This includes discussion of DSP applications such as two band digital crossover system,woofers, sqawkers, tweeters, interference cancellation in ECG, speech noise reduction, speech coding and compression, CD recording system
This document discusses using dual tone multi-frequency (DTMF) technology to control a robot autonomously. DTMF uses tone signals transmitted over phone lines to send commands. A DTMF decoder chip receives the tones and uses them to control a microcontroller and motors. Infrared sensors allow the robot to navigate obstacles under phone control without infrastructure. Potential applications include automated factory vehicles, security robots, and mine detection. While simple, this approach demonstrates using basic technologies like DTMF and sensors for autonomous navigation.
This document discusses correlative-level coding and its applications in baseband pulse transmission systems. Correlative-level coding introduces controlled intersymbol interference to increase signaling rate. It allows partial response signaling and maximum likelihood detection at the receiver. Specific techniques discussed include duobinary signaling and modified duobinary signaling. The document also covers tapped-delay line equalization using adaptive algorithms like least mean square to compensate for channel distortion. Decision feedback equalization and its implementation are summarized as well. Eye patterns are described as a tool to evaluate signal quality in such systems.
This document provides an overview of digital signal processing (DSP). It begins by defining an analog signal and a digital signal. It then describes the basic components of a DSP system, which includes an analog-to-digital converter (ADC) to convert the analog input signal to digital, a digital signal processor to process the digital signal, and a digital-to-analog converter (DAC) to reconstruct the analog output signal. Finally, it discusses some advantages and limitations of DSP systems compared to analog systems and provides examples of DSP applications.
The document provides an overview of adaptive filters. It discusses that adaptive filters are digital filters that have self-adjusting characteristics to changes in input signals. They have two main components: a digital filter with adjustable coefficients and an adaptive algorithm. Common adaptive algorithms are LMS and RLS. Adaptive filters are used for applications like noise cancellation, system identification, channel equalization, and signal prediction. The key aspects of adaptive filter theory and algorithms like LMS, RLS, Wiener filters are also covered.
RADAR uses radio waves to detect distant objects. It transmits pulses and measures properties of the reflected pulses, including range, angles, size, and speed of targets. RADAR signal processing involves measuring distance using transit time or frequency modulation, measuring speed using Doppler effect, and reducing interference through techniques like moving target indication and constant false alarm rate processing. The signal processor separates targets from clutter based on Doppler shifts and amplitude. RADAR has military, navigation, and civilian applications including air traffic control and law enforcement.
This document discusses several digital signal processing applications:
1) A two-band digital crossover system that splits an audio signal into low and high frequencies to be played through different speakers.
2) An ECG system that uses notch filters to remove 60Hz interference from power lines and allow detection of heart rate.
3) Speech noise reduction and coding systems that compress speech signals for transmission.
4) The compact disc recording and playback system which uses anti-aliasing filters, sampling, quantization, encoding, and laser etching to store digital audio that is then reconstructed through decoding, interpolation, DAC, and filtering.
This document discusses using dual tone multi-frequency (DTMF) technology to control a robot autonomously. DTMF uses tone signals transmitted over phone lines to send commands. A DTMF decoder chip receives the tones and uses them to control a microcontroller and motors. Infrared sensors allow the robot to navigate obstacles under phone control without infrastructure. Potential applications include automated factory vehicles, security robots, and mine detection. While simple, this approach demonstrates using basic technologies like DTMF and sensors for autonomous navigation.
This document discusses correlative-level coding and its applications in baseband pulse transmission systems. Correlative-level coding introduces controlled intersymbol interference to increase signaling rate. It allows partial response signaling and maximum likelihood detection at the receiver. Specific techniques discussed include duobinary signaling and modified duobinary signaling. The document also covers tapped-delay line equalization using adaptive algorithms like least mean square to compensate for channel distortion. Decision feedback equalization and its implementation are summarized as well. Eye patterns are described as a tool to evaluate signal quality in such systems.
This document provides an overview of digital signal processing (DSP). It begins by defining an analog signal and a digital signal. It then describes the basic components of a DSP system, which includes an analog-to-digital converter (ADC) to convert the analog input signal to digital, a digital signal processor to process the digital signal, and a digital-to-analog converter (DAC) to reconstruct the analog output signal. Finally, it discusses some advantages and limitations of DSP systems compared to analog systems and provides examples of DSP applications.
The document provides an overview of adaptive filters. It discusses that adaptive filters are digital filters that have self-adjusting characteristics to changes in input signals. They have two main components: a digital filter with adjustable coefficients and an adaptive algorithm. Common adaptive algorithms are LMS and RLS. Adaptive filters are used for applications like noise cancellation, system identification, channel equalization, and signal prediction. The key aspects of adaptive filter theory and algorithms like LMS, RLS, Wiener filters are also covered.
RADAR uses radio waves to detect distant objects. It transmits pulses and measures properties of the reflected pulses, including range, angles, size, and speed of targets. RADAR signal processing involves measuring distance using transit time or frequency modulation, measuring speed using Doppler effect, and reducing interference through techniques like moving target indication and constant false alarm rate processing. The signal processor separates targets from clutter based on Doppler shifts and amplitude. RADAR has military, navigation, and civilian applications including air traffic control and law enforcement.
This document discusses several digital signal processing applications:
1) A two-band digital crossover system that splits an audio signal into low and high frequencies to be played through different speakers.
2) An ECG system that uses notch filters to remove 60Hz interference from power lines and allow detection of heart rate.
3) Speech noise reduction and coding systems that compress speech signals for transmission.
4) The compact disc recording and playback system which uses anti-aliasing filters, sampling, quantization, encoding, and laser etching to store digital audio that is then reconstructed through decoding, interpolation, DAC, and filtering.
Orthogonal Frequency Division Multiplexing (OFDM)Gagan Randhawa
The document discusses Orthogonal Frequency Division Multiplexing (OFDM), including its principles, advantages, disadvantages and applications. OFDM divides the available spectrum into multiple orthogonal subcarriers, each modulated with a low data rate stream. This makes OFDM robust to multipath fading and intersymbol interference. While OFDM provides high data rates and spectral efficiency, it suffers from issues like high peak-to-average power ratio and sensitivity to frequency errors. OFDM is used in technologies like WiFi, WiMAX and digital audio/video broadcasting.
