ENGR180 COMMUNICATION .pdf

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Copyright 2015 John Olsen - All Rights ReservedCopyright 2015 John Olsen - All Rights Reserved

Engineering 180System Engineering

Dr. John D. Olsen, PEThales-Raytheon Systems LLC

[email protected](Cell) 714.402.3395

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Copyright 2015 John Olsen - All Rights Reserved

Lecture 1Case Study: Communication Systems

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John Olsen IntroductionRetired from Raytheon Corporation. Last Position:Technical Director, Thales-Raytheon Systems LLC.The U.S. operations of the Raytheon-Thalestrans-Atlantic joint venture company.

40 years of engineering and business leadership experience spanningCommunications, Command and Control and Radar systems.

UCLA, Anderson School, Executive Management Program Graduate,January 1997.

USC, Ph.D., Electrical Engineering, June 1978. USC, Engineer, Electrical Engineering, June 1976. USC, MS, Electrical Engineering, January 1975. Newark College of Engineering, BSEE (Summa Cum Laude), June 1973.

BoD INCOSE 1995-1996

President, Greater Los Angeles Chapter, AUSA 2002-2004

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Question?

What comes to your mind with the words

Communications System?

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21st Century Communication System Examples

Cell Phones

Satellite Radio (XM and Sirius)

Satellite TV/HDTV (e.g., DirecTV™, DishNet™)

Internet/World-Wide Web

Blackberry & Smartphones

Voice over IP (VoIP)

Fiber Optics

Google images

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Comm Segment Overview

Objectives:

Illustrate principles of complex system design through communications example

Direct Broadcast Satellite Television (e.g., DirecTV™, DishNet™)

Learn about Communications Technologies that are familiar to you

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Outline – Communications Case Study

Lecture 1 Communication System Introduction andBasicsEvolution of Communications in defense and commercialapplicationsCommunications System DefinitionCommunications ModesElectromagnetic Spectrum & Radio Frequency SpectrumRadio Wave Propagation Loss, Rain Loss, Terrain LossAntennasData Rate and BandwidthAnalog and Digital SignalsLecture 2-4 Communications System EngineeringExample – Direct Broadcast Satellite Television

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Communications Systems – Definition

Provide the capability to transfer

Information(1) between sender(s)

and a distant receiver(s) at the speed

of light(2)

1. Information may be voice, text, facsimile, video,computer-to-computer, sensors, etc.

2. Speed of light = 186,000 miles per second or 3 x 108

meters per second

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Communications System Chronology

1838 Telegraph (Samuel Morse) Wired

1876 Telephone (Alexander Gram Bell) Wired

1895 Marconi “Wireless” Telegraph

1900s Telephones in Cities with Patch Panel Switchboards

1920 Broadcast AM Radio

1948 Television, Black and White

1954 Television, Color (NTSC)

1960 LASER

1960s Broadcast FM Radio

1963 Geo-Synchronous Satellite (SYNCOM)

1969 ARPA Net (UCLA, Leonard Klienrock)

1970s PCM Telephone System, Electronic Switching System

1977 Fiber Optic Communications

1982 International Maritime Satellite (INMARSAT)

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Definition of Communications System

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Time Line for Communication System

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Communications System Chronology (Cont’d)

1980s-1995 Global Positioning System (GPS)

1983 Analog Cell Phones (AMPS)

1994 DirecTVTM

1990s Digital Cell Phones (TDMA, CDMA)

1998 Iridium Satellite Phones

2001 Global Packet Radio System (i.e., Blackberry)

2001-2002 XM and Sirius Satellite radio

2002 Broadcast HD Radio and Broadcast HD TV

2004 HD DirecTV

2000s VoIP (VonageTM, EarthlinkTM, SkypeTM, etc.)

2009 Only Digital Broadcast Television (DTV)

2011 4G (Long Term Evolution) Cellular System

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Military Communications Evolution

1861-1865 Flag Signaling in Civil War (Birth of Army Signal Corps)

1880s Field Telegraph Keys with Rolls of Wire

1900s High Frequency (HF) Radio (Long Distance Morse Code and voice)

1920s Ground to Ground VHF Radios

1940s Airborne UHF radio service

1950s Defense Switched Network

1970s Defense Satellite Communications System (DSCS)

1980s MilStar EHF

1994 Tactical Internet

1990s UHF Follow-on

1990s Global Information GIG; Defense version of WWW

2008 Wideband Gap-Filler Satellite System

2012 Mobile User Objective System (MUOS)

2020+? Tactical Satellite System

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Question?

