DETECTION OF MULTITONE SIGNALS

摘要

A device for the communication of noisy data comprises transmission means to encode a digital signal into at least two analogue tone frequency signals and transmit them, receiving means (6) sampling each analogue tone frequency over a period of time substantially greater than 40ms, the samples of the analogue tone frequency each being decoded when possible into a digital signal, and a valid digital signal being accepted for outputting when at least a predetermined number of samples taken in said period of time give rise to the same digital signal.