Comparator circuits compare two input voltages and produce a logic output signal that is high or low depending on which input is larger. Real comparators do not have an abrupt transition and have very high voltage gain in the transition region. Comparators are often used as interfaces between analog and digital circuits by converting analog signals to logic levels. Open-collector outputs are useful for this by producing either 0V or the supply voltage at their outputs. Schmitt triggers, which are comparators with positive feedback, are commonly used as they introduce hysteresis which helps eliminate unwanted output transitions from noise.
Digital signal processing involves the analysis, interpretation, and manipulation of signals such as sound, images, and sensor data. It represents analog waveforms as discrete numeric values by sampling the waveform at regular intervals. There are two categories of signal processing: analog and digital. Digital signal processing has advantages over analog like greater noise immunity, multi-directional transmission, security, and smaller size. It has applications in areas like digital filtering, video and audio compression, speech processing, image processing, and radar/sonar processing.
This document discusses vestigial sideband (VSB) modulation. VSB modulation is a compromise between single sideband (SSB) and double sideband suppressed carrier (DSB-SC) modulation that overcomes some of the drawbacks of SSB. In VSB, one sideband and a vestige of the other sideband are transmitted together, requiring less bandwidth than DSB but more than SSB. VSB modulation is commonly used for television signal transmission to reduce the bandwidth requirement compared to DSB.
DSP Applications in medical field:Hearing aid, ECG, Blood pressure monitor.
Noise filtering,Fast fourier transform and Bandpass & FIR filter on matlab.
The document discusses equalization techniques used to mitigate inter-symbol interference (ISI) in digital communication systems. Equalization aims to remove ISI and noise effects from the channel. It is located at the receiver and uses techniques like linear equalizers, decision feedback equalization, and maximum likelihood sequence estimation to estimate the channel response and minimize the error between transmitted and received symbols while balancing noise. As the wireless channel changes over time, adaptive equalization is used where the equalizer periodically trains and tracks the changing channel response.
This presentation provides an overview of digital signal processing (DSP). It defines key terms like signal and signal processing and explains the basic principles and components of DSP systems. The presentation notes that DSP has advantages over analog processing like accuracy, flexibility, and ease of operation. It provides examples of DSP applications in areas like audio, communications, biomedicine, and more. In conclusion, the presentation emphasizes that DSP involves manipulating digital numbers using programmed instructions and is widely used in modern applications.
This document provides an overview of decimation and interpolation in multirate signal processing. It discusses downsampling by an integer factor M, which reduces the sampling rate by taking every M-th sample and discarding the rest. Downsampling can cause aliasing if the signal is not bandlimited, so a low-pass filter is used beforehand. The document also covers properties like linearity and time-variance, identities for cascading systems, and polyphase decomposition to more efficiently implement decimation filters when the number of coefficients is a multiple of the decimation factor. Examples and illustrations are provided using MATLAB code.
This document discusses Nyquist's criterion for distortionless transmission of binary signals over a baseband channel. It states that intersymbol interference (ISI) can be eliminated by choosing a transmit filter response P(f) that satisfies the Nyquist criterion. An ideal rectangular pulse shape meets the criterion but is physically unrealizable. A more practical raised cosine pulse is proposed, which introduces a rolloff factor to trade off excess bandwidth for slower decay. The full-cosine case provides additional zero-crossings that aid synchronization but doubles the bandwidth.
The document discusses three main methods for generating single-sideband suppressed carrier (SSB-SC) signals: the filter method, phase shift method, and Weaver method. The filter method uses a balanced modulator followed by a filter to remove the unwanted sideband. The phase shift method uses two balanced modulators with one audio input phase shifted 90 degrees. The Weaver method uses four balanced modulators, two audio filters, and two 90 degree phase shifters to generate the SSB signal without a filter or complex phase shifter.
This document discusses multirate digital signal processing. It explains that multirate systems use multiple sampling rates to process digital signals. Common operations in multirate systems are decimation, which decreases the sampling rate, and interpolation, which increases it. Decimation and interpolation can be realized through filtering and downsampling/upsampling. The document also provides examples of multirate applications like digital audio conversion and discusses tools like polyphase filters used in multirate signal processing.
The document discusses the instrumentation amplifier (IA). It begins by introducing the IA, noting its high input impedance, precisely adjustable gain using a single resistor, and high common mode rejection. It then describes the two stages of an IA: the first offers high input impedance and sets the gain, while the second is a differential amplifier with feedback and grounding that offers very high input impedance. Applications discussed include using a thermistor in a bridge circuit with an IA to indicate temperature.
This document discusses adaptive equalization techniques used in wireless communications. It begins by describing different types of interference such as co-channel, adjacent channel, and inter-symbol interference that affect wireless transmissions. Equalization is introduced as a technique to counter inter-symbol interference by concentrating dispersed symbol energy back into its time interval. Adaptive equalization is specifically discussed as it can track time-varying mobile channel characteristics using algorithms like zero forcing, least mean squares, and recursive least squares. The key components of an adaptive equalizer including its operating modes in training and tracking are also outlined.
This document discusses the basics of differential amplifiers. It defines differential amplifiers as circuits that amplify the difference between two input signals. It describes the differential gain, common mode gain, and common mode rejection ratio of differential amplifiers. It also outlines the four main configurations that differential amplifiers can have: dual input balanced output, dual input unbalanced output, single input balanced output, and single input unbalanced output. The document is intended as an introduction to differential amplifiers.
Signal and System, CT Signal DT Signal, Signal Processing(amplitude and time ...Waqas Afzal
Signal and System(definitions)
Continuous-Time Signal
Discrete-Time Signal
Signal Processing
Basic Elements of Signal Processing
Classification of Signals
Basic Signal Operations(amplitude and time scaling)
The document discusses discrete Fourier series, discrete Fourier transform, and discrete time Fourier transform. It provides definitions and explanations of each topic. Discrete Fourier series represents periodic discrete-time signals using a summation of sines and cosines. The discrete Fourier transform analyzes a finite-duration discrete signal by treating it as an excerpt from an infinite periodic signal. The discrete time Fourier transform provides a frequency-domain representation of discrete-time signals and is useful for analyzing samples of continuous functions. Examples of applications are also given such as signal processing, image analysis, and wireless communications.
