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Questions and Answers
Which of the following are types of wireless waves?
Which of the following are types of wireless waves?
The speed of light in a vacuum is approximately 300,000 km/s.
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?
What type of wireless transmission uses reflected light, allowing for communication without direct alignment?
Diffused transmission
Infrared light is ______ to the human eye.
Infrared light is ______ to the human eye.
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Match the following components with their function in infrared wireless transmission:
Match the following components with their function in infrared wireless transmission:
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Which of these is NOT a limitation of infrared transmission?
Which of these is NOT a limitation of infrared transmission?
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Radio waves can penetrate through most solid objects, including metallic barriers.
Radio waves can penetrate through most solid objects, including metallic barriers.
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What is the primary advantage of using spread spectrum transmission over narrow-band transmission?
What is the primary advantage of using spread spectrum transmission over narrow-band transmission?
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In Frequency Hopping Spread Spectrum (FHSS), transmissions rapidly switch between multiple frequencies based on a ______ sequence.
In Frequency Hopping Spread Spectrum (FHSS), transmissions rapidly switch between multiple frequencies based on a ______ sequence.
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Match the following modulation techniques with their corresponding type of modulation:
Match the following modulation techniques with their corresponding type of modulation:
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Which of these is NOT an advantage of digital modulation?
Which of these is NOT an advantage of digital modulation?
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Bluetooth technology uses Direct Sequence Spread Spectrum (DSSS) for its data transmission.
Bluetooth technology uses Direct Sequence Spread Spectrum (DSSS) for its data transmission.
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What is the main difference between ASK and FSK?
What is the main difference between ASK and FSK?
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Mobile phone communication, Wi-Fi networks, and AM/FM radio broadcasting are all examples of using ______ waves for data transmission.
Mobile phone communication, Wi-Fi networks, and AM/FM radio broadcasting are all examples of using ______ waves for data transmission.
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Which of these is NOT a feature of radio waves for data transmission?
Which of these is NOT a feature of radio waves for data transmission?
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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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Description
Explore the fundamentals of wireless data transmission in this lecture. Learn about the speed of wireless signals, the types of signals used, and the basics of infrared light transmission. Gain insights into how data is encoded for transmission and the characteristics of various wireless transmission methods.
