S. Mandayam/ ECOMMS/ECE Dept./Rowan University

Electrical Electrical Communications SystemsCommunications Systems

ECE.09.331ECE.09.331 Spring 2007Spring 2007

Shreekanth MandayamECE Department

Rowan University

http://engineering.rowan.edu/~shreek/spring07/ecomms/

Lab 3: Pre-lab InstructionLab 3: Pre-lab Instruction

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

ECOMMS: TopicsECOMMS: Topics

Probability

Inform ation

Entropy

Channel Capacity

Discrete

Pow er & Energy Signals

Continuous Fourier Transform

Discrete Fourier Transform

Baseband and Bandpass Signals

Com plex Envelope

G aussian Noise & SNR

Random VariablesNoise Calculations

Continuous

Signals

AMSw itching M odulator

Envelop Detector

DSB-S CProduct M odulatorCoherent Detector

Costas Loop

SSBW eaver's MethodPhasing M ethod

Frequency M ethod

Frequency & Phase M odulationNarrow band/WidebandVCO & S lope Detector

PLL

Analog

Source EncodingHuffm an codes

Error-control EncodingHam m ing Codes

Sam plingPAM

Q uantizationPCM

Line Encoding

Tim e Division M uxT1 (DS1) Standards

Packet Sw itchingEthernet

ISO 7-Layer Protocol

BasebandCODEC

ASKPSKFSK

BPSK

Q PSK

M -ary PSK

Q AM

BandpassM O DEM

DigitalDigital Com m Transceiver

Systems

Electrical Comm unication Systems

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

PlanPlan• FM Signal and Spectrum

• FM Detection • Slope Detector

• FM Generation• Voltage Controlled Oscillator (VCO)

• Phase Locked Loop (PLL)• FM Detection

• Lab Project 3

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

FM Signal & SpectrumFM Signal & SpectrumSingle-tone FM Signal

Single-tone FM Spectrum

])(2cos[)()(

)()(

)]2sin(2cos[

2

tnffJAts

eJAtg

tftf As(t)

mcn

nc

tnfj

nnc

mfcc

m

0 fc-3fm fc-2fm fc-fm fc fc+fm fc+2fm fc+3fm

|S(f)| / (Ac/2)

f

J0()

J1()

J2()J3()

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

FM DetectionFM DetectionFM Signal,

dttd

tv

dttd

tm

tmtf

tmDftf

dttd

tf

ttft

t As(t)

o

i

fci

i

c

c

)()(

detector FM ideal theofoutput The

)()(

)()(

)(21

)(

)(21

)(

)(2)( where

)](cos[

We need a frequency-voltageconverter

SlopeDetector

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

Slope DetectorSlope Detector

AMDetector

m(t) Freq Inst.

Signal FM

!!Signal! AM

m(t) Amplitude Inst.

(t)m~Frequency-voltage

converterLPF Envelope Detector

|H(f)|

f

t

fi (t)

vo(t)

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

FM GenerationFM Generation

VoltageControlledOscillator

f0=fc

m(t)

ControlVoltage

InstantaneousFrequency

)(21

)( tmDftf fci

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

Oscillators: PrincipleOscillators: Principle

A

SignalSource

Amplifier

FeedbackNetwork

Output+

-

vi

vs vo

AA

v

vA

vAA

v

AvAv

vvAAvv

vv

vvv

i

of

io

io

fsio

of

fsi

1

1

)1(

)(

Barkhausen Criteria for oscillation:

A = -1

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

OscillatorsOscillators

Schmitt Trigger Oscillator

Waveforms

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

Intersil 8038 Precision Waveform Intersil 8038 Precision Waveform Generator/Voltage Controlled OscillatorGenerator/Voltage Controlled Oscillator

v10

t

Vc1

Vc2

Switch Open,C charges

Switch Closed,C discharges

Flip-FlopChanges

State

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

Phase Locked LoopPhase Locked Loop

PhaseDetector

VCO

LPF Afi

fvco

fi -fvco

Loop Filter

vo

ffo

CaptureRange,

fC

Hold (lock) Range, fH

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

Lab Project 3:Lab Project 3:Frequency Modulation and Frequency Modulation and

Detection Detection

http://engineering.rowan.edu/~shreek/spring07/ecomms/lab3.html

S. Mandayam/ ECOMMS/ECE Dept./Rowan University

SummarySummary