solid contender for remote innovation and more robust communication.
Design and simulation an optimal enhanced PI controller for congestion avoida...TELKOMNIKA JOURNAL
In this paper, snake optimization algorithm (SOA) is used to find the optimal gains of an enhanced controller for controlling congestion problem in computer networks. M-file and Simulink platform is adopted to evaluate the response of the active queue management (AQM) system, a comparison with two classical controllers is done, all tuned gains of controllers are obtained using SOA method and the fitness function chose to monitor the system performance is the integral time absolute error (ITAE). Transient analysis and robust analysis is used to show the proposed controller performance, two robustness tests are applied to the AQM system, one is done by varying the size of queue value in different period and the other test is done by changing the number of transmission control protocol (TCP) sessions with a value of ± 20% from its original value. The simulation results reflect a stable and robust behavior and best performance is appeared clearly to achieve the desired queue size without any noise or any transmission problems.
Improving the detection of intrusion in vehicular ad-hoc networks with modifi...TELKOMNIKA JOURNAL
Vehicular ad-hoc networks (VANETs) are wireless-equipped vehicles that form networks along the road. The security of this network has been a major challenge. The identity-based cryptosystem (IBC) previously used to secure the networks suffers from membership authentication security features. This paper focuses on improving the detection of intruders in VANETs with a modified identity-based cryptosystem (MIBC). The MIBC is developed using a non-singular elliptic curve with Lagrange interpolation. The public key of vehicles and roadside units on the network are derived from number plates and location identification numbers, respectively. Pseudo-identities are used to mask the real identity of users to preserve their privacy. The membership authentication mechanism ensures that only valid and authenticated members of the network are allowed to join the network. The performance of the MIBC is evaluated using intrusion detection ratio (IDR) and computation time (CT) and then validated with the existing IBC. The result obtained shows that the MIBC recorded an IDR of 99.3% against 94.3% obtained for the existing identity-based cryptosystem (EIBC) for 140 unregistered vehicles attempting to intrude on the network. The MIBC shows lower CT values of 1.17 ms against 1.70 ms for EIBC. The MIBC can be used to improve the security of VANETs.
Conceptual model of internet banking adoption with perceived risk and trust f...TELKOMNIKA JOURNAL
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The appearance of uncertainties and disturbances often effects the characteristics of either linear or nonlinear systems. Plus, the stabilization process may be deteriorated thus incurring a catastrophic effect to the system performance. As such, this manuscript addresses the concept of matching condition for the systems that are suffering from miss-match uncertainties and exogeneous disturbances. The perturbation towards the system at hand is assumed to be known and unbounded. To reach this outcome, uncertainties and their classifications are reviewed thoroughly. The structural matching condition is proposed and tabulated in the proposition 1. Two types of mathematical expressions are presented to distinguish the system with matched uncertainty and the system with miss-matched uncertainty. Lastly, two-dimensional numerical expressions are provided to practice the proposed proposition. The outcome shows that matching condition has the ability to change the system to a design-friendly model for asymptotic stabilization.
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Evaluation of the weighted-overlap add model with massive MIMO in a 5G systemTELKOMNIKA JOURNAL
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Reagentless iron detection in water based on unclad fiber optical sensorTELKOMNIKA JOURNAL
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Impact of CuS counter electrode calcination temperature on quantum dot sensit...TELKOMNIKA JOURNAL
In place of the commercial Pt electrode used in quantum sensitized solar cells, the low-cost CuS cathode is created using electrophoresis. High resolution scanning electron microscopy and X-ray diffraction were used to analyze the structure and morphology of structural cubic samples with diameters ranging from 40 nm to 200 nm. The conversion efficiency of solar cells is significantly impacted by the calcination temperatures of cathodes at 100 °C, 120 °C, 150 °C, and 180 °C under vacuum. The fluorine doped tin oxide (FTO)/CuS cathode electrode reached a maximum efficiency of 3.89% when it was calcined at 120 °C. Compared to other temperature combinations, CuS nanoparticles crystallize at 120 °C, which lowers resistance while increasing electron lifetime.
