Speech production by unconverted digital signals
First Claim
1. Apparatus for producing speech from digitally encoded speech samples without the use of a digital-to-analog converter, comprising:
- (a) speech computation means for producing a sequence of said digitally encoded samples;
(b) a computer central processing unit;
(c) a speaker; and
(d) control means connected to said central processing unit and said speaker for applying to said speaker a square wave signal having a duty cycle controlled by said speech computation means in accordance with the values of said samples;
(e) said square wave signal having a constant frequency in the ultrasonic range; and
(f) said control means including;
(i) first and second timers;
(ii) means for causing said first timer to count a first predetermined time interval;
(iii) means for continually polling said first timer to detect the end of said time interval;
(iv) means for causing said second timer to count a second time interval when said end of said first interval is detected, said second interval being a function of said sample values, and to put out said square wave signal in response thereto.
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Accused Products
Abstract
Improved speech sounds are produced from an all-software speech generating program on a computer which does not have a digital-to-analog converter by polling a first timer connected to the computer'"'"'s speaker until a time-out is found, then applying a sample time value to a second timer so connected, and restarting the first timer. This results in the generation of a variable-duty-cycle carrier without interfering with the computer'"'"'s operation. In an alternative embodiment, the first timer is used to generate an interrupt at regular intervals, and a sample time value from a storage buffer is then applied to the second timer.
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Citations
4 Claims
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1. Apparatus for producing speech from digitally encoded speech samples without the use of a digital-to-analog converter, comprising:
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(a) speech computation means for producing a sequence of said digitally encoded samples; (b) a computer central processing unit; (c) a speaker; and (d) control means connected to said central processing unit and said speaker for applying to said speaker a square wave signal having a duty cycle controlled by said speech computation means in accordance with the values of said samples; (e) said square wave signal having a constant frequency in the ultrasonic range; and (f) said control means including; (i) first and second timers; (ii) means for causing said first timer to count a first predetermined time interval; (iii) means for continually polling said first timer to detect the end of said time interval; (iv) means for causing said second timer to count a second time interval when said end of said first interval is detected, said second interval being a function of said sample values, and to put out said square wave signal in response thereto.
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2. Apparatus for producing speech from digitally encoded speech samples without the use of a digital-to-analog converter, comprising:
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(a) speech computation means for producing a sequence of said digitally encoded samples; (b) a computer central process unit; (c) a speaker; and (d) control means connected to said central processing unit and said speaker for applying to said speaker a square wave signal having a duty cycle controlled by said speech computation means in accordance with the values of said samples; (e) said square wave signal having a constant frequency in the ultrasonic range; and (f) said control means including; (i) first and second timers; (ii) a buffer for storing said sample values; (iii) means for causing said first timer to cyclically count first predetermined time intervals; (iv) means for interrupting said central processing unit in synchronization with said time intervals to apply a sample value stored in said buffer to said second timer so as to cause it to count a second interval which is a function of said stored sample value, and to put out said square wave signal in response thereto; and (v) means for causing sad central processing unit to compute and store and sample values in said buffer between interrupts. - View Dependent Claims (3, 4)
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Specification