# What is the no overload region of a quantizer?

I was watching a video on quantization noise and the instructor kept referring to the "no overload" region of a quantizer? Could anyone please explain what that term means?

• never heard that term before, but I guess it's the area of the quantizer between its minimum and maximum input value boundary? – Marcus Müller Jul 21 '17 at 16:02
• Was it a sigma-delta modulator? In these one-bit quantizers, if the signal slope is too large, the converter can't keep up (it's overloaded). – MBaz Jul 21 '17 at 16:10
• My guess is that the overload region, is when the input amplitude is larger than the dynamic range of the converter. When this happens, some converters have a saturation recovery time associated with the overload, so there may be a period of time when the signal drops back into the dynamic range but the converter remains overloaded for some time. Since you saw the video, perhaps you could respond if this makes sense. – user28715 Jul 21 '17 at 16:36
• @MBaz, delta modulation is not the same thing as sigma-delta. the latter doesn't have a problem with slope. – robert bristow-johnson Jul 21 '17 at 18:34
• @robertbristow-johnson Indeed I got them mixed up -- thanks for the correction. – MBaz Jul 22 '17 at 18:55

Associated with every $N$ point quantizer is a partition of the real line $\mathcal R$ into $N$ cells or atoms $R_i$, for $i = 1,2,\cdots, N$. The $i$th cell is given by $\mathcal R_i=\{x \in \mathcal R: Q(x) = y_i\} \equiv Q^{-1}(y_i)$, the inverse image of $y_i$ under $Q$. It follows from this definition that $\bigcup_i \mathcal R_i = \mathcal R$ and $R_i\bigcap R_j = \emptyset$ for $i \neq j$. A cell that is unbounded is called an overload cell. Each bounded cell is called a granular cell. Together all of the overload (granular) cells are called the overload region (granular region).
• the width of the "No overload (no saturation) region" is 7 units. i would widen it by $\frac12$ unit on both sides so that there are 8 valid levels. – robert bristow-johnson Jul 22 '17 at 22:16