Dear forum members, first post for me, and I have a question: what exactly
is beat error? More precisely, let us denote by t_1 the time between a tic
and the following toc, and by t_2 the time between a toc and the following
tic of a watch movement. Assume that these quantities are stable enough.
There seems to be disagreement on whether the beat error is t_1-t_2 or
(t_1-t_2)/2. In particular:
* We have this document of the Witschi company
paragraph 1.2.2 in page 5. And other similar manuals from Witschi.
* We have no precise definition from the makers of the Vibrograh machine,
neverthelss in this manual
at page 4, we find a diagram indicating that the beat error is the
distance between the two parallel lines of dots generated by the machine,
and this, in fact, turns out to be (t_1-t_2)/2.
* We have this page on the MicroSet website
informing us that "MicroSet will measure the length of two beats and
compare them. It will then display the difference between them".
* We have other resources on the web, for instance this page
* We have a few posts on this very forum, for instance lysanderxiii's
post in this thread
tells us that "2.8 ms means the swing in one direction is 2.8 ms longer
than the the other direction".
I couldn't find a definite answer, yet I didn't venture into the technical
litterature. Anyway the fact that Wischi (industry standard) and MicroSet
(very solid repuatation) seem to disagree on their definition needs to be
explained, doesn't it? If one had the two mechines side by side, he could
throw a movement intentionally out of beat by various amounts, and then
compare the readings.
Hope that someone can explain my little impasse, and thank you all in
advance for reading!