Raven Workbench Signals (SignalSource)

In Raven, a SignalSource (also known as a Raven Signal or .ravensignal file) is a specialized format used to define and track a collection of audio files that make up a dataset.

This applies to all Raven Workbench applications.

What is a SignalSource?

A SignalSource is an enhanced list file. While a simple list file might only contain a list of filenames, a SignalSource tracks comprehensive metadata for the entire dataset, including:

• File Locations: Absolute or relative paths to the underlying audio files.
• Absolute Time Reference: The precise calendar time when each file or sample was recorded.
• Durations: The length of each individual file and the total duration of the signal.
• Sample Counts: The exact number of audio samples in each file.
• Sampling Rate and Format: Technical details about the audio data.
• Gap Handling: Information on how to handle time gaps between sequential files (e.g., whether to pad them with silence or treat them as contiguous).

Gap Handling and Padding

When working with datasets consisting of multiple audio files, Raven can handle time gaps between those files in different ways. This is particularly relevant when the files have precise absolute time references.

Padding with Silence

If Pad Gaps is enabled, Raven fills the gaps between sequential files with silent samples. This provides a clear visual representation of when data is missing in the spectrogram and waveform views.

It is important to note that Raven's time axis accurately reflects the time even without padding, as the axis is reset at every file boundary. Padding simply gives an accurate visual display of the temporal gaps.

• When to use Padding:

  • Continuous Monitoring: When you have a recording system that was intended to run continuously but experienced dropouts or lost data. Padding makes these "missing data" areas visible, ensuring that the visual timeline of the entire dataset is continuous and easy to interpret in relation to the calendar clock.
  • Visualizing Gaps: When it's important to see the exact timing and duration of gaps between files.

• When NOT to use Padding:

  • Duty Cycle Data: When data is recorded on a fixed schedule (e.g., 5 minutes of recording every hour). In this case, padding would create 55-minute blocks of silence between every 5 minutes of data, making the dataset extremely difficult to navigate and visually sparse.
  • Independent Files: When the files in the SignalSource are not part of a continuous time series and their relative timing is not important for the analysis.

Purpose and Usage

Documentation of Data Results

To ensure the reproducibility and traceability of analysis, Raven stores a copy of the SignalSource with each Selection Table and LTSA (Long-Term Spectral Average). This ensures that the original data source is always documented alongside the resulting data, even if the original audio files are moved or the environment changes.

Dataset Portability

SignalSource files are the primary mechanism for moving datasets between different Raven Workbench applications. By sharing a .ravensignal file, users can ensure that other researchers or applications are looking at the exact same temporal and spatial configuration of the data.

Working with SignalSource Files

• Creation: SignalSources are typically created when opening a folder of files or a "List File" in Raven.
• Saving: You can save a SignalSource as a .ravensignal file to preserve the dataset configuration.
• Loading: Opening a .ravensignal file in Raven restores the entire dataset with all its timing and file associations intact.