Full scale
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In electronics and signal processing, the maximum amplitude a digital system can represent. Also known as full code, a signal has reached full scale when it has reached the maximum (or minimum) representable value. In unsigned fixed point, this occurs when all bits are 1s, but this is a simplified analysis. Full scale also occurs when the minimum value (or maximum rarefaction amplitude) is reached, which would be represented as all 0s. Further, many digital systems use other digital encoding methods, such as two's complement wherein all 1s or all 0s actually occur around the zero crossing, and the maximum and minimum values are not as simply described.
Once a signal has reached full scale all headroom has been utilized, and any further increase in amplitude results in an error known as clipping.
An important observation is that digital information only represents its analog equivalent, and must be reconstructed in order to reveal the original information. It is possible, therefore, for the signal represented by the digital data to exceed full scale even if the digital data does not.
The concept is also used in analogue systems, where full scale may be defined by the maximum voltage available, or the maximum deflection (Full Scale Deflection or FSD) or indication of an analogue instrument such as a moving coil meter.