In place of the commercial Pt electrode used in quantum sensitized solar cells, the low-cost CuS cathode is created using electrophoresis. High resolution scanning electron microscopy and X-ray diffraction were used to analyze the structure and morphology of structural cubic samples with diameters ranging from 40 nm to 200 nm. The conversion efficiency of solar cells is significantly impacted by the calcination temperatures of cathodes at 100 °C, 120 °C, 150 °C, and 180 °C under vacuum. The fluorine doped tin oxide (FTO)/CuS cathode electrode reached a maximum efficiency of 3.89% when it was calcined at 120 °C. Compared to other temperature combinations, CuS nanoparticles crystallize at 120 °C, which lowers resistance while increasing electron lifetime.
A progressive learning for structural tolerance online sequential extreme lea...TELKOMNIKA JOURNAL
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Electroencephalography-based brain-computer interface using neural networksTELKOMNIKA JOURNAL
This study aimed to develop a brain-computer interface that can control an electric wheelchair using electroencephalography (EEG) signals. First, we used the Mind Wave Mobile 2 device to capture raw EEG signals from the surface of the scalp. The signals were transformed into the frequency domain using fast Fourier transform (FFT) and filtered to monitor changes in attention and relaxation. Next, we performed time and frequency domain analyses to identify features for five eye gestures: opened, closed, blink per second, double blink, and lookup. The base state was the opened-eyes gesture, and we compared the features of the remaining four action gestures to the base state to identify potential gestures. We then built a multilayer neural network to classify these features into five signals that control the wheelchair’s movement. Finally, we designed an experimental wheelchair system to test the effectiveness of the proposed approach. The results demonstrate that the EEG classification was highly accurate and computationally efficient. Moreover, the average performance of the brain-controlled wheelchair system was over 75% across different individuals, which suggests the feasibility of this approach.
Adaptive segmentation algorithm based on level set model in medical imagingTELKOMNIKA JOURNAL
For image segmentation, level set models are frequently employed. It offer best solution to overcome the main limitations of deformable parametric models. However, the challenge when applying those models in medical images stills deal with removing blurs in image edges which directly affects the edge indicator function, leads to not adaptively segmenting images and causes a wrong analysis of pathologies wich prevents to conclude a correct diagnosis. To overcome such issues, an effective process is suggested by simultaneously modelling and solving systems’ two-dimensional partial differential equations (PDE). The first PDE equation allows restoration using Euler’s equation similar to an anisotropic smoothing based on a regularized Perona and Malik filter that eliminates noise while preserving edge information in accordance with detected contours in the second equation that segments the image based on the first equation solutions. This approach allows developing a new algorithm which overcome the studied model drawbacks. Results of the proposed method give clear segments that can be applied to any application. Experiments on many medical images in particular blurry images with high information losses, demonstrate that the developed approach produces superior segmentation results in terms of quantity and quality compared to other models already presented in previeous works.
Automatic channel selection using shuffled frog leaping algorithm for EEG bas...TELKOMNIKA JOURNAL
Drug addiction is a complex neurobiological disorder that necessitates comprehensive treatment of both the body and mind. It is categorized as a brain disorder due to its impact on the brain. Various methods such as electroencephalography (EEG), functional magnetic resonance imaging (FMRI), and magnetoencephalography (MEG) can capture brain activities and structures. EEG signals provide valuable insights into neurological disorders, including drug addiction. Accurate classification of drug addiction from EEG signals relies on appropriate features and channel selection. Choosing the right EEG channels is essential to reduce computational costs and mitigate the risk of overfitting associated with using all available channels. To address the challenge of optimal channel selection in addiction detection from EEG signals, this work employs the shuffled frog leaping algorithm (SFLA). SFLA facilitates the selection of appropriate channels, leading to improved accuracy. Wavelet features extracted from the selected input channel signals are then analyzed using various machine learning classifiers to detect addiction. Experimental results indicate that after selecting features from the appropriate channels, classification accuracy significantly increased across all classifiers. Particularly, the multi-layer perceptron (MLP) classifier combined with SFLA demonstrated a remarkable accuracy improvement of 15.78% while reducing time complexity.
