Patent EP0145374A2 successfully refreshed from Google Patents.
US4003084A
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Method of and means for testing a tape record/playback system
Assignee: National Aeronautics and Space Administration
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Filing: 1975-03-25
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Granted: 1977-01-11
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Expires: 1995-03-25
Abstract
Abstract A tape record/playback system is tested by first deriving an analog test signal and a band-limited digital reference signal from a pseudo-noise (PN) sequence generator driven by a clock signal and recording said signals on respective tracks of the system during operation thereof in a record mode. During the playback mode of operation of the system, a delayed analog reference signal without time base variations is reconstructed from the played back reference signal and compared with the played back test signal in order to obtain an error signal that is a measure of the performance of the system.
Inventors
- 👤 with respect to an invention of Fletcher James C. Administrator of the National Aeronautics and Space Administration
- 👤 Gabriel R. Wallace
- 👤 William E. Salter
- 👤 Glenn D. Weathers
- 👤 Sidney S. Gussow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:09
CPC Classifications
G; G11; G11B; G11B27/00; G11B27/36; G01; G01R; G01R27/00; G01R27/28; G11B20/00; G11B20/10; G11B20/18; G11B20/1816; G11B20/182
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
119 words
A method for testing a tape record/playback system comprising the steps of: a. deriving an analog test signal and band-limited digital reference signals from a pseudo-noise sequence generator driven by a reference clock signal; b. recording said test signal and said reference signals on respective tracks of the system during operation thereof in a record mode; c. playing back the recorded signals during the playback mode of operation of the system; d. reconstructing a delayed analog reference signal without time base variations from the played back reference signals; and e. comparing the played back test signal with the reconstructed analog reference signal to obtain an error signal that is a measure of the performance of the tape record/playback system.
Claim 2
Independent Claim
119 words
A method for testing a tape record/playback system comprising the steps of: a. deriving an analog test signal and band-limited digital reference signals from a pseudo-noise sequence generator driven by a reference clock signal; b. recording said test signal and said reference signals on respective tracks of the system during operation thereof in a record mode; c. playing back the recorded signals during the playback mode of operation of the system; d. reconstructing a delayed analog reference signal without time base variations from the played back reference signals; and e. comparing the played back test signal with the reconstructed analog reference signal to obtain an error signal that is a measure of the performance of the tape record/playback system.
Claim 3
Dependent Claim
27 words
A method according to claim 1 wherein the analog test signal is formed by passing the output of the pseudo-noise sequence generator through a spectrum shaping filter.
Claim 4
Dependent Claim
31 words
A method according to claim 2 wherein the band-limited digital reference signals are constituted by a band-limited clock signal and a band-limited pseudo-noise sequence signal derived from the pseudo-noise sequence generator.
Claim 5
Dependent Claim
18 words
A method according to claim 3 wherein the band-limited clock signal is obtained by differentiating the clock signal.
Claim 6
Dependent Claim
25 words
A method according to claim 4 wherein the band-limited pseudo-noise sequence signal is obtained by differentiating and filtering the output of the pseudo-noise sequence generator.
Claim 7
Dependent Claim
52 words
A method according to claim 5 wherein reconstructed clock and reconstructed pseudo-noise sequence signals are developed from the played back band-limited clock signal and the band-limited pseudo-noise sequence signals, and the analog reference signal is developed by delaying the reconstructed pseudo-noise sequence signal and then passing it through a spectrum shaping filter.
Claim 8
Dependent Claim
18 words
A method according to claim 6 wherein the delay introduced into the reconstructed pseudo-noise sequence signal is variable.
Claim 9
Dependent Claim
155 words
Apparatus for testing a tape record/playback system comprising: a. means for driving a pseudo-noise sequence generator by a clock signal for producing a pseudo-noise sequence signal; b. means responsive to said pseudo-noise sequence signal for producing an analog test signal, and band-limited digital reference signals; c. a two-state mode control means; d. means to change said mode control means to a first state for effecting the recording of said test signal and said reference signals on respective tracks of the system; e. means to change said mode control means to a second state for effecting the playback of the recorded signals; f. means responsive to the played back reference signals for producing a delayed analog reference signal without time base variations; and g. comparison means responsive to the played back test signal and the reconstructed analog reference signal for obtaining an error signal that is a measure of the performance of the tape record/playback system.
Claim 10
Dependent Claim
155 words
Apparatus for testing a tape record/playback system comprising: a. means for driving a pseudo-noise sequence generator by a clock signal for producing a pseudo-noise sequence signal; b. means responsive to said pseudo-noise sequence signal for producing an analog test signal, and band-limited digital reference signals; c. a two-state mode control means; d. means to change said mode control means to a first state for effecting the recording of said test signal and said reference signals on respective tracks of the system; e. means to change said mode control means to a second state for effecting the playback of the recorded signals; f. means responsive to the played back reference signals for producing a delayed analog reference signal without time base variations; and g. comparison means responsive to the played back test signal and the reconstructed analog reference signal for obtaining an error signal that is a measure of the performance of the tape record/playback system.
Claim 11
Dependent Claim
27 words
A test set according to claim 8 including a spectrum shaping filter responsive to the output of the pseudo-noise sequence generator for forming the analog test signal.
Claim 12
Dependent Claim
46 words
A test set according to claim 9 including means responsive to the output of the pseudo-noise sequence generator and the clock signal for producing a band-limited clock signal and a band-limited pseudo noise sequence signal, the last two mentioned signals constituting the band-limited digital reference signals.
Claim 13
Dependent Claim
22 words
A test set according to claim 10 including means for differentiating and filtering the clock signal for forming the band-limited clock signal.
Claim 14
Dependent Claim
24 words
A test set according to claim 11 including means for differentiating and filtering the pseudo-noise sequence signal for forming the band-limited pseudo-noise sequence signal.
Claim 15
Dependent Claim
63 words
A test set according to claim 12 including means responsive to the played back band-limited clock signal and pseudo-noise sequence signals for reconstructing the clock and the pseudo-noise sequence signals, means for delaying the reconstructed pseudo-noise sequence signal, and means for passing the delayed pseudo-noise sequence signal through a spectrum shaping filter for producing said delayed analog reference signal without time base variations.
Claim 16
Dependent Claim
58 words
A test set according to claim 8 wherein said comparison means measures the RMS difference between the played back test signal and the reconstructed analog reference signal whereby said RMS difference is a measure of signal distortion resulting from all sources of signal distortion except for that signal distortion caused by time-base errors occuring during the record/playback process.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-01-11 | 1980-07-12 | 1981-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-01-11 | 1984-07-12 | 1985-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-01-11 | 1988-07-12 | 1989-01-11 | $7700.00 | Window Closed / Lapsed |