Attenuation control for adjustable attenuation elements - uses two=way counter whose signal is applied to random access ROM providing time dependent attenuation

摘要

The attenuators are adjustable by a digital signal and their operationis controlled by a two-way counter for the pulses of a clock pulse signal which produces the digital signal. The output signal of the counter is passed through programmable read-only memories with random access. They are so programmed, one preceded by an inverter that the desired attenuation characteristic is achieved. An adder sums-up the final output at the terminal. A setting unit adjusts the clock pulse signal frequency. A flip-flop produces the start-stop signal for the counter. Another flip-flop provides the characteristics for the counting mode. The course of the attenuation can now be easily altered by readjusting one of the programmable read-only memories.