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Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
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The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
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This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
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It is now-a-days very important for the people to send or receive articles like imported furniture, electronic items, gifts, business goods and the like. People depend vastly on different transport systems which mostly use the manual way of receiving and delivering the articles. There is no way to track the articles till they are received and there is no way to let the customer know what happened in transit, once he booked some articles. In such a situation, we need a system which completely computerizes the cargo activities including time to time tracking of the articles sent. This need is fulfilled by Courier Management System software which is online software for the cargo management people that enables them to receive the goods from a source and send them to a required destination and track their status from time to time.
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Low-frequency response test device of electret condenser microphone
1. TELKOMNIKA Telecommunication, Computing, Electronics and Control
Vol. 18, No. 3, June 2020, pp. 1368~1375
ISSN: 1693-6930, accredited First Grade by Kemenristekdikti, Decree No: 21/E/KPT/2018
DOI: 10.12928/TELKOMNIKA.v18i3.14831 1368
Journal homepage: http://journal.uad.ac.id/index.php/TELKOMNIKA
Low-frequency response test device
of electret condenser microphone
Erni Yudaningtyas1
, Achsanul Khabib2
, Waru Djuriatno3
, Zakiyah Amalia4
,
Ramadhani Kurniawan Subroto5
1,3,5
Department of Electrical Engineering, University of Brawijaya, Indonesia
2,4
Department of Electrical Engineering, State Polytechnic of Malang, Indonesia
Article Info ABSTRACT
Article history:
Received Aug 2, 2019
Revised Jan 31, 2020
Accepted Feb 26, 2020
Arterial pulse measurement using electret condenser microphone requires
the standard to validate the value of the measurement. This standard
requires the test device to reproducing the mechanical vibration to emulate
the arterial pulse vibration. The main objective of this paper is to discuss
the test device of electret condenser microphone using class A amplifiers and
low-frequency loudspeaker. To validate this pulse measurement, this class A
amplifier is examined under an experimental setup. The experiments showed
that the device can be used as an alternative solution to generate the mechanical
signal source to simulate the human arterial pulse.
Keywords:
Class A amplifier
Electret condenser microphone
Loudspeaker
Low-frequency
Test device This is an open access article under the CC BY-SA license.
Corresponding Author:
Erni Yudaningtyas,
Department of Electrical Engineering,
University of Brawijaya, Indonesia.
Email: erni@ub.ac.id
1. INTRODUCTION
An electret condenser microphone (ECM) is a microphone designed in the audio frequency range
about 20 Hz-20 kHz [1, 2]. ECM is utilized to accurately measure the arterial pulse in the low-frequency i.e,
1 Hz [2, 3]. The arterial pulse frequency is around 1.5-2.1 Hz at the normal condition of human [4-8].
The ECM works to detect the arterial pulse and is operated by taking a mechanical signal from the arterial
pulse [3]. This ECM is used to measure arterial pulses frequently [9-13]. The arterial pulse measurement is
based on the Traditional Chinese Medicine method [14-16]. Even though ECM has been conducted by many
kinds of literature, the research on ECM is still relevant today. In [3], the arterial pulse recording device has
been designed from ECM using a mechanical filter and electronic filter [17]. In practical applications, this
ECM requires a tool to determine the response of electrical and mechanical responses such that it can be
known whether this ECM is stationery at the frequency of 0.5-10 Hz. By considering this problem, the test
device is required to examine and obtain the frequency response of ECM or even can be used as a human
pulse emulator.
Since the pulse frequency is typically low frequency, between 0.5-2 Hz, special treatment is
implemented to satisfy these frequency ranges. The previous works related to ECM for the application
of low-frequency device has not yet been conducted. The test device based ECM to obtain the frequency
response is constructed in this paper. The test device generates the mechanical signal coming from
the loudspeaker. In this paper, the type of loudspeakers used is an oval woofer type from the TV [18].
