Electrical and Computer Engineering Science & Engineering Saturday Seminar 23 January, 2010 Marinos...

Electrical and Computer Engineering

Science & Engineering Saturday Seminar

23 January, 2010Marinos N. Vouvakis

[email protected]

Special Thanks to: Baird Soules, Kris Hollot, Maciej Ciesielski, Wayne Burleson,

Pat Kelly, Sandip Kundu, Russ Tessier

What Electrical & Computer Engineering Can

Do for You?

2Electrical and Computer Engineering

Who Am I?

Professional:• Assistant Professor in ECE (5 years at UMass)• Teaching: Electromagnetics, Mathematics, Antennas• Research: Computational Electromagnetics & Antennas

Education:• PhD 2005, The Ohio State University• MS 2002, Arizona State University• Dipl. Ing 1999, Democritus University of Thrace,

Greece Personal:

• Hellenic National, Crete• 33 years old (single)• Favorite Music: Velvet Underground, Slint, Fugazi • Favorite Sport: Basketball• Hobbies: Traditional Greek music, politics, history,

play with my cats.


Seminar Objectives

Why am I doing this? Science vs. Engineering? What is Electrical & Computer Engineering?

• What are major ECE sub-areas?• What are the trends?

A Closer look at some basic concepts ECE:• Analog CKTs (sensing & signals)• Digital (entering the Digital world)• Wireless (the communications revolution)

Demos• Sensing & Transducers (Chris)• Sampling & Bits (Baird, Marinos)


Why am I participation on this Seminar Series?

The Vision• I want to make impact on society.• Engineering is key to a better future

for humans and our environment.

The Problem• Low engineering enrolments nationwide.• Alarming enrolment trends.• Most teachers do not have engineering

background.

A Possible solution• When incoming students are aware about

engineering is, they are likely to choose it.

• Educate teachers about engineering.


Science and Engineering


Science vs. Engineering

Science: Why things happen the way they happen?

Example: Movement of objects (force, friction, etc)

Engineering: Creative problem solving.• More formally: engineering is the

discipline, art and profession of acquiring and applying knowledge to design and implement materials, structures, machines, devices, systems, and processes that realize a desired objective.

Example: Wheel!!

Engineering = applied science


Science vs. Engineering (cont’d)

Remember

Apply

Analyze

Evaluate

Understand

Create

The Taxonomy of Learning

Engineering

Q: Can we have engineering without science (or vise-versa)?


Science and EngineeringObservation

Instrumentation

First Principles

Intuition

Science

Engineering

Mathematics


Science and Engineering (cont’d)

Science

Engineering

Technology Society

Technology logic = (art/craft)+(knowledge/logic)

Beliefs/behaviors


Engineering Grand Challenges*1. Make solar energy economical2. Provide energy from fusion3. Provide access to clean water4. Reverse-engineer the brain5. Advance personalized learning6. Develop carbon sequestration methods7. Engineer the tools of scientific discovery8. Restore and improve urban infrastructure9. Advance health informatics10. Prevent nuclear terror11. Engineer better medicines12. Enhance virtual reality13. Manage the nitrogen cycle14. Secure cyberspace *Source: US. National Academy of Engineering


Electrical & Computer Engineering


What do Electrical and Computer Engineers do?



“Any sufficiently advanced technology is indistinguishable from

magic.”http://en.wikipedia.org/wiki/Arthur_C._Clarke


Inside the iPhone 3G

“Any sufficiently advanced technology is indistinguishable from

magic.”http://en.wikipedia.org/wiki/Arthur_C._Clarke


Electrical and Computer Engineering

“Electrical engineering is an engineering discipline that deals with the study and/or application of electricity, electronics and electro-magnetism.”

“Computer engineering is a discipline that combines elements of both electrical engineering and computer science. Computer engineers are involved in many aspects of computing, from the design of individual microprocessors, personal computers, and supercomputers, to circuit design.”

