SMT Spectrum Peak Search.vi Calculates a Peak Value Different than Power Spectrum GraphPrimary Software: LabVIEW Development Systems>>LabVIEW Professional Development SystemPrimary Software Version: 7.1 Primary Software Fixed Version: N/A Secondary Software: N/A Hardware: Modular Instruments>>RF Measurement Devices>>PXI-5660
Problem: On the front panel of ni5660 Peak Search.vi and RFSA Spectrum Peak Search Application Example.vi, there is a Peaks cluster containing peak frequency and peak amplitude values for peaks that the Spectral Measurements Toolkit (SMT) Peak Search measurement VI finds. Why isn't the frequency or amplitude value identical to what the Power Spectrum graph indicates? Solution: Both of these example VIs use SMT Spectrum Peak Search.vi as a subVI. This VI implements a patented peak search algorithm that is more advanced than simply searching the array of power spectrum data points for peaks and returning their values. The algorithm obtains peak power and frequency values that do not necessarily occur directly on spectral lines. It also accounts for the effects spectral windowing may have on the data. The result is a more accurate peak measurement than simply picking out a point from an array. For more information on the SMT Spectrum Peak Search VI, refer to page 43 of the Spectral Measurements Toolkit User Guide that can be found in the Related Links section below. The following screenshot is of the SMT Peak Search Example for RFSA.vi. The cursor represents the measured peak location, which is clearly offset from the spectrum data in both frequency and amplitude.
Related Links:
Attachments:  - Peak Search.JPG
Report Date: 05/26/2005 Last Updated: 12/07/2007 Document ID: 3LP1LLE |
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