VTEC Applied Science: Unit 1 Physics

Lecture on Analog and Digital Signals

What is a Signal?

• A signal is information traveling from one place to another.
• Types of signals:
  • Television Signal: Uses radio waves.
  • Electrical Signal: Travels in a wire, e.g., microphone producing electrical signals.
  • Internet Signal: Can be infrared or visible, travels via Ethernet or fiber optic cable.
  • Mobile Phone Signal: Uses microwaves.
  • Wi-Fi Signal: Uses microwaves and radio waves.
  • Bluetooth Signal: Similar to Wi-Fi and mobile signals.

Analog Signals

• When viewed on an oscilloscope, they show varying frequencies and amplitudes.
• Examples include:
  • FM Radio: Electrical signals to loudspeakers.
  • Sound produced by speakers: Analog in nature.

Digital Signals

• Composed of binary digits (bits): 1s and 0s.
• Amplitude is either on/off, up/down, or a binary 1/0.
• Examples include:
  • Internet
  • Mobile phone signals
  • Bluetooth
  • Wi-Fi
  • Digital television
  • Digital radio

Converting Analog to Digital

• Analog to Digital Converter (ADC): Converts analog signals to digital signals.
• Process: Sampling
  • ADC samples the voltage value many times per second to create a binary code.
  • Sampling Rate: Number of samples per second (e.g., 44,000 samples/sec for high-quality music, around 8,000 samples/sec for telephone).
  • Sampling Sensitivity: Number of levels and their closeness affect accuracy.

Digital Images

• Images are split into pixels, each with a binary code.
• Pixels are small and not visible individually under normal circumstances.
• Television screens consist of RGB picture elements (LCD or LED).

Advantages of Digital Signals

• Can carry more information in the same bandwidth.
• Easier to filter interference in digital signals.
• Compatible with digital computer memory and processing.
• Broadband allows handling of vast information with minimal delay.

Disadvantages of Digital Signals

• Processing may introduce delays.
• Quality depends on sample settings (sampling rate, pixel count, etc.).

Bandwidth and Frequency Allocation

• Bandwidth: Part of the electromagnetic spectrum used for signals.
• Governed allocation to prevent interference among different users (e.g., public, private companies, military, air traffic control).
• Digital signals allow more data through the same bandwidth compared to analog signals.
  • Example: Transition from 6 analog TV channels to hundreds of digital channels with improved quality using the same bandwidth.