Learn Analog Communication : From Basics to Advance

Learn amplitude modulation by examining how a low frequency modulating signal alters the amplitude of a high frequency carrier to generate the modulated signal, within a continuous modulation framework.

The lecture explains time-domain analysis of amplitude modulation, including carrier, sidebands, and the modulation index, and distinguishes singleton from multiton amplitude modulation with bandwidth concepts.

Analyze single tone amplitude modulation by visualizing modulating and carrier signals and how the modulation index dictates carrier amplitude, reconstruction, and potential overlap.

Define the modulation index as the ratio of the modulating signal amplitude to the carrier amplitude, using Emax and Emin of the AM signal. It equals Am over Ac.

Calculate the power needed to transmit an amplitude-modulated signal, covering carrier and sideband powers and the total power equation.

Explore amplitude modulation fundamentals and derive carrier and sideband relationships in AM signals. Calculate bandwidth, power, and the modulation index with worked examples.

Explore amplitude modulation concepts, compute modulation index and percent modulation, and analyze carrier and sideband powers. Learn to represent time-domain signals and sketch the frequency spectrum of AM signals.

Explore the frequency domain representation of amplitude modulation using Fourier transforms to convert time-domain signals into spectra, and examine how the modulating signal shifts the carrier and defines bandwidth.

Explore the frequency domain representation of am with single-tone modulation, revealing carrier impulses at fc and symmetric sidebands at fc ± fm, and determine the resulting modulation bandwidth.

Explore multitone amplitude modulation, where the modulating signal contains multiple frequencies. Analyze the AM signal with a carrier, sidebands, bandwidth, and the total modulation index from summed tones.

Analyze the efficiency of amplitude modulation, showing how carrier power, sideband energy, and the modulation index influence total power and transmitter efficiency.

Analyze two amplitude modulation problems by calculating the modulation index, carrier power, total power, and bandwidth for single and multitone signals.

Explore generation of amplitude-modulated signals using carrier and modulating signals, square-law modulators, nonlinear devices, and band-pass filtering to shape and transmit the modulation.

Explore square law modulation, where a carrier and a low-frequency modulating signal generate multiple frequency components, and learn to use band-pass filtering with fc > 3 fm max to avoid overlap.

Switching modulator uses two switching devices to achieve am-like modulation, preserving center frequency fc and bandwidth, with operation depending on carrier amplitude exceeding the modulating signal and resulting on/off states.

Explore square-law, envelope, and coherent (synchronous) detectors for am demodulation; assess modulation index effects and the role of low-pass filtering in extracting audio from modulated signals.

Explore the envelope detector, a simple analog demodulator using a diode, capacitor, and resistor to recover the modulating envelope from an AM signal.

Introduces double sideband suppressed carrier (dsb-sc) and explains how suppressing the carrier reduces power wastage, transmitting only the upper and lower sidebands for efficient modulation.

Explore time-domain and frequency-domain representations of double-sideband suppressed-carrier modulation (DSB-SC), showing how the modulating signal creates upper and lower sidebands with no carrier, enabling significant power savings.

Balanced modulator multiplies the modulating and carrier signals to produce a DSB signal with carrier suppression, using a 180-degree phase shift and subtraction/addition to cancel the carrier.

Learn how a ring modulator uses a diode ring and transformer network to multiply the modulating and carrier signals, producing DSB output filtered by a band-pass filter.

Explore the synchronous detector for demodulating double sideband with carrier signals, contrast with envelope detectors, and examine quadrature null effects and why single sideband modulation can be more efficient.

Explore amplitude modulation techniques, including DSB with full carrier, DSB suppressed carrier, and single sideband, highlighting carrier suppression, sideband efficiency, and power savings.

Explore time-domain and frequency-domain views of single sideband modulation, comparing power efficiency with DSB and other techniques, and analyze carrier, upper and lower sidebands, and bandwidth.

Explore generation of single-sideband modulation using the filter method, including how a band-pass filter selects one sideband, the role of mechanical filters, and the drawbacks of interchanging sidebands.

Explore the Hilbert transform and its 90-degree phase shift. Show how positive frequencies get minus 90 degrees and negative frequencies get plus 90 degrees.

Learn the phase-shift method for single sideband modulation in analog communication, using Hilbert transform and 90-degree phase shifts with balanced modulators and summation to generate an SSB signal.

Analyze synchronous detection for single sideband demodulation and vestigial sideband techniques, and compare these with envelope, DSB, and traditional demodulation in analog communication.

Compare amplitude modulation techniques—DSB with carrier, DSB-suppressed carrier, SSB, and vestigial sideband—covering time and frequency domain representations, bandwidth, efficiency, and radio broadcasting applications.

Explore angle modulation as changing the carrier angle by the modulating signal, and learn the two types—frequency modulation and phase modulation.

Explore frequency modulation (fm) by showing how the carrier frequency changes with the modulating signal, introducing instantaneous frequency, angle modulation concepts, and frequency sensitivity, including singleton fm.

