Apparatus and method for generating a low frequency AC signal
First Claim
1. An apparatus for generating a low frequency AC signal, said apparatus comprising:
- means for generating a first sinusoidal signal oscillating at a first frequency;
means for sampling said first sinusoidal signal at a second frequency; and
means for converting said sampled signal into a second sinusoidal signal oscillating at a third frequency, said third frequency being the difference between said first frequency and said second frequency.
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Accused Products
Abstract
An apparatus and method for generating a low frequency AC signal such as a ringing voltage signal for a telephone subscriber interface unit or the like. The apparatus comprises an oscillator which drives a pair of counters whose outputs differ by a desired low frequency. The output of the first counter is fed to a controlled current source so as to excite a resonant tank circuit and thereby provide a high voltage sinusoidal signal. The output of the second counter drives a switch which samples the high voltage sinusoidal signal. An alias frequency is thus generated which is filtered by an output capacitor. The method comprises steps which follow directly from the above-described apparatus.
128 Citations
12 Claims
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1. An apparatus for generating a low frequency AC signal, said apparatus comprising:
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means for generating a first sinusoidal signal oscillating at a first frequency; means for sampling said first sinusoidal signal at a second frequency; and means for converting said sampled signal into a second sinusoidal signal oscillating at a third frequency, said third frequency being the difference between said first frequency and said second frequency. - View Dependent Claims (2, 3, 4)
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5. A method for generating a low frequency AC signal, said method comprising the steps of:
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generating a first sinusoidal signal oscillating at a first frequency; sampling said first sinusoidal signal at a second frequency; and converting said sampled signal into a second sinusoidal signal oscillating at a third frequency, said third frequency being the difference between said first frequency and said second frequency. - View Dependent Claims (6, 7, 8)
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9. An apparatus for generating a low frequency AC signal, said apparatus comprising:
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a first circuit for generating a first sinusoidal signal oscillating at a first frequency; a second circuit for sampling said first sinusoidal signal at a second frequency; and a third circuit for converting said sampled signal into a second sinusoidal signal oscillating at a third frequency, said third frequency being the difference between said first frequency and said second frequency. - View Dependent Claims (10, 11, 12)
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Specification