Easier to understand by exploring example systems


Electrical Engineering

Fields & Waves• Electromagnetics• Microwaves/RF• Optics/Photonics• Antennas/Remote Sensing

Electronics• Circuit Analysis• Electronics

Control• Control Theory• Power Systems• Power Electronics



Communications• Communication Systems• Wireless Comm.• Antennas/Radio Wave Propagation• Microwaves and RF

Signal Processing• Signals and Systems• Signal Processing & Communications• Image Processing



Semiconductor Technologies• Solid State Physics• Nano-electronics

First Transistor: 1947

32nm TRIGATE Transistor: 2005

Microelectronics• VLSI Ckts• Embedded Ckts• Fabrication

TechnologiesPentium processor


Computer Engineering

Computer Design• Hardware Organization &

Design• Embedded Systems Systems• Computer Architecture

Computer Programming Software• Algorithms• Computer Graphics


Computer Engineering Networking

• Computer Networks & Internet• Cryptography• Trustworthy Computing

Bioengineering• Bio-informatics• Bio-sensors• Bio-electronics


EE/CE Salary

In Electrical Engineering salary rises fast with experience• Mobility, Flexibility, Job Satisfaction among highest

Do not focus just on starting salaries EETIMES salary survey 2006


Job Satisfaction: EETIMES Survey


Future ECE Job Prospects* Computer hardware engineers are expected to have employment growth of 4 percent

over the projections decade, for all occupations. Although the use of information technology continues to expand rapidly, the manufacture of computer hardware is expected to be adversely affected by intense foreign competition. As computer and semiconductor manufacturers contract out more of their engineering needs to both domestic and foreign design firms, much of the growth in employment of hardware engineers is expected to take place in the computer systems design and related services industry.

Electrical engineers are expected to have employment growth of 2 percent over the projections decade. Although strong demand for electrical devices including electric power generators, wireless phone transmitters, high-density batteries, and navigation systems should spur job growth, international competition and the use of engineering services performed in other countries will limit employment growth. Electrical engineers working in firms providing engineering expertise and design services to manufacturers should have better job prospects.

Electronics engineers, are expected to experience little to no employment change over the projections decade. Although rising demand for electronic goods including communications equipment, defense-related equipment, medical electronics, and consumer products should continue to increase demand for electronics engineers, foreign competition in electronic products development and the use of engineering services performed in other countries will limit employment growth. Growth is expected to be fastest in service-providing industries particularly in firms that provide engineering and design services.

*Bureau of Labor & Statistics


An advanced “engineering” system

ReactReact

Electrical & Computer Engineering Systems


Analog Electrical CKTs (Sensing & Power)

ReactReact


Charge & Electric Current Each electron carries an electrical charge, q of –1.602x10-19 coulombs [C]

1 [C] = the charge of 6.242x1018 electrons

Current, I or i• flow rate of electrical charge through a conductor or a circuit element

• Unit: ampere [A]. 1A=1C/s• Current-charge relationship: )()( tq

dt

dti


Direct Current (DC) & Alternating Current (AC) DC

• Current that is constant with time• For examples, I=3A or V=12V

AC• Current that varies with time and reverses its direction periodically (sinusoidal)

• For example,

v(t)VP cos 2 ft

Nikola Tesla(1856 – 1943)

Thomas Edison (1847 – 1931)


Water-Model Analogy

We cannot see electric current flowing in a wire

Water-model or fluid-flow analogy helps us visualize the behaviors of electrical circuits and elements

Electric Current = flow of electrical charges

(Water) Current = flow of water molecules Assumptions

• Frictionless pipes• No gravity effect• Incompressible water

i(t)

wire / pipe

cross section


Material Types

Conductors• Electric currents flow easily.• Examples: copper, gold, aluminum…

Insulators• Do not conduct electricity.• Examples: ceramics, plastic, glass, air…

Semiconductors• Sometimes conductors, sometimes insulators• Examples: silicon, germanium• Applications: transistors

Superconductors• Perfect conductors when cooled• Applications: MRI, astronomy


Voltage Voltage

• Measured between two points (terminals)• Energy transferred per unit of charge that flows from one terminal to the other

• Intuitive interpretations: potential difference, water pressure in water model

• Variable: • Unit: volt [V]

