RSS Feeds
Design and the Frequency Domain
By Gricha Raether, LabVIEW Product Manager, National Instruments -- Design News, May 17, 2004
As a design engineer, you are tasked with understanding a specific problem, designing a prototype solution, testing it, and verifying that it is ready for production. This entails the acquisition of data from a physical system and thorough analysis and processing of that data. Whether your work is in the field of communications, life sciences, consumer electronics, scientific research, or any other discipline that deals with signals, you need to inspect these signals in the frequency domain. Picking the right tools to inspect your data is essential and not always easy given the number of tools and techniques available.
You could use one tool to design the prototype, another one to acquire the data, and a third tool to analyze it. But there is a better option: use one tool for everything. With hundreds of configuration-based functions, National Instruments LabVIEW goes beyond making it simple to acquire data. LabVIEW offers hundreds of frequency-domain analysis functions, ranging from FFTs to joint time-frequency analysis and wavelets. You can open high-level functions (Express VIs) and configure the parameters in a dialog window. As soon as you select the proper analysis algorithm, you can immediately see the effect that it will have on your acquired data, eliminating the need for thoroughly understanding the underlying theory.
For example, one of the hundreds of built-in functions is the Spectral Measurements Express VI. This Virtual Instrument provides all the necessary tools to analyze the spectral content of signals. It offers typical functions such as magnitude (peak and rms), power spectrum, and phase. This Express VI also includes tools to ensure that the results are accurate. In practical applications, you obtain only a finite number of samples of the signal. To decompose the signal in terms of infinitely long sinusoids, the FFT implicitly extends the finite time record by repeating it in a periodic fashion. If your sampled data does not contain exactly one cycle of an underlying periodic signal, the periodic extension property of the FFT may produce artificial discontinuities at the boundaries of the sampled data. These discontinuities result in spectral leakage, or a smearing of energy from your actual frequency to all other frequencies. Because spectral leakage changes the amplitude and frequency measurement, you must minimize this effect to ensure accurate spectral measurements. You can take advantage of nine windowing algorithms in the Spectral Measurements Express VI to reduce spectral leakage.
In addition to the more than 400 built-in functions, you can add application-specific toolkits for signal modulation analysis, spectral measurements, sound and vibration, order analysis, and wavelets. Best of all, you don't need a Ph.D. to take advantage of these analysis tools as they provide immediate visualization of how the data is manipulated and the results you can expect.
Learn more about LabVIEW-based analysis at www.ni.com/labview.
Sponsored Content
Technology Marketplace
Talkback
DN's Resource Center Get Free Information, Made Easy
-
Unique & Personal Capabilities catalog
Control Line Equipment, Inc. | Design Guide
Request Item -
How to Create Lasting Bonds with Adhesives, Sealants & Coatings
Master Bond | White Paper
Request Item
