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US 4,068,176 AGranted
Direct reading sinad meter
AssigneeThe Singer Company
InventorJames Everett McTaggart
Life of this patent
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Abstract
The disclosed circuitry accepts from a radio receiver under test audio signals consisting of the signal plus noise and distortion (S + N + D), levels, and subtracts from it a separately generated signal (- S) corresponding in frequency and amplitude to the audio signal without noise and distortion. The resulting absolute value of noise plus distortion (N + D) is applied to a meter which may be calibrated to indicate the SINAD ratio.
Claims10
A noise and distortion meter comprising:
- input circuitry adapted for coupling to the output terminal of a radio receiver under test for receiving an output signal including noise and distortion from said receiver;
- circuit means coupled to said input circuit for leveling the output of said receiver under test to a constant level;
- signal generating means coupled to the output of said circuit means for generating a signal corresponding in frequency, phase, and amplitude to the signal portion of said receiver output;
- and
- means coupled to said circuit means and to said signal generating means for subtracting said generated signal from said receiver output to produce an output signal comprising said receiver noise and distortion.
2 more elements
Dependencies are inferred from the claim text.