Lecture 2Lecture 2Signal Conditioning, Data Acquisition

By Hung NguyenBy Hung NguyenMaritime Engineering and Hydrodynamics

Chapter 2Chapter 2• Learning Outcomes• Learning Outcomes

– pp. 2-3• Contents:

– Signal conditioningSignal conditioning• Amplifier (Operational Amplifier)• Wheatstone bridge circuit• Wheatstone bridge circuit

– Recording, display and indicating devices (self study)(self-study)

– Data acquisition systems (how signals are d i d i i i d i )processed via data acquisition devices)

Chapter 2Chapter 2

• Functions of signal conditioning:– Amplification (weak > strong)p ( g)– Signal modification/conversion

Impedance matching– Impedance matching– Demodulation– Isolation– Filtering (lowpass filter, reconstruction filter)g ( p , )– Linearization

Chapter 2Chapter 2

A lifi• Amplifier:

• Examples (1-2)O ti l A lifi (O A )• Operational Amplifier (Op Amp)

Chapter 2Chapter 2

• Operational Amplifier– -In: inverting inputg p– +In: non-inverting input

V+: pos supply voltage– V+: pos supply voltage– V-: neg supply voltage

Symbolhttp://ourworld.compuserve.com/homepages/Bill_Bowden/opamp.htm

Symbol

Op Ampp p

O A k d Quad• Op Amp: common packages and typical pin-outs

Quad

• 8-pin DIP

http://www.national.com/mpf/LM/LM741.html• Metal Can (TO-5)

http://www.ee.bilkent.edu.tr/~ee411/LM741.pdf

DIP = Dual Inline Package

Op AmpOp AmpOp Amp Tutorial: http://holbert.faculty.asu.edu/ece201/opamp.html

• Op Amp: Ideal Op Amp

EEi

Vout = -AEi

Zin = infinityZout = 0Zout 0A = high

Op AmpOp Amp

• Op Amp: ideal Op Amp

FOUT IN CL IN

RV V A VR

= − = ×OUT INV V=

Common inverting Voltage follower circuit1R OUT IN

Op AmpOp Amp• Op Amp: applications (p 90) Comparator• Op Amp: applications (p.90) PID Controller

Transmitter, S.C., etc.

11

FOUT V

RRV −=

AdditionFlash tutorial on Op Amp:http://holbert faculty asu edu/ece201/opamp html

Addition

http://holbert.faculty.asu.edu/ece201/opamp.html

http://www.youtube.com/watch?v=F0OLkHGcptY Multiplication

Applications of Op AmpApplications of Op Amp• Temperature transmitterTemperature transmitter

Chapter 2Chapter 2

• Summary of operational amplifiers– Amplifying circuitp y g– Non-inverting

Inverting– Inverting– Many applications: addition, multiplication,

diff ti l t t t ltdifferential, comparator, current-to-voltage, voltage-to-current, PID control circuits

Chapter 2Chapter 2• Wheatstone bridge:Wheatstone bridge:• Kirchhoff’s laws

ABCA: V = I1R1 + (I1 – I3)R2ADCA: V = I R + (I + I )RADCA: V = I2R3 + (I2 + I3)R4ABDCA: V = I1R1 + I3R5 + (I2 + I3)R4ADBCA: V = I2R3 – I3R5 + (I1 – I3)R2ABDA: 0 = I1R1 – I3R5 – I2R3ABDA: 0 I1R1 I3R5 I2R3BCDB: 0 = (I1 – I3)R2 – (I2 + I3)R4 – I3R5ABCDA: 0 = I1R1 + (I1 – I3)R2 – (I2 + I3)R4 – I2R3

Chapter 2Chapter 2• Wheatstone bridge:Wheatstone bridge:

• Null (balanced) condition (Vo = 0):i i R i R d• vAB = vAD, i.e. i1R1 = i2R3 and