This document provides an introduction to digital signal processors (DSPs). It outlines the historical development of DSPs, from early transistor-based processors in the 1970s to modern 4th generation DSPs with specialized instruction sets and architectures. The document also discusses the large and growing DSP market, the internal architecture of DSPs including Harvard architecture and multiply-accumulate functions, and applications of DSPs such as automotive, communications, consumer electronics, and more. Examples of DSP applications in music processing are also provided.
A signal is a pattern of variation that carry information.
Signals are represented mathematically as a function of one or more independent variable
basic concept of signals
types of signals
system concepts
This document discusses key characteristics and concepts related to radio receivers. It covers sensitivity, selectivity, fidelity, noise figure, image frequency rejection, double spotting, tracking and alignment. Sensitivity refers to a receiver's ability to amplify weak signals and is determined by factors like noise power, receiver noise figure, and amplifier gain. Selectivity is a receiver's ability to differentiate the desired signal from unwanted signals, and depends on tuned circuit quality factor. Fidelity measures how accurately a receiver can reproduce the original signal. Noise figure is the ratio of input signal-to-noise ratio to output signal-to-noise ratio. Image frequency rejection and tracking/alignment are also summarized.
ECG Signal Denoising using Digital Filter and Adaptive FilterIRJET Journal
1. The document discusses methods for denoising electrocardiogram (ECG) signals, including digital filters and adaptive filters.
2. It evaluates the performance of Savitzky-Golay filters, band pass filters, and adaptive noise cancellation techniques for removing noise from ECG signals and improving the signal-to-noise ratio.
3. The key filters discussed are Savitzky-Golay filters, Tompkins filters, Butterworth band pass filters, and least mean square adaptive filters, analyzing their ability to reduce noise like powerline interference, baseline drift, and motion artifacts from ECG data.
Electrocardiography is a medical topic that has piqued engineers' curiosity. One of the most essential signals observed in heart patients is the electrocardiogram (ECG). The electrocardiogram, or ECG, is an extremely valuable medical device. The objective of an ECG is to assist clinicians in quickly diagnosing human or animal heart activity and detecting aberrant heart activities. The heart's job is to contract rhythmically, pump blood to the lungs for oxygenation, and then return this oxygenated blood to the rest of the body. The spread of electrical signals created by the heart pacemaker, the Sinoatrial (SA) node, maintains and signals this precise rhythm. Detecting such electrical activity in the heart can aid in the detection of a variety of cardiac problems
Orthogonal Frequency Division Multiplexing (OFDM)Gagan Randhawa
The document discusses Orthogonal Frequency Division Multiplexing (OFDM), including its principles, advantages, disadvantages and applications. OFDM divides the available spectrum into multiple orthogonal subcarriers, each modulated with a low data rate stream. This makes OFDM robust to multipath fading and intersymbol interference. While OFDM provides high data rates and spectral efficiency, it suffers from issues like high peak-to-average power ratio and sensitivity to frequency errors. OFDM is used in technologies like WiFi, WiMAX and digital audio/video broadcasting.
Comparator circuits compare two input voltages and produce a logic output signal that is high or low depending on which input is larger. Real comparators do not have an abrupt transition and have very high voltage gain in the transition region. Comparators are often used as interfaces between analog and digital circuits by converting analog signals to logic levels. Open-collector outputs are useful for this by producing either 0V or the supply voltage at their outputs. Schmitt triggers, which are comparators with positive feedback, are commonly used as they introduce hysteresis which helps eliminate unwanted output transitions from noise.
Digital signal processing involves the analysis, interpretation, and manipulation of signals such as sound, images, and sensor data. It represents analog waveforms as discrete numeric values by sampling the waveform at regular intervals. There are two categories of signal processing: analog and digital. Digital signal processing has advantages over analog like greater noise immunity, multi-directional transmission, security, and smaller size. It has applications in areas like digital filtering, video and audio compression, speech processing, image processing, and radar/sonar processing.
This document discusses vestigial sideband (VSB) modulation. VSB modulation is a compromise between single sideband (SSB) and double sideband suppressed carrier (DSB-SC) modulation that overcomes some of the drawbacks of SSB. In VSB, one sideband and a vestige of the other sideband are transmitted together, requiring less bandwidth than DSB but more than SSB. VSB modulation is commonly used for television signal transmission to reduce the bandwidth requirement compared to DSB.
DSP Applications in medical field:Hearing aid, ECG, Blood pressure monitor.
Noise filtering,Fast fourier transform and Bandpass & FIR filter on matlab.
The document discusses equalization techniques used to mitigate inter-symbol interference (ISI) in digital communication systems. Equalization aims to remove ISI and noise effects from the channel. It is located at the receiver and uses techniques like linear equalizers, decision feedback equalization, and maximum likelihood sequence estimation to estimate the channel response and minimize the error between transmitted and received symbols while balancing noise. As the wireless channel changes over time, adaptive equalization is used where the equalizer periodically trains and tracks the changing channel response.
This presentation provides an overview of digital signal processing (DSP). It defines key terms like signal and signal processing and explains the basic principles and components of DSP systems. The presentation notes that DSP has advantages over analog processing like accuracy, flexibility, and ease of operation. It provides examples of DSP applications in areas like audio, communications, biomedicine, and more. In conclusion, the presentation emphasizes that DSP involves manipulating digital numbers using programmed instructions and is widely used in modern applications.
This document provides an overview of decimation and interpolation in multirate signal processing. It discusses downsampling by an integer factor M, which reduces the sampling rate by taking every M-th sample and discarding the rest. Downsampling can cause aliasing if the signal is not bandlimited, so a low-pass filter is used beforehand. The document also covers properties like linearity and time-variance, identities for cascading systems, and polyphase decomposition to more efficiently implement decimation filters when the number of coefficients is a multiple of the decimation factor. Examples and illustrations are provided using MATLAB code.
This document discusses Nyquist's criterion for distortionless transmission of binary signals over a baseband channel. It states that intersymbol interference (ISI) can be eliminated by choosing a transmit filter response P(f) that satisfies the Nyquist criterion. An ideal rectangular pulse shape meets the criterion but is physically unrealizable. A more practical raised cosine pulse is proposed, which introduces a rolloff factor to trade off excess bandwidth for slower decay. The full-cosine case provides additional zero-crossings that aid synchronization but doubles the bandwidth.
