Main Page | See live article | Alphabetical index

Limiting

Limiting: Any process by which a specified characteristic (usually amplitude) of the output of a device is prevented from exceeding a predetermined value. Note 1: Hard limiting ("clipping") is a limiting action in which there is (a) over the permitted dynamic range, negligible variation in the expected characteristic of the output signal, and (b) a steady-state signal, at the maximum permitted level, for the duration of each period when the output would otherwise be required to exceed the permitted dynamic range in order to correspond to the transfer function of the device. Note 2: Soft limiting is limiting in which the transfer function of a device is a function of its instantaneous or integrated output level. The output waveform is therefore distorted, but not clipped.

Sources: from Federal Standard 1037C and from MIL-STD-188

In biology, physiology, and ecology, a limiting factor is one that controls a process, such as organism growth or species population size or distribution. The concept is based upon the Law of the Minimum put forth by the German geochemist, Justus von Liebig in 1840. It can be easy to conceive how a limiting resource (say, food) controls a process (say, growth) by running low or running out. However, some biological and ecological processes are controlled by too much of a factor (such as heat) rather than too little. Or, processes may be controlled by complex interactions of factors (Shelford, 1952). Walter Taylor (1934) proposed the following broad, restatement of the law of the minimum:

"The functioning of an organism is controlled or limited by that essential environmental factor or combination of factors present in the least favorable amount. The factors may not be continuously effective but only at some critical period during the year or perhaps only during some critical year in a climatic cycle."

References