A Tektronix PC-Based Spectrum Analyzer is configured to report signals that fall outside a user-defined mask. This procedure is a valuable quality assurance tool for large production runs. It is fast and accurate.
Hi again and welcome to our 75th Test and Measurement Video. Right now we will look once more at the Tektronix RSA306 PC-Based Spectrum Analyzer. The topic is More on Transient Capture – Mask Test and Act on Violation.
Before diving in, since the Tektronics RSA306 is a real-time instrument, we’ll review the differences between this and the swept-spectrum analyzer.
Both of these instruments display amplitude as power on the Y-axis and frequency on the X-axis. How they do this is wherein they differ, affecting their ability to process high-frequency signals.
The swept-spectrum analyzer uses an old technology – superheterodyne frequency reduction, a century-old method for combining the output of a local oscillator with an RF-modulated carrier in order to create an unvarying and lower difference frequency that is more amenable to amplification and detection.
This worked well for early spectrum analyzers, but the disadvantage is that they could not evaluate all frequencies within a given band simultaneously. For this reason, narrow-band, brief transients were missed and low-amplitude signals obscured beneath more powerful transmitted energy.
The real-time spectrum analyzer transcends these limitations and permits the user to see brief transients and weak signals that would otherwise be missed.
In today’s demonstration, we’ll see how the Mask feature in SignalVu-PC enables us to automatically and selectively save events of interest. With the RSA306 PC-Based Spectrum Analyzer, Tektronix demoboard and PC (with SignalVu-PC installed) all cabled together, we can proceed. As for the demoboard, keep the same settings as in Video 74. Just for review, in case they have been changed, the power button should be On. The Row and Column buttons should be set so that the demoboard output is Infrequent Hopping. The Run Mode should be Free Run.
As for the RSA306 with SignalVu-PC installed in the computer, keep the same settings as in Video 74, or recall Setting Demo5_DPX.tiq. Then click Run. The interesting thing to note is that even after the demoboard and the PC are powered down, the previous settings are preserved.
Continuing with the RSA settings in the PC, under the Tools menu, click Mask Test.
Select DPX: Trace 1 from Search In.
Select Outside Mask in Test For.
Click Edit Limits to open the Mask Test Editor.
In the Mask Test Editor, select DPX Trace 1 as the Reference.
Click Auto Draw to generate a mask automatically adjusted to the reference.
In regard to the Mask Test Editor, the margins between the mask and reference trace can be specified by X Margin and Y Margin.
The points can be added, edited or deleted.
You can also create a Frequency Mask by using the manual method.
In the DPX display, click the Settings button.
Select Trace 1 under the Traces tab.
Under Tools, select Mask Test.
Under the Actions tab, select Beep, Save Acquisition Data, Save Trace and Save picture.
Click Enable Test.
When a violation is detected, the instrument will beep, and save all your selected format of files into the selected folder automatically.
The RSA306 in the Run mode can sound a beep, stop acquisitions, save acquisition data, save trace data and save a picture of the display. In Replay mode, it can sound a beep and stop analyzing. Files can be saved in the native format of SignalVu-PC (.tiq) or in comma separated variables or MATLAB 5 (.MAT) format.
The folder for saving files can be selected from Save as . . .
Setting up a mask and testing for violations is valuable in checking a production run of components, PCB’s, equipment or a network.
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