Digital tone decoder
AssigneeMotorola, Inc.
InventorsHarold Garth Nash, Jack Whitmore
Life of this patent
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Abstract
A digital tone decoder includes means for generating a timing signal, zero crossing counter means for generating a decode signal after a predetermined number of zero crossings in response to an incoming time domain signal and for generating a reset signal at a predetermined time after the decode signal is sent to reset said zero crossing counter means to zero, and decoder means coupled to said zero crossing counter and to said timing means for generating an output signal at one of a plurality of output terminals corresponding to the frequency of the incoming signal upon receipt of the decode signal from said zero crossing counter means, said decoder means being reset to an initial state upon receipt of the reset signal.
Claims10
A digital tone decoder comprising:
- a. means for generating a timing signal;
- b. zero crossing counter means for generating a decode signal after a predetermined number of zero crossings in response to an incoming time domain signal and for generating a reset signal at a predetermined time after the decode signal is sent to reset said zero crossing counter means to zero;
- c. decoder means coupled to said zero crossing counter and to said timing means for generating an output signal at one of a plurality of output terminals corresponding to the frequency of the incoming signal upon receipt of the decode signal from said zero crossing counter means, said decoder means being reset to an initial state upon receipt of the reset signal;
- and
- d. means for selectively modifying the number of zero crossings of said time domain signal appearing at the input to said zero crossing counter
A digital tone decoder including a digital noise blanking circuit for converting a noisy time domain signal input signal into a series of transitional pulses comprising:
- a. means for generating a timing signal;
- b. first means for converting zero axis crossings of the noisy input signal into clusters of transitional pulses;
- c. second means for generating a single transitional pulse for each of the clusters of transitional pulses;
- d. zero crossing counter means for generating a decode signal after receiving a predetermined number of transitional pulses from said second means and for generating a reset signal at a predetermined time after the decode signal is sent to reset said zero crossing counter means to zero;
- e. decoder means coupled to said zero crossing counter and to said timing means for generating an output signal at one of a plurality of output terminals corresponding to the frequency of the incoming signal upon receipt of the decode signal from said zero crossing counter means, said decoder means being reset to an initial state upon receipt of the reset signal;
- and
- f. means for selectively modifying the number of zero crossings of said time domain signal appearing at the input to said zero crossing counter .
Dependencies are inferred from the claim text.