Wireless Sensor System Design A Joint Course of the University of South Florida and Tennessee Technological University Spring 2002 Lecture 5 - Systems

Wireless Sensor System Design

A Joint Course of the University of South Florida

and Tennessee Technological University

Spring 2002

Lecture 5 - Systems Engineering / Effective Presentations

Tennessee TechUNIVERSITY

USF EEL 4935/TTU ECE 4720SPECIAL TOPIC: WIRELESS SENSOR SYSTEMS


Weekly Lecture Topics Course Introduction Analog and Digital Modulation Methods (1/11) Fundamentals of Antennas and Propagation (1/18) Signal Processing Techniques (1/25) Microwave Systems: Communications Hardware, Noise, Linearity (2/1) System Test, Evaluation and Documentation / Effective Presentation

Styles (2/8) Preliminary Design Review (student presentations*) (2/15) Microwave Sensor Technology (2/22) @ TTU Modern Wireless Communication Systems (3/1) TBD (3/8) Critical Design Review (student presentations*) (3/22) Microelectromechanical Systems (MEMS) Sensors (4/5) Wireless Sensor System Research (Paul Flikkema from NAU) from USF (4/12) Review / Course Wrap-up (4/19)

* On-site internal reviews/preparation will precede inter-university presentations.



Today’s Tutorial

Systems Engineering What is it? Why is it needed? Answer through example:

Communication Satellites How does this relate to our project?

Design Integration Test Documentation



What is a Communication Satellite?

Repeater in the sky

Two main subsystems: Support functions (BUS) Specific functions

(PAYLOAD)

D/C

AM

P

14 GHz 12 GHz

Note: Full system consists of both space and earth segments



Block Diagram for a Satellite System

s tru c tu res

p ro p u ls ion

p o w er

th e rm a l

co n tro ls

B U S

p a ss ive

a c tive

a n te nna

P A Y L O A D

S a te llite



Block Diagram of Payload Subsystem

f ilte rs

co u p le rs/iso la to rs

sw itch es

w a ve gu ide

P a ssive C o m p o ne n ts

a m p lif ie rslo w -p o w er

d o w n /upco n ve rte rs

a m p lif ie rsh ig h -po w er

A c tive C om p on e n ts

h o rn s/fe e d n e tw o rks

re fle c to rs

s tru c tu res

A n te nn as

P A Y L O A D



Types of Engineers Needed

Numerous disciplines with specialized talents EE

Controls, Electronics, Microwave Devices Antenna, Communications

ME Structures, Dynamics, Thermal

ChemE Propulsion, Fuel Cells



? ? ?

Who understands the BIG PICTURE?



Who understands the BIG PICTURE?

Systems Engineer Broad base / interdisciplinary knowledge Not about knowing all the answers About knowing and asking the right questions Liaison between subsystems and

management/customers



Typical Systems Engineering Problem

Efficiency of 100 W TWTAs are 55 % vs. 60% DC load/unit = 181 W vs. 167 W 14.3 W/unit delta 24 units: 344 W extra

Overall bad situation: Solution 1: Live with it Solution 2: Back-off output power

inDCinRF

outRF

PP

P

__

_



Solution 1: Live with it

s tru c tu res

p ro p u ls ion

p o w er

th e rm a l

co n tro ls

B U S

p a ss ive

a c tive

a n te nna

P A Y L O A D

S a te llite Excess power: needed from solar

panels/batteries




s tru c tu res

p ro p u ls ion

p o w er

th e rm a l

co n tro ls

B U S

p a ss ive

a c tive

a n te nna

P A Y L O A D


panels/batteries dissipated as heat




s tru c tu res

p ro p u ls ion

p o w er

th e rm a l

co n tro ls

B U S

p a ss ive

a c tive

a n te nna

P A Y L O A D



Excess heat: larger heat sinks




s tru c tu res

p ro p u ls ion

p o w er

th e rm a l

co n tro ls

B U S

p a ss ive

a c tive

a n te nna

P A Y L O A D



Excess heat: larger heat sinks larger spacing between

units

Other involved groups: reliability, layout,mass properties, propulsion, launch, etc.