2. TELKOMNIKA Telecommun Comput El Control
Low-frequency response test device of electret condenser microphone (Erni Yudaningtyas)
1369
The loudspeaker is then operated in the frequency range 0,5-10 Hz for mechanical vibration such that it can
be used as a pulse emulator. The additional device that is able to drive the loudspeaker is often called a signal
amplifier or an amplifier.
The class A amplifier is selected to eliminate the distortion of the signal. Class A amplifier has
continuous current flows without any distortion because the transistor is operated continuously [19]. This
type of amplifier is a kind of amplifier exhibiting low efficiency as the current flowing in the transistor is
continuous. This study discusses the displacement response on a test device when given a low-frequency
signal from a signal generator amplified by the class A amplifier. Displacement amplifier used as
a mechanical signal source is also utilized as a pulse emulator and mechanical signal generator. Figure 1
shows the configuration of the low-frequency response test the device of ECM using a low-frequency
amplifier and loudspeaker. In front of the loudspeaker, soft silicon rubber is installed and responsible to
increase mechanical coupling between the loudspeaker and ECM. The detail description of the mechanical
coupling has been discussed in [3].
Figure 1. The configuration of the low-frequency response test device of ECM
based low-frequency loudspeaker [3]
To observe the speaker impedance, the impedance test is required to measure the speaker impedance
in the range frequency of 0,5-10 Hz. In this study, the impedance of the speaker is tested using a vector
network analyzer (VNA) [20, 21] type Bode-100. In addition, the low-frequency amplifier is analyzed to
observe the impedance of the amplifier. This paper discusses test devices using low-frequency amplifiers
and low-frequency loudspeakers to measure the response of ECM for arterial pulse sensor [22, 23].
The experimental result has verified the proposed benchmarks.
This paper organized as follows: section 1 introduces the background of this research which is about
the introduction of arterial pulse sensors using ECM and how the background of the test device is made to
determine the frequency response of the ECM that is used as an arterial pulse sensor. Section 2 introduces the
material and the method used in designing arterial pulse test devices, the material consists of low-frequency
loudspeaker and low-frequency amplifiers. The method describes how to operate the arterial pulse test device.
The Results and Discussion are discussed in section 3. And the last, section 4 presents the Conclusion.
2. MATERIAL AND METHOD
To implement the proposed test device, some components are realized to this test device such as
the loudspeaker with low-frequency characters, the amplifier without distortion and has high linearity
and measurement device i.e. oscilloscope and vector network analyzer. The detailed components of
the overall system are explained as follows.
2.1. Low-frequency loudspeaker
Commonly, the existing speaker has a frequency response in the range between 20 Hz to 20 kHz,
however, in this study, the proposed speaker is designed to satisfy the frequency range of 0.5-10 Hz. Figure 2
shows the schematic equivalent circuit of the proposed speaker. The proposed speaker consists of two
components, i.e: the electrical and the mechanical component. The electrical component is composed by
the moving coil, while the mechanical component consists of diaphragm and spring.
According to Figure 2, the mathematical model of the loudspeaker can be derived as follows:
𝑆𝑝( 𝜔) = 𝑗𝜔𝐿 + 𝑅𝑒 +
1
𝑗(𝜔𝐶𝑚−
1
𝜔𝐿𝑚
)+
1
𝑅𝑚
(1)
where the loudspeaker impedance is represented by 𝑆𝑝(𝜔), the resistance of the loudspeaker coil is assumed
by 𝑅𝑒, the inductance of the loudspeaker coil is denoted by 𝐿𝑒, the mass of diaphragm is represented by 𝐶𝑚,
3. ISSN: 1693-6930
TELKOMNIKA Telecommun Comput El Control, Vol. 18, No. 3, June 2020: 1368 - 1375
1370
the spring diaphragm of the loudspeaker is related by 𝐿𝑚 and the losses of spring diaphragm is represented
by 𝑅𝑚. The parameters of the low-frequency loudspeaker are described in Table 1.
