Sampling a Real-world Signal through Data Acquisition

Data acquisition is the process whereby a signal that measures some real-world physical condition is sampled at a specified interval such that the acquired samples are converted into a numeric representation.  This digital signal counterpart can then undergo further digital signal processing as may be required for the user's end application.  The NEXTWave Signal Processing Lab data analysis software includes analog I/O functions that can be used to acquire and generate real-world data through the use of a standard PC sound card or dedicated data acquisition hardware.

Using an A/D Function to Acquire an Input Signal with NEXTWave SPL

In this example NEXTWave SPL is used to acquire a real-world signal through an analog-to-digital (A/D) acquisition process.  The resulting digitized signal is then analyzed in both time and frequency domains.  The step-by-step process shown below illustrates the ease of use provided by the NEXTWave SPL programming and analysis environment.

 

speech signal

 

Step 1:  Select the Sound Card A/D function and add it to the Design Waveform menu ribbon

 

Step 2:  Configure the Sound Card A/D function.  For this example, we've set its sample rate to 22050 Hz and are using a framesize of 1024 samples.

Step 3:  Select the Run control operation to cause NEXTWave SPL to execute continuous frame processing.

Step 4: Observe the acquired signal in the Time Domain waveform display.

 

Step 5: Observe the acquired signal in the Frequency Domain as a spectrogram display.

speech spectrogram