Digital Communication Techniques Quiz

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Questions and Answers

What is the primary difference between analog and digital transmission?

Analog transmission uses discrete signals while digital transmission uses continuous signals.

Analog transmission is typically slower than digital transmission.

Digital transmission provides less noise interference compared to analog transmission. (correct)

Digital transmission converts data into binary form, while analog transmission does not. (correct)

Which scanning technique can represent information through pulse timings?

Pulse Position Modulation (PPM) (correct)

Pulse Amplitude Modulation (PAM)

Frequency Modulation (FM)

Pulse Width Modulation (PWM)

Which statement best describes a bandwidth consideration in digital communication?

Increasing bandwidth reduces the amount of noise in the system.

Bandwidth determines the range of frequencies used for signal transmission. (correct)

Bandwidth considerations are irrelevant to the quality of digital signals.

Higher bandwidth always leads to lower data transmission speed.

What is a characteristic feature of Pulse Width Modulation (PWM)?

The width of each pulse varies according to the sample value. Signup and view all the answers

Which technique allows for a more robust representation against noise in digital signals?

Pulse Position Modulation (PPM) Signup and view all the answers

Which scanning technique is used to create a composite video signal in television broadcasting?

Interlaced scanning Signup and view all the answers

What is a significant difference between VHF and UHF in television broadcasting?

VHF offers better long-distance propagation. Signup and view all the answers

What determines the maximum data throughput for a communication channel?

The bandwidth of the channel Signup and view all the answers

Which modulation technique is used in television to reduce bandwidth while transmitting signals?

Single-Sideband Transmission (SSB) Signup and view all the answers

How does the concept of persistence of vision contribute to the illusion of motion in film?

It allows images to be perceived as a continuous motion when flashed rapidly. Signup and view all the answers

What is the effect of a standing wave along a transmission line due to impedance mismatch?

It leads to power loss due to reflections. Signup and view all the answers

How does progressive scanning differ from interlaced scanning?

Progressive scanning shows all lines in a frame at once. Signup and view all the answers

What role do negative picture pulses play in analog television systems?

They assist in synchronization. Signup and view all the answers

Which of the following coaxial cables is commonly used for cable television?

RG-6 Signup and view all the answers

What is the bandwidth range typically required for HD transmission?

10-20 MHz Signup and view all the answers

What is the purpose of the Standing Wave Ratio (SWR) in transmission lines?

To assess the efficiency of power transfer. Signup and view all the answers

What type of antenna is commonly described as simple and widely used, especially in radio and TV applications?

Dipole antenna Signup and view all the answers

What is a benefit of using Vestigial Sideband (VSB) modulation in television transmission?

It simplifies receiver design. Signup and view all the answers

What essential aspect does persistence of vision contribute to in television?

It enables perception of continuous motion from still frames. Signup and view all the answers

Why is UHF particularly favored for digital television broadcasting?

It offers more bandwidth for HD broadcasting. Signup and view all the answers

Study Notes

Electrical and Electronics Gadgets

Uninterruptible Power Supply (UPS):
- A backup power source for connected devices during power outages or voltage fluctuations.
- During normal operation, the UPS charges an internal battery while providing power to devices.
- In case of a power outage, the UPS automatically switches to battery mode, providing power to the devices.
- The internal inverter converts DC power from the battery to AC power for the devices.
Inverter:
- Converts DC (Direct Current) power into AC (Alternating Current) power.
- Receives DC input from sources like batteries or solar panels.
- Uses electronic circuits to switch the DC power, creating an AC output.
- This AC output can power household appliances and electronic devices.
Stabilizer:
- Regulates and stabilizes voltage to protect electrical appliances from voltage fluctuations.
- Senses the incoming voltage and compares it to a set reference level.
- Adjusts the voltage using transformers or electronic circuits if it exceeds or falls below the set level.
Switched-Mode Power Supply (SMPS):
- Converts electrical power efficiently by using switching regulators.
- Receives AC input from the mains supply and converts it to DC using rectifiers.
- The DC is switched on and off rapidly using transistors, creating a high-frequency signal.
- This signal is transformed to the desired output voltage using a transformer.
- The output is filtered and regulated to provide a stable DC voltage for devices.

Radio Wave Propagation

Radio Wave Propagation: Explains how radio waves travel from one place to another (from transmitter to receiver), similar to how sound waves travel.
Types of Radio Wave Propagation:
- Ground Wave Propagation: Radio waves travel along the Earth's surface.
  - Used for low and medium frequencies (below 3 MHz).
  - Suitable for short to medium distances (up to 100-300 km).
  - Example: AM radio, military, and maritime communication.
- Sky Wave Propagation: Radio waves bounce off the ionosphere and return to Earth.
  - Best for high frequencies (3 to 30 MHz).
  - Useful for long distances (thousands of kilometers).
  - Example: Shortwave radio (international broadcasting) and amateur radio (ham radio).
- Space Wave Propagation: Radio waves travel in a straight line between the transmitter and the receiver.
  - Requires a clear line of sight (no obstacles).
  - Used for very high and ultra-high frequencies (VHF and UHF).
  - Example: FM radio, television broadcasting, mobile phones, and satellite communication.