The document discusses three main methods for generating single-sideband suppressed carrier (SSB-SC) signals: the filter method, phase shift method, and Weaver method. The filter method uses a balanced modulator followed by a filter to remove the unwanted sideband. The phase shift method uses two balanced modulators with one audio input phase shifted 90 degrees. The Weaver method uses four balanced modulators, two audio filters, and two 90 degree phase shifters to generate the SSB signal without a filter or complex phase shifter.
This document discusses multirate digital signal processing. It explains that multirate systems use multiple sampling rates to process digital signals. Common operations in multirate systems are decimation, which decreases the sampling rate, and interpolation, which increases it. Decimation and interpolation can be realized through filtering and downsampling/upsampling. The document also provides examples of multirate applications like digital audio conversion and discusses tools like polyphase filters used in multirate signal processing.
The document discusses the instrumentation amplifier (IA). It begins by introducing the IA, noting its high input impedance, precisely adjustable gain using a single resistor, and high common mode rejection. It then describes the two stages of an IA: the first offers high input impedance and sets the gain, while the second is a differential amplifier with feedback and grounding that offers very high input impedance. Applications discussed include using a thermistor in a bridge circuit with an IA to indicate temperature.
This document discusses adaptive equalization techniques used in wireless communications. It begins by describing different types of interference such as co-channel, adjacent channel, and inter-symbol interference that affect wireless transmissions. Equalization is introduced as a technique to counter inter-symbol interference by concentrating dispersed symbol energy back into its time interval. Adaptive equalization is specifically discussed as it can track time-varying mobile channel characteristics using algorithms like zero forcing, least mean squares, and recursive least squares. The key components of an adaptive equalizer including its operating modes in training and tracking are also outlined.
This document discusses the basics of differential amplifiers. It defines differential amplifiers as circuits that amplify the difference between two input signals. It describes the differential gain, common mode gain, and common mode rejection ratio of differential amplifiers. It also outlines the four main configurations that differential amplifiers can have: dual input balanced output, dual input unbalanced output, single input balanced output, and single input unbalanced output. The document is intended as an introduction to differential amplifiers.
Signal and System, CT Signal DT Signal, Signal Processing(amplitude and time ...Waqas Afzal
Signal and System(definitions)
Continuous-Time Signal
Discrete-Time Signal
Signal Processing
Basic Elements of Signal Processing
Classification of Signals
Basic Signal Operations(amplitude and time scaling)
The document discusses discrete Fourier series, discrete Fourier transform, and discrete time Fourier transform. It provides definitions and explanations of each topic. Discrete Fourier series represents periodic discrete-time signals using a summation of sines and cosines. The discrete Fourier transform analyzes a finite-duration discrete signal by treating it as an excerpt from an infinite periodic signal. The discrete time Fourier transform provides a frequency-domain representation of discrete-time signals and is useful for analyzing samples of continuous functions. Examples of applications are also given such as signal processing, image analysis, and wireless communications.
This document provides an introduction to digital signal processors (DSPs). It outlines the historical development of DSPs, from early transistor-based processors in the 1970s to modern 4th generation DSPs with specialized instruction sets and architectures. The document also discusses the large and growing DSP market, the internal architecture of DSPs including Harvard architecture and multiply-accumulate functions, and applications of DSPs such as automotive, communications, consumer electronics, and more. Examples of DSP applications in music processing are also provided.
A signal is a pattern of variation that carry information.
Signals are represented mathematically as a function of one or more independent variable
basic concept of signals
types of signals
system concepts
This document discusses key characteristics and concepts related to radio receivers. It covers sensitivity, selectivity, fidelity, noise figure, image frequency rejection, double spotting, tracking and alignment. Sensitivity refers to a receiver's ability to amplify weak signals and is determined by factors like noise power, receiver noise figure, and amplifier gain. Selectivity is a receiver's ability to differentiate the desired signal from unwanted signals, and depends on tuned circuit quality factor. Fidelity measures how accurately a receiver can reproduce the original signal. Noise figure is the ratio of input signal-to-noise ratio to output signal-to-noise ratio. Image frequency rejection and tracking/alignment are also summarized.
ECG Signal Denoising using Digital Filter and Adaptive FilterIRJET Journal
1. The document discusses methods for denoising electrocardiogram (ECG) signals, including digital filters and adaptive filters.
2. It evaluates the performance of Savitzky-Golay filters, band pass filters, and adaptive noise cancellation techniques for removing noise from ECG signals and improving the signal-to-noise ratio.
3. The key filters discussed are Savitzky-Golay filters, Tompkins filters, Butterworth band pass filters, and least mean square adaptive filters, analyzing their ability to reduce noise like powerline interference, baseline drift, and motion artifacts from ECG data.
Electrocardiography is a medical topic that has piqued engineers' curiosity. One of the most essential signals observed in heart patients is the electrocardiogram (ECG). The electrocardiogram, or ECG, is an extremely valuable medical device. The objective of an ECG is to assist clinicians in quickly diagnosing human or animal heart activity and detecting aberrant heart activities. The heart's job is to contract rhythmically, pump blood to the lungs for oxygenation, and then return this oxygenated blood to the rest of the body. The spread of electrical signals created by the heart pacemaker, the Sinoatrial (SA) node, maintains and signals this precise rhythm. Detecting such electrical activity in the heart can aid in the detection of a variety of cardiac problems
Amplifiers, filters and digital recording systemsBenjamin Jacob
The document describes the key components of a cardiac electrophysiology (EP) lab, including recording systems, amplifiers, filters, catheters, and other equipment. It discusses the purpose and function of diagnostic and ablation catheters, signal processing components like amplifiers, filters, and A/D conversion. It also covers topics like appropriate gain and filter settings, sources of noise, and the functions of an EP recording system including real-time monitoring, review capabilities, and additional analysis tools.
Technical details of one of the two first color-flow Doppler two- dimensional real-time cardiac ultrasound systems.
Moving blood flow is displayed in color in real time superimposed on a real-time grayscale anatomical image.
The document discusses fundamentals of electronic communications including filters, oscillators, equalizers, and crossovers. It provides details on different types of filters including high pass, low pass, and band pass filters. It also covers topics such as quality factor, bandwidth, cutoff frequency, slope, resonance frequency, and applications of oscillators in receivers, transmitters, and other systems.
