Reflected Binary Counters

Abstract

The progressive codes are a special class of the binary codes. In these codes successive code words differ in 1 bit only. This is a useful feature, for example in mechanical analog-to-digital converters where the position of a shaft has to be translated into a digital word. When using code discs with the natural binary code for this purpose, ambiguities in the sensing of the code strips on the disc (mechanical or photographic) by means of a reading device are practically unavoidable. These ambiguities depend on the precision of the code marks on the disc and that of the mutual positions of the sensors. For example, when in the transition from 7 to 8 (0111 to 1000) the 1, 2 and 4 sensors can test 0 signals and that the 8 sensor can only test a 1 signal after that, the 0 state will be indicated as an intermediate state between 7 and 8. Possibly combinations of states 1, 2 and 4 will also occur during this transition.