Experiment 3: Analog Data Acquisition and Aliasing
This experiment demonstrates the effects of sampling rate on the reconstruction of analog signals. Students use a program provided in to sample and display a sine wave in oth the time and frequency domains. As the frequency increases the Nyquist sampling rate is reached and exceeded. An aliased signal appears in both the time and frequency plots. The activity introduces the anti-aliasing filter and examines its use to reduce the level of frequencies above the Nyquist sampling rate.
This lab requires several LabVIEW Virtural Instrument (VI) programs. Clicking on the LabVIEW Programs menu selection downloads a zip file with all programs. Copy these files to the computer used to perform this lab before you begin.
The demonstration video tours the National Instruments Measurement and Automation Explorer (NI_MAX) software used to interface between the data acquisition hardware and the LabVIEW Programming Environment. The video also show how to create a analog voltage measurement task. In creating this task, the user can define the input channel, set the sampling rate, determine the input scale, and set the number of samples taken.
Presentation Times:
- Part 1: 9:37 Overview of NI-MAX and Creating a Data Acquisition Task
- Part 2: 9:07 National Instrument Meaxurement and Automation Explorer (NI-MAX)
- Part 3: 3:01 Using the Signal Analysis VI Phase Systems
- Part 4: 2:13 Aliasing Displayed on the Signal Analysis VI