Figure 2. The Modeling of Loudspeaker
Table 1. The parameter of
the loudspeaker modelling
Parameter Description Value
𝑅𝑒 Loudspeaker coil resistance 6.1 Ω
𝐿𝑒 Loudspeaker coil inductance 0.11 mH
𝐿𝑚 Spring diaphragm of the
loudspeaker
7.5 mH
𝑅𝑚 Spring diaphragm losses 8.9 Ω
𝐶𝑚 Diaphragm mass 306 µF
Amplifier Class A Amplifier 1-1000
Hz
According to Figure 2, the loudspeaker has a resonant frequency. The resonant frequency is
the relationship between the mechanical resonant frequency of the diaphragm and the moving coil
represented in (2) as follows:
𝑓𝑟𝑒𝑠 =
1
2𝜋
√
𝑆
𝑀
(2)
where 𝑓𝑟𝑒𝑠 is the resonant frequency of the loudspeaker, 𝑆 is the stiffness of the spring compliance
loudspeaker and 𝑀 is the mass (weight) of all components moving on the loudspeaker. 𝑆 is a notation for
the loudspeaker stiffness system in centimetres per dyne which consists of a spider or spring system that
positions the moving part again at the rest position. This moving part position can move forward
or backwards from the rest position according to the signal given to the loudspeaker. The strength of this
spring will determine how much force is given by voice-coil. The greater the value of 𝑆, the greater the force
that the moving coil must be given. Whereas, 𝑀 represents all components loaded from loudspeakers such as
diaphragms, cones, and moving coils as well as included in this 𝑀 component. Based on the aforementioned
explanation, it can be concluded that the type of woofer loudspeaker has the character of S which is lower
than other types of loudspeakers and 𝑀 is greater than other types of loudspeakers.
To find out the force acting on the diaphragm of the loudspeaker provided by the voice coil,
the combination of the electrical and mechanical domain must be incorporated and added. Magnetizing force
to obtain a large force that affects the moving force of the loudspeaker represented in the following:
𝑓 = 𝐵𝑙𝑖
𝑒 = 𝐵𝑙𝑢 (3)
where 𝐵 is the magnetic field strength (𝑇), 𝐼 is the length of the conductor in the magnetic field (𝑚),
𝑓 is the force in Newton (𝑁), 𝑢 is the speed from moving the moving part loudspeaker (𝑚/𝑠), 𝑖 is the current
passing through the moving coil from the loudspeaker (𝐴) and 𝑒 is the voltage supplying moving coil from
the loudspeaker (𝑉). Mechanical quality factor and electrical quality factor are represented this following (4):
𝑄 𝐸𝑆 = 2𝜋𝑓𝑆 𝐶 𝑚 𝑅 𝑒
𝑄 𝑀𝑆 = 𝑓𝑆 𝐶 𝑚 𝑅 𝑚 (4)
𝑓𝑆 =
1
2𝜋√ 𝐶 𝑚 𝑅 𝑚
where 𝑄 𝑀𝑆 represents the mechanical quality factor, 𝑄 𝐸𝑆 denotes the electrical quality factor and 𝑓𝑆 is
the resonance frequency.
2.2. Low-frequency amplifier
Since the audio amplifier [24] has a frequency response in the range frequency of 20-20 kHz,
the amplifier is conditioned in the range frequency of 0.5-10 Hz. In this paper, the basic principle of
the low-frequency amplifier using modified Class A is introduced. The schematics of the circuit are
shown in Figure 3 and Figure 4. The proposed amplifier is composed by Darlington transistors and several
passive components.
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Figure 3. The proposed of low-frequency amplifier
based class-A amplifier
Figure 4. Signal conditioner
The parameters of the proposed amplifier are listed in Table 2. 𝑅 𝐵 is a resistor that acts as a buffer
between the signal source and the main circuit such that it does not overload the signal generator, 𝑅 𝑉𝐵
and 𝑅 𝐵𝐺 is a voltage divider that provides voltage and current to the base of 𝑇1 transistor, 𝑅 𝐶 is a resistor that
regulates the current of Darlington transistors 𝑇1 and 𝑇2. RE is the resistor to compensate the deviation
of Darlington transistors 𝑇1 and 𝑇2, CE is to compensate for the sine wave signal and the 𝑅 𝐵2 is the resistor to
compensate between the loudspeaker and amplifier.
