Circuit for generating dual-tone multi-frequency signals and high/low-tone signals
First Claim
1. A circuit for generating dual-tone multi-frequency and high/low-tone signals from digital data, comprising:
- a signal controlling logic circuit for decoding the digital data, in response to a digital control signal, to generate a plurality of low-frequency selecting decoding signals for selecting the frequency of a low-frequency group, a plurlaity of high-frequency selecting decoding signals for selecting the frequency of a high-frequency group, a low-frequency group enabling signal and a high-frequency group enabling signal;
a circuit means for generating first clock pulses exhibiting a fixed frequency;
a low frequency dividing circuit for generating second clock pulses having a second frequency of a fixed multiple of a particular frequency selected from said low-frequency selecting decoding signals by counting and decoding said first clock pulses;
a high frequency dividing circuit for generating third clock pulses having a third frequency of a fixed multiple of a particular frequency selected from said high-frequency selecting decoding signals by counting and decoding said first clock pulses;
first clock means, enabled by said low-frequency group enabling signal, for generating a plurality of fourth pulses having a duty cycle of 50% through division of said second clock pulses, said fourth pulses having an odd frequency component of a higher-harmonic wave;
second clock means, enabled by said high-frequency group enabling signal, for generating a plurality of fifth pulses having a duty cycle of 50% through division of said third clock pulses, said fifth pulses having an odd frequency component of a higher-harmonic wave; and
a signal synthesizing circuit coupled to said first and second clock means, for synthesizing dual-tone multi-frequency signals to eliminate said odd frequency higher-harmonic wave components of said fourth and fifth pulses upon reception of said fourth and fifth clock pulses.
1 Assignment
0 Petitions
Accused Products
Abstract
A circuit for generating dual-tone multi-frequency (DTMF) signals and high/low-tone signals from digital data with designating frequencies of high-tone or high-frequency group and frequencies of low-tone or low-frequency group, and at least one digital control signal. The circuit includes a signal controlling logic circuit for decoding the digital data in response to the digital control signal, a circuit for generating a fixed clock pulse, a frequency dividing circuit of low-frequency group for generating first clock pulses, a frequency dividing circuit of high-frequency group for generating second clock pulses, first clock device for generating a plurality of pulses having a duty cycle of 50% by dividing the first clock pulses, second clock device for generating a plurality of pulses having a duty cycle of 50% by dividing the second clock pulses, and a signal synthesizing circuit for synthesizing the dual-tone multi-frequency signals or high/low-tone signals of analog sine-wave deprived of higher-harmonic wave component by inputting the clock pulses of the odd frequency.
18 Citations
30 Claims
-
1. A circuit for generating dual-tone multi-frequency and high/low-tone signals from digital data, comprising:
-
a signal controlling logic circuit for decoding the digital data, in response to a digital control signal, to generate a plurality of low-frequency selecting decoding signals for selecting the frequency of a low-frequency group, a plurlaity of high-frequency selecting decoding signals for selecting the frequency of a high-frequency group, a low-frequency group enabling signal and a high-frequency group enabling signal; a circuit means for generating first clock pulses exhibiting a fixed frequency; a low frequency dividing circuit for generating second clock pulses having a second frequency of a fixed multiple of a particular frequency selected from said low-frequency selecting decoding signals by counting and decoding said first clock pulses; a high frequency dividing circuit for generating third clock pulses having a third frequency of a fixed multiple of a particular frequency selected from said high-frequency selecting decoding signals by counting and decoding said first clock pulses; first clock means, enabled by said low-frequency group enabling signal, for generating a plurality of fourth pulses having a duty cycle of 50% through division of said second clock pulses, said fourth pulses having an odd frequency component of a higher-harmonic wave; second clock means, enabled by said high-frequency group enabling signal, for generating a plurality of fifth pulses having a duty cycle of 50% through division of said third clock pulses, said fifth pulses having an odd frequency component of a higher-harmonic wave; and a signal synthesizing circuit coupled to said first and second clock means, for synthesizing dual-tone multi-frequency signals to eliminate said odd frequency higher-harmonic wave components of said fourth and fifth pulses upon reception of said fourth and fifth clock pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A circuit for generating dual-tone multi-frequency and high/low-tone signals from digital data, comprising:
-