• vBC = vDC, i.e. i1R2 = i2R4Rx

313211

RR

RR

RiRi

RiRi

=⇔=

• In general424221 RRRiRi

x 4BD

R RV VR R R R

⎛ ⎞= −⎜ ⎟+ +⎝ ⎠1 x 3 4R R R R+ +⎝ ⎠

Chapter 2Chapter 2

• Wheatstone bridge:– Example (p. 2-7): R = 120 Ohms, V = 5 Vp (p ) ,– Determine the Vo when one resistor’s value

changes by 1 2 Ohmschanges by 1.2 Ohms

Chapter 2Chapter 2

• Example: an RTD temp transmitter– RTD resistance at 0oC: RRTD0 = 500ΩRTD0

– R1 = R2 = 500 Ω, R3 used to null (R3 = 500Ω)

RTD resistance at 50oC: R = 625 Ω– RTD resistance at 50oC: RRTD50 = 625 Ω– What is the output voltage?

Chapter 2Chapter 2

• Wheatstone bridge:– Applications: Signal conditioning (temperature pp g g ( p

transmitter)

RTD 4-20 mARTD(Temperature sensor)

Chapter 2Chapter 2• Wheatstone bridge:

– Applications: level transmitter

Chapter 2Chapter 2

• Wheatstone bridge:– Capacitance type of flow meterp yp

Chapter 2Chapter 2

• Wheatstone bridge circuit:– Signal conditioning (with Op Amp)g g ( p p)– Electronic transmitters (level, flow, etc.)

RTD transmitters– RTD transmitters– Strain gauges– Resistance meters (Ohmeters)

Chapter 2Chapter 2• Data acquisition (DAQ):q ( )

Analog WorldDigital World

ActuatorDAC

ProcessAnalog

Process

ADCAnalog

PC/Software DAQ Sensor

ADC

(Digital) (ADC & DAC)Data communication

Chapter 2Chapter 2

• Data acquisition systems (digital)– RS-232– Ethernet

Chapter 2Chapter 2D t i iti t (di it l)• Data acquisition systems (digital)

Chapter 2Chapter 2• Data acquisition systems (digital)• Data acquisition systems (digital)

http://www.masplantiz.com/solutions/sensor-data-acquisition

Chapter 2Chapter 2D t i iti t (di it l)• Data acquisition systems (digital)

http://www.geo-integration.com/products/G001.htm

Chapter 2Chapter 2• Data acquisition systems (digital)Data acquisition systems (digital)

http://www.dynesystems.com/data-acquisition.htm

Chapter 2 (DAQ)Chapter 2 (DAQ)

• National Instruments: PCI 6036E

Sensors Actuators

Chapter 2 (DAQ)Chapter 2 (DAQ)• National Instruments: USB-6009National Instruments: USB 6009

Hardware + Drivers

Software: LabVIEW, MATLAB/SimulinkDrivers MATLAB/SimulinkMS VS

Ch 4: Data acquisitionCh 4: Data acquisition

• National Instruments: USB 6009– Demo

• LabVIEW• SimulinkSimulink

4-20 mA 1-5 V uin

I/E Converter

uin

Ph i l i bl T 0 100 C

USB 6009

Physical variable: Temp 0-100oC

Chapter 2Chapter 2

• Data acquisition – Demo– Simulated temperature measuring system p g y

(Simulink & LabVIEW)– Real RTD temperature transmitterReal RTD temperature transmitter

Chapter 2Chapter 2

• Summary– Signal conditioningg g

• Amplifier – Operational amplifier• Wheatstone bridgeWheatstone bridge• Data acquisition systems (with demos)

Recording indicating devices (self-study)– Recording, indicating devices (self-study)

References Learning resourcesReferences – Learning resources

• Online lecture on DAQ systems:– http://www.youtube.com/watch?v=I 9Pwyxhep y _ y

40&feature=channel• Online lectures on signal conditioning:• Online lectures on signal conditioning:

– http://www.youtube.com/watch?v=MGC2LWeNKSI&f t h lNKSI&feature=channel

– http://www.youtube.com/watch?v=fjP6vamXnDI&feature=channel

Further readingFurther reading

• Johnson:– Chapter 2 Analog signal conditioningp g g g– Chapter 3 Digital signal conditioning

Any Questions?Any Questions?