CDC 3D152 Flashcards
(779 cards)
What is modulation?
Process of modifying any characteristic of a signal so that it varies in-step with value of another signal.
Analog-to-Digital Technique?
Digital-to-Analog Technique?
PCM
CVSD
What are the two basic types of modulation?
Analog & Digital
What are the three basic types of analog modulation?
AM / FM / PM
What are the three basic types of analog modulation used to convert digital signals?
ASK / FSK / PSK
What is the simplest form of PSK?
BPSK
What analog modulation technique is similar to QPSK?
QAM
Why is DPSK better than PSK?
Easier to implement / more robust
What are the 4 basic types of pulse modulation?
PAM / PDM / PPM / PCM
How does ADPCM differ from PCM?
ADPCM = 4 bits; 32K
PCM = 8 bits; 64K
How does ADM differ from DM?
Signal’s step size may vary from sample to sample
What is a simple form of ADM?
CVSD
What frequencies are present at output of AM modulator?
Carrier Frequency, Carrier + MF, Carrier - MF
MF = Modulating Frequency
What components of AM modulated sine wave carries information signals?
Upper/Lower Sidebands
What are the 2 bands of frequencies located below and above the carrier in AM modulated signals called?
Upper/Lower Sidebands
Which sideband of AM modulated signal is a mirror-image of the modulating signal?
Lower Sideband
How does the bandwidth required to transmit an AM signal compare to that for transmitting the modulating signal by itself?
Bandwidth required = 2x that of modulating signal itself.
What is the predominant characteristic of SSBSC modulation?
All of the transmitter power can be used for transmission of info signal located in one sideband w/out carrier.
What advantage does SSBSC have over other forms of AM?
6 to 1 improvement.
What makes SSBSC more efficient?
Reduced bandwidth / greater power efficiency.
In AM, what products are present in the resultant waveform?
Carrier, upper sideband, lower sideband.
What term is used for additional sidebands that cause unwanted bandwidth and distortion transmitted in AM signal?
Splatter
What problem is associated with all forms of AM?
Susceptibility to interference.
What determines amount of deviation of an FM carrier?
Amplitude of modulating signal.