Forouzan Chapter 5 Identification Flashcards
_ is the process of changing one of the characteristics
of an analog signal based on the information in the digital data.
Digital-to-analog conversion
Digital-to-analog conversion can be accomplished in several ways: _, _, and _.
amplitude shift
keying (ASK),frequency shift keying (FSK),phase shift keying (PSK)
_ combines ASK and PSK.
Quadrature amplitude modulation (QAM)
In_, the amplitude of the carrier signal is varied to create signal
elements. Both frequency and phase remain constant while the amplitude changes.
amplitude shift keying
In _, the frequency of the carrier signal is varied to represent
data.
frequency shift keying
In _, the phase of the carrier is varied to represent two or more different
signal elements. Both peak amplitude and frequency remain constant as the
phase changes.
phase shift keying
A constellation diagram shows us the amplitude and phase of a _,
particularly when we are using two carriers (one in-phase and one quadrature).
signal element
_ is a combination of ASK and PSK.
_uses two carriers, one in-phase and the other quadrature, with different
amplitude levels for each carrier.
Quadrature amplitude modulation,QAM
_ is the representation of analog information by an
analog signal. Conversion is needed if the medium is bandpass in nature or if only
a bandpass bandwidth is available to us.
Analog-to-analog conversion
Analog-to-analog conversion can be accomplished in three ways: _, _, and _.
amplitude modulation
AM),frequency modulation (FM),phase modulation (PM
In _, the carrier signal is modulated so that its amplitude varies with the
changing amplitudes of the modulating signal. The frequency and phase of the carrier
remain the same; only the amplitude changes to follow variations in the information.
AM transmission
In _, the frequency of the carrier signal is modulated to follow the
changing voltage level (amplitude) of the modulating signal.
FM transmission
In _, the phase of the carrier signal is modulated to follow the
changing voltage level (amplitude) of the modulating signal. The peak amplitude
and frequency of the carrier signal remain constant, but as the amplitude of the
information signal changes, the phase of the carrier changes correspondingly.
PM transmission