| 摘要 |
The invention relates to a method of detecting alternating signals from the telephone band which is applicable to the detection of multi frequency code signalling signals transmitted over the telephone lines, using an adjustable amplifying device 1, a programmable filtering device consisting of a filter 2 with switchable capacitances and of its control comprising an oscillator 3 and a variable frequency divider 4, a detection device consisting of a peak detector 5 and of an analog digital convertor 6, and a microprocessor 7. This method is notable in that the various processing steps are executed by the said devices under the control of the program recorded in the microprocessor. <IMAGE>
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