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communicationsystems

chapter 2 adn 3

QuestionAnswer
the most elementary reciever device tuned radio frequency reciever
the minimum input RF signal to a reciever required to produce a specified audio signal at output sensitivity
input noise level to a reciever noise floor
the extent to which a reciever can differentiate between the desired signal and other signals selectivity
another name for diode detector envelope detector
another name for synchronous detector or product detector heterodyne detector
the mixer stage in a superheterodyne reciever that mixes the RF signal with a local oscillator signal to form the intermediate frequency signal first detector
small variable cap in parellel with each section of a ganged capacitor trimmer
small variable cap in series with each ganged tuning capacitor in a superheterodyne reciever to provide near perfect tracking at the low end of tuning range padder capacitor
have small internal capacitance that vaires as a function of their reverse bias voltage varactor diodes
another name for varactor diodes varicap diodes
undisired input frequency in a superheterodyne reciever that produces the same intermediate frequency as the desired input signal image frequency
superheterodyne reciever design that has two seperate mixers, local oscillators, and image frequencys to avoid image frequency problems double conversion
distortion that results from undesired mixer outputs cross modulation
another name for mixers converters/first detectors
troubleshooting by injecting an input signal and tracing it throughh a circuit signal injection
impressing a low frequency intelligence signal onto a higher frequency carrier signal modulation
characterised by a nonlinear output versus input signal relationship nonlinear device
band of frequency in a modulator from the creation of sum-frequencies between the carrier and information signals upper sideband
band of freq produced in a modulator from the creation of difference freq between the carrier and information signals lower sideband
measure of hte extent to which a carrier voltage is varied by the intelligence for AM system percentage modulation
another name for percent modulation modulation index/modulation factor
when an excessive intelligence signal overdrives an AM modulator producing modulation over 100% overmodulation
distortion resulting in an overmaodulated AM transmission creating excessive bandwidths sideband splatter
a modulation system where the intelligence is injected into the base of a transistor base modulation
a capacitor that cancels fed-back signals to suppress self oscillation neutralizing capacitor
higher frequency self oscillations in RF amps parasitic oscillations
stage that generates the AM signal modulated amplifier
amplified stage that amplifies a signal prior to reaching the final amplifier stage in a transmitter driver amplifier
ensuring that an oscillator starts by turning the dc on and off keying
improper bias or low carrier signal power in AM modulator low excitation
have modualtion applied to the output of the device high-level modulation
have modulation applied to an input of the device low-level modulation
the decrease in dc output current in an AM modulator usually caused by low excitation downward modulation
instrument used to measure the harmonic content of a signal by displaying a plot of amplitude verses frequency spectrum analyzer
undesired frequency components of a signal spurs
extra frequency components that appear in the spectral display of a signal, signifying distortion spurious frequencies
the baseline on a spectrum analyzer display noise floor
expression specifying the fundamental frequency component of a signal with respect to its largest harmonic in dB relative harmonic distortion
a measure of distortion that takes all significant harmonics into account total harmonic distortion
resistive load used in place of an antenna to test a transmitter without radiating the output signal dummy antenna
grid modulation circuits is a class ___ RF amp Class A
the process of applying modulation to the driver in a transistor modulator pre-modulation
2 reasons you dont get the bandwidth you sohuld 1) the TRF(Tuned radio frequency) reciever 2)our implementation of the AM broadcast scheme
process of pulling the audio signal out of the carrier and sidebands(RF envelope) detection (demodulation)
the generations of new frequencies by mixing or multiplying two oscillating waveforms heterodyne
Created by: seggerling