What would you think would be unique

requirements of a Military or Defense

Communications System?

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Example Military Communication System Requirements

Confidentiality (secrecy, protection from Eavesdropping)

Authentication of source and non-alterable message content (protection from “spoofing”)

Operate without Infrastructure (e.g., Cell towers)

Covert (hid the signal from interception; e.g., Special Op units)

Protection from Direction Finding and Location

Protection from Brut-Force Jamming (Electronic Warfare)

Protection from Sophisticated Attacks – Just like Internet Hackers (called Information Warfare)

Redundancy (no single point of failure)

Are These Requirements Really Unique to the Military vs Commercial?

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Communication Evolution Drivers

Bell Laboratories through 1983 Breakup of ATT

Defense Department (in particular Defense Advanced Research Agency –DARPA)

Telecom and Dot-Com Boom 1980s and 1990s

Bell Labs and the Defense Department led the developments In Communications up to the 1980’, but now the Commercial Telecommunications Industry far out invests the DoD

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Radio Frequency and Wave Length

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System requirements for military communication systems

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Wave Length and Radio Frequency

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Electromagnetic Spectrum

700 600 500 400

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The Radio Frequency (RF) Spectrum

AM Radio

FM Radio

Cell Services GPS

XM Radio

DirecTV

0.3 3 30 300 3,000 30,000 300,000

LF HF VHF UHF SHF EHF

Mega-Cycles per Second (Mega-Hertz, MHz)

Broadcast TV

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Radio Wave Propagation

Free Space Propagation loss = L

PTX = Transmitter Power in WattsAEff = Effective Antenna Area in m2

dm = Distance (radius) in meters = Wavelength in metersG = Antenna Gain

AEff

dm

PTX

PRX PAVE •= AEff

PTX=4dm

2

Watts/m2PAVE =PTX

4d2m

G = 4AEff

2

G

=4dm

2 =

FC

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Radio Frequency (DirecTV)

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Equations for Radio Wave Propagation

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Free Space Propagation Loss


Signal Power Levels are expressed in deci-Bells or dBs; PdB = 10 Log (P)

Propagation Loss in dB = 32.4 + 20Log(dKm) + 20Log (FMHz)

Example: Using the equations above compute the free space propagation loss for a radio signal at 12.5 GHz and for a distance of 40,000 Km. Compute as both a loss number in scientific notation and in deci-Bells

=4dm

2 =

FC

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Exploded View of Broadcast TV Spectrum

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Economic Value of Spectrum

United States 2008 wireless spectrum auction From Wikipedia, the free encyclopedia

The United States 700 MHz FCC wireless spectrum auction, officially known as Auction73,[1] was started by the Federal Communications Commission (FCC) on January 24,2008 for the rights to operate the 700 MHz frequency band in the United States.

Original usage The 700 MHz spectrum was previously used for analog televisionbroadcasting, specifically UHF channels 52 through 69. The FCC has ruled that theswitch to digital television has made these frequencies no longer necessary forbroadcasters, due to the improved spectral efficiency of digital broadcasts

Results of the auction

Auction 73 generally went as planned by telecommunications analysts. In total, Auction 73raised $19.592 billion. Notably, Verizon Wireless and AT&T Mobility togetheraccounted for $16.3 billion of the total revenue.

$>$100 Billion in federal revenues generated since 1993 by FCC spectrum license auctions

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Earth

Communications Modes – 1

Ground Wave

Sky Wave

Examples:CB RadioPRS

Examples:Amateur“Ham” RadioVoice of AmericaBroadcast Radio

AM Broadcast “Clear Channels”

Ionosphere

Radio Waves Refracted Back to Earth

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Airborne Radio

Mobile Radio –Scattering Environment

Cell Base Station Tower

Antenna Tower

Line-of-Sight Microwave

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Economic Value of Spectrum

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Communication Model 1

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Communication Model 2

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Satellite Communications –“SATCOM”– Telecommunications

– DirecTVTM

– XM RadioTM

– IridiumTM

Co-Axial Cable– Cable Television

Twisted Wire Pair– Telephone Local Loop– Digital Subscriber Line (DSL)

Fiber Optic Cable– Backbone of WWW– Coming to Homes (FTTH)