A band pass filter allows signals between two specific frequencies to pass through, while blocking signals of other frequencies. To create a passive band pass filter, a low pass filter is connected in series with a high pass filter. This passes a selected range of frequencies while attenuating frequencies outside this range. In this project, the student designs a passive band pass filter with cutoff frequencies of 19 kHz and 39 kHz by using resistors R1 of 83 ohms and R2 of 500 ohms, along with capacitors C1 and C2 both of 0.01 microfarads. The student then tests the filter on different frequencies and charts the output voltages to analyze the filter's performance.
The document discusses the basics of signal processing in polysomnography (PSG) systems from the physiological signals being recorded to their digital representation. It covers topics like: where EEG signals originate from neurons, the analog components like electrodes, amplifiers and filters used to process analog signals, and the digital components like sampling rate and resolution that determine the digital waveform display. The key stages of signal processing from the patient to the PSG tracing are also outlined.
Development of a receiver circuit for medium frequency shift keying signals.inventionjournals
Frequency shift keying (fsk) mode of digital signal information transfer switches between two predetermined frequencies of the carrier wave, either by modulating one sine wave oscillator or by switching between two oscillators.The need for a receiver to decode an fsk signal along the transmitting medium from a digital source code within about 5 kilometer radius for security monitoring of environment informed this work. The design of a receiver circuit at a frequency of 500 kHzfor an input frequency shift keying (fsk) signal from a transmitter is presented. The receiver is to receive an RF signal, amplify it, filter it to remove unwanted signals, and recover the desired base band information. It consists of an amplifier, tuned circuitsand mixers which filters the base-band information. A comparator circuit is incorporated, to detect the digital signal received. The output from the comparators is the digital equivalent of the coded signals sent by the transmitter circuit, and transferred to a microcontroller circuit, to act as a coded signal representing information from the transmitting end. The bode-plot response of the receiver to the incoming signals using a FET tuned circuit, shows that only frequencies above 470kHz, and below 495kHz are allowed to pass through the network with a resonant frequency of 483.553 kHz and a gain of 27.734dB, while others are totally attenuated. The reliability of the designed receiver circuit was evaluated for a 1 year continuous operating period and was found to be 74.7%.Area of application of this work include electronic policing of a defined environment with good success
ADF7021 High Performance Narrowband ISM TransceiverPremier Farnell
The ADF7021 is a narrowband transceiver that operates in the 80-650MHz and 862-940MHz bands. It supports modulation schemes like 2FSK, 3FSK, and 4FSK. The transceiver has a programmable output power from -16dBm to +13dBm. Its receiver sensitivity is -123dBm at 1kbps FSK. It has features like automatic frequency control and a UART/SPI interface for microcontroller interfacing. The document provides details on the ADF7021's block diagram, modulation schemes, and serial interface.
Efficient signal acquisition in multi channel neural systemsAshwath Krishnan
This document summarizes a research paper on developing an efficient multi-channel neural recording system. The system aims to integrate neural recording devices, rapid data analysis to detect seizure onsets, and signal injection to mitigate seizures into an implantable system. Key challenges addressed include scalability, safety standards, power limitations, and noise. The proposed system uses a low-power, low-noise amplifier and second-order delta-sigma ADC per channel, along with a digital FIR filter. Testing showed the system achieves 12% better noise efficiency than prior work, addressing scalability challenges across power, area, and noise.
Biomedical Instrumentation Presentation on Infrared Emitter-Detector and Ardu...Redwan Islam
In this project, we measured human heart rate using IR emitter and detector, Arduino board and some other low cost component. We observed heart rate of some individuals with IR emitter and detector, Arduino Board and Processing 2.0 software, and attached the result in the report. We compared the cost of heart rate monitor that uses IR emitter and detector, and the one that uses pulse sensor.
3.1 structure of a wireless communicaiton linkJAIGANESH SEKAR
The document describes the structure of a wireless communication link. It involves various processes between the transmitter and receiver including source coding, channel coding, modulation, upconversion to radio frequency, propagation over the wireless channel, downconversion to baseband, and decoding. Key components are the analog to digital converter and digital to analog converter, local oscillators, filters, amplifiers, modulators, demodulators, multiplexers, and decoders. The goal is to transmit digital data over an analog wireless channel reliably while accounting for noise and interference.
Automated Traffic Density Detection and Speed MonitoringBharat Biyani
Designed and proposed an RF system to detect speed and traffic density with a RADAR unit in remote areas and to provide real-time monitoring of the traffic density data with a satellite link. Based on calculated parameters, required RF components from real vendors were identified. The system model is then simulated with the obtained parameters in AWR Virtual System Simulator and analyzed nominal and worst case cascaded gain, noise figure, P1dB and OIP3. The general deviation expected in these parameters was determined by performing yield analysis.
This document discusses band pass filters that are constructed using a combination of low pass and high pass filters integrated with operational amplifiers. It provides equations to calculate key filter parameters like resonance frequency, bandwidth, and cutoff frequencies based on resistor and capacitor values. Simulation results show that as the near infrared operating wavelength increases, the filter capacitance increases, resistance decreases, resonance frequency and cutoff frequencies decrease, and gain increases. The document examines these filter characteristics over a wide range of parameters.
The document discusses NF's LI5600 series of lock-in amplifiers. The series includes 4 models - the LI5660, LI5655, LI5650, and LI5645 - which cover frequency ranges from 1 mHz to 11 MHz and have sensitivities down to 10 nV. Key features include simultaneous dual frequency measurements, fractional harmonic measurements, high dynamic reserve up to 100 dB, fast update rates up to 1.5 MS/s, and applications in scanning probe microscopes, terahertz spectroscopy, and other advanced research fields. The lock-in amplifiers provide stable and precise measurement of extremely small alternating signals.
The document discusses sampling a signal using an impulse train. It introduces the impulse train as a theoretical concept consisting of a series of narrow spikes that match the original signal at sampling instants. This allows making an "apples-to-apples" comparison between the original analog signal and the sampled signal. The Fourier transform of the impulse train is a train of Dirac delta functions. Sampling a signal is equivalent to multiplying it with the impulse train. The Fourier transform of the sampled signal is equal to the original Fourier transform multiplied by the Fourier transform of the impulse train.
