This is the summary notes of the important terms and concepts in Chapter 6 of the book "Electronic Communications System" by Wayne Tomasi. The notes are properly synchronized and concise for much better understanding of the book. Make sure to familiarize this review notes to increase the chance of passing the ECE Board Exam.
CHAPTER 6 |
SINGLE – SIDEBAND COMMUNICATIONS SYSTEMS |
Items |
Definitions |
Terms |
1 |
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 ) |
2 |
A form of amplitude modulation in which the carrier is totally suppressed and one of the sidebands removed. |
AM Single-sideband Suppressed Carrier ( SSBSC ) |
3 |
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 ) |
4 |
It is the reinserted carrier in SSBRC for demodulation purposes. |
Pilot Carrier |
5 |
A form of amplitude modulation in which a single carrier frequency is independently modulated by two different modulating signals. |
AM Independent Sideband ( ISB ) |
6 |
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 ) |
7 |
________ is the picture portion of a commercial television broadcasting signal. |
VSB System |
8 |
Are obvious advantages of single-sideband suppressed- and reduced- carrier transmission over conventional double- sideband full-carrier transmission? |
Bandwidth Conservation and Power Efficiency |
9 |
This ratio determines the degree of intelligibility of a received signal. |
Signal-to-Noise Ratio |
10 |
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 |
11 |
A condition in double-sideband transmission where one sideband is significantly attenuated. |
Sideband Fading |
12 |
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 |
13 |
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 |
14 |
A product modulator where the output signal is the product of the modulating signal and the carrier. |
AM Modulator |
15 |
Modulator circuits that inherently remove the carrier during the modulation process. |
DSBSC Modulators |
16 |
A circuit that produces a double-sideband suppressed-carrier signal. |
Balanced Modulator |
17 |
A balanced modulator that is constructed with diodes and transformers. Sometimes called balanced lattice modulator. |
Balanced Ring Modulator |
18 |
The small carrier component that is always present in the output signal of a balanced modulator. |
Carrier Leak |
19 |
The operation of this balanced modulator as the balanced ring modulator is completely dependent on the switching action of diodes D1 through D4 under the influence of the carrier and modulating signal voltages. |
Balanced Bridge Modulator |
20 |
A double-balanced modulator/demodulator that produces an output signal that is proportional to the product of its input signals. |
LM1497 / 1596 Balanced Modulator IC |
21 |
The circuit where the carrier is reinserted. |
Linear Summer |
22 |
Three methods for single-sideband generation. |
Filter, Phase-Shift, and Third Method |
23 |
Types of single-sideband filters. |
Crystal Lattice, Ceramic, Mechanical, Saw Filters |
24 |
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 |
25 |
Filters that use acoustic energy rather than electro-mechanical energy to provide excellent performance for precise bandpass filtering. |
Surface Acoustic Wave Filters |
26 |
Reflected energy that cancels and attenuates the incident wave energy. |
Heterodyne |
27 |
Reflected energy that aids the incident wave energy. |
Constructive Interference |
28 |
A transducer which launches the acoustic wave in only one direction. |
Unidirectional Transducer |
29 |
Any difference between the transmit and receive local oscillator frequencies produces a _______ in the demodulated information signal. |
frequency offset error |
30 |
Fifty hertz or more offset is distinguishable by a normal listener as a _______. |
tonal variation |
31 |
A narrowband PLL that tracks the pilot carrier in the composite SSBRC receiver signal and uses the recovered carrier to generate coherent local oscillator frequencies in the synthesizer. |
Carrier Recovery Circuit |
32 |
An SSB receiver that uses a PLL carrier recovery circuit and a frequency synthesizer to produce coherent local and beat frequency oscillator frequencies. |
Multichannel Pilto Carrier |
33 |
Systems that provide narrowband voice communications for land-mobile services with nearly the quality achieved with FM systems and do it using less than one-third the bandwidth. |
Amplitude-Compandoring Single-Sideband ( ACSSB ) |
34 |
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 |
35 |
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 |
36 |
Single-sideband transmitters are rated in ________ and ________. |
Peak Envelope Power ( PEP ) & Peak Envelope Voltage ( PEV ) |
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