US4068176A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Direct reading sinad meter
Assignee: LIBRASCOPE Corp A CORP OF DELAWARE
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Filing: 1976-08-17
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Granted: 1978-01-10
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Expires: 1996-08-17
Abstract
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.
Inventors
- 👤 James Everett McTaggart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 02:02
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/26; G01R19/00; G01R19/10; G01R23/00; G01R23/16; G01R23/20
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
115 words
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.
Claim 2
Dependent Claim
115 words
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.
Claim 3
Dependent Claim
102 words
The meter claimed in claim 1 wherein said signal generating means includes: a filter coupled to the output of said circuit means for transmitting the signal portion and rejecting substantially all of the noise and distortion portions of said receiver output; a phase locked loop coupled to said filter and controlled by the signal transmitted thereby; a gain controlled amplifier coupled to said phase locked loop, said amplifier being controlled by the signal transmitted by said filter and by the signal output of said amplifier for adjusting said signal output to a level corresponding to said signal portion of said receiver output.
Claim 4
Dependent Claim
59 words
The meter claimed in claim 1 wherein said signal generating means produces an ouput signal that is inverted in phase from said signal portion of said receiver output, and wherein said means for subtracting said generated signal from said receiver output includes a resistor summing circuit coupled to the outputs of said circuit means and said gain controlled amplifier.
Claim 5
Dependent Claim
14 words
The meter of claim 1 wherein said circuit means includes a gain control amplifier.
Claim 6
Dependent Claim
24 words
The meter of claim 1 further including an output meter coupled to said means for substracting to indicate the level of said output signal.
Claim 7
Dependent Claim
15 words
The meter claimed in claim 5 wherein said output meter is calibrated in SINAD values.
Claim 8
Dependent Claim
14 words
The meter of claim 1 wherein said circuit means includes a gain control amplifier.
Claim 9
Dependent Claim
19 words
The meter of claim 1 wherein said input circuitry includes means for adjusting the level of said receiver output.
Claim 10
Dependent Claim
21 words
The meter of claim 2 further including phase adjusting means coupled between said phase locked loop and said gain control amplifier.
Claim 11
Dependent Claim
20 words
The meter according to claim 1 wherein said constant level output of said circuit means in a constant r.m.s. level.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-01-09 | 1981-07-11 | 1982-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-01-09 | 1985-07-11 | 1986-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-01-09 | 1989-07-11 | 1990-01-10 | $7700.00 | Window Closed / Lapsed |