This document discusses vibration signal filtering. It introduces fast Fourier transforms and digital filtering as two primary methods used today to filter digitized vibration measurement values. It describes the main types of vibration signal filters: low-pass filters which allow low frequencies to pass but block high frequencies; high-pass filters which do the opposite; band-pass filters which allow a band of frequencies between high and low cut-off limits to pass; and band-stop filters which block a band of frequencies. Figures are provided to illustrate how each filter type influences the frequency spectrum of a noise signal.
RLC circuits can be used as filters to selectively pass or block ranges of frequencies. There are four main types of filters: low-pass filters which allow low frequencies to pass and block high frequencies, high-pass filters which do the opposite, band-pass filters which allow a band of frequencies to pass while blocking those outside the band, and band-stop filters which block a band of frequencies while passing others. Each type of filter can be made by different combinations of resistors, inductors and capacitors in series or parallel configurations, with the center frequency and bandwidth determined by the component values. Filters have many applications including use in audio systems, wireless transmitters and receivers, and imaging processing.
This document provides an overview and agenda for an oscilloscope fundamentals workshop. The agenda covers choosing an oscilloscope, probing basics including passive probe compensation and ground lead effects, vertical system components like input coupling and scale, sampling and acquisition concepts like aliasing and rate, horizontal system parameters, trigger systems including runt triggering, and using an oscilloscope for EMI debugging. Hands-on workshops are included to demonstrate various topics like probe compensation, ground loop effects, input coupling, aliasing, display update rate, and using near-field probes for EMI analysis. The goal is to review important oscilloscope concepts and allow participants to experiment with the effects of different settings and probe techniques.
A report on ultrasonic distance measurementitfakash
The document describes an ultrasonic distance meter circuit. It consists of a microcontroller that encodes and transmits ultrasonic pulses via a transmitter. When the pulses reflect off an object, a receiver detects the echo and the microcontroller calculates the distance based on the time elapsed. It displays the measured distance on an LCD screen. The circuit uses various components like a voltage regulator, microcontroller, LCD, buzzer, and ultrasonic transducers to transmit pulses, receive echoes, and determine distances to objects.
This document discusses probabilistic models for inference using Hidden Markov Models (HMM) and Bayesian networks. It provides references on HMM, Bayesian probability, and temporal models. It explains that probabilistic models are needed to handle uncertain knowledge and probabilistic reasoning, unlike logic-based models. The document outlines contents on learning and inference in HMM and Bayesian networks. It discusses uncertainty, Bayesian probability, generative models, inferences in Bayesian networks, and using temporal models like HMM. Mathematical representations of inference in HMM are also presented.
This document defines key terminology related to artificial intelligence, including agent, autonomous robot, blackboard, environment, forward chaining, backward chaining, heuristics, knowledge engineering, percepts, pruning, rule, shell, task, and Turing test. It provides a definition or brief description of each term.
Ridges are elevated areas that are narrow with steep sides and a small, narrow top. They form because of geological processes like erosion or folding and faulting of the Earth's crust. Ridges can occur in mountainous areas and underwater as well as in plains and tablelands across different types of terrain.
Performance appraisal/ assessment in higher educational institutes (HEI)Minakshi Atre
This document outlines assessment criteria and methodology for evaluating the performance of university/college teachers based on their teaching, research, and other academic activities. It provides details on calculating research scores for various publications and academic activities. Key points include:
- Assessment is based on evidence like publications, project sanctions, and student awards.
- Teachers are evaluated on teaching, administrative duties, student guidance, organizing seminars, and research output.
- Research publications are scored based on journal impact factor, with higher impact journals earning more points.
- Guidelines address scoring for joint publications and research supervision.
- The maximum points allowed from categories like invited lectures and policy papers is 30% of the total research score.
This document provides an overview of digital signal processing (DSP) preliminaries. It discusses key topics like sampling, discrete-time signals, the sampling theorem, analog to digital conversion, aliasing, and the relationship between analog and digital frequencies. It also introduces important figures in the development of DSP like Harry Nyquist, Claude Shannon, and Alan Turing. Examples are provided to illustrate the sampling theorem and cases where it guarantees the original analog signal can or cannot be recovered from samples. An overview of a typical DSP block diagram and advantages of DSP over analog signal processing are also presented.
Waltz algorithm in artificial intelligenceMinakshi Atre
The document discusses the Waltz algorithm for constraint satisfaction problems. It presents the algorithm in three parts. Part 1 discusses constraints in search and knowledge representation, and how constraint propagation allows reaching a global solution using local search. It provides an example of line labeling in computer vision. Part 2 discusses how constraints can reduce complexity in perceptual tasks like line drawings. It explains Waltz's labeling scheme and valid junction configurations. Part 3 works through an example of applying Waltz labeling to a pyramid drawing, showing how constraints successively eliminate possible labelings until a unique solution is reached.
The document discusses perception in artificial intelligence. It defines perception as acquiring, interpreting, and organizing sensory information. Perception involves both sensation, where sensors convert signals into data, and higher-level processes that make sense of the data. The document then discusses challenges in perception like abstraction and uncertainty in relations. It also notes perception is influenced by both internal and external factors beyond just signals.
This document discusses search algorithms and problem solving through searching. It begins by defining search problems and representing them using graphs with states as nodes and actions as edges. It then covers uninformed search strategies like breadth-first and depth-first search. Informed search strategies use heuristics to guide the search toward more promising areas of the problem space. Examples of single agent pathfinding problems are given like the traveling salesman problem and Rubik's cube.
The document discusses the composite video signal (CVS) which consists of picture information, blanking pulses, and synchronizing pulses. It provides details on:
1) The CVS contains horizontal and vertical sync pulses to synchronize the transmitter and receiver scanning and blank retrace lines.
2) Blanking pulses are added during the horizontal and vertical retrace intervals to make the retraces invisible.
3) The sync pulses occupy the upper 25% of the signal amplitude while the picture information varies between 10-75% to encode brightness levels.
4) Horizontal sync pulses are added at the end of each line and vertical sync pulses are added after each field is scanned.
The document discusses MPEG-2 video compression. It explains that MPEG-2 builds on MPEG-1 by providing backward compatibility and exploiting both intraframe and interframe redundancies to achieve high compression ratios. It describes how video frames are organized into Groups of Pictures (GOPs) containing I, P, and B frames. The compression steps of discrete cosine transform, weighting, re-quantization, entropy coding, and run length coding are explained. It also discusses how motion compensation of P and B frames further reduces file sizes by only encoding differences between frames.
