Signal transmitting apparatus using a/d converter and monostable control

Abstract

An amplitude adjustment circuit transmits an analog signal to an analog-to-digital converter. If the resulting digital signal reaches the maximum permissible digital value, a monostable control circuit is triggered to cause the amplitude adjustment circuit to reduce the level of the analog signal a certain amount. If the digital signal again reaches the maximum permissible digital value before the control circuit returns to its stable condition a second monostable circuit is triggered (and the first one is retriggered) to cause the amplitude adjustment circuit to reduce the level of the analog signal another amount. The unstable interval for the second monostable circuit is shorter than for the first, and, in the absence of further triggering, both such circuits return to their stable states in succession. The digital signals are used to reconstruct the analog signal in apparatus similar to the encoding apparatus and including amplitude adjustment apparatus controlled by the amplitude compression signals.