Table 2. The parameter of proposed amplifier
Parameters Value
𝑅 𝐵1 100 Ω
𝑅 𝑉𝐵 10 KΩ
𝑅 𝐵𝐺 1 KΩ
𝑅𝑐 8 Ω
𝑅 𝐸 24 Ω
𝑅 𝐵2 14 Ω
𝑇1 2N3035
𝑇2 2N3055
𝐶 𝐸 3.3 µF
To determine the voltage of amplifier affecting the force of loudspeaker, the force of motor using
Ohm's law relating to a Lorentz actuator can be calculated. The motor voltage must be replaced by a short
circuit to determine the impedance of a voltage source [25]. The force of loudspeaker which affecting
the amplifier voltage can be described by
𝐹 = 𝐵𝑖𝑙 =
𝐵𝑉𝑠 𝑙
𝑅 𝑐
[𝑁] (5)
where 𝐵 is the flux density of the loudspeaker magnetic field around the coil in Tesla [𝑇]. 𝑙 is the length
of the voice coil inside the magnetic field. To determine the dynamic response 𝑇𝐹,𝑥 of the cone displacement
𝑥 which related to mass 𝑚 to drive the force of excitation 𝐹 can be described by
𝑇𝐹,𝑥( 𝜔) =
𝑥
𝐹
=
𝐶𝑠
−
𝜔2
𝜔0
2+2𝑗𝜁
𝜔
𝜔0
+1
(6)
where 𝜔 = 2𝜋𝑓, ζ is damping ratio, 𝐶𝑠 is compliance and the resonant frequency of mechanical part 𝜔0 is
calculated by: 𝜁 =
𝑐
2√𝑘𝑚
, 𝐶𝑠 =
1
𝑘
and𝜔0 = √
𝑘
𝑚
.
The resonant frequency of the mechanical part is called "eigenfrequency" [11] and denotes as 𝑓0.
The 𝑓0 is equal to 𝜔0/2𝜋 called by fundamental resonant frequency. Around its the fundamental frequency,
the loudspeaker actuator is matched with the force due to the displacement of the cone against the stiffness
of the loudspeaker suspension. In this study, the loudspeaker resonant frequency 𝑓0 is 193 Hz, but
the loudspeaker is operated at a lower frequency in the range of 0.5-10 Hz by designing a special amplifier
that is able to operate at a very low frequency such that can drive the motor force of loudspeaker.
The complete description of the experimental setup of the low-frequency amplifier is later discussed in
the following section.
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2.3. Experimental setup
This study proposes a new test device for testing a performance of the ECM that operates in
the frequency of arterial pulse region. In addition, test devices can be used for mechanical pulse emulator
the same as the arterial pulse. To design the test device, the researchers conduct an experiment by measuring
the impedance and gain of loudspeaker using a Bode-100 type vector network analyzer (VNA). Based on
the experiment, it can be obviously seen that the loudspeaker impedance rate in the frequency
range 0.5-10 Hz. In addition, the gain of the loudspeaker is also measured using this VNA in the frequency
range 0.5-10 Hz.
To characterize the Class A amplifier, the output voltage on the amplifier is conditioned constant
even though the input frequency is varied in the range of 0.5-10 Hz. This output voltage is then represented
by displacement of the diaphragm of the loudspeaker. This displacement is then conditioned at a desired
constant value by varying the input voltage of the signal generator. In order to verify the performance
of the proposed test device, a novel class A power amplifier design and a low-frequency loudspeaker are
verified in Figure 5. The test benchmark consists of several components i.e: signal generator, digital storage
oscilloscope, power supply, Class A amplifier and loudspeaker. Each of those components has its function.