signal controlling logic means for decoding the digital data, in response to a digital control signal, to generate a plurality of signals; means for generating a first fixed clock pulse; low frequency dividing means for generating second clock pulses from first signals generated by said signal controlling logic circuit by counting and decoding said first clock pusles; high frequency dividing means for generating third clock pulses from second signals generated by said signal controlling logic circuit by counting and decoding said first clock pulses; first clock generating means, enabled by a third signal generating means by said signal controlling logic circuit, for generating a plurality of fourth pulses through division of said second clock pulses of said low frequency dividing circuit, and said fourth pulses having an odd frequency component of a higher-harmonic wave; second clock generating means, enabled by a fourth signal generated by said signal controlling logic circuit, for generating a plurality of fifth pulses through division of said third clock pulses of said high frequency dividing circuit, and said fifth pulses having an odd frequency component of a higher-harmonic wave; and signal synthesizing means couple to said first and second clock means, for synthesizing the dual-tone multi-frequency signals upon reception of said fourth and fifth clock pulses genrated by said first and second clock generators to eliminate said odd frequency higher harmonic wave components. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. A method for generating dual-tone multi-frequency and high/low tone signals comprising the steps of:
-
receiving data control signals and digital data through an input bus from a central processing unit; decoding the data signals to generate low-frequency selecting decoding signals, high-frequency selecting decoding signals, low-frequency group enabling signals and high-frequency group enabling signals; generating first and second clock pulses from said low-frequency selecting decoding signals and said high-frequency selecting decoding signals, respectively; dividing the frequency of said first pulse to generate third clock pulses upon enabling by said low-frequency group enabling signal and dividing the frequency of said second clock pulse in said second clock generator to generate fourth clock pulses upon enabling by said high-frequency group enabling signals; and
;attenuating the harmonics of said third and fourth pulses to produce said dual-tone multi-frequency signal or said high/low-tone signal. - View Dependent Claims (23)
-
-
24. A circuit for generating dual-tone multi-frequency and high/low-tone signals from digital data, comprising:
-
input means for conducting input data, representing low frequency signals, high frequency signals, low frequency enable signals, high frequency enable signals, and fifth harmonic wave control signals, and control signals; signal controlling logic for decoding said input data, in response to said first control signals, to generate a plurality of low-frequency selecting decoding signals for selecting the frequency of a low-frequency group, a plurality fo high-frequency selecting decoding signals for selecting the frequency of a high-frequency group, a low-frequency group enabling signal and a high-frequency group enabling signal; circuit means for generating first clock pulses exhibiting a fixed frequency; low frequency dividing means for generating second clock pulses having a second frequency of a fixed multiple of a particular frequency selected from said low-frequency selecting decoding signals by counting and decoding said first clock pulses; high frequency dividing means for generating third clock pulses having a third frequency of a fixed multiple of a particular frequency selected from said high-frequency selecting decoding signals by counting and decoding said first clock pulses; first clock means, enabled by said low-frequency group enabling signal, for generating a plurality of fourth pulses through division of said second clock pulses, said fourth pulses having an odd frequency component of a higher-harmonic wave; second clock means, enabled by said high-frequency group enabling signal, for generating a plurality of fifth pulses through division of said third clock pulses, said fifth pulses havin an odd frequency component of a higher-harmonic wave; and a signal synthesizing circuit coupled to said first and second clock means, for synthesizing dual-tone multi-frequency signals to eliminate said odd frequency higher-harmonic wave components of said fourth and fifth pulses upon reception of said fourth and fifth clock pulses. - View Dependent Claims (25, 26, 27, 28, 29)
-
-
30. A circuit for generating dual-tone multi-frequency and high/low-tone signals from digital data, comprising:
-
input means for conducting input data and input control signals; signal controlling logic means for decoding said input data, in response to said digital control signals, to generate a plurality of frequency selecting decoding signals; circuit means for generating first clock pulses exhibiting a fixed frequency; frequency dividing means for generating second clock pulses having a second frequency of a fixed multiple of a particular frequency selected from said frequency selecting decoding signals by counting and decoding said first clock pulses; clock means for generating a plurality of third pulses through division of said second clock pulses, said third pulses having an odd frequency component of a higher-harmonic wave; and signal synthesizing means coupled to said clock means, for synthesizing dual-tone multi-frequency signals to eliminate said odd frequency higher-harmonic wave components of said third pulses upon reception of said third clock pulses.
-
Specification