Modulation Flashcards by Third Burgos

Standard AM Range

535-1605 kHz

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Standard AM Intermediate Frequency

455 KHz

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Standard AM Equation

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used to describe the amount of amplitude change (modulation) present in an AM waveform signal

AM modulation index

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AM modulation index formula

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AM Current and Voltage Relationship

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AM Power Relationship

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AM Modulation by several signals (voltage, current, sideband power, and modulation index)

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Additional side frequencies produced by overmodulation or distortion in an AM system

splatter

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Crystal Amplifier that provides stable carrier frequency at low power

Crystal Oscillator

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Class A RF amplifier that isolates the crystal oscillator to improve its stability

Buffer amplifier

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Class C Amplifier that raises the output of the buffer to a level sufficient to drive the modulated RF amplifier

Intermediate Power Amplifier

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Class C RF amplifier that supplies energy which is required to drive the antenna system at the rated RF power for high level modulation.

Modulated Power Amplifier

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class A pre-amplifier that raises the level of the input AF after being subjected to processing and filtering.

Speech Amplifier

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class A/B/AB that supplies the necessary audio power to drive the class B modulator. It amplifies the output of the speech amplifier.

Driver Amplifier

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class B AF output amplifier that varies the plate voltage of the class C RF amplifier.

Push-Pull Modulator

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class A/B/AB amplifier which provides linear power amplification of the amplitude-modulated output signal from the class C modulated power amplifier.

Linear Power Amplifier

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It is also known as peak detector. It consists of a diode in series with an RC low pass filters.

Diode Envelope Detector

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The first rectifying detector. A thin, pointed wire known as cat whiskers is pressed against the surface of the crystal, when a sensitive spot is found, more current flows in one direction than in the opposite thus rectification occurs.

Crystal Detector

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Type of detector using amplifying devices like transistors in place of a diode to provide rectification and amplification at the same time.

Power Detector

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consist of a tuned circuit, a rectifier and an RC low pass filter for the recovery of the modulating signal. It has better sensitivity than diode detector.

Grid Leak Detector

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Detector that employs a tickler coil which generates energy from the plate circuit into the grid circuit of the of the triode.

Regenerative & Autodyne Detector

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extraction of the information signal from AM signal

Detection

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any frequency, phase, or amplitude variations that are present in the demodulated waveform that were not in the original information signal

Distortion

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measure of the ability of communication system to produce, at the output of the receiver, an exact replica of the original source information.

Fidelity

earliest types of AM receivers. Components include antenna, RF amplifier, detector, AF amplifier, and speaker.

Tuned Radio Frequency Receiver (TRF)

to mix two frequencies together in a nonlinear device or to translate one frequency to another using nonlinear mixing.

Heterodyne

receiver parameter that is used to measure the ability of the receiver to accept a given band of frequencies and reject all others.

Selectivity

also know as the receiver threshold. It is the minimum RF signal level that can be detected at the input to the receiver and still produce a usable demodulated information signal.

Sensitivity

merit that measures just how close to a perfect tuner or tuner component can be, and it affects the bandwidth and selectivity of a certain receiver.

Quality (Q) factor

Q formulas and resonant frequency formula

ratio of the bandwidth 60dB below maximum signal level and bandwidth 3dB below maximum signal level.

Shape Factor

Shape Factor Formula

noise reduction ratio achieved by reducing the bandwitdh

Bandwidth Improvement

Bandwidth Improvement Formula

reduction in noise figure due to the reduction in bandwidth expressed in decibels

Noise Figure Improvement (NFI)

Noise Figure Improvement Formula

Phenomenon where in the local oscillator frequency is tuned to a frequency higher than than the input RF frequency.

High Side Injection/ High Beat Injection

Phenomenon where in the local oscillator frequency is tuned to a frequency lower than the input RF frequency.

Low Side Injection/ Low Beat Injection

High & Low Side Injection Formulas

High & Low Side Injection Formulas for Image Frequency

Any frequency other than the selected radio frequency carrier that will produce cross product frequency that is equal to intermediate frequency.

Image Frequency

numerical measure of the ability of a pre-selector to reject the image frequency.

Image Frequency Rejection Ratio (IFRR)

Image Frequency Rejection Ratio (IFRR) formulas

Rejection Factor formula

used to keep the receiver audio turned off until an RF signal appears at the receiver input.