Water models• For constant voltage sources• Constant-pressure water pump• Constant-torque motor

Alessandro Volta (1745 – 1827) 21 ,,,),( VVVVtv outin


Rules of Current Flow - Kirchhoff’s Current Law Kirchhoff’s current law (KCL)

• Conservation of electrical currents• The sum of all the currents into a node is zero

• The sum of the currents entering a node equals the sum of the currents leaving a node

N

nn ti

1

0)(

node

1i

2i

3i

0321 iii321 iii

1i

2i

3i

Gustav Kirchhoff

(1824 – 1887)


Rules of Current Flow - Kirchhoff’s Voltage Law Kirchhoff’s voltage law (KVL)

• Conservation of energy• The sum of the voltages around any closed path (loop) is zero

Example

N

nn tv

1

0)(

loop 1 loop 2

1

5

3

9+_

+

+

+_

_3

12

4

+

+

+_

_

_ _

loop 3

09351 :1 Loop VVVV 054123 :2 Loop VVVV

09341231 :3 Loop VVVVVV


CKT Components - The Resistor Resistor

• Electrical component that resists the current flow

• Variable: R [ohm] or

Water models for a resistor

constriction

R R

sponge

R

=~


Resistors in Practice

Power SuppliesResistive Touch-screenIncandescent Light Bulb


Rules of Current Flow - Ohm’s Law

Ohm’s Law

Power dissipated in a resistor

Rtitv )( )(

R

+_

)(tv

)(ti

R

tvRtitvtitp

)()()( )( )(

22

v(t)

i(t)

Georg Ohm(1789 – 1854)


Resistors in Series

1 R+

_

++

+

_

__

)( ti

)( tv1 v

2 v3 v

2 R

3 R)()()()( :KCL 321 titititi

)()()()( :KVL 321 tvtvtvtv

))(()()()()( :Law sOhm' 321321 RRRtiRtiRtiRtitv

+

_

+

_

)( ti

)( tv eqR =

v(t)i(t)Req Req R1 R2 R3


Resistors in Parallel

)()()()( :KCL 321 titititi )()()()( :KVL 321 tvtvtvtv

321321

111)(

)()()()( :Law sOhm'

RRRtv

R

tv

R

tv

R

tvti

+

_

+

_

)( ti

)( tv eqR =

i(t)v(t)

Req

+

_

)( ti

)( tv1 R 2 R 3 R

)( 1 ti )( 2 ti )( 3 ti

Req 1

1 R1 1 R2 1 R3


CKT Components - The CapacitorCapacitor Capacitor & Capacitance

• Stores energy through storing charge • Construction: separating two sheets of conductor by a thin layer of insulator

• Variable: C• Unit: Farad [F]. 1F=1 coulomb per volt

capacitor

C

Michael Faraday (1791-1867)

)()( tCvtq


CKT Components - The Capacitor Capacitor (cont’d)(cont’d)

++++++

__

___

_i(t) electron flow

+ _)( tv

piston spring

Water Model:

CKT Model:


Capacitor Equations

Current:

Voltage:

Energy Stored:

C+_ )( tv

)( ti

t

t

tvdttiC

tv0

)( )(1

)( 0

e(t)1

2Cv2 (t)

i(t)Cdv(t)

dt

MATH (Integration) = CKT (capacitor) !!!


Basic Capacitors ArrangementsBasic Capacitors Arrangements)( ti

+

_

+_)( tv

Ceq C1 C2 C3

+

_

)( ti

)( tv1 C 2 C 3 C

1 i 2 i 3 i

1 C

Parallel:

+

_

++

+

_

__

)( ti

)( tv1 v

2 v3 v

3 C

2 CSeries:

+

_

+_)( tv

1

Ceq

1

C1

1

C2

1

C3


CKT Components - The InductorInductor

• Stores energy through storing magnetic field• Construction: coiling a wire around some type of form

• Variable: L [Henry] or [H]. • When the electric current changes in the coil, it creates a magnetic field around the wire which induces voltage across the coil

+

_

)( tvL

)( tiJoseph Henry (1797-1878)


