Autoleveller Dead Length & Residual Variation

The shortest correctable wavelength is taken as twice the dead length, the sampling limit below which a periodic fault cannot be resolved at all — a real leveller degrades gradually as wavelength approaches it rather than failing at a step, so treat the figure as an optimistic boundary and not a specification. Note the direction of the speed term: raising delivery speed shortens the dead time but the dead length changes only through the servo component, so the machine does not become blinder in metres as fast as operators expect — but the correction quality within the band does fall, because the servo has fewer millimetres to act in. Short-wave faults are the ones an open-loop leveller cannot touch by construction, and they are exactly the drafting waves generated inside the machine itself, downstream of the measuring point. Sliver CV is also not yarn CV: levelling corrects mass per unit length, not fibre orientation, hooks or short-fibre distribution, and a perfectly levelled sliver still spins badly if the fibre inside it is wrong.