Experiment 21: Digital Audio Signal Analysis

Objective: Analyze digital audio signals, such as I2S or SPDIF, to understand their data transmission and format.

Background:

Digital audio interfaces like I2S (Inter-IC Sound) and SPDIF (Sony/Philips Digital Interface Format) are widely used for transmitting high-quality audio data between devices. These protocols ensure accurate audio reproduction by encoding and transmitting audio data as digital signals.

Steps:

  1. Set Up the Hardware:
    • Identify the audio protocol to analyze (e.g., I2S or SPDIF).
    • Connect the logic analyzer to the appropriate interface lines (e.g., SD, SCK, WS for I2S or SPDIF signal line).
    • Ensure proper grounding between the analyzer and the audio source.
  2. Configure the Software:
    • Open the logic analyzer software and select the correct protocol decoder.
    • Set the sampling rate high enough to capture the audio signal accurately.
    • Adjust the protocol settings to match the audio source (e.g., bit depth, sample rate).
  3. Capture the Audio Signal:
    • Play an audio sample or generate a test signal through the audio interface.
    • Record the transmitted data using the logic analyzer.
  4. Analyze the Data:
    • Examine the captured waveform and decoded data for correctness.
    • Check synchronization signals like word select (WS) or channel status bits in SPDIF.

Expected Outcome:

Develop a clear understanding of digital audio signal structures and learn to analyze protocols such as I2S and SPDIF for audio data transmission.