See the difference between Cat I and Cat IV.
The four TCAT categories are not the same test with more sliders. Below is one synthesized machine case -- switch between the four categories and watch what each one is actually asked to do with it. Every plot on this page is computed live from that one signal, not a picture.
One machine, one fault, one measurement point.
Deliberately ordinary: a motor–pump train with an outer-race bearing defect. What changes below is not the machine — it is what each category is asked to do with the same evidence, and what evidence it is and is not given.
Same signal. Four different questions.
Cat I never names a fault. The only questions are: can this reading be trusted, and if so, what is its alarm status?
I-4 bad-data recognitionI-5 alarm/zone readingI-6 observation, not diagnosis
Settings are already chosen for you (that is Cat III's job). Read the evidence, reach for the discriminating test, name the fault.
Raw resolution alone will not settle this — run the envelope check (II-7) before you decide.
II-1 settings already chosen for youII-3 systematic spectrum readingII-6 Fault Matrix discriminating testII-7 envelope demodulation
Now you choose the acquisition. Same fault, same confound tone nearby — watch it merge into one blurred peak, or split into two, as you change resolution.
III-1 design acquisition, resolution/time trade-off at the limit
Best resolution, envelope analysis run, evidence genuinely strong — and still confounded: only one of the train's four bearing housings was measured. What is the honest call?
IV-4 prove a measurement trustworthy, or show why it is not
Synthetic, and that is the strength, not the caveat.
Every signal on this page is generated to specification, in your browser, from known bearing geometry and a known fault. That means the ground truth is exact -- which is precisely what makes it possible to grade "is this diagnosis right" honestly. Nothing on this page is a recording of a real machine, and nothing here is presented as one.
The bearing geometry and defect-frequency formulae are the same ones TIERA's own synthetic case generator uses, cross-checked mechanically rather than assumed.
TCAT is a TIERA-issued credential aligned with the ISO 18436-2 body of knowledge. It is not an accredited ISO certification, TIERA is not an ISO certification body, and TCAT training hours do not count towards the formal training an accredited ISO 18436 certification requires.
If what you just watched felt unfamiliar rather than obvious, you are not TCAT's audience yet — and that is a fine place to be. TCAT assesses people who already work with vibration data; it does not teach the subject from zero. The honest starting point is the free TIERA 101 primers: self-paced, beginner-first, no cost, and they issue a completion badge when you finish. Go there first if that is where you actually are — nothing about TCAT is a reason to skip them, and nothing you do there is required before you come back.
Want to know which category you should sit?
Send us a line and we will help you find the right rung.