Signal conditioning Noisy. Key Functions of Signal Conditioning: Amplification Filter  Attenuation  Isolation  Linearization.

Slides:



Advertisements
Similar presentations
Chapter 12 Transformers. Chapter 12 Transformers.
Advertisements

CHAPTER 3: SPECIAL PURPOSE OP-AMP CIRCUITS
Lecture 4: Signal Conditioning
Frequency modulation and circuits
MECHATRONICS SENSORS.
Principles of Telecommunications Technology Chapter 2.
Principles of Electronic Communication Systems
Principles of Telecommunications Technology Chapter 2.
Announcements Troubles with Assignments… –Assignments are 20% of the final grade –Exam questions very similar (30%) Deadline extended to 5pm Fridays, if.
Instrumentation: ground and noise Temperature Measurement.
CMPE 118 MECHATRONICS Introduction to Sensors Or, How the world gets into our programs.
9/29/2004EE 42 fall 2004 lecture 131 Lecture #13 Power supplies, dependent sources, summary of ideal components Reading: Malvino chapter 3, Next:
전자 회로 1 Lecture 1 임한조 아주대학교 전자공학부
Department of Information Engineering357 Operation amplifier The tail, large impedance gives high CMRR Mirror as active load. High gain Follower as buffer.
Example Problem You are measuring the EEG of a patient and accidently choose two different types of electrodes for EEG lead. One of them has a source impedance.
Lecture 101 Capacitors (5.1); Inductors (5.2); LC Combinations (5.3) Prof. Phillips March 7, 2003.
Principles of Electronic Communication Systems
Chapter 6 FM Circuits.
Lecture - 4 Inductance and capacitance equivalent circuits
DC-DC Fundamentals 1.1 An Introduction
Storey: Electrical & Electronic Systems © Pearson Education Limited 2004 OHT 4.1 Actuators  Introduction  Heat Actuators  Light Actuators  Force, Displacement.
Announcements Assignment 3 due now, or by tomorrow 5pm in my mailbox Assignment 4 posted, due next week –Thursday in class, or Friday 5pm in my mailbox.
Content Op-amp Application Introduction Inverting Amplifier
Electrical Fundamentals
ELECTRONICS PRIMER. Assignment: WEB-based Electronics Tutorial Basic definitions Components Ohm's Law LEDs and Transistors Additional electronics tutorials.
Lecture 2 Most basic facts from Electricity needed for understanding telecommunications Local transmission lines in the telephone system Decibels Signals.
Passive components and circuits
ECE 590 Microwave Transmission for Telecommunications Noise and Distortion in Microwave Systems March 18, 25, 2004.
Electromagnetic Induction
Basic Circuit Components
SIGMA-DELTA ADC SD16_A Sigma-Delta ADC Shruthi Sujendra.
1 Fundamentals of Microelectronics  CH1 Why Microelectronics?  CH2 Basic Physics of Semiconductors  CH3 Diode Circuits  CH4 Physics of Bipolar Transistors.
TRANSISTOR TUNED AMPLIFIERS. Inroduction  Sometimes it is desired that an amplifier should amplify either a single frequency or a narrow band of frequencies.
Field Effect Transistor. What is FET FET is abbreviation of Field Effect Transistor. This is a transistor in which current is controlled by voltage only.
Announcements Please read Chapter 3; start on Chapter 6
McGraw-Hill © 2008 The McGraw-Hill Companies, Inc. All rights reserved. Principles of Electronic Communication Systems FM Circuits.
Copyright © 2009 Pearson Education, Inc. Chapter 33 Inductance, Electromagnetic Oscillations, and AC Circuits Part II.
Lecture 9: Modeling Electromechanical Systems 1.Finish purely electrical systems Modeling in the Laplace domain Loading of cascaded elements 2.Modeling.
Introduction to Power Supplies
ABE425 Engineering Measurement Systems Operational Amplifiers (OpAmps) Dr. Tony E. Grift Dept. of Agricultural & Biological Engineering University of Illinois.
Lecture 3: Bridge Circuits
Measurement of High Voltages and Currents In industrial testing and research laboratories, it is essential to measure the voltages and currents accurately,
Lecture 4: Signal Conditioning
Displacement and Motion Measurement
Digital to Analog Converter (DAC)
Grounding.
Basic Circuit Components Name: gohel khushbu dilipbhai. Enrollment no: Subject : Basic electronics Branch : Co(Shift -1)
Signal Conditioning Elements (SCE). 6/13/2016Measurement & Transducers2 1. Voltage dividers Example :Potentiometer circuit.
J.PRAKASH.  The term power quality means different things to different people.  Power quality is the interaction of electronic equipment within the.
Chapter 21 Magnetic Induction and Chapter 22.9: Transformers.
The wireless charge will convert the RF signal at 900MHz frequencies into a DC signal,and then store the power into a mobile battery.
Different Types of Voltage Regulators with Working Principle.
Principles of Electronic Communication Systems. Chapter 6 FM Circuits.
Electric Pressure Transducer
ELECTRONICS PRIMER.
Hartley Oscillator Circuit Theory Working and Application
14.1 Introduction Earlier we noted that capacitors store energy by producing an electric field within a piece of dielectric material Inductors also store.
(3) Signal Conditioning
Basic Circuit Components
INDUSTRIAL ELECTRONICS/ELECTRICITY
Different Types of Transistors and Their Functions
Grounding.
AUTOMATIC STREET LIGHT CONTROL USING LDR
MECH 373 Instrumentation and Measurements
MECH 373 Instrumentation and Measurements
Introduction to electronic communication systems
Amateur Extra Q & A Study Pool
Reading: Malvino chapter 3, Next: 4.10, 5.1, 5.8
Content Op-amp Application Introduction Inverting Amplifier
Biopotential amplifiers
Presentation transcript:

