Random on Random (RoR) Test
Some vibration environments are characterized by quasi-periodic excitation from reciprocating or rotating machines (like rotor blades, propellers, or pistons). A good way to simulate this is with one or more high-level narrow-band or sinusoidal vibration components superimposed on a low-level broadband random profile. These are called mixed-mode random tests.
There are two types of mixed mode random tests supported in EDM: Sine on Random (SoR) and Random On Random (RoR). In each of these test types, an additional vibration profile is placed on top of the regular broadband random profile. In Sine On Random, this additional profile consists of one or more sine waves that sweep through a specified frequency range. The random profile may represent a base excitation or background noise level, and the sine waves represent strong single-frequency excitation. This mimics some real-world situations better than a random test by itself.
A Random on Random test superposes one or more high-level narrow-band random profiles on top of the broadband random test profile. These narrow-band profiles can be swept through a specified frequency range.
When RoR is running, the random narrow-band profiles are shown superimposed on the broadband random profile.