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 |