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Key Terms

F = Carrier Frequency of the Signal

B = Bandwidth of the Signal

Note – Bandwidth of Signal Generally < 10% of Carrier Frequency

Information Rate (ie, Data Rate) ~ Bandwidth

ExamplesAM Radio @ 1 MHz 3 KHz BandwidthVHF Radio @ 88 MHz 25 KHz BandwidthUHF Radio at 300 MHz 50 KHz Bandwidth FM Radio (88-108 MHz) 180 KHz BandwidthBroadcast Television (49- 960 MHz) 6 MHz BandwidthCoaxial Cable (e.g., cable TV) ~ 2 GHz Bandwidth Fiber cable of Laser Comm 10 Giga Bits per Second (OC-192)

Note the Radio Frequency Spectrum is a Very Valuable Resource; FCC auctions of Spectrum for Cell service in Major markets have gone for 100’s of Million to 10’s of Billions of Dollars

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Antenna Gain Concept

Antenna Gain refers to the ability to focus the energy ina direction and it is measuredby the Gain “G” relative to an “Isotropic” antenna

Ideal

Real World

3.6º3.6º

100 x 50 = 104/2= 37 dB Gain“Pencil Beam”

Main Lobe 35 dB Gain

1st Side Lobes Down 25 dB;< 1:200th

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Communication Mode 3

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Antenna Examples

Yagi TV Antenna

Reflector

Parabolic Dish

Definition of Parabola

Example DirecTV– Elevation BW 3º

– Azimuth BW 3º

Whip

“Feed” Active Element

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Atmospheric Attenuation of Radio Waves

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Frequency Selection Trade-Space

Propagation Loss ( Increased Range)

Bandwidth (Information Carrying Capacity)

Gain and Directivity for fixed Aperture Area

Electronics (Historically)

Lower Frequencyfavored

Higher Frequencyfavored

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Analog Comm Signals

AM - Information is Carried in the Amplitude of the SignalExamples:

•Broadcast AM Radio•Television Video

FM - Information is Carried in the Frequency of the SignalExamples:

•FM Broadcast Radio•Television Audio

Amplitude Modulation (AM)

Frequency Modulation (FM)

Analog Modulation – Information is embedded onto the carrier signal with a continuous range of values

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Digital Comm Signals

Information is Digital from a fixed and limited “Alphabet”

– Binary (0,1 or -1,+1)

– Octal (0 to 7 or 000, 001, … 111)

Phase-Shift Keying (PSK)

10 1RF Carrier

Frequency

Frequency-Shift Keying (FSK)

0

- Delta F + Delta F

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Advantages of Digital Comm

Perfect Recovery of Signal(noise is not additive with repeaters)For sufficient Signal-to-Noise Ration (SNR)

Powerful Error Control Coding can be utilized

Can Exploit Sophisticated Source Encoding (e.g., MP3, MPEG, JPEG, etc.)

Digital does not degrade slowly like analog – it either works or does not ( steep receiver operating curve) – Example DirecTV

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Why is FM Radio Superior to AM Radio?

Higher Information Bandwidth (20 KHz vs 3 KHz) – High Fidelity

Higher Carrier Bandwidth (200 KHz vs 10 KHz)

FM is more noise immune – Noise Signal Amplitude can be eliminated as only the signal’s frequency variations carry the information

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References

1. Radio – Wikipedia

2. Radio System Design for Telecommunications (1 – 100 GHz) Roger L. Freeman, John Wiley & Sons, 1987

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READING ASSIGNMENTS

For Session 2

1. Review Course Briefings on System Engineering (Dr Kung, Weeks 1-3)

2. Review Communications Background in Comm Lecture 1

3. Web search (eg, Google) and read, DirecTV - Wikipedia

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Copyright 2015 John Olsen - All Rights ReservedCopyright 2015 John Olsen - All Rights


Lecture 2Dr. John D. Olsen, PE

Thales-Raytheon Systems [email protected](Office) 714.446.4299(Cell) 714.402.3395

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Lectures 2Case Study: Communication Systems

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Lecture 1 Communication System Introduction and Basics

Lecture 2 Communications System EngineeringExample – Direct Broadcast Satellite TelevisionOperational Architecture View (OV-1)

“Gate” Briefings for Management Go-ahead

Solving the Key Technical Challenges

Complex Systems Engineering Lessons Learned

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Conceptualizing a Direct Broadcast Satellite Television Service – Operational View (OV-1)

200 Channels of High Quality Digital Television 100 Channels Pay-per-

View

Full CONUS Coverage Higher Reliability than

Cable TV Advanced Anti-Piracy

Security Growth to HDTV

Geo-Stationary Orbit

High Power Satellite “Bus”

DBS Transponders

Small Customer Receiving Antenna

Satellite UpLink & Program Facility Pay per View Billing Link

Telephone

Affordable, User Friendly

User Receiver/Terminal

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Top System Engineering Challenges of DBS Television

Link Power-Bandwidth Budget from Geo-Orbit Satellite to Small User Receiver Antenna

High Data Rate of Digital Television

Electronics Complexity and Cost of User Equipment

How did the team develop a “Balanced” and

Economically Viable System Design?

