Circuitry for multiplying a PCM signal by a sinusoid
AssigneeRCA Corporation
InventorCharles B. Dieterich
Life of this patent
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Abstract
Apparatus for multiplying a sampled data signal by a sinusoid having a period which is a multiple of the sample rate includes a plurality of sample scaling means to scale the sampled data signal by factors corresponding to the sine of angle .theta. over an angular range of 90 degrees in angular increments of 2.pi. divided by said multiple. A multiplexer multiplexes the scaled samples at the sample rate to produce a signal corresponding to the sampled data signal multiplied by the sinusoid. An embodiment is described for demodulating the stereo difference signal of a BTSC sound signal with serial-bit digital processing circuitry.
Claims15
Apparatus for multiplying sampled data signals, including a component having a predetermined frequency, by a sinusoid, comprising:
- a terminal for applying said sampled data signal;
- a plurality of scaling circuits respectively coupled to said terminal, for providing a plurality of signals representing said sampled data signal scaled by factors corresponding substantially to trigonometric ratios representing one of the sines and cosines of angular increments between 0 degrees and at least 90 degrees;
- and
- multiplexing means coupled to said plurality of scaling circuits for sequentially applying said plurality of signals to an output terminal in an order to produce an output signal corresponding to said sampled data signal multiplied by a sinusoid;
- and
- means coupled to said multiplexing means, and responsive to said output signal, for phase locking said sinusoid to said component having a predetermined frequency.
Apparatus for processing sampled data signals, including a sinusoidal component, comprising:
- means for applying said sampled data signal;
- a plurality of scaling means coupled to said means for applying said sampled data signal, for providing a plurality of samples corresponding to said sampled data signals respectively substantially scaled by sinusoidal trigonometric ratios of angles in increments of 2.pi./N where N is an integer equal to the ratio of the period of said sinusoidal component to the period of the rate of occurrence of said sampled data signal;
- multiplexing means coupled to said plurality of scaling means for selectively applying, at said sample rate, said scaled signals to an output terminal in a sequence to produce a signal corresponding to said sampled data signals multiplied by a sinusoid;
- and
- means coupled to the output terminal of said multiplexing means for phase locking the rate of sample occurrence of said sampled data signal to said sinusoidal component.
Apparatus for digitally processing a signal including a pilot component, said apparatus comprising:
- an input terminal for applying said signal;
- means, having a control input terminal, for providing a sampling signal at a predetermined rate;
- an analog-to-digital converter coupled to said input terminal and responsive to said sampling signal for providing PCM samples at said predetermined rate and corresponding to said signal;
- a plurality of scaling means coupled to said analog-to-digital converter, for providing a plurality of samples corresponding to said PCM samples respectively scaled by factors substantially corresponding to sinusoidal trigonometric ratios of angles in increments of 2.pi./N, where N is an integer;
- multiplexing means, coupled to said plurality of scaling means, for selectively applying at said predetermined rate, said scaled samples to a first output terminal in a sequence to produce a signal corresponding to said PCM samples mulitplied by a sinusoid having a period N times the reciprocal of said predetermined rate;
- and
- means coupled to said first output terminal and said control input terminal for synchronizing said sampling signal to said pilot component.
Apparatus for processing sampled data signals, including a sinusoidal component, comprising:
- means for applying said sampled data signal;
- a plurality of scaling means coupled to said means for applying sampled data signal, for providing a plurality of samples corresponding to said sampled data signals respectively substantially scaled by sinusoidal trigonometric ratios of angles in increments of 2.pi./N where N is an integer equal to the ratio of the period of said sinusoidal component to the period of the rate of occurrence of said sampled data signal;
- multiplexing means coupled to said plurality of scaling means for selectively applying, at said sample rate, said scaled signals to an output terminal in a sequence to produce a signal corresponding to said sampled data signals multiplied by a sinusoid;
- and
- means coupled to the output terminal of said multiplexing means for phase locking said sinusoidal component to said sinusoid.
Dependencies are inferred from the claim text.