CKT Components - The Inductor Inductor (cont’d)(cont’d) Operation

• When the electric current changes in the coil, it creates a magnetic field around the wire which induces voltage across the coil

Water model analogy

)()( tidt

dLtv

Bi-directional turbine driving a flywheel

Passive, driven by current; no motor

Momentum


Inductor Equations

Current:

Voltage:

Energy Stored:

)()( tidt

dLtv

t

t

tidttvL

ti0

)( )(1

)( 0

e(t)1

2Li2 (t)

+

_

)( tvL

)( ti

MATH (differentiation) = CKT (inductor) !!!


Basic Inductor ArrangementsBasic Inductor Arrangements)( ti)( ti

1 L+

_

++

+

_

__)( tv

1 v

2 v3 v

3 L

2 L

+

_

)( tv 321 LLLLeq

+

_

)( ti

)( tv1 L 2 L 3 L

)( ti+

_

)( tv321

1111

LLLLeq

Parallel:

Series:


CKT Components - The Transistor Transistor is active component (generates

energy) Controls the flow of currents Construction: combine semiconductor materials

(many different implementations)

The key element in any ECE application

B (base)

C (collector)

E (emitter)

John BareenWalter BrattainWilliam Shockley(1947)

*Julius Edgar Lilienfield (1925)!!


Transistor Operation

Use base voltage to control current flow on collector• Amplification (analog CKTs)• Switching (digital CKTs)

B (base)

C (collector)

E (emitter)amplifierswitch

0

1


Circuit Schematics

connection no connection

R

resistor

+

battery

+_

voltage source

current source

terminals capacitor

V V I

C

inductor

L

ground transistor

wires


An Analog CKT SystemHigh-End Sound Amplifier

CKT design

Hardware Implementation


Digital Electrical CKTs (Process)

ReactReact


The Digital World

Biological Systems:

Electrical Systems:

1 agccccagtc agcgtcacca cgccgtatgt ggaggacatc tcagagccgc ccctgcatga 61 cctctactgc agtaaactgc tggacctggc cttcctgctg gacggctcct ccaagctgtc121 ggaggctgag tttgatgtgc taaaggtctt tgtggtggac atgatggagc ggctgcacat181 ctcccagaag cggatccgtg tggccgtggt ggagtaccac gatggctcgc actcctacat241 cgacctcagg gacaggaagc agccttcgga gctgcggcgc atcgctggtc aggtgaagta

1 01000101 00101011 11010010 11110011 01111000 00101101 61 00111011 00101110 00010000 00000001 10000000 01101111121 10101010 00110111 11000110 01011100 01110001 00111011181 00000000 11011101 01011110 00101111 00010010 10010100241 00101011 01010111 01011110 00101010 10000101 01011010


The Digital World

Biological Systems:

Electrical Systems:


Binary in History

Yin-Yang EmblemPa Kua: Eight Trigrams

Binary exists for thousand of years in ancient Chinese history: yin-yang 8 trigrams 64 hexagrams

G. Leibniz, 1679: formal development of the system of binary arithmetic

G. Leibniz(1646-1716)


Signal, Signals, Signals

Continuous-Amplitude Discrete-Amplitude

Continuous -Time (Space) Local telephone,

cassette-tape recording,photograph telegraph

Discrete -Time (Space)

Switched capacitor filter, speech storage chip, half-tone photography

CD, DVD, cellular phones, digital camera & camcorder

t

x(t)

t

x(t)

n

x[n]

n

x[n]


Why Digital?

Robust (less susceptible to noise)

Simple (deals with 0s & 1s)


Entering and Exiting the Digital World…


Entering and Exiting the Digital World… (cont’d)


Sampling

t

x(t)

t

x(t)

Increases the sampling rate and the amplitude resolution by a factor of 2

t

x(t)^

x̂(t)

t


700Hz

Sampling (cont’d) Sampling rate:

• How fast should we sample? • Fewer samples are needed for a slowly-changing signal. More samples are required for fast-changing signals

• What is the critical sampling rate? Consider the sampling of a simple sinusoid300Hz

Sampling rate: 1000Hz


Sampling (cont’d)

Aliasing • Ambiguity in the reconstruction: 700Hz sinusoid can be mistakenly identified as a 300Hz sinusoid in example

• Generally, aliasing error results from not having enough samples for fast-changing signals

• To avoid aliasing, sample fast enough!