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Recall from Dr Pao What is System Engineering?

System Engineering is an interdisciplinary, comprehensive approach to solving complex problems and satisfying stakeholder requirements.

Interdisciplinary: team approach (concurrent engineering, integrated product team), broad knowledge

Approach: Not an exact science

Stakeholder requirements: Who are the stakeholders? The requirements are multi-dimensional

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SE Concepts to be demonstrated by DBS Case Study

New Concept Visualization from the Convergence of Multiple Enabling Technologies

Need for Systems Engineers & Architects to Rapidly Assess Broad Input Data into Tradeoffs and Alternative Decisions

Systems-of-Systems Engineering

Iterative Process of Systems Engineering

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What is a Senior Systems Engineer? Architect? Technical Director?John’s View – An Individual with Broad Engineering, Management and Creative

Skills – High Depth X Breadth Product

Engineering Skills

Depth and Breadth of Technical Skills

Engineering, Science or Math formal education

Significant understanding of many disciplines (analysis, hardware, software, electrical design, mechanical design, Industrial engineering/production engineering, specialty engineering, human factors)

Management Skills Leadership

Communications

Customer Understanding

Marketing

Governement and Public Relations

Business and Finance

Visionary – Creativity – Visualize the Possibilities

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Nationwide Subscription Television Service –Functional Baseline

Potential Physical Architectures

1. Cable

2. DBS

3. Aerostat Fleet

Program-

ming

Subscriber

Management

and Billing

DistributionUser/Home

Receiving

and Decoding

Usage

Reporting

Logging

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DBS Management Proposal – Gate 1 (Hypothetical)

John’s 3 Questions to Address

What – Direct Broadcast Satellite Television Service System Developer and Service Provider (ie, a New Line of Business)

How Leverage HS-601 High Power Satellite “Bus,” Military Global

Broadcast Service (GBS) Experience and World’s Leading Provider of Communications Satellites Capabilities

Obtain Pioneer Preference License for the Orbital Slots and Frequency Allocations

Estimated 3 Years to Initial Service Capability; $500M Development Costs

Why – ROI – Project >$1B Business within 3 Years of Operation

“This is the type of Proposal that gets our interest. Proceed to Gate 2.”

circa early 1991

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Gate 2 (Pursue) – Direct Broadcast Satellite Television Business Proposition circa 1991

1. Concept Overview, OV-1

2. Top Level Stakeholder Requirements

3. Initial Business Assessment

4. Investment Cash Flow

5. Risk Assessment

6. Recommendation

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Conceptualizing a Direct Broadcast Satellite Television Service – Operational View (OV-1)

200 Channels of High Quality Digital Television 100 Channels Pay-per-

View

Full CONUS Coverage Higher Reliability than

Cable TV Advanced Anti-Piracy

Security Growth to HDTV

Geo-Stationary Orbit

High Power Satellite “Bus”

DBS Transponders

Small Customer Receiving Antenna

Satellite UpLink & Program Facility Pay per View Billing Link

Telephone

Affordable, User Friendly

User Receiver/Terminal

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Initial Top Level Stakeholder Requirements

HS-601 High Power Satellite Bus 200 Channels of High Quality Digital Television

100 Channels Pay-per-View

Full CONUS Coverage “Dazzling” Picture Quality Small User/Home Antenna Size (<= 18 inches) Small VCR Size “Television Top Box,” Receiver User Receiver Cost – Initial Less than $500 Can be Installed by Homeowner Higher Reliability than Cable TV Advanced Anti-Piracy Security Growth to HDTV Leverage GBS Experience in IIS Division <= 3 years to Develop and IOC (Initial Operational

Capability) Cost to Implement < $2B Maximum Cash Required of $1B

From 10 Ft Dia.

