Prelim 4 Flashcards
A form of amplitude modulation
in which the carrier is transmitted at full power but only one of the
sidebands is transmitted.
AM Single-sideband Full Carrier
SSBFC
A form of amplitude modulation
in which the carrier is totally suppressed and one of the sidebands removed.
AM Single-sideband Suppressed
Carrier ( SSBSC )
A form of amplitude modulation
in which one sideband is totally removed and the carrier voltage is reduced
to approximately 10% of its unmodulated amplitude. Sometimes called
single-sideband reinserted carrier.
AM Single-sideband Reduced
Carrier ( SSBRC )
It is the reinserted carrier in
SSBRC for demodulation purposes.
Pilot Carrier
A form of amplitude modulation
in which a single carrier frequency is independently modulated by two
different modulating signals.
AM Independent Sideband ( ISB )
A form of amplitude modulation
in which the carrier and one complete sideband are transmitted, but only part
of the second sideband is transmitted.
AM Vestigial Sideband ( VSB )
Are obvious advantages of
single-sideband suppressed- and reduced- carrier transmission over
conventional double- sideband full-carrier transmission?
Bandwidth Conservation and
Power Efficiency
This ratio determines the
degree of intelligibility of a received signal.
Signal-to-Noise Ratio
With double-sideband
transmission, the two sidebands and carrier may propagate through the
transmission media by different paths and therefore, experience different
transmission impairments. This condition is called ________.
Selective Fading
A condition in double-sideband
transmission where one sideband is significantly attenuated.
Sideband Fading
A form of selective fading
where there is a reduction of the carrier level of a 100%-modulated wave that
will make the carrier voltage less than the vector sum of the two sidebands.
Carrier-Amplitude Fading
A condition where the relative
positions of the carrier and sideband vectors of the received signal change,
causing a decided change in the shape of the envelope, causing a severely
distorted demodulated signal.
Carrier or Sideband Phase Shift
A product modulator where the
output signal is the product of the modulating signal and the carrier.
AM Modulator
Modulator circuits that
inherently remove the carrier during the modulation process.
DSBSC Modulators
A circuit that produces a
double-sideband suppressed-carrier signal.
Balanced Modulator
The circuit where the carrier
is reinserted.
Linear Summer
The process of combining
transmissions from more than one source and transmitting them over a common
facility, such as metallic or optical fiber cable or a radio-frequency
channel.
Multiplexing
A transmission that can be used
to combine hundreds or even thousands of narrowband channels into single,
composite wideband channel without the channels interfering with each other.
Single-Sideband
Suppressed-Carrier Transmission
An SSB transmission wherein the carrier is suppressed
Single-Sideband
Suppressed-Carrier Transmission
Single-sideband transmitters
are rated in ________ and ________.
Peak Envelope Power ( PEP )
& Peak Envelope Voltage ( PEV )
4 ADVANTAGES OF SINGLE-SIDEBAND TRANSMISSION
Power conservation
Bandwidth conservation
Selective fading
Noise reduction
2 DISADVANTAGES OF SINGLE-SIDEBAND TRANSMISSION
Complex receivers
Tuning difficulties
Types of single-sideband
filters.
Crystal Lattice, Ceramic,
Mechanical, Saw Filters
A mechanically resonant
transducer that receives electrical energy, converts it to mechanical
vibrations, and then converts the vibrations back to electrical energy at its
output.
Mechanical Filter
Filters that use acoustic
energy rather than electro-mechanical energy to provide excellent performance
for precise bandpass filtering.
Surface Acoustic Wave Filters