The signal generator produces the sine wave. The Class A amplifier is supplied by the power supply,
the loudspeaker generates the mechanical vibration driven from the Class A amplifier. To measure
the amplitude response, digital storage oscilloscope (DSO) is connected to the terminal 𝑉𝑖𝑛 and 𝑉𝑜𝑢𝑡 of
Class A amplifier. The experimental setup parameters are listed in Table 3.
The experimental setup of the proposed system is clearly shown in Figure 5, while the detailed test
device is shown in Figure 6. The ECM stand is the ECM holder aiming to support and maintain the ECM
position. ECM is the focus of research which is the main objective in this study. Soft silicon rubber is utilized
to adjust mechanical coupling between the loudspeaker and ECM diaphragms. The description of the ECM
system as an arterial pulse sensor is explained in detail in [3]. In this research, the main topic is the design
of a test device to generate a mechanical signal such as human pulse arterial signals which the loudspeaker is
conditioned in the frequency range 0.5-10 Hz with a displacement of 0-1.5 𝑚𝑚 𝑝𝑝.
Table 3. The parameter of experimental setup
Parameters Specification
Power Supply 20 V DC
Function generator KMOON, Dual-channel DDS signal Generator
DSO Hantek MSO5074F, 4 channel DSO, 70 MHz
Figure 5. The photograph of the low-frequency
response test device of the ECM
Figure 6. The configuration of loudspeaker
and ECM
3. RESULT AND DISCUSSION
Figure 7 depicts the loudspeaker impedance measurement using VNA type Bode 100 from Omicron
Lab. In this impedance measurement, the loudspeaker is stationary and there is no object hitching on this
loudspeaker. Then, the VNA is set to kick the loudspeaker in the range 0.5-10 Hz. The frequency response
of the loudspeaker is measured by VNA and shown in Figure 8. Based on the measurement, the loudspeaker
has the impedance at about 7.09 Ω. Figure 8 shows the loudspeaker gain in the frequency range of 1-10 Hz.
However, the loudspeaker gain tends to be constant at about 0.2477 in the frequency range of 3-10 Hz.
In future, it can be interpreted in the frequency range of 310 Hz that this loudspeaker has a gain of 0.2477 dB.
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Figure 7. The loudspeaker impedance measurement using VNA
Figure 8. The loudspeaker gain measurement using VNA
The voltage ratio between the voltage signal generator which represented as 𝑉𝑖𝑛 and the amplitude
voltage at loudspeaker which denoted as 𝑉𝑜𝑢𝑡 in every 0.5 Hz sampling is shown in Figure 9. It can be clearly
seen that the ratio of the test device system tends to decrease when the frequency is getting higher. It implies
that the test device system will require larger 𝑉𝑖𝑛 if the frequency is raised. Figure 9 shows that the frequency
response value is not fixed. Therefore, signal conditioners as shown in Figure 4 are added as shown in Figure
10 indicating the input voltage 𝑉𝑖𝑛 from a signal generator in every 0.5 Hz. Figure 11 shows the frequency
response after signal conditioners from Figure 10 are added. Consequently, the diaphragm displacement of the
test device is stationary at the range 3.36 to 3.46 at the frequency range of 0.5-10 Hz as depicted by Figure 11. It
can be clearly seen that the loudspeaker is operated at low frequencies and can be used as a test device.
Figure 9. The voltage ratio between the voltage signal generator which represented as 𝑉𝑖𝑛 and the amplitude
voltage at speaker which denoted as 𝑉𝑜𝑢𝑡 in every 0.5 Hz
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Figure 10. The voltage of the signal generator which denotes as V_in in every 0.5
Figure 11. The diaphragm displacement of the loudspeaker in 𝑚𝑚 𝑝𝑝
4. CONCLUSION
The low-frequency response test devices of ECM has been successfully implemented. The test
device has been successfully verified with constant displacement. So the proposed test device is able to used
as a low-frequency response test device.
ACKNOWLEDGEMENT
The research project was supported by the Department of Electrical Engineering University
of Brawijaya.
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