Title :
Multifrequency tone detection by zero-interval analysis
Author_Institution :
Post Office Research Department, Ipswich, UK
Abstract :
An algorithm is presented which enables a microprocessor to analyse the zero intervals of the multifrequency signals from a pushbutton telephone. A model has shown that, with a 100 kHz clock, the component frequencies of any signal can be predicted to within ±1% from a 30 ms sample, but the speech immunity requires improvement.
Keywords :
computerised signal processing; signal detection; telephone sets; microprocessor; multifrequency tone detection; pushbutton telephone; zero interval analysis;
Journal_Title :
Electronics Letters
DOI :
10.1049/el:19770003
