Here is a time sample: $Q = \{(t_i, x_i) | 0 \leq x_i \leq x_{i+1}, 1 \leq i \leq n\}$
and rules:
(1) $T_1 \leq t_{i+1} - t_i < T_2$ where $T_1, T_2 > 0$
(2) $x_i$ comes with error:
$x_i = \lfloor x(t_i) \rfloor$ where $\lfloor x \rfloor$ - whole part of $x$, $x(t_i)$ - voluntary unknown law of object motion.
How we can find (approximately but sufficiently accurate) speed of the object at the given time?