Wireless Data Transmission - CSIS 4501, Lecture 2

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Questions and Answers

Which of the following are types of wireless waves?

  • Radio waves (correct)
  • Infrared light (correct)
  • Ultraviolet light
  • Sound waves

The speed of light in a vacuum is approximately 300,000 km/s.

True (A)

What type of wireless transmission uses reflected light, allowing for communication without direct alignment?

Diffused transmission

Infrared light is ______ to the human eye.

<p>invisible</p>
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Match the following components with their function in infrared wireless transmission:

<p>Emitter (LED) = Transmits the signal Detector = Receives the signal Line-of-Sight = Requires a clear, unobstructed path Diffused = Relies on reflected infrared light</p>
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Which of these is NOT a limitation of infrared transmission?

<p>High mobility (D)</p>
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Radio waves can penetrate through most solid objects, including metallic barriers.

<p>False (B)</p>
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What is the primary advantage of using spread spectrum transmission over narrow-band transmission?

<p>Improved interference resistance and security</p>
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In Frequency Hopping Spread Spectrum (FHSS), transmissions rapidly switch between multiple frequencies based on a ______ sequence.

<p>hopping</p>
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Match the following modulation techniques with their corresponding type of modulation:

<p>Amplitude Modulation (AM) = Frequency Modulation Frequency Modulation (FM) = Amplitude Modulation Phase Modulation (PM) = Phase Modulation Amplitude Shift Keying (ASK) = Amplitude Modulation Frequency Shift Keying (FSK) = Frequency Modulation Phase Shift Keying (PSK) = Phase Modulation</p>
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Which of these is NOT an advantage of digital modulation?

<p>Increased susceptibility to interference (A)</p>
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Bluetooth technology uses Direct Sequence Spread Spectrum (DSSS) for its data transmission.

<p>False (B)</p>
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What is the main difference between ASK and FSK?

<p>ASK uses different amplitudes to represent binary values, while FSK utilizes different frequencies</p>
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Mobile phone communication, Wi-Fi networks, and AM/FM radio broadcasting are all examples of using ______ waves for data transmission.

<p>radio</p>
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Which of these is NOT a feature of radio waves for data transmission?

<p>Limited range (C)</p>
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Flashcards

Wireless Data Transmission

Transmission of data through electromagnetic waves without using physical wires.

Types of Wireless Waves

The two basic types are Infrared light and Radio waves.

Electromagnetic Spectrum

Range of all types of electromagnetic radiation including radio waves and gamma rays.

Infrared Light

A type of wireless wave adjacent to visible light, invisible to human eyes.

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Advantages of Infrared Transmission

Less interference and does not penetrate walls, ensuring data security.

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Emitter in Infrared Transmission

Device (like an LED) that transmits infrared signals to a receiver.

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Detector in Infrared Transmission

Device that receives the infrared signals from the emitter.

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Directed Transmission

A method of transmission requiring a direct line of sight between emitter and detector.

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Diffused Transmission

Transmission that relies on reflected infrared light for communication without direct alignment.

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Examples of Infrared Transmission

Used in TV remote controls, wireless peripherals, and device data transfers.

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Infrared Transmission Advantages

Infrared transmission is secure and experiences no interference from radio waves.

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Infrared Transmission Limitations

Infrared has limited range (15m), requires line-of-sight, and lacks mobility.

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Radio Waves

Radio waves are widely used for wireless communication, capable of long-distance travel without line-of-sight.

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Analog Modulation Types

Analog signals can be modulated using AM, FM, or PM to transmit data.

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Digital Data Representation

Digital data is represented as binary code (1s and 0s) for transmission.

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Digital Modulation Types

Digital data can be modulated using ASK, FSK, or PSK techniques.

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Advantages of Digital Modulation

Digital modulation has efficient bandwidth, lower power, resistance to interference, and easier error correction.

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Spread Spectrum Techniques

Spread spectrum methods improve security and reduce interference by using wider frequency ranges.

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Frequency Hopping Spread Spectrum (FHSS)

FHSS switches rapidly between different frequencies to reduce interference.

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Direct Sequence Spread Spectrum (DSSS)

DSSS uses chipping codes for increased security, appearing as noise to unwanted receivers.

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Study Notes

Wireless Data Transmission - CSIS 4501, Lecture 2

  • Wireless signals travel at the speed of light (300,000 km/s).
  • Two main types of wireless signals are infrared light and radio waves.
  • Data is encoded into signals for transmission. Signals can be analog or digital.
  • The electromagnetic spectrum encompasses various waves including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

Infrared Light Transmission

  • Infrared light is invisible and adjacent to visible light on the electromagnetic spectrum.
  • Infrared transmission is less susceptible to interference from other signals.
  • Infrared does not penetrate walls, enhancing security.
  • Infrared transmission requires an emitter (e.g., LED) and a detector for signal exchange.
  • Directed transmission (line-of-sight) needs an unobstructed path. Diffused transmission uses reflected light.
  • Examples include TV remotes, some wireless peripherals, and specialized device communication.
  • Limited range (typically up to 15 meters).
  • Lack of mobility and requires line-of-sight.

Radio Wave Transmission

  • Radio waves are generated by electric current in a wire, producing a magnetic field that propagates outward.
  • Radio waves travel long distances and penetrate most solid objects (except metals).
  • Common uses include FM/AM radio, Wi-Fi, mobile phones, and Bluetooth.

Analog Data Transmission

  • Analog data is modulated onto analog signals.
  • Amplitude Modulation (AM) varies signal amplitude. Used in AM radio, susceptible to interference.
  • Frequency Modulation (FM) varies signal frequency. Used in FM radio, less susceptible to interference.
  • Phase Modulation (PM) varies signal phase.

Digital Data Transmission

  • Digital data is represented as binary code (1s and 0s).
  • Digital modulation methods include Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), and Phase Shift Keying (PSK).
  • Digital modulation is more efficient, has lower power consumption and better interference resistance.
  • Examples include modern Wi-Fi, cellular networks, and satellite communication.

Spread Spectrum Techniques

  • Narrow-band transmissions are susceptible to interference.
  • Spread spectrum transmissions distribute signals across a broader frequency range. This improves security and resistance to interference.
  • Frequency Hopping Spread Spectrum (FHSS) rapidly switches between frequencies. Bluetooth and early Wi-Fi use this technique.
  • Direct Sequence Spread Spectrum (DSSS) adds redundant "chipping codes" to the signal. Modern Wi-Fi (802.11b/g/n) uses this.

Key Differences (Infrared vs. Radio Waves)

Feature Infrared Radio Waves
Range Short (up to 15m) Long
Interference Minimal Susceptible
Mobility Limited High
Security Good (walls block signal) Requires encryption
Common Uses TV remotes, some peripherals Wi-Fi, cellular networks

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