Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
communicationsystems
chapter 2 adn 3
| Question | Answer |
|---|---|
| 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
Popular Computers sets