Shaped Random Function Enables Tailored Random Signal Generation

The Shaped Random function, which is capable of producing a carefully tailored random spectrum,  is available in all of Crystal Instrument’s dynamic signal analyzers. The various constructions of the profiles can produce types of noise such as white noise, pink noise, and more.

The Shaped Random function allows a tailored signal generation. Very similar to the Vibration Control System’s (VCS) Random test, the Dynamic Signal Analyzer (DSA) Shaped Random test provides a pure Gaussian random signal with a user-specified profile, but without the control loop.

The user is able to define the profile by keying in the frequency points and their specific amplitude levels. This will define a profile, which later can be generated and eventually fed to an exciter. In addition, the import option allows the user to import pre-defined profiles.

The below screenshot demonstrates the profile setup window.

This screenshot below shows input channel response based on the profile that was defined by the user in the previous step. 

One benefit the Shaped Random function offers is tailoring the profile in a way to reduce the effect of the resonance frequencies on the UUT (Unit Under Test).

The below screenshot is the Frequency Response Function (FRF) signal showing a resonance peak at ~1700 Hz.

Using the Shaped Random capabilities, now we can either import a profile or create a profile that reduces the effects of the peak. The profile with the eliminated peak based on the FRF signal is shown below.

The flexibility of the Shaped Random Function enables the user to take advantage of this function in many possible ways based on the application.