Explore how a modulating signal determines a frequency modulated carrier through frequency deviation and modulation index, illustrating how the carrier frequency sweeps between limits while preserving carrier amplitude.

Explore narrowband FM (NBFM): a single-tone modulating signal yields a low modulation index (β<1) and a compact carrier–sideband spectrum, contrasting with wideband FM (β≥1).

Explore phasor diagrams of narrowband FM and AM, illustrating carrier and upper/lower sidebands, vector addition for the modulated signal, and the corresponding frequency spectrum and wideband FM generation notes.

Explore wideband fm by expressing a modulated signal as a real part of an exponential, revealing its frequency spectrum, multiple frequency components, and the modulation index via bessel functions.

Explore the wideband fm ideal representation with infinite sidebands and infinite bandwidth. Apply the 70 percent of the maximum amplitude rule to filter components and identify the primary spectrum.

Explore wideband FM concepts by deriving a finite number of sidebands, understand bandwidth limits up to 200 khz per FCC, and analyze carrier, sidebands, modulation index, and efficiency.

Explore how phase modulation alters the carrier phase according to the modulating signal, define phase deviation and modulation index, and contrast PM with FM for single-tone scenarios.

Generate nbpm and nbfm using a balanced modulator with carrier and modulating signals under narrowband conditions, including 90-degree phase shifts and fm-pm relationships.

Explore multitone modulation of fm, analyze the total modulation index for various frequency and phase relationships, and review FCC standard bandwidth and deviation values for radio broadcasting.

Solve problems on frequency modulated signals, compute total modulation index for orthogonal modulating signals, determine frequency deviation and bandwidth, and classify as narrowband or wideband fm with percentage modulation.

Explore how fm transmitters generate frequency modulation through direct and indirect methods using voltage-controlled oscillators and varactor-based reactance, with Hartley lc oscillators and key parameters like frequency deviation.

Explore the indirect generation of wideband fm by using a narrowband efm generator and mixer to shift the carrier, with frequency multipliers increasing the carrier frequency and modulation index.

Contrast AM and FM by how the carrier amplitude or frequency follows the modulating signal; explain modulation index, bandwidth, and FCC standards for radio broadcasting, plus linear vs nonlinear modulation.

Learn how transmitters convert low-frequency modulating signals to high-frequency carrier waves via AM, FM, and PM, and how modulators and power amplifiers enable analog communication.

Learn how a radio receiver picks up modulated radio frequency signals, recovers the baseband information, and tunes with LC circuits and tuned amplifiers while managing bandwidth and quality factor.

Explore modulation-based receiver types, AM receivers and FM receivers, and examine receiver blocks like tuned radio frequency and super receiver, plus characteristics such as selectivity, sensitivity, fidelity, and dynamic range.

Explore the tuned radio frequency receiver (trf), its rf amplifiers, demodulator, and amplifier stages, highlighting high sensitivity but poor selectivity compared with superhet receivers.

Understand how superheterodyne receivers convert high frequencies to an intermediate frequency to improve selectivity and avoid image interference, aided by radio-frequency amplification, tuning circuits, and demodulation.

Explore super-heterodyne receivers, detailing how mixers and local oscillators convert high frequencies to a 455 kHz intermediate frequency, enabling image frequency rejection and stable tuning.

Explore how a superheterodyne receiver uses amplifiers and a local oscillator. Convert signals to an intermediate frequency and apply standard values like 55 kHz (am).

Explains super-heterodyne receivers, image frequency, and image rejection ratio, using station frequency, intermediate frequency, and quality factor, with AM receiver examples around 455 kHz.

this lecture explains why pre-emphasis and de-emphasis circuits are used in fm transmission to boost high-frequency components at the transmitter and restore them at the receiver, improving signal-to-noise ratio.

Explore fm receiver architecture from antenna to output, detailing rf front end, mixer and local oscillator, intermediate frequency at 10.7 mhz, amplitude limiters and demodulation methods, plus preemphasis and deemphasis.

Demonstrate how efm modulation signals are demodulated using differentiators and envelope detectors, highlighting frequency and phase discrimination, pll and ratio detectors, with amplitude limiters.

Explore frequency discrimination methods using tuning circuits, envelope detectors, and 180-degree phase shifts, outlining fast discriminators, ratio detectors, and the balance slope detector for demodulation.

Explore how a phase-locked loop demodulates frequency-modulated signals by using a voltage-controlled oscillator, mixer, phase detector, and loop filter to recover the modulating signal.

Learn how a phase-locked loop uses a phase detector, negative feedback, and a voltage-controlled oscillator to demodulate FM signals, with a low-pass filter to produce the output.

Explore noise in analog communication, distinguishing internal and external noise, thermal and flicker noise, partition noise, and Johnson noise, and understand their impact on bandwidth and signal integrity.

Explore thermal noise and maximum power transfer in analog circuits, and how temperature, resistance, bandwidth, and signal-to-noise ratio govern amplifier and receiver performance.