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  • LV Digital Comm display tagshide tags

    This module is included inLens: Analog / Digital Communications with National Instruments LabVIEW
    By: Sam ShearmanAs a part of collections:"SubVI Specifications for "Communication Systems Projects with LabVIEW"", "Communication Systems Projects with LabVIEW"

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    ""Communication Systems Projects with LabVIEW" features ten projects that draw upon a library of over 40 subVIs constructed as part of the project activities. Each module in this manual completely […]"

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sam_GrabAudio.vi

Module by: Ed Doering. E-mail the author

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Summary: Build a LabVIEW subVI to wait for audio level to exceed a user-defined threshold, and then record audio for a specified time interval.

Table 1
LabVIEWtop.png This module refers to LabVIEW, a software development environment that features a graphical programming language. Please see the LabVIEW QuickStart Guide module for tutorials and documentation that will help you:
• Apply LabVIEW to Audio Signal Processing
• Get started with LabVIEW
• Obtain a fully-functional evaluation edition of LabVIEW

Note:

Visit LabVIEW Setup to learn how to adjust your own LabVIEW environment to match the settings used by the LabVIEW screencast video(s) in this module. Click the "Fullscreen" button at the lower right corner of the video player if the video does not fit properly within your browser window.

LabVIEW SubVI: sam_GrabAudio.vi

  • Description: Wait for audio to exceed a user-defined threshold, and then record audio for a specified time interval. This subVI depends on sam_ListenForAudio.vi.
  • Category: Speaker-air-microphone (SAM) channel ("sam" prefix)

Inputs (Controls)

  1. duration [s] (1) -- DBL
  2. threshold level (0.1) -- DBL
  3. fs [Hz] (22050) -- DBL
  4. error in (no error) -- error cluster

Parentheses ( ) indicate default value; square brackets [ ] designate units.

Outputs (Indicators)

  1. waveform out -- waveform
  2. error out -- error cluster

Required Behavior

  • Use sam_ListenForAudio.vi to continually acquire audio samples in 1024-sample blocks. Once "sam_ListenForAudio" completes execution (i.e., then the audio level exceeds threshold level), record audio for duration seconds at the sampling frequency fs.
  • The audio output of sam_ListenForAudio.vi serves as the beginning of the audio signal waveform out.
  • The sound-card must be cleaned up using "Graphics and Sound | Sound | Input | Sound Input Clear" once the audio has been recorded.

LabVIEW Coding Tips

View the screencast video in Create a SubVI in LabVIEW to learn the mechanics of subVIs.

Refer to the Figure 1 screencast video for LabVIEW coding tips and techniques specific to this subVI.

Figure 1: [video] LabVIEW coding tips and techniques for sam_GrabAudio.vi
Figure 1 (subVI_sam_GrabAudio-vi.htm)

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A lens is a custom view of Connexions content. You can think of it as a fancy kind of list that will let you see Connexions through the eyes of organizations and people you trust.

What is in a lens?

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Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

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