700Hz

Sampling rate increases to: 1400Hz


Sampling & Aliasing in Digital Images


Example: Digital Audio

processing or storage of digital signal (e.g., MP3)


Analog to Digital Recording Chain

• Microphone converts acoustic waves to electrical energy. It’s a transducer.

• Analog signal: continuously varying electrical energy of the sound pressure wave.

• ADC (Analog to Digital Converter) converts analog to digital electrical signal.

• Digital signal: digital representation of signal in binary numbers.

• DAC (Digital to Analog Converter) converts digital signal in computer to analog for your headphones.

ADC


Digital Quantization3-bit quantization: use 3 bits to represent values 0,1,…7

0

1

2

3

4

5

6

7

Amplitude

Measure amplitude at each tick of sample clock

Time

5 6 7 7 5 4 3 1 2 5 7 5 7 4


Decimal-Binary Conversion

Divide the decimal number repeatedly until the quotient is zero. The remainders in reverse order give the number’s equivalent binary form

343/2 171 1

171/2 85 1

85/2 42 1

42/2 21 0

21/2 10 1

10/2 5 0

5/2 2 1

2/2 1 0

1/2 0 1

Quotient Remainder

343 = 10101011110 2

1 x 2 + 0 x 2 + 1 x 2 + 0 x 2 + 1 x 2 + 0 x 2 + 1 x 2 + 1 x 2 + 1 x 2 = 343

8 7 6 5 4

3 2 1 0


The Digital Audio Stream

This is what appears in a sound file, along with a header that indicates the sampling rate, bit depth and other things

Each number is then converted to binary and stored in a register

5 6 7 7 5 4 3 1 2 5 7 5 7 4

101 110 111 111 101 100 101 001 010 101 111 101 111 100

A series of sample numbers, to be interpreted as instantaneous amplitudes • one number for every tick of the sample clockFrom previous example:


Examples of quantization vs. resolution

64x64, 8 bit, 4 kBLower resolution

256x256, 1 bit, 8 kB256x256, 4 bit, 32 kB256x256, 8 bit, 64 kB 256x256, 2 bit, 16 kB


Digital Technology: DVD

Digital Versatile Disc or Digital Video Disc First appeared in the US market in March 1997 Employ the same red laser as in CDs Higher-density multi-layer discs to improve

storage capacity DVD Audio: 192-kHz 24-bit sampling rate!


Digital Technology: DVD

Specification CD DVD

Track Pitch 1600 nm 740 nm

Min. Pit Length 830 nm 400/440 nm

Storage Capacity 780 MB 4.38-15.9 GB


Binary Logic - Logic Gates


Binary Arithmetic - Addition

Addition

Binary Decimal

0+0=0 0+0=0

0+1=1 0+1=1

1+0=1 1+0=1

1+1=10 1+1=2

Simple observation


Binary Arithmetic - Addition (cont’d)

Inputs Outputs

A B Sum Carry

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

Truth Table of Half-Adder

XOR AND

AB

Sum

Carry

What about n-bit inputs?


Principle of Binary Addition

Binary addition• Very similar to decimal addition • Starting from least significant bit (LSB), keep track of partial sum & carry until reaching most significant bit (MSB)

• Simpler than decimal addition: only 0 and 1 are involved

Example1101100

1011101+

carry

1

0

0

0

0

1

1

1

0

1

0

1

1

1

1

LSBMSB

Binary Addition

108

93+

carry

Decimal Addition

201

11


Binary Arithmetic - Addition the Full Adder

We need to add three bits (A, B, and Carry), not two as in the half-adder

This is called a full adder

Inputs Outputs

0 0 0 0 0

0 0 1 1 0

0 1 0 1 0

0 1 1 0 1

1 0 0 1 0

1 0 1 0 1

1 1 0 0 1

1 1 1 1 1

Carry-inCarry-out

Sum

FA

iA iB

iCoC

S

iA iB iC S oC


Binary Arithmetic - the N-bit Full Adder

Ci

A0 B0

S0

A1 B1

S1

A2 B2

S2

A3 B3

S3

A4 B4

S4

A5 B5

S5

A6 B6

S6

A7 B7

S7

Co

S8

first carry in, set to 0 here

last carry out,overflow bit

8-bit Full Adder

CKT = MATH (= $$$$$)


