US3693076A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Computer controlled rf noise and modulation analyzer
Assignee: Westinghouse Electric Corp
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Filing: 1971-06-22
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Granted: 1972-09-19
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Expires: 1991-06-22
Abstract
Abstract A computer controlled test set capable of measuring FM and AM noise of an RF signal as well as the index of modulation, RF power level and the linearity of a ramped FM signal output from a microwave signal oscillator included in a unit under test.
Inventors
- 👤 John L Nugent
- 👤 Harvey M Masters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:17
CPC Classifications
G; G01; G01R; G01R29/00; G01R29/06; G01R23/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
380 words
A system controlled by means of a digital computer for making noise spectrum analysis and other related tests upon a unit under test providing an RF output, comprising in combination: a variable RF frequency source including means for having the output frequency thereof externally controlled; computer interface apparatus intercoupling said variable frequency source to said digital computer, said computer operating to select the frequency output from said variable RF frequency source; an RF mixer coupled to the outputs of said variable RF frequency source and to said unit under test, respectively, for providing an IF signal resulting from heterodyning the RF frequency outputs therefrom; a frequency limiter means coupled to the output of said mixer for providing an output corresponding substantially to a predetermined IF frequency; a controlled frequency source adapted to operate within the range of said predetermined IF frequency; detector circuit means coupled to and responsive to inputs from said limiter means and said controlled frequency source and being operable to cancel the If frequency and provide an output comprising a noise signal; a phase lock loop circuit coupled between the output of said detector circuit means and said controlled frequency source, being responsive to the output of said detector to generate and apply a control signal to said controlled frequency source for phase locking the output of aid controlled frequency source to said predetermined IF frequency; a sweep generator coupled to said variable RF frequency source for selectively varying the output frequency thereof over a predetermined frequency range which includes the output frequency of the unit under test; first circuit means coupled to and responsive to the output of said detector circuit means for generating an output signal indicative of phase lock and including means coupling the output signal corresponding to phase lock to said computer and to said sweep generator for deactivating the sweep upon the occurrence of phase lock; spectrum analyzer means coupled to the output of said detector circuit and controlled by said computer for providing a signal selectively indicative of the spectral characteristics of said noise signal; second circuit means coupled to the output of said spectrum analyzer for measuring the spectral characteristics of said noise signal and providing a signal corresponding thereto to said computer whereby said computer provides a suitable readout.
Claim 2
Independent Claim
380 words
A system controlled by means of a digital computer for making noise spectrum analysis and other related tests upon a unit under test providing an RF output, comprising in combination: a variable RF frequency source including means for having the output frequency thereof externally controlled; computer interface apparatus intercoupling said variable frequency source to said digital computer, said computer operating to select the frequency output from said variable RF frequency source; an RF mixer coupled to the outputs of said variable RF frequency source and to said unit under test, respectively, for providing an IF signal resulting from heterodyning the RF frequency outputs therefrom; a frequency limiter means coupled to the output of said mixer for providing an output corresponding substantially to a predetermined IF frequency; a controlled frequency source adapted to operate within the range of said predetermined IF frequency; detector circuit means coupled to and responsive to inputs from said limiter means and said controlled frequency source and being operable to cancel the If frequency and provide an output comprising a noise signal; a phase lock loop circuit coupled between the output of said detector circuit means and said controlled frequency source, being responsive to the output of said detector to generate and apply a control signal to said controlled frequency source for phase locking the output of aid controlled frequency source to said predetermined IF frequency; a sweep generator coupled to said variable RF frequency source for selectively varying the output frequency thereof over a predetermined frequency range which includes the output frequency of the unit under test; first circuit means coupled to and responsive to the output of said detector circuit means for generating an output signal indicative of phase lock and including means coupling the output signal corresponding to phase lock to said computer and to said sweep generator for deactivating the sweep upon the occurrence of phase lock; spectrum analyzer means coupled to the output of said detector circuit and controlled by said computer for providing a signal selectively indicative of the spectral characteristics of said noise signal; second circuit means coupled to the output of said spectrum analyzer for measuring the spectral characteristics of said noise signal and providing a signal corresponding thereto to said computer whereby said computer provides a suitable readout.
Claim 3
Dependent Claim
16 words