Signal conditioning Noisy

Key Functions of Signal Conditioning: Amplification Filter  Attenuation  Isolation  Linearization

ATTENUATION Attenuation is a general term that refers to any reduction in the strength of a signal. occurs with any type of signal, whether digital or analog. Voltage Divider Most data acquisition system inputs can measure voltages only within a range of 5 to 10 V. Voltages higher than this must be attenuated.

Simplest attenuation circuit V out = V in ( R 2 / R 1 +R 2 ) It is essential that any attenuator or voltage divider is driven from a low impedance source the load (the impedance connected to the output) must be high compared to the divider output impedance. It is generally considered that the signal source should have an impedance of at most 1/10 that of the attenuator, and the load should have an impedance (at least) 10 times the attenuator's output impedance.

There is a need to measure or monitor electrical signals from multiple sensors. So normally they are connected to a multiplexer

However, for multiplexer inputs, the output impedance of a simple voltage divider circuit is much too high For example, consider a 10:1 divider reading 50 V. If a 900 kΩ and a 100 kΩ resistor are chosen to provide a 1 MΩ load to the source, the impedance seen by the analog multiplexer input is about 90 kΩ, still too high for the multiplexed reading to be accurate. When the values are both downsized by a factor of 100 so the output impedance is less than 1 kΩ, but the voltage measurement will be affected as well. Hence, simple attenuation circuit is not practical with multiplexed inputs.

Buffered Voltage Divider The low impedance loading effect of simple voltage dividers can be overcome using unity-gain buffer amplifiers on divider outputs. A dedicated unity-gain buffer has high-input impedance in the MΩ range and does not load down the source, as does the network in the previous example. Moreover, the buffers’ output impedance is extremely low, which is necessary for the multiplexed analog input. An op amp or a transistor serves as an impedance matching buffer to prevent the load from affecting the divider’s output voltage.

ISOLATION Isolated signal conditioning products protect and preserve valuable measurements and control signals, as well as equipment, from the dangerous and degrading effects of noise, transient power surges, internal ground loops, and other hazards present in industrial environments. Methods of Implementing Isolation Isolation requires signals to be transmitted across an isolation barrier without any direct electrical contact. Light-emitting diodes (LEDs), capacitors, and inductors are three commonly available components that allow electrical signal transmission without any direct contact. The principles on which these devices are based form the core of the three most common technologies for isolation – i.optical, ii.capacitive iii.inductive coupling.

Optical Isolation Optical isolation uses an LED along with a photodetector device to transmit signals across an isolation barrier using light as the method of data translation. LEDs produce light when a voltage is applied across them A photodetector receives the light transmitted by the LED and converts it back to the original signal. ADVANTAGE: immunity to electrical and magnetic noise DISADVANTAGE: transmission speed, which is restricted by the LED switching speed, high-power dissipation, and LED wear.

Capacitive Isolation Capacitive isolation is based on an electric field that changes with the level of charge on a capacitor plate. This charge is detected across an isolation barrier and is proportional to the level of the measured signal. ADVANTAGE: immunity to magnetic noise. support faster data transmission rates DISADVANTAGE: capacitive coupling involves the use of electric fields for data transmission, it can be susceptible to interference from external electric fields.

Inductive Coupling Isolation − current through a coil of wire produces a magnetic field. − current can be induced in a second coil by placing it in close vicinity of the changing magnetic field from the first coil. − The voltage and current induced in the second coil depend on the rate of current change through the first. − This principle is called mutual induction and forms the basis of inductive isolation. ADVANTAGE: support faster data transmission rates DISADVANTAGE: susceptible to interference from external magnetic fields. Inductive isolation uses a pair of coils separated by a layer of insulation. Insulation prevents any physical signal transmission Signals can be transmitted by varying current flowing through one of the coils, which causes a similar current to be induced in the second coil across the insulation barrier.

LINEARIZATION Most sensor outputs are non-linear with respect to the applied stimulus. As a result, their outputs must often be linearized in order to yield the correct measurements. For example: Thermocouples, for example, have a nonlinear relationship from input temperature to output voltage Two methods of linearization (can be analog or digital) i.Software linearization ii.Hardware linearization

Basically, it is a process of mapping/linearizing the output from the sensors with the stimulus in order to achieve the correct measurements Plot of voltage versus temperature for three types of thermocouple By taking the slope of these data Plot of nominal Seebeck coefficient versus temperature for three types of thermocouple

An ideal linear thermocouple would have a constant Seebeck coefficient selecting a thermocouple for a particular temperature range, we should choose one whose Seebeck coefficient varies as little as possible over that range For range between 250  C to 500  C Type S has wider range of useful temperature For range between 400  C to 750  C

MID TERM EXAM 30 th March am, venue will be announced later Up until Lecture 5 including the handout notes