The Systems Approach(divide and conquer)


System - An external view

Inputs

System (Perform Function) Outputs

System: A collection of interacting elements that form an integrated whole


Digital Hardware Building Block Hierarchy

Digital system (1)

Circuit board (1-4)

Chip (5-100)

Logic gate (1k-500k)

Transistor (1M-10M)


PC Motherboard Level

Processor

I/O bus slots Graphics

Processorinterface

Memory

Disk & USB interfaces


Chip Level (Pentium 4 Processor)


Logic Gate Level

NAND Gate Chip


Transistor Level

Uses Polysilicon-Diffusion Capacitance

Cross-section Layout

M1 wordline

Diffusedbit line

Polysilicongate

Polysiliconplate

Capacitor

Metal word line

Poly

SiO2

Field Oxiden+ n+

Inversion layerinduced byplate bias

Poly


Software Software

• Contains instructions for the computer to accomplish certain tasks

• Flexible, easy to modify, copy, and transport Data manipulations

• Arithmetic operations: additions, multiplications, logarithms, trigonometric functions…

• Logic operations: from OR, AND, NOT to complex logic functions…

• Conditional operations: if then else… For ECE research and development

• Matlab, Mathematica, Maple, Mathcad, Labview, Cadence, develop our own software using programming languages such as C++, Java, FORTRAN…


Software Building Block Hierarchy

Assembly code• Most basic low-level programming codes• Different and need to be optimize per processor

type

Operating System (OS)• Set of basic instructions for I/O, file system,

resource sharing, security, graphical user interface (GUI)

• UNIX/Linux, Windows, MS-DOS, MacOS…

High-level programming language• Provide more general, more powerful, more

abstract instructions for the computer• Visual BASIC, FORTRAN, C, C++, Java…

Application• User-friendly software package for popular

applications• Word processors, email & web browser, games…

C++: x++Fortran: x=x+1

UNIX: ls –l rm *.*DOS: dir del *.*

MOV 520 R0ADD R0 R1

WordExplorerSims


Communication CKTs (Sense/React)

ReactReact


Cell Phone A cell phone is a very complex system that can receive input signals in

various forms (electromagnetic waves from base station, sound from microphone, text from key pad) and convert them to several desired types of output signals (sound through speaker, electromagnetic waves to base station, graphics to screen)


Cell Phones: Inside

front back LCD & keypad

microprocessor flash memory speaker, microphone


Cell Phone System


Sound Fundamentals

Sound waves: vibrations of air particles

Fluctuations in air pressure are picked up by the eardrums

Vibrations from the eardrums are then interpreted by the brain as sounds


Harmonics in Music Signals

The spectrum of a single note from a musical instrument usually has a set of peaks at harmonic ratios

If the fundamental frequency is f, there are peaks at f, and also at (about) 2f, 3f, 4f…

Best basis functions to capture speech & music: cosines & sines


Frequency How fast a vibration happens

• High frequency -> fast vibration (voice/music: soprano)• Low frequency -> slow vibration (voice/music: baritone)

The frequency f is the inverse of the period T

Sinusoidal frequency

Units• Period: second (unit of time)• Frequency: 1/sec or hertz [Hz]• Phase: radians

Tf

1

2

1

Tf


Music Signals: Piano


Frequency Spectrum - Audio

f (Hz)0 20k10k

Human Auditory System 20Hz-20kHz

f (Hz)0 20k10k

FM Radio Signals 100Hz-12kHz

f (Hz)0 20k10k

AM Radio Signals 100Hz-5kHz

f (Hz)0 20k10k

Telephone Speech 300Hz-3.5kHz

kHzfkHzf sampling 6.63.3max


Frequency Spectrum - Music Signals

tttt

ttttx

13cos17.011cos12.09cos5.07cos14.0

5cos5.03cos75.0cos)(

frequency lfundamenta2 f


Large size devicesSmall bandwidthSmall antenna gainLarge penetrationSmall resolution

Small size devicesLarge BandwidthLarge antenna gainSmall penetrationLarge resolution

Aeronautical comm120 - 130 MHzMaritime comm157 - 162 MHzVHF wireless, TV169 - 600 MHzCellular phones900, 1800, 2400 MHzDetection of buriedland mines(900 - 2000 MHz)Microwave imaging of tumors1100 - 1200 MHzRadio astronomy1413 MHzMicrowave ovens2400 MHzBluetooth wireless2400 MHzGlobal position sat1600, 1200 MHzAirport appr. radar2700 MHzSatellite weather12 GHzSatellite TV14 GHzSatellite comm20 - 22 GHzAdv. environ. radars37, 98, 220 GHz

c

f

Transmitting & Receiving Information via Electromagnetic

c : speed of lightf : frequency


Modulation


Modulation• Using higher-frequency sinusoids to carry signals

• More efficient transmission & allow multi-user sharing

Pulse modulation

Amplitude modulation

Frequency modulation

Modulation (cont’d)

Morse code, infrared remote control…

AM radio stations,video part of TV signals…

FM radio stations,Cell phones, cordless phones…


An advanced RF /microwave system

T/Rswitch

Antenna PA Mixer

LNALO

VCO

DSP/Processor

A/D

PowerSupply

waveguide

Radio Frequency Systems


Modem Transmission

Frequency-shift keying (FSK)• Uses analog sinusoids of different frequencies to

carry digital signals

0 1 0 0 1

300 3300

frequency1070 1270 2025 2225

ReceiveTransmit

0 1 0 1


Cell Phones

Motorola Razr BlackBerry

Apple iPhoneGoogle G1

Frst cell phone 1973 DynaTAC 1983

Sony Ericsson Xperia X1 Nokia N96


The Cell Approach Cellular telephone

system is based on the principle of radio communication

Coverage area is divided into hexagonal cells (each covers around 10 square miles)

Non-adjacent cells can reuse the same frequencies

Low-power transmitters: both phones & base stations

Each city has a Mobile Telephone Switching Office (MTSO)

Each carrier: 832 radio frequencies

Duplex system: 395 voice channels & 42 control channels

Each cell: 56 voice channels


From Cell to Cell System Identification

(SID) code to check for available service

MTSO uses the control channels to identify where the user is & assign frequencies

MTSO handles the hand-off switching between cells based on signal strengths

Everything happens within seconds or even less!


Cell Phone Tower

Antenna Array

Switching, RF and Power Electronics


What Next?

1. Connect & collaborate with UMass Amherst ECE faculty1. Teacher development grants2. Summer research experience for teachers

2. Recommend exceptional high-school juniors/seniors summer research at UMass.

3. Invite UMass Profs to High-school student seminars.4. M5 Open house for students and Teachers.5. Spread the word to students & colleagues.6. Participate on upcoming ECE SESS(more in-depth).

Marinos N. [email protected]


Disclaimer

Some materials (drawings, figures, text) presented in these slides was obtained from the following web resources:

1.http://images.google.com/imghp?hl=en&tab=wi2.http://www.ecs.umass.edu/ece/engin112/3.http://thanglong.ece.jhu.edu/Course/137/Lectur

es/4.http://www.ecs.umass.edu/public/ece_docs/ECE_3

03_syllabus_S09.pdf5.http://www.nae.edu/6.http://www.bls.gov/oco/ocos027.htm#outlook7.http://www.engtrends.com/IEE/0806D.php8.http://www.eetimes.com/news/latest/

showArticle.jhtml?articleID=206903802

Electrical and Computer Engineering Science & Engineering Saturday Seminar 23 January, 2010 Marinos...

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