Squelch Circuit/ Muting Circuit

circuit that generates a DSB signal, suppressing the carrier and leaving only the sum and difference frequencies at the output.

Balanced Modulator

DSBSC Current & Voltage Relationship

Power Saving for DSBSC and SSBSC

SSBSC Current & Voltage Relationship

It is the RMS power developed at the crest of the modulation envelope.

Peak Envelope Power (PEP)

PEP and Pave formulas

SSBSC generation simplest method. Consists of one balanced modulator.

Filter Method

SSBSC generation method that makes used of two balanced modulators and two phase shifters.

Phase Shift Method

SSBSC generation method that consists of four balanced modulators. It retains the advantages of the phase shift method without the disadvantage of the AF phase shift method.

Third (Weaver) Method

amplitude modulation which one sideband is totally removed and the carrier voltage is reduced to approximately 10% of its unmodulated amplitude.

Single Sideband Reduced/Reinserted Carrier (SSBRC)

a form of AM in which single carrier frequency is independently modulated by two different modulated signals. It contains different information for each sideband.

Independent Sideband (ISB)

form of AM which the carrier and one complete sideband is transmitted, but only one part of the second sideband is transmitted.

Vestigial Sideband (VSB)

Analog modulation technique where the frequency of the carrier is varied proportional to the information signal.

Frequency Modulation (FM)

Standard FM Range

88-108 MHz

Standard FM intermediate Frequency

10.7 MHz

Standard FM Equation

Amount of carrier change in carrier frequency produced by the modulating signal

Frequency Deviation

Frequency Deviation Formula

ratio of deviation and the modulating signal frequency. It determines the number of significant pairs of sidebands.

FM modulation Index

FM modulation Index Formula

Worst case modulation index

Deviation Ratio

Deviation Ratio Formula

FM Percent Modulation Formula

It is the peak to peak frequency deviation

Carrier Swing

Carrier Swing Formula

Rule which is an approximation and gives transmission bandwidths that are slightly narrower than the bandwidths. It defines a bandwidth that includes approximately 98% of the total power in the modulated wave.

Carson’s Rule/Approximate Bandwidth/Practical Bandwidth

Carson’s Rule Formula

an FM system either relatively low modulation index (m <= 0.25)

Narrowband FM

an FM system with relatively large modulation index (m > 100)

Wideband FM

FM generation method in which the output is already an FM signal (such as reactance modulator, varactor diode modulator)

Direct FM Generation

FM generation method wherein the signal is first phase-modulated before producing the FM signal. It is most widely used since PM is cheaper to produce than FM

Indirect FM Generation Method

Indirect method of generating FM using oscillator for frequency stability with a phase-modulated buffer stage.

Armstrong Modulator

FM detection method in which a frequency-modulated signal is fed to a circuit that is tuned to receive the signal in the slope of a response curve

Slope Detector

FM detector using two slope detectors

Round-Travis Detector

FM detection method wherein changes in the magnitude of the input signal will give rise to the amplitude changes in the resulting output voltage.

Foster-Seeley Discriminator/ Center tapped or phase discriminator

Ratio Detector

Variation of the Foster-Seeley discriminator which includes an amplitude limiter which improves the limiting action.

extracts the original information signal from the composite IF waveform by multiplying two quadrature signals.

Quadrature Detector/Coincidence Detector

Simplest and easiest to understand FM detector. It is a closed-loop feedback control system in which either the frequency or the phase of the feedback signal is the parameter of interest rather than the magnitude of the signal’s voltage or current.

Phase Locked Loop (PLL)

PLL Functional Blocks

Phase Detector, Loop Filter, Voltage-Controlled Oscillator (VCO)

Lock range is to _____ lock; Capture range is to ______ lock

maintain, acquire

Lock range in peak to peak is ______; Capture range in peak to peak is _____

Hold-in Range; Pull-in Range

Pre-emphasis uses a _______, while De-Emphasis network uses a _______

high pass filter, low pass filter

inherent ability of an FM receiver to diminish the effect of interfering signals. It is the ability of the FM receiver to differentiate between two signals received at the same frequency.

Capture Effect

noise-reduction effect that occurs with strong FM signals.

Threshold Effect

used to remove sporadic, high amplitude noise transients of short duration, such as impulse noise.

Limiter/Clipper

Analog modulation technique where the phase of the carrier is varied proportional to the information signal.

Phase Modulation

Standard PM Equation