1. Electrical Communications Systems ECE.09.433 Spring 2019
Lab 3: Pre-lab Instruction
Shreekanth Mandayam
ECE Department
Rowan University

2. ECOMMS: Topics

3. Plan FM Signal and Spectrum FM Detection FM Generation
Slope Detector
FM Generation
Voltage Controlled Oscillator (VCO)
Phase Locked Loop (PLL)
Lab Project 3

4. FM Signal & Spectrum Single-tone FM Signal Single-tone FM Spectrum
fc-3fm fc-2fm fc-fm fc fc+fm fc+2fm fc+3fm
|S(f)| / (Ac/2) f
J0(b)
J1(b)
J2(b)
J3(b)

5. FM Detection FM Signal, We need a frequency-voltage converter Slope
Detector

6. Slope Detector Frequency- AM voltage Detector converter LPF
Envelope Detector
|H(f)| f t
fi(t)
vo(t)

7. FM Generation Voltage Controlled Oscillator f0=fc m(t) Control
Instantaneous
Frequency
m(t)

8. Oscillators: Principleb S
Signal
Source
Amplifier
Feedback
Network
Output + - vi vs vo
Barkhausen Criteria for oscillation:
Ab = -1

9. Oscillators
Waveforms
Schmitt Trigger Oscillator

10. Phase Locked Loop Phase Detector VCO LPF A fi fvco fi -fvco vo fo f
Loop Filter vo
Hold (lock) Range, fH
Capture
Range, fC fo f

11. Lab Project 3: Frequency Modulation and Detection

12. Summary