To 18 Inch Dia

*Note - hypothetical

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Gate 2 AsideCommercial Business Perspective - ROI

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Expected Cash Flow* ($M)


Expenditures and Revenue1991 1992 1993 1994 1995 1996 1997 1998 1999

DBS Payload Development (Qty =2) 50 200 200 50Satellite Bus Builds (Qty =2) 50 200 200 50Satellite Launch (Qty =2) 10 40 60 40Facilities and Business Sytems 50 100 100 50Operations 0 0 20 50 75 100 125 125 125Calendar Year Expenditures 160 540 580 240 75 100 125 125 125Cummulative Expenditures 160 700 1280 1520 1595 1695 1820 1945 2070Revenue 0 0 0 150 300 600 1200 2400 4800Cummulative Revenue 0 0 0 150 450 1050 2250 4650 9450Net Cash Flow -160 -700 -1280 -1370 -1145 -645 430 2705 7380

Subscribers by Year 0.25 0.5 1 2 4 8

Cash Flow

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DBS Television Business - Risk Assessment

RISK Current Risk Assessment

Mitigation Strategy Expected Closure Date

Satellite Orbit Slot and Frequencies

Submit Pioneer Preference License in 60 Days

Engage WDC HQ Office in Lobbying Campaign

12 Months

200 Channel Capacity

Create Compression Technology Laboratory

Engage Motion Pictures Experts Group (MPEG)

30 Months

Satellite Prime Power

Develop and Track Detailed Power Budget & Forecast

Form Multidiscipline 6-Sigma Team to Work Budget

9 Months

Satellite Weight Develop and Track Detailed Weight Budget & Forecast

Form Multidiscipline 6-Sigma Team to Work Budget

18 Months

Anti- Piracy Security

Leverage Expertise in Defense Sector of Company

Hire Information Security Experts and Consultants

24 Months

User Receiver/ Decoder Cost

Partner with Commercial Electronics Companies

Moore’s Law

12 Months

User Installation Capable

Design Built-in Set-up Tools

Conduct User Installation Trials

18 Months


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Gate 2 – Direct Broadcast Satellite Television Business Proposition - Recommendations

Continue to Preliminary Design Review and Market & Business Plan Dev. Assign Key Engineering Team to Address Technical Challenges and

Alternatives Assign Key Team to Develop Plan, including schedule, costs, key staffing and risk

identification and mitigation plans

Decisions and Action Items Decision to Go-Forward through PDR and Business Plan Development John Smith will be re-assigned immediately to full time as Program Manager; Dr

Bill Jones reassigned full time as Technical Director Specifically Address Strategic Partnering Plan for Programming and User

Equipment Engineering and functional manager are directed that this project has highest

priority and all support requests from Mr. Smith and Dr. Jones are to be honored Budget is $5M; Report back in 3 months VP Marketing to Enlist Outside Marketing Firm to Independently Assess DBS TV

Price & Feature elasticity Market Size & Revenue Projections Government Relations Director and Staff in Washington DC is directed to give

highest priority to resolving any FCC issues wrt to the DBS Pioneer Preference License

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Geo – Stationary Satellite

EquatorSun

22,250 Miles

DirecTV Satellite is Geo-Stationary at

101º West Longitude

Axis

Geo-Stationary Orbital Plane

Earths Orbit of SunOrbital height is computed using Kepler’s laws of Orbital Motion

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Homework Assignment

Technical Performance Measures (TPM)Define one TPM for each of:DTV System Level

Satellite Subsystem

Receiver Decoder Unit

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References

1. Direct Broadcast Satellite Communications, An MPEG Enabled service, Donald C. Mead. Addison-Wesley Wireless Communications Series, Upper Saddle River, NJ 2000

2. DirecTV - Wikipedia, the free encyclopedia

3. Radio System Design for Telecommunications (1 – 100 GHz), Roger L. Freeman, John Wiley & Sons, 1987

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Lecture 3


[email protected](Office) 714.446.4299(Cell) 714.402.3395

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Lecture 2-4 Communications System EngineeringExample – Direct Broadcast Satellite TelevisionOperational Architecture View (OV-1)




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DBS Radio Frequencies and Orbital Slots

WARC and RARCs Determine RF Frequency Spectrum Allocations – Major meetings every 5 Years WARC – World Administrative Radio Council RARC – Regional Administrative Radio Council (eg, Western Hemisphere is

Region 2)

1977 WARC Allocated Frequencies and Orbital Slots to DBS Orbital Spacing of 9 degrees between Orbital Slot Clusters

1983 RARC Confirmed Allocation for Region 2 Eight Orbital Positions (Full CONUS - 101, 110 and 119 degrees West Longitude) Frequency Allocation 17.3 – 17.8 GHz Uplink; 12.2 – 12.7 GHz Downlink 32 Frequency Channels for each orbital slot @ 24 MHz EIRP maximum 57 dBW

Note – Vision in 1977 and 1983 was each 24 MHz Frequency Channel would support 1 Color Television Channel for total of 32 Color Channels

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Communications Satellite and Transponders

Frequency Translator

Uplink Downlink

Payload Transponders

“Bent Pipe”

Solar Power Arrays

• Uplink has High Signal Power and Gain

• Downlink Determines the Received SNR

17.3-

17.8 GHz12.2-

12.7 GHz

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Frequency Division Multiple Access

Transponders cover one Channel

Guard Band

16 Channels each of 24 Mhz bandwidth times 2 Polarizations

Frequency

Guard band used to control & reduce interference between channels

Frequency Allocation = 500 MHz

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Radio Wave Propagation encore


PTX = Transmitter Power in WattsAEff = Effective Antenna Area in m2

dm = Distance (radius) in meters = Wavelength in metersG = Antenna Gain

AEff

dm

PTX

PRX PAVE •= AEff

PTX=4dm

2

Watts/m2PAVE =PTX

4d2m

G = 4AEff

2

G

=4dm

2 =

FC

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Distance to DBS Satellite*

Satellite to Equator 22,250 Miles or 37,200 Km

Slant Range from Satellite to Receiver for CONUS@ Minimum Elevation (27 degrees North Latitude)

= 38,257 Km

@ Maximum Elevation (54 degrees North Latitude) = 40,324 Km

*Reference 1, Page 35

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Propagation Loss Example Calculation

Using the equations below compute the free space propagation loss for a radio signal at 12.45 GHz and for a distance of 40,324 Km. Compute the propagation loss as a number and in deciBellsPropagation loss = L

=4dm

2 =

FC

Propagation Loss in dB = 32.4 + 20Log(dKm) + 20Log (FMHz)

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Noise = Thermal Noise (K T B)Where:

K = Boltzman’s Constant (1.38 X 10-23 Joules/Degree Kelvin)T = Temperature in Degrees KelvinB = Bandwidth

Communications Range

In dB PRX = PTX + GTX – LP + GRX - LRX

Noise Power Received = NRX = 10 Log (KTB) + Pinterference

Received Signal-to-Noise Ratio (SNR) Power Ratio Determines the Quality of the Received Signal

SNR = PRX - NRX = PTX + GTX - LP + GRX - LRX - 10 Log (KTB) - PInterference

Receiver Operating Curve Determine Performance for a Given SNR (depends on signal modulation technique, including analog or digital)

Transmitter Receiver

Propagation Loss LP

Noise

Interference

GTX GRX

PTX PRX , NRX

If the Signal Propagates Forever in Free Space, then what limits the range?

LRX

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DBS to Home Receiver Link Analysis

Link Element Value Units CommentsEIRP 53 dBw

EIRP maximum 57 dBW by Regional Administrative Radio Council (RARC)

Path Loss at 12.45 GHz -206.45 dBto Continental US (per earlier calculation)

Power at Receiver Antenna -153.45 dBw

Gain of Receiver Dish Antenna 32.355 dB See reference 1, page 37

Power at Receiver -121.1 dBw

KT @ 125 degrees Kelvin -207.6 dBW/HzBoltzman' Constant, 125 degreee Kelvin Sky Temperature

B @ 24 MHz 73.8 dB-Hz

KTB -133.8 dBw

Signal Power to Noise Power Ratio 12.7 dBNote: +3 dB or 15.7 dB for 56 dBw Power Transmitter

What Data Rate and Error Rate Would this SNR Provide?

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Receiver Operating Curves

QPSK Modulation and Error. Correcting Codes. By: Michael DeLucca. Temple University. For : EE 551 Prof James A Brennan. May 7, 2003 ...

DTVCoding Gain

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Need for Link Margin for Rain Attenuation

Reference 1, page 46

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DBS Broadcast Antenna Design –Multi-disciplinary Engineering Elegance


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Basic Digital Communication Link Elements

ChannelEncoder Modulator

RF RF

Demod-ulator

e.g., RS

Encoder

e.g.,FSK, QPSK

Noise

Channel Decoder

Interference

SourceEncoder

e.g., MPEG

Encoder

Information Decoder

Digital Communications Systems Utilize Powerful

Source and Channel Coding Technologies

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Source Channel Coding

Objective to Most Efficiently Represent the Information (Information Theory addresses how to measure the actual information content and theoretical minimum data rate to perfectly represent the data) Eliminate Redundancy

Example - Usually not much has changed from one frame of Video to the next No Data Periods (speech pauses, between Bursts of Data)

Huffman Coding – Variable length “Code-words” are used so that the Information which occurs more frequently are assigned the shorter code words Morse Code Examples

e is assigned . t is - i is . . a is . - n is - . m is - - s is . . . o is - - - h is . . . . b is - . . . x is - . . - q is - - . -

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Source Coding continued

Discussion Questions Is Morse Code optimized for every language that uses the

alphabet?How about Hawaiian?

Run-length CodingCode the length of a string of 1s or 0s1111111100111111111 would be 8 2 9Very effective for facsimile

Discussion –Advantages of variable length code-words?Disadvantages of variable length code-words?

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Digital Video Encoding

30 Frames per Second

Color – Red, Green & Blue Frames

500 “PIXELs” per Scan Line

480 Active Lines

per Frame

Raster Scan or

CCD Readout

500 X 480 Pixels/Frametimes

8 Bits Per Pixel

times

3 Color Frames

times

30 Frames Per Second

=

172.8 MBPS!!!!!

Analog TV

4.2 MHz BW

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Digital Video Compression




480 Active Lines

per Frame

Raster Scan or

CCD Readout

Exploit

• Spatial Redundancy

• Inter-frame Redundancy

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MPEG Video Coding




480 Active Lines

per Frame

Raster Scan or

CCD Readout

Color Transform R, G, B Y, Cr, Cb

Every 15th “I” - Frame

Intra-Frame Coding - Discrete Cosine Transform (8 X 8 blocks)

Quantizer, run-length coding, Huffman Coding

Intermediate “P” and “B” Frames Predictive Coded – Motion Compensation

Compression Ratios 40-60 !!!!

SYSTEM ENGINEERING


11/6/2015

8

SYSTEM ENGINEERING


SYSTEM ENGINEERING


References




11/6/2015

1

SYSTEM ENGINEERING



Lecture 4



SYSTEM ENGINEERING



SYSTEM ENGINEERING








Lecture 4 Comm Case Study Review

11/6/2015

2

SYSTEM ENGINEERING


Channel Error Control Coding

Add Redundancy to Detect and Correct Errors

Error Detection CodeParity Check Code 0110101 0

Detects all single errors and odd number or errors, but cannot detect even number of errors nor correct any errors

Error Correction CodeAdd more redundancy so that you can detect and

correct errors

Example Hamming CodesSingle error 7,4 Hamming code – adds 3 bits of

redundancy to every 4 bits of information

SYSTEM ENGINEERING


Sophisticated Error Correction Codes

Reed- Solomon Codes (non binary channel information)Example 31,15 RS Code: 15 32-ary Symbols + 16 32-ary

Redundancy SymbolsCan correct any pattern of 7 errors or any pattern where 2 x erasures +

# errors < 15

Convolutional CodesConcatenated Codes – codes applied on top of one

anotherTypically Data is First Encoded by Reed Solomon Code

Then Interleaving or spreading-out of the symbols from the same RS code word to mitigate “burst errors”

Then Typically a Convolutional Code is applied before being sent over the channel

SYSTEM ENGINEERING


Receiver Operating Curve for DirecTV

DTVCoding Gain

Coding Gain > 6 dB


11/6/2015

3

SYSTEM ENGINEERING


DBS Vision – Technology Brought Together to Make the Vision Realizable

High Power Satellite Bus 3800 Watts Prime Power

Efficient TWTs and LNAs Close Link to 18’ Antenna

Powerful Error Correction 6 dB Margin for Rain

(but 5-6 transponders for 1 Digital Channel)

MPEG 2 Compression 6-7 Digital Channels per

Transponder

32 Transponders 200+ Digital Channel DBSTelevision System

Economically Viable System!

+

+

+

X=

SYSTEM ENGINEERING


What might be the Major Subsystem Elements and IPTs to Perform the Detailed Design of DBS TV?

DBS TV

System

Solar Cells PropulsionStation

Keeping

Stabaliz-

ationTT&C Antennas

Power

MngmntMechanical

Antennas Transponders Mechanical Reliability Software

Satellite

BusLaunch

Services

DBS

Payload

Digital

Compression

Comm

Analysis Uplink

Ground Station

Program-

mingRegulatory

Liaison

User Receiver

Decoder

MarketingPartnering &

LicensingFacilities

Security

SYSTEM ENGINEERING


DBS Case Study – SE Lessons Learned

The Power of the Breadth of Knowledge Brought to bear by the Experienced SEs and Multi-disciplinary Teams

Business Case Presentation to Executive ManagementComplex Systems Engineering Requires Domain

Knowledge, SE Discipline and CreativitySE Leaders must possess Technical Knowledge,

Customer Understanding, Business Acumen and Leadership Skills

Power of “Back-of-the Envelope” Analyses (rapid analysis, synthesis, evaluation spirals)

Must have Experience to be an Effective Senior SEMoore’s Law What’s cheaper comm or processing?

11/6/2015

4

SYSTEM ENGINEERING


Comm Case Study Recap and Expected Learnings

SYSTEM ENGINEERING


References




11/6/2015

1

SYSTEM ENGINEERING



Lecture 4



SYSTEM ENGINEERING



SYSTEM ENGINEERING








Lecture 4 Comm Case Study Review

11/6/2015

2

SYSTEM ENGINEERING


Channel Error Control Coding

Add Redundancy to Detect and Correct Errors

Error Detection CodeParity Check Code 0110101 0

Detects all single errors and odd number or errors, but cannot detect even number of errors nor correct any errors

Error Correction CodeAdd more redundancy so that you can detect and

correct errors

Example Hamming CodesSingle error 7,4 Hamming code – adds 3 bits of

redundancy to every 4 bits of information

SYSTEM ENGINEERING


Sophisticated Error Correction Codes

Reed- Solomon Codes (non binary channel information)Example 31,15 RS Code: 15 32-ary Symbols + 16 32-ary

Redundancy SymbolsCan correct any pattern of 7 errors or any pattern where 2 x erasures +

# errors < 15

Convolutional CodesConcatenated Codes – codes applied on top of one

anotherTypically Data is First Encoded by Reed Solomon Code

Then Interleaving or spreading-out of the symbols from the same RS code word to mitigate “burst errors”

Then Typically a Convolutional Code is applied before being sent over the channel

SYSTEM ENGINEERING


Receiver Operating Curve for DirecTV

DTVCoding Gain

Coding Gain > 6 dB


11/6/2015

3

SYSTEM ENGINEERING


DBS Vision – Technology Brought Together to Make the Vision Realizable

High Power Satellite Bus 3800 Watts Prime Power

Efficient TWTs and LNAs Close Link to 18’ Antenna

Powerful Error Correction 6 dB Margin for Rain

(but 5-6 transponders for 1 Digital Channel)

MPEG 2 Compression 6-7 Digital Channels per

Transponder

32 Transponders 200+ Digital Channel DBSTelevision System

Economically Viable System!

+

+

+

X=

SYSTEM ENGINEERING


TPMs encore – Flow-down of 200 Channel TPM

System Level200 Channels Full CONUS Coverage600 MBPS @ 10-12 BERPicture Compression Ratio @ Picture “Quality”Availability/Rain Margin

Satellite Level

Power Available to Transmitter, Watts

TWT Transmit Power

Transmitter/Antenna Loss

User Terminal Level

Antenna Gain

Amplifier Gain and Noise Figure

Receiver Losses

Processing Power, GFLOPs

Unit Cost

Development Time

Satellite UpLink & Program Facility

Content for 200 Channels

SYSTEM ENGINEERING


What might be the Major Subsystem Elements and IPTs to Perform the Detailed Design of DBS TV?

DBS TV

System

Solar Cells PropulsionStation

Keeping

Stabaliz-

ationTT&C Antennas

Power

MngmntMechanical

Antennas Transponders Mechanical Reliability Software

Satellite

BusLaunch

Services

DBS

Payload

Digital

Compression

Comm

Analysis Uplink

Ground Station

Program-

mingRegulatory

Liaison

User Receiver

Decoder

MarketingPartnering &

LicensingFacilities

Security

11/6/2015

4

SYSTEM ENGINEERING


DBS Case Study – SE Lessons Learned

The Power of the Breadth of Knowledge Brought to bear by the Experienced SEs and Multi-disciplinary Teams

Business Case Presentation to Executive ManagementComplex Systems Engineering Requires Domain

Knowledge, SE Discipline and CreativitySE Leaders must possess Technical Knowledge,

Customer Understanding, Business Acumen and Leadership Skills

Power of “Back-of-the Envelope” Analyses (rapid analysis, synthesis, evaluation spirals)

Must have Experience to be an Effective Senior SEMoore’s Law What’s cheaper comm or processing?

SYSTEM ENGINEERING


Comm Case Study Recap and Expected Learnings

SYSTEM ENGINEERING


References




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