One method of improving the sensitivity and immunity talk of a multifrequency receiver.

摘要

This invention relates to a method for improving the sensitivity and IMMUNITY OF MEMBERS OF A RECEIVER FREQUENCY UNTO with a reception DTMF. According to a first aspect of the invention, the number of steps ZERO input signal ACCOUNT FOR ONE OF A SERIES INTERVAL MEASUREMENT IN REAL TIME TO FREQUENCIES OCCURRING IN GROUP LOW FREQUENCY AND THE GROUP OF HIGH FREQUENCY a DTMF signal. AT THE END OF EACH measurement intervals, the number of zero crossings in a range of current measurement COMPARE TO EACH GROUP OF FREQUENCY a corresponding number of zero crossings in a number of measurement intervals PRECEDING THE NEAREST AND ESTABLISHING THE MAGNITUDE any differences. INPUT SIGNAL treated as a DTMF signal when the difference is at most equal to a value EXTENT PERMITTED. According to a second aspect of the invention, DETERMINED IN REALTIME an energy parameter representative POWER TONE input signal IN EACH OF THE BANDS GROUP DTMF FREQUENCY FOR EACH OF A SERIES INTERVAL MEASURING. AT THE END OF EACH MEASUREMENT RANGES, THE AVERAGE VALUE OF TOTAL MEASURED PARAMETERS DETERMINED FOR MEASURING RANGES FROM THE BEGINNING OF A CURRENT SIGNAL. DETERMINED Deference BETWEEN EACH OF THE PARAMETERS OF CURRENT ENERGY IN THE TWO BANDS AND AVERAGE VALUE OF CERTAIN PARAMETERS AND ARE DETERMINED AT LEAST THREE THRESHOLD VALUES FOR THIS DISPUTE, namely a normal value below which IS CONSIDERED TO THERE IS A DTMF signal, at least one value greater than normal and at least a lower value than normal. It IS HOLDING A CHECK TO BE IF EXISTS DIFFERENCE IN ANY OF THE BANDS ARE ABOVE NORMAL VALUE, AND IN THIS CASE, IS FIND OUT IF THE DIFFERENCE IN QUESTION IS ALSO OR ABOVE THE VALUE HIGHER THAN NORMAL . COMPARE THE DIFFERENCE OF BAND WITH OTHER SMALLER THAN NORMAL VALUE FOR SO IF THE DIFFERENCE TO ESTABLISH OR IS BELOW THIS VALUE, IN WHICH CASE THERE IS CONSIDERED a DTMF signal. In a third aspect, WHEN IS THE FIRST TIME FREQUENCY INTERFERENCE DURING ONE OF A SERIES INTERVAL MEASUREMENT WHEN decodes a DTMF signal, ANOTA this and IF RETURNS TO FIND THE SAME TONE OF INTERFERENCE IN AN INTERVAL MEASUREMENT SUBSEQUENT, tolerates TONE INTERFERENCE.