Solution 2: Reduce RF output

s tru c tu res

p ro p u ls ion

p o w er

th e rm a l

co n tro ls

B U S

p a ss ive

a c tive

a n te nna

P A Y L O A D

S a te llite Idea: Don’t impact BUS Back off output from

100 W to 91.8 W -0.4 dB change Could eat all the design

margin! Customer is paying for

EIRP!



Flow top level specifications to subsystems Flow subsystem specs to units Example: EIRP spec of 55 dBW

Repeater 100 W Amplifier: 20.00 dbW Output Losses: -1.50 dB

Antenna Gain: 38.00 dBi Feed Losses/efficiency: -1.00 dB

Margin > 0.50 dB

Systems Design Strategy

Beating specat a cost?



Spec Flow Example Continued

Output Losses -1.50 dB Isolator -0.15 Waveguide* -0.15 *Layout dependent

Switch -0.15 Waveguide* -0.20 Output Filter -0.40 Isolator -0.15 Waveguide* -0.10 Coupler -0.15 Total -1.45 dB

Margin .05 dB

Note: subsystemand unit margins

Known measured value: -0.12 dB



Design Evaluation

Proposal Preliminary Design Review (PDR)

internal and external review of system design, schedule and test plan

results in action items Critical Design Review (CDR)

same, but more of it! Test spec and test results



Testing: Early and Often

1. Unit Level Ambient Test Burn in, Thermal and

Vibration Ambient Test

2. Subsystem Integration & Test Test as sections Test as subsystem

3. System Test Ambient Test Environmental: Thermal

Vac & Vibe Ambient Test

4. In Orbit Payload Test Bus Test

Testing costs $$$ but ensures reliability



What goes in a Specification?

Interface and Performance attributes Physical

Mass Dimensions, Layout

Power DC in Efficiency

Thermal RF and DC dissipation

RF I/O levels Efficiency

Other I/O Telemetry Command Control



Other Documentation

Specifications: Unit Subsystem System Test

Design review packages System Summary Test Data



Systems Engineering on USF/TTU Project

Subsystem Design

System Integration

Design Review

Design for Test

Documentation



TTU and USF Wireless Sensor System

Sensor: Temperature, Light Intensity, Humidity & Location

Data for 12APR02

Time Sensor °C Intensity Humidity1532 26 24 70% 50%1533 14 25 65% 55%1544 29 30 0% 60%… … … … …… … … … …… … … … …

Historical Data:By timeBy sensorBy location

Sensor 14: °C

Date/time

Sensor n

http://www.ece.tntech.edu/472s02/dsp/



How can we ensure it will all work together?

Design Strategy: Break the system into subsystems Break subsystems into components Peer review of design Design for test

Integration Strategy: Test and document individual components Test and document subsystem performance Test and document system level performance

Flow of Spec

PDR/CDR



Example: Design for Test - RF Transmitter

How can component and subsystem performance be determined in the same design? Design board to accommodate both!

X

VCO

BPF

AM

P



Board Layout (AM transmitter)

VC

O

BPF

AM

PXVCO_cntrl

Carrier

Baseband

TX_out

AMP_inMIX_out

Note: other I/O’s areneeded (e.g., power)

BNC connector



VCO Testing

VC

O

BPF

AM

PXVCO_cntrl

Carrier

Baseband

TX_out

AMP_inMIX_out



Mixer Testing

VC

O

BPF

AM

PXVCO_cntrl

Carrier

Baseband

TX_out

AMP_inMIX_out



Modulator Testing

VC

O

BPF

AM

PXVCO_cntrl

Carrier

Baseband

TX_out

AMP_inMIX_out



Subsystem Testing

VC

O

BPF

AM

PXVCO_cntrl

Carrier

Baseband

TX_out

AMP_inMIX_out



Delivered Subsystem

VC

O

BPF

AM

P

X

X X

X

VCO_cntrl

Baseband

TX_out



What goes in our specs?