This document provides an overview of digital television (DTV) standards and technologies. It discusses:
1. The DVB standard architecture and key components like MPEG transport streams.
2. Video and audio coding standards used in DTV like MPEG-1, MPEG-2, MPEG-4, and H.264.
3. The ATSC digital television standard developed in the United States, including its use of 8-VSB modulation, forward error correction techniques, and the "cliff effect" in reception.
Satellite digital audio radio service (SDARS) broadcasts digitally encoded audio entertainment material from orbiting satellites or terrestrial repeaters to receivers. XM uses 12.5MHz of spectrum divided between satellites and repeaters, employing QPSK modulation. Repeaters use COFDM modulation. SDARS provides national coverage and many live radio channels, delivering commercial-free, digital quality audio via satellites stationed above the US and repeaters to enhance coverage. XM and Sirius launched competing satellite radio services in the early 2000s, later merging in 2008 with FCC approval.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Electric vehicle and photovoltaic advanced roles in enhancing the financial p...IJECEIAES
Climate change's impact on the planet forced the United Nations and governments to promote green energies and electric transportation. The deployments of photovoltaic (PV) and electric vehicle (EV) systems gained stronger momentum due to their numerous advantages over fossil fuel types. The advantages go beyond sustainability to reach financial support and stability. The work in this paper introduces the hybrid system between PV and EV to support industrial and commercial plants. This paper covers the theoretical framework of the proposed hybrid system including the required equation to complete the cost analysis when PV and EV are present. In addition, the proposed design diagram which sets the priorities and requirements of the system is presented. The proposed approach allows setup to advance their power stability, especially during power outages. The presented information supports researchers and plant owners to complete the necessary analysis while promoting the deployment of clean energy. The result of a case study that represents a dairy milk farmer supports the theoretical works and highlights its advanced benefits to existing plants. The short return on investment of the proposed approach supports the paper's novelty approach for the sustainable electrical system. In addition, the proposed system allows for an isolated power setup without the need for a transmission line which enhances the safety of the electrical network
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Redefining brain tumor segmentation: a cutting-edge convolutional neural netw...IJECEIAES
Medical image analysis has witnessed significant advancements with deep learning techniques. In the domain of brain tumor segmentation, the ability to
precisely delineate tumor boundaries from magnetic resonance imaging (MRI)
scans holds profound implications for diagnosis. This study presents an ensemble convolutional neural network (CNN) with transfer learning, integrating
the state-of-the-art Deeplabv3+ architecture with the ResNet18 backbone. The
model is rigorously trained and evaluated, exhibiting remarkable performance
metrics, including an impressive global accuracy of 99.286%, a high-class accuracy of 82.191%, a mean intersection over union (IoU) of 79.900%, a weighted
IoU of 98.620%, and a Boundary F1 (BF) score of 83.303%. Notably, a detailed comparative analysis with existing methods showcases the superiority of
our proposed model. These findings underscore the model’s competence in precise brain tumor localization, underscoring its potential to revolutionize medical
image analysis and enhance healthcare outcomes. This research paves the way
for future exploration and optimization of advanced CNN models in medical
imaging, emphasizing addressing false positives and resource efficiency.
ACEP Magazine edition 4th launched on 05.06.2024Rahul
This document provides information about the third edition of the magazine "Sthapatya" published by the Association of Civil Engineers (Practicing) Aurangabad. It includes messages from current and past presidents of ACEP, memories and photos from past ACEP events, information on life time achievement awards given by ACEP, and a technical article on concrete maintenance, repairs and strengthening. The document highlights activities of ACEP and provides a technical educational article for members.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
4. 1. NEED
Many applications require entire range of
frequencies
Not possible for single speaker to handle
Beyond capability of single speaker driver
So we engineers often combine several drivers
such as speaker cones and horns
They cover different range of frequencies resulting
in full audio range
6. 2 WHAT ARE HORN SPEAKERS?
A horn loudspeaker is
a loudspeaker or loudspeaker element which
uses an acoustic horn to increase the overall
efficiency of the driving element(s).
The horn serves to improve the coupling efficiency
between the speaker driver and the air.
10. 3 DESIGNING TWO-BAND DIGITAL CROSSOVER
SYSTEM
Two speaker drivers
Woofers: low frequencies ( 20 Hz to 5kHz)
Sub-woofer: 20 to 200 Hz
Tweeters: high frequencies (2kHz to 20 kHz) can go
high till 10kHz
incoming digital audio signal is split into two bands
by using a low pass filter and a high pass filter in
parallel
Amplification of separated signals
Sending them to corresponding speaker drivers
So the objective is
11. OBJECTIVE IS TO DESIGN LPF AND HPF
objective is to design the low pass filter and the
high pass filter so that their combined frequency
response is flat, while keeping transition as
sharp as possible to prevent audio signal
distortion in the transition frequency range
12. Although traditional crossover systems are
designed using active circuits (analog systems)
or passive circuits, the digital crossover system
provides a cost-effective solution with
programmable ability, flexibility, and high
quality.
14. CHOOSING FILTERS
In the design of this crossover system, one
possibility is to use an FIR filter, since it provides a
linear phase for the audio system
However, an infinite impulse response (IIR) filter
can be an alternative.
Based on the transition band of 800 Hz and the
pass band ripple and stop band attenuation
requirements, the Hamming window is chosen for
both low pass and high pass filters.
We can determine the number of filter taps as 183,
each with a cutoff frequency of 1,000 Hz.
