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Questions and Answers
Digital modulation involves transmitting digitally modulated analog signals called ______ between points in a communication system.
Digital modulation involves transmitting digitally modulated analog signals called ______ between points in a communication system.
carriers
Traditional analog modulation systems such as AM, FM, and PM are being replaced by digital modulation systems due to their advantages in processing and ______.
Traditional analog modulation systems such as AM, FM, and PM are being replaced by digital modulation systems due to their advantages in processing and ______.
noise immunity
Digital transmission systems require a physical medium such as wire, cable, or ______ between the transmitter and receiver.
Digital transmission systems require a physical medium such as wire, cable, or ______ between the transmitter and receiver.
fiber optic cable
In Amplitude Shift Keying (ASK), the ______ of the carrier is varied in proportion to the information signal.
In Amplitude Shift Keying (ASK), the ______ of the carrier is varied in proportion to the information signal.
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Frequency Shift Keying (FSK) varies the ______ of the carrier proportional to the information signal.
Frequency Shift Keying (FSK) varies the ______ of the carrier proportional to the information signal.
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Both the amplitude and phase are varied in ______, which is a form of digital modulation.
Both the amplitude and phase are varied in ______, which is a form of digital modulation.
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Digital microwave communications systems are one of the four common applications of ______.
Digital microwave communications systems are one of the four common applications of ______.
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The precoder in a transmitter converts data levels and encodes incoming data into ______ that modulate an analog carrier.
The precoder in a transmitter converts data levels and encodes incoming data into ______ that modulate an analog carrier.
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The transmitter begins with input data that is pre-processed by a ______.
The transmitter begins with input data that is pre-processed by a ______.
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Information capacity is often expressed as a ______ rate.
Information capacity is often expressed as a ______ rate.
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Hartley's law relates information capacity, bandwidth, and ______ time.
Hartley's law relates information capacity, bandwidth, and ______ time.
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The signal at the receiver is filtered and then applied to a ______ and decoder circuit.
The signal at the receiver is filtered and then applied to a ______ and decoder circuit.
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Critical components for the demodulation process include clock and carrier ______ circuits.
Critical components for the demodulation process include clock and carrier ______ circuits.
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Study Notes
Digital Modulation
- Electronic communications involves transmission, reception, and processing of information using electronic circuits.
- Information is defined as communicated knowledge or intelligence between points.
- Digital modulation transmits digitally modulated analog signals (carriers) in communication systems.
- Digital modulation is sometimes called digital radio because digitally modulated signals can travel through the atmosphere, enabling wireless communication.
- Traditional analog systems (AM, FM, PM) are being replaced by digital systems, offering advantages like ease of processing, multiplexing, and noise immunity.
- Digital communication has different meanings for various people. In this context, it includes high-frequency analog carriers modulated by low-frequency digital signals (digital radio) and digital pulse transmission systems.
- Digital transmission systems need a physical link (cable, wire, fiber optic) between transmitter and receiver. The link can be a metallic cable, optical fiber, or a combination of both, or it could be free space.
- Digital modulation differentiates from analog modulation in the nature of the modulating signal. Analog modulation systems use analog signals, whereas digital systems use digital signals.
- Digital signals can be computer-generated data or digitally encoded analog signals.
- Different forms of digital modulation include:
- Amplitude Shift Keying (ASK): Varying the amplitude of the carrier proportional to the information signal.
- Frequency Shift Keying (FSK): Varying the frequency of the carrier proportional to the information signal.
- Phase Shift Keying (PSK): Varying the phase of the carrier proportional to the information signal.
- Quadrature Amplitude Modulation (QAM): Varying both the amplitude and phase of the carrier proportionally to the information signal.
Applications of Digital Modulation
- Digital modulation suits various applications, including:
- Low-speed voice-band data communication modems (e.g., personal computers).
- High-speed data transmission systems (e.g., broadband DSL).
- Digital microwave and satellite communication systems.
- Cellular telephone systems (e.g., PCS).
- Cable and wireless systems.
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Description
This quiz covers the fundamentals of digital modulation in electronic communications. It discusses the transition from analog to digital systems and the advantages of digital modulation techniques. You will learn about the significance of digital signals in communication systems and their applications in wireless communication.