Modulation and Demodulation

Modulation: Adding information (like voice, music, or data) to a carrier signal.
- Necessary to transmit information efficiently over long distances.
Types of Modulation:
- Amplitude Modulation (AM): The amplitude (strength) of the carrier signal changes based on the message signal.
- Frequency Modulation (FM): The frequency of the carrier signal changes based on the message signal.
- Phase Modulation (PM): The phase (position) of the carrier signal changes based on the message signal.
Demodulation: The reverse process of modulation, extracting the original information from the modulated carrier signal.

Antenna Types and Fundamentals

Antennas: Devices that convert electrical energy to radio waves and vice-versa.
Dipole Antenna: A simple antenna consisting of two conductors (wires) placed end-to-end.
Monopole Antenna: A single conductor mounted above a ground plane.
Yagi-Uda Antenna: Consists of multiple elements (a driven, a reflector and several directors) for high directivity.
Parabolic Reflector Antenna: A parabolic dish that reflects signals to a focal point for high gain and directivity.
Patch Antenna: A flat rectangular or circular radiating element mounted above a ground plane.
Loop Antenna: A loop of wire used in RFID systems

Digital Modulation and Demodulation Techniques

Digital modulation: Encoding information into a carrier signal for transmission.
- Essential for transmitting digital data efficiently over communication channels
Digital signal:
- Values that change
- Can be represented in binary form (1s and 0s)
Amplitude Shift Keying (ASK): The amplitude of a carrier signal is changed to represent the digital signal.
Frequency Shift Keying (FSK): The frequency of a carrier signal changes based on the digital signal being transferred
Phase Shift Keying (PSK): The phase of the carrier signal is altered to represent the digital signal.
Quadrature Amplitude Modulation (QAM): Combines both amplitude and phase modulation to encode multiple bits per symbol.
Sampling, Quantization, and Encoding: Process of converting an analog signal into a digital signal:
- Sampling: Measuring the amplitude of an analog signal at discrete intervals.
- Quantization: Mapping sampled values to discrete levels.
- Encoding: Converting quantized values into a binary code for transmission.
Multiplexing: Combining multiple signals into a single signal over a shared medium.
- Time Division Multiplexing (TDM): Divides time into slots to assign different signals.
- Frequency Division Multiplexing (FDM): Divides the frequency spectrum into sub-bands, each carrying a separate signal.
Demultiplexing: The reverse process of multiplexing, separating a combined signal into its original components.
PAM,PPM and PWM: Different ways to encode information into pulse signals.

Telecommunications

Cell Site: Base station providing coverage for a geographic area (cell).
Handoff: Transferring a call from one cell site to another as the user moves.
Frequency Reuse: Using the same frequency band in different cells that are far apart to minimize interference.
GSM: A digital mobile communication standard using time-division multiple access.
CDMA: Another digital mobile communication technology using spread-spectrum.
Mobile Phone Features: Voice calling, text messaging, internet access, camera, GPS, applications, Bluetooth, and Wi-Fi.

Television Transmitters and Optical Fibers

Television Transmitters: Devices sending TV signals over the air.
- Receive input signals (audio and video).
- Modulate the audio and video signals.
- Combine audio and video signals via frequency division multiplexing (FDM).
- Amplify or boost signal strength
- Transmit the signals as electromagnetic waves through an antenna.
Optical Fiber Equipment: Uses glass or plastic fibers to transmit data over long distances as light signals.
- Light signals transmit information.

Electrical and Electronic Gadgets

UPS (Uninterruptible Power Supply): Provides backup power during outages or voltage fluctuations.
Inverter: Converts DC power into AC power.
Stabilizer: Regulates voltage to protect appliances.
Switched-Mode Power Supply (SMPS): Highly efficient power supply that uses switching regulators.

E-Governance

E-Governance: Objectives include improving service delivery, enhancing transparency, empowering citizens and reducing red tape.
Work Plan and Infrastructure:
- Work Plan: Needs assessment, technology implementation, capacity building, monitoring and evaluation.
- Infrastructure: Data centers, networking, security framework, and database management systems.
Anti-Virus Software crucial to maintaining security of e-governance infrastructure by detecting and removing viruses and malware, protecting against cyberattacks, and meeting data protection requirements.

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Description

Test your knowledge on key concepts of digital communication techniques and video broadcasting. This quiz covers topics such as modulation, scanning techniques, and bandwidth considerations. Perfect for students studying telecommunications or media technology.