Analog Communication
Amplitude Modulation Basics
Definition, modulation index, time domain equation.
AM Frequency Spectrum
Carrier, upper and lower sidebands, bandwidth.
AM Power Relations
Carrier power, sideband power, modulation efficiency.
AM DSB-FC
Double sideband full carrier, classic AM generation.
AM DSB-SC
Suppressed carrier, balanced modulator, power saving.
AM SSB
Single sideband, filter method, phase shift method.
AM Modulators
Square law modulator, switching modulator circuits.
AM Demodulators
Envelope detector, synchronous detector.
FM Basics
Frequency deviation, modulation index, narrowband vs wideband.
Bessel Functions in FM
Spectrum analysis, sideband amplitudes, carrier null.
Narrowband FM
Approximation to AM, phasor representation.
FM Demodulation Basics
Slope detector, balanced slope detector.
Foster-Seeley Discriminator
Phase shift discriminator operation.
Pre-emphasis and De-emphasis
SNR improvement, time constants.
Noise Taxonomy
External vs Internal, Shot, Thermal, Flicker, Burst noise.
Thermal Noise
Johnson-Nyquist noise voltage, bandwidth dependence.
Signal to Noise Ratio
Input SNR, Output SNR, SNR in dB.
Noise Figure
Definition F, relation to noise temperature Te.
Friis Formula
Cascaded noise figure calculation.
Noise in AM Systems
Figure of merit, coherent detection SNR.
Noise in FM Systems
Figure of merit, capture effect, threshold effect.
FM Threshold Extension
FMFB, PLL extension methods.
Superheterodyne Receiver
Mixer, IF amplifier, image frequency.
Image Frequency Rejection
Selection of IF, RF filter role.
Direct Conversion Receiver
Zero-IF, homodyne, advantages and DC offset issues.
Automatic Gain Control
AGC principle, simple AGC circuit.
Sampling Theorem
Nyquist rate, aliasing, reconstruction.
PAM
Pulse Amplitude Modulation.
PCM Basics
Pulse Code Modulation, quantization levels.
Quantization Noise
Uniform vs Non-uniform quantization.
Companding
A-law, Mu-law compression.
Delta Modulation
1-bit quantization, slope overload, granular noise.
DPCM
Differential Pulse Code Modulation.
Communication Channels
Wireline, optical fiber, wireless, satellite.
Link Budget
Friis transmission equation, path loss, fade margin.
FDM
Frequency Division Multiplexing hierarchy.
Television Basics
Scanning, composite video signal.
Indirect FM Generation
Armstrong method, frequency multipliers.
Direct FM Generation
Varactor diode modulator, VCO.
White Noise
Power spectral density, autocorrelation.
Equivalent Noise Temperature
System temperature, antenna temperature.
Receiver Parameters
Sensitivity, Selectivity, Fidelity.
TRF Receiver
Tuned Radio Frequency receiver, selectivity issues.
Natural vs Flat Top Sampling
Aperture effect.
PWM
Pulse Width Modulation, generation and detection.
PPM
Pulse Position Modulation.
Adaptive Delta Modulation
Variable step size ADM.
Analog vs Digital Comm
Noise immunity, bandwidth, cost, complexity comparison.
Hybrid Systems
Modems, DSL, using digital data over analog lines.
Applications
Radio broadcasting vs Cellular networks.
Transition to Digital
Why TV and Radio are moving to digital standards.
Carson's Rule
Bandwidth estimation, B = 2(df + fm).
VSB Modulation
Vestigial Sideband, TV transmission application.
Costas Loop
Carrier recovery for DSB-SC.
Ratio Detector
Amplitude limiting property.
PLL Demodulator
Phase Locked Loop as FM detector.
Stereo FM
Multiplexing L+R and L-R signals.
Double Conversion
Two IF stages for selectivity and image rejection.
Tracking and Alignment
Local oscillator padding, trimming.
PM Basics
Phase modulation equation, modulation index.
TDM
Time Division Multiplexing, T1/E1 frames.