Interface (I/O) attributes DC

Voltages/Currents Connector type

Baseband Voltages Bandwidth Expected signals Connector type

RF Center frequency Bandwidth/Power Connector type

Other Physical dimensions Anything that might

effect the BIG picture



Wrap Up

Component level performance can effect all other subsystems

Systems engineers understand complex relationships and know what questions to ask

Specs are used to coordinate the efforts of different engineering groups

Design reviews check and double check methodology Test and document early and often!



Bottom Line

Appreciation of the systems engineering approach to developing complex designs.

Reference

G. Gordon and W. Morgan, Principles of Communications Satellites, Wiley, New York, 1993



Technical Presentations

Scenario: 20 minute conference presentation 1 of 6 in your session 150 sessions in a week

You want to make your presentation (out of ~900) memorable!



Technical Presentations

What is meant by “effective”?

You get your message across. What is the problem? Why is it important? What did you do?

Don’t bore your audience.

Motivation to listen



Three Basic Rules

1. Know your audience Be sure everyone understands your motivation Be sure most people get the big picture of what you

are doing Be sure a few people get the details

2. Know your presentation: Practice

3. Leave them wanting more



A True StoryC o n s i d e r t h e u n k n o w n n o n - m a g n e t i c m e d i a t o b e a s t a c k o f h o m o g e n e o u s i s o t r o p i c l o s s y

d i e l e c t r i c l a y e r s . A s s u m e t h a t p r o b i n g a n d m e a s u r i n g r e f l e c t i o n r e s p o n s e i s p e r f o r m e d a t t h e t o p o ft h e m e d i a . T h i s m e t h o d o l o g y i s n o t u n c o m m o n ; e . g . , r a d i o e c h o s o u n d i n g o f g l a c i e r s i s p e r f o r m e di n t h i s m a n n e r . U s i n g t h e h o m o g e n e o u s w a v e e q u a t i o n a s a s t a r t i n g p o i n t , [ 2 ] s h o w e d t h ed e v e l o p m e n t o f a d i s c r e t e - t i m e t w o - c o m p o n e n t w a v e f o r m u l a t i o n f o r E M p r o p a g a t i o n t h r o u g h ah o m o g e n e o u s l o s s y d i e l e c t r i c l a y e r ( 1 ) . E q u a t i o n ( 1 ) d e s c r i b e s t h e r e l a t i o n s h i p b e t w e e n d o w n w a r d

a n d u p w a r d t r a v e l i n g w a v e s { 11 , nn UD } a t t h e t o p o f t h e thn 1 l a y e r t o t h e d o w n w a r d a n d

u p w a r d t r a v e l i n g w a v e s { nn UD , } o f t h e thn l a y e r j u s t a b o v e i t .

n

n

t

t

nn

nn

nnnnn

n

U

D

z

zr

s

srU

Dn

n

0

01

1

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1,

1,

1,1,1

1 ( 1 )

L o s s i n t h e l a y e r i s m o d e l e d b y t h e a s y m m e t r y o f t r a n s f e r c o e f f i c i e n t s )2exp( 11,1, nnnnn ARr

a n d )2exp( 11,1, nnnnn ARs . T h e c u m u l a t i v e l o s s i s g i v e n b y ni iiinA 01 cos ; w h e r e i

i s t h e a t t e n u a t i o n c o e f f i c i e n t , i i s t h e l a y e r t h i c k n e s s a n d i i s t h e a n g l e o f p r o p a g a t i o n i n t h e thi

l a y e r . T h e t i m e f o r w a v e t o p r o p a g a t e t h r o u g h t h e thn l a y e r i s g i v e n b y nnnnt cos .

