Patent ID: 6683948
Filing Date: 2004-01-27
Classification: H04M

Abstract:
A device for automatically identifying DTMF and FSK system, comprising:a signal detector for detecting signals on a telephone line; a DTMF decoder for decoding DTMF signals; a FSK decoder for decoding FSK signals; and a microprocessor which is driven when the signal detector detects a signal on the telephone line for only activating the DTMF decoder to calculate frequency spectrum of the detected signal, wherein, when the calculated frequency spectrum conforms to DTMF frequency spectrum, it is determined that a DTMF system is in use, and when the calculated frequency spectrum only has a frequency of about 1,200 Hz or 1,300 Hz, it is determined that a FSK system is in use, so as to deactivate the DTMF decoder and activate the FSK decoder.