Arrangement for controlling the amplitude of an electric signal for a digital electronic apparatus and corresponding method of control
AssigneeIng. C. Olivetti & C., S.p.A.
InventorsAlessandro Graciotti, Massimo Bertagna
Life of this patent
Estimating the term…
Abstract
In a digital system for amplitude modulation, the logical signal at acoustic frequency is modulated by means of an ultrasonic frequency signal, the duty-cycle of which can be varied by means of a program. More particularly, the modulating signal is generated by a cyclic counter. The duty-cycle is programmed by writing the corresponding numerical value to a register with a capacity equal to that of the counter. An adder, adding the value of the counter each time to that of the register, generates a carry signal which gives consent to the acoustic signal only for a part of the relative cycle of the modulating signal.
Claims10
An arrangement for controlling the amplitude of an electric signal for a digital electronic apparatus, comprising a generator of a first logical signal of constant amplitude and of a frequency comprised within a predetermined frequency band, and a utilizing device sensitive to the amplitude of said signal, wherein said first logical signal defines a mark-space ratio and a main value, and wherein said arrangement further comprises a generator of a second logical signal with a frequency much greater than the frequencies of said band, a digital circuit for varying the mark-space ratio (duty-cycle) of said second signal, and a circuit for modulating said first logical signal according to said second signal so as to reduce the mean value of said first signal correspondingly.
A method of controlling the amplitude of an electric signal in a digital environment, wherein a first logical signal defining a mean value is generated at constant amplitude and at low frequency, and comprising the following steps:
- a second logical signal defining a mark-space ratio is generated at a frequency much greater than the frequency of the first signal, the mark-space ratio of said second signal is determined selectively, and said first signal is modulated with said second signal, whereby the mean value of said first signal is reduced correspondingly.
Dependencies are inferred from the claim text.