15. frequency responses for the designed lowpass filter
and highpass filter are given in Figure 7.26(a),
and for the lowpass filter, highpass filter, and
combined responses in Figure 7.26(b)
The crossover frequency is 1000 Hz for both the
filters
16. LPF AND HPF : MAGNITUDE RESPONSES
COURTESY: DSP BY LI TAN
19. 60 HZ HUM ELIMINATOR AND HEART
RATE DETECTION USING
ELECTROCARDIOGRAPHY (ECG)
2nd APPLICATION
20. ECG
Electrocardiogram
ECG is a small electrical signal captured from an ECG sensor
ECG signal is produced by the activity of the human heart,
thus
can be used for
heart rate detection,
fetal monitoring,
and diagnostic purposes
Unwanted 60 Hz interference in recorded data
interference comes from
the power line and
includes magnetic induction,
displacement currents in leads or in the body of the patient,
effects from equipment interconnections, and other imperfections
21. ALTHOUGH USING PROPER GROUNDING OR
TWISTED PAIRS MINIMIZES SUCH 60-HZ EFFECTS,
ANOTHER EFFECTIVE CHOICE CAN BE
USE OF A DIGITAL NOTCH FILTER, WHICH
ELIMINATES THE 60-HZ INTERFERENCE WHILE
KEEPING ALL THE OTHER USEFUL INFORMATION
23. HUM NOISE
Corrupted signal is useless without signal
processing
It is sufficient to eliminate the 60-Hz hum frequency
with its second and third harmonics in most
practical applications.
We can complete this by cascading with notch
filters having notch frequencies of 60 Hz, 120 Hz,
and 180 Hz, respectively
26. ECG WAVE
Single pulse of the ECG is depicted in Figure
It’s characterized by five peaks and valleys, labeled P, Q, R, S,
and T.
Highest positive wave is the R wave.
Shortly before and after the R wave are negative waves called Q
wave and S wave.
P wave comes before the Q wave, while the T wave comes after
the S wave.
Q, R, and S waves together are called the QRS complex.
Properties of the QRS complex, with its rate of occurrence and
times, highs, and widths, provide information to cardiologists
concerning various pathological conditions of the heart.
The reciprocal of the time period between R wave peaks (in
milliseconds) multiplied by 60,000 gives the instantaneous heart
rate in beats per minute.
On a modern ECG monitor, the acquired ECG signal is displayed
for diagnostic purposes.
28. a major source of frequent interference is the
electric-power system
Such interference appears on the recorded ECG
data due to
electric-field coupling between the power lines and the
electrocardiograph or patient, which is the cause of the
electrical field surrounding mains power lines
Another cause is magnetic induction in the power line,
whereby current in the power line generates a magnetic
field around the line.
Sometimes, the harmonics of 60-Hz hum exist due to
nonlinear sensor and signal amplifier effects.
If such interference is severe, the recorded ECG data
become useless
29. ECG ENHANCEMENT FOR HEART RATE
DETECTION
To significantly reduce 60-Hz interference, we apply
signal enhancement to the ECG recording system
The 60-Hz hum eliminator removes the 60-Hz
interference and has the capability to reduce its second
harmonic of 120 Hz and its third harmonic of 180 Hz.
The next objective is to detect the heart rate using the
enhanced ECG signal.
We need to remove DC drift and to filter muscle noise,
which may occur at approximately 40 Hz or more.
If we consider the lowest heart rate as 30 beats per
minute, the corresponding frequency is 30/60 = 0.5 Hz.
Choosing the lower cutoff frequency of 0.25 Hz should
be reasonable
30. Thus, a bandpass filter with a passband from 0.25 to 40
Hz (range 0.67– 40 Hz, discussed in Webster [1998]),
either FIR or IIR type, can be designed to reduce such
effects.
The resultant ECG signal is valid only for the detection
of heart rate.
Notice that the ECG signal after bandpass filtering with
a passband from 0.25 to 40 Hz is no longer valid for
general ECG applications, since the original ECG signal
occupies the frequency range from 0.01 to 250 Hz
(diagnostic-quality ECG), as discussed in Carr and
Brown (2001) and Webster (1998).
The enhanced ECG signal from the 60-Hz hum
eliminator can serve for general ECG signal analysis
31. SUMMARIZING THE DESIGN SPECIFICATIONS FOR
THE HEART RATE DETECTION APPLICATION
System outputs: Enhanced ECG signal with 60-Hz
elimination
Processed ECG signal for heart rate detection
60 Hz eliminator:
Harmonics to be removed: 60 Hz (fundamental)
120 Hz (second harmonic) 180 Hz (third harmonic)
3 dB bandwidth for each filter: 4 Hz
Sampling rate: 600 Hz ( 5 times 120 for child)
Notch filter type: Second-order IIR
Design method: Pole-zero placement Band-pass
filter:
32. Passband frequency range: 0.25–40 Hz
Passband ripple: 0.5 dB
Filter type: Chebyshev fourth order
Design method: Bilinear transformation
DSP sampling rate: 600 Hz
46. CD RECORDING
A compact-disc (CD) recording system is described
in Figure
The analog audio signal is sensed from each
microphone and then fed to the anti-aliasing
lowpass filter.
Each filtered audio signal is sampled at the industry
standard rate of 44.1 kilo-samples per second,
quantized, and coded to 16 bits for each digital
sample in each channel.
The two channels are further multiplexed and
encoded, and extra bits are added to provide
information such as playing time and track number
for the listener.
47. The encoded data bits are modulated for storage,
and more synchronized bits are added for
subsequent recovery of sampling frequency.
The modulated signal is then applied to control a
laser beam that illuminates the photosensitive layer
of a rotating glass disc.
When the laser turns on and off, the digital
information is etched onto the photosensitive layer
as a pattern of pits and lands in a spiral track.
This master disc forms the basis for mass
production of the commercial CD from the
thermoplastic material.
48. During playback, as illustrated in Figure, a laser
optically scans the tracks on a CD to produce a
digital signal.
The digital signal is then demodulated.
The demodulated signal is further oversampled by
a factor of 4 to acquire a sampling rate of 176.4 kHz
for each channel and is then passed to the 14-bit
DAC unit.
For the time being, we can consider the
oversampling process as interpolation, that is,
adding three samples between every two original
samples in this case
49. After DAC, the analog signal is sent to the anti-
image analog filter, which is a lowpass filter to
smooth the voltage steps from the DAC unit.
The output from each anti-image filter is fed to its
amplifier and loudspeaker.
The purpose of the oversampling is to relieve the
higher-filter-order requirement for the anti-image
lowpass filter, making the circuit design much
easier and economical
50. Software audio players that play music from CDs,
such as Windows Media Player and RealPlayer,
installed on computer systems, are examples of
DSP applications.
The audio player has many advanced features,
such as a graphical equalizer, which allows users to
change audio with sound effects such as boosting
low-frequency content or emphasizing high-
frequency content to make music sound more
entertaining