F o r o u r p u r p o s e , t h e s i g n i f i c a n c e o f ( 1 ) i s t h a t i t i s i d e n t i c a l t o t h a t o f t h e a s y m m e t r i c l a t t i c ef i l t e r f r o m D S P t h e o r y . T h i s f o r m u l a t i o n a l l o w s f o r t h e u s e o f f a s t l a y e r s t r i p p i n g a l g o r i t h m s ( i . e . ,L e v i n s o n o r S c h u r ) t o s o l v e t h e i n v e r s e p r o b l e m a n d t o r e c o n s t r u c t t h e t r a n s f e r ( o r P A R C O R i nD S P ) c o e f f i c i e n t s a s a f u n c t i o n o f t i m e ( o r s p a c e ) . G i v e n a s e t o f c o e f f i c i e n t s , t h e f o r w a r ds c a t t e r i n g p r o b l e m c a n b e s o l v e d b y r u n n i n g t h e a l g o r i t h m s b a c k w a r d s a n d s y n t h e s i z i n g a r e s p o n s e .B o t h p r o b l e m s a r e s o l v e d e x a c t l y , i n c l u d i n g a c c o u n t i n g f o r m u l t i p l e r e f l e c t i o n s .



Slides

Be comfortable with the format (technology) Don’t have too many slides Don’t read your slides! Don’t put too much on your slides

A clear and well-described picture IS worth a thousand words

Use colors and shapes



Traffic Monitoring Sensor - Case Study

900 MHz Signal Relay

Antenna2.45 GHz Hardware20 MHz Hardware

Radar Subsystem Signal Analysis

2.45 GHz

20 MHz

LNA

Coupler

Demodulator

ModulatorAntenna

Signal Conditioning

PhaseDetector

Microwave tower Microwave tower

DAQProcessingWeb Posting

AntennaTransmitterReceiver



Traffic Monitoring Sensor - Case Study

900 MHz Signal Relay

Antenna2.45 GHz Hardware20 MHz Hardware

Radar Subsystem Signal Analysis

2.45 GHz

20 MHz

LNA

Coupler

Demodulator

ModulatorAntenna

Signal Conditioning

PhaseDetector

Microwave tower Microwave tower

DAQProcessingWeb Posting

AntennaTransmitterReceiver



Things Microsoft never told you.

Don’t let gimmicks bog down your presentation content over flash

Make sure the colors are appropriate to the presentation method

Be sure versions are compatible Pre-load and check your files Have a back up!



Another way of looking at things

Personal style – eye contact with audience, speaking with authority, show your own high interest, good posture, etc.

Voice – single tones are only good for RF measurements!

Movement – force the audience to keep their eyes alert, and watch you not just the slides

Time and space – if you don’t spend time on the material why should your audience?

Adjust to audience – are they following you?



Preliminary Design Review - Next Friday (15Feb)

Internal reviews by teams TTU on Wednesday (13Feb) USF on TBD.

TTU will have 30 minutes and USF 15 minutes on Friday. Teams will need to work together to produce a single presentation

for each school.

No formal report is to be written, but all the relevant information should be in the presentation slides (provide hard copy). Design details, specifications, I/O, test and integration schedule Each school should also address the open issues that need to be

resolved so that integration with the other sub-systems can take place.



February Week 4 (28-1)

First progress report Week 5 (4-8)

Review peer reports Week 6 (11-15)

Preliminary Design Review Week 7 (18-22)

Weller at TTU

Two Month Course Schedule

1. All inputs are due on Friday of the specified week - no exceptions2. Reviews of peer reports must be completed before the lecture on Friday

March Week 8 (25-1)

Second progress report Week 9 (4-8)

Review peer reports Spring Break (11-15) Week 10 (18-22)

Critical Design Review Week 11 (25-29)

No TTU class (F)



Anything else?

Documents

Wireless Sensor System Design A Joint Course of the University of South Florida and Tennessee Technological University Spring 2002 Lecture 5 - Systems