electrical and computer engineering science & engineering saturday seminar 23 january, 2010...
TRANSCRIPT
Electrical and Computer Engineering
Science & Engineering Saturday Seminar
23 January, 2010Marinos N. Vouvakis
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.
3Electrical and Computer Engineering
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)
4Electrical and Computer Engineering
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.
5Electrical and Computer Engineering
Science and Engineering
6Electrical and Computer 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
7Electrical and Computer Engineering
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)?
8Electrical and Computer Engineering
Science and EngineeringObservation
Instrumentation
First Principles
Intuition
Science
Engineering
Mathematics
9Electrical and Computer Engineering
Science and Engineering (cont’d)
Science
Engineering
Technology Society
Technology logic = (art/craft)+(knowledge/logic)
Beliefs/behaviors
10Electrical and Computer Engineering
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
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Electrical & Computer Engineering
12Electrical and Computer Engineering
What do Electrical and Computer Engineers do?
13Electrical and 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
14Electrical and Computer Engineering
Inside the iPhone 3G
“Any sufficiently advanced technology is indistinguishable from
magic.”http://en.wikipedia.org/wiki/Arthur_C._Clarke
15Electrical and Computer Engineering
What do Electrical and Computer Engineers do?
16Electrical and Computer Engineering
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
17Electrical and Computer Engineering
Electrical Engineering
Fields & Waves• Electromagnetics• Microwaves/RF• Optics/Photonics• Antennas/Remote Sensing
Electronics• Circuit Analysis• Electronics
Control• Control Theory• Power Systems• Power Electronics
18Electrical and Computer Engineering
Electrical Engineering
Communications• Communication Systems• Wireless Comm.• Antennas/Radio Wave Propagation• Microwaves and RF
Signal Processing• Signals and Systems• Signal Processing & Communications• Image Processing
19Electrical and Computer Engineering
Electrical Engineering
Semiconductor Technologies• Solid State Physics• Nano-electronics
First Transistor: 1947
32nm TRIGATE Transistor: 2005
Microelectronics• VLSI Ckts• Embedded Ckts• Fabrication
TechnologiesPentium processor
20Electrical and Computer Engineering
Computer Engineering
Computer Design• Hardware Organization &
Design• Embedded Systems Systems• Computer Architecture
Computer Programming Software• Algorithms• Computer Graphics
21Electrical and Computer Engineering
Computer Engineering Networking
• Computer Networks & Internet• Cryptography• Trustworthy Computing
Bioengineering• Bio-informatics• Bio-sensors• Bio-electronics
22Electrical and Computer Engineering
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
23Electrical and Computer Engineering
Job Satisfaction: EETIMES Survey
24Electrical and Computer Engineering
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
25Electrical and Computer Engineering
An advanced “engineering” system
ReactReact
Electrical & Computer Engineering Systems
26Electrical and Computer Engineering
Analog Electrical CKTs (Sensing & Power)
ReactReact
27Electrical and Computer Engineering
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
28Electrical and Computer Engineering
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)
29Electrical and Computer Engineering
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
30Electrical and Computer Engineering
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
31Electrical and Computer Engineering
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
32Electrical and Computer Engineering
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)
33Electrical and Computer Engineering
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
34Electrical and Computer Engineering
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
=~
35Electrical and Computer Engineering
Resistors in Practice
Power SuppliesResistive Touch-screenIncandescent Light Bulb
36Electrical and Computer Engineering
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)
37Electrical and Computer Engineering
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
38Electrical and Computer Engineering
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
39Electrical and Computer Engineering
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
40Electrical and Computer Engineering
CKT Components - The Capacitor Capacitor (cont’d)(cont’d)
++++++
__
___
_i(t) electron flow
+ _)( tv
piston spring
Water Model:
CKT Model:
41Electrical and Computer Engineering
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) !!!
42Electrical and Computer Engineering
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
43Electrical and Computer Engineering
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)
44Electrical and Computer Engineering
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
45Electrical and Computer Engineering
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) !!!
46Electrical and Computer Engineering
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:
47Electrical and Computer Engineering
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)!!
48Electrical and Computer Engineering
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
49Electrical and Computer Engineering
Circuit Schematics
connection no connection
R
resistor
+
battery
+_
voltage source
current source
terminals capacitor
V V I
C
inductor
L
ground transistor
wires
50Electrical and Computer Engineering
An Analog CKT SystemHigh-End Sound Amplifier
CKT design
Hardware Implementation
51Electrical and Computer Engineering
Digital Electrical CKTs (Process)
ReactReact
52Electrical and Computer Engineering
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
53Electrical and Computer Engineering
The Digital World
Biological Systems:
Electrical Systems:
54Electrical and Computer Engineering
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)
55Electrical and Computer Engineering
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]
56Electrical and Computer Engineering
Why Digital?
Robust (less susceptible to noise)
Simple (deals with 0s & 1s)
57Electrical and Computer Engineering
Entering and Exiting the Digital World…
58Electrical and Computer Engineering
Entering and Exiting the Digital World… (cont’d)
59Electrical and Computer Engineering
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
60Electrical and Computer Engineering
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
61Electrical and Computer Engineering
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
62Electrical and Computer Engineering
Sampling & Aliasing in Digital Images
63Electrical and Computer Engineering
Example: Digital Audio
processing or storage of digital signal (e.g., MP3)
64Electrical and Computer Engineering
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
65Electrical and Computer Engineering
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
66Electrical and Computer Engineering
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
67Electrical and Computer Engineering
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:
68Electrical and Computer Engineering
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
69Electrical and Computer Engineering
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!
70Electrical and Computer Engineering
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
71Electrical and Computer Engineering
Binary Logic - Logic Gates
72Electrical and Computer Engineering
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
73Electrical and Computer Engineering
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?
74Electrical and Computer Engineering
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
75Electrical and Computer Engineering
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
76Electrical and Computer Engineering
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 (= $$$$$)
77Electrical and Computer Engineering
The Systems Approach(divide and conquer)
78Electrical and Computer Engineering
System - An external view
Inputs
System (Perform Function) Outputs
System: A collection of interacting elements that form an integrated whole
79Electrical and Computer Engineering
Digital Hardware Building Block Hierarchy
Digital system (1)
Circuit board (1-4)
Chip (5-100)
Logic gate (1k-500k)
Transistor (1M-10M)
80Electrical and Computer Engineering
PC Motherboard Level
Processor
I/O bus slots Graphics
Processorinterface
Memory
Disk & USB interfaces
81Electrical and Computer Engineering
Chip Level (Pentium 4 Processor)
82Electrical and Computer Engineering
Logic Gate Level
NAND Gate Chip
83Electrical and Computer Engineering
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
84Electrical and Computer Engineering
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…
85Electrical and Computer Engineering
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
86Electrical and Computer Engineering
Communication CKTs (Sense/React)
ReactReact
87Electrical and Computer Engineering
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)
88Electrical and Computer Engineering
Cell Phones: Inside
front back LCD & keypad
microprocessor flash memory speaker, microphone
89Electrical and Computer Engineering
Cell Phone System
90Electrical and Computer Engineering
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
91Electrical and Computer Engineering
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
92Electrical and Computer Engineering
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
93Electrical and Computer Engineering
Music Signals: Piano
94Electrical and Computer Engineering
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
95Electrical and Computer Engineering
Frequency Spectrum - Music Signals
tttt
ttttx
13cos17.011cos12.09cos5.07cos14.0
5cos5.03cos75.0cos)(
frequency lfundamenta2 f
96Electrical and Computer Engineering
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
97Electrical and Computer Engineering
Modulation
98Electrical and Computer Engineering
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…
99Electrical and Computer Engineering
An advanced RF /microwave system
T/Rswitch
Antenna PA Mixer
LNALO
VCO
DSP/Processor
A/D
PowerSupply
waveguide
Radio Frequency Systems
100Electrical and Computer Engineering
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
101Electrical and Computer Engineering
Cell Phones
Motorola Razr BlackBerry
Apple iPhoneGoogle G1
Frst cell phone 1973 DynaTAC 1983
Sony Ericsson Xperia X1 Nokia N96
102Electrical and Computer Engineering
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
103Electrical and Computer Engineering
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!
104Electrical and Computer Engineering
Cell Phone Tower
Antenna Array
Switching, RF and Power Electronics
105Electrical and Computer Engineering
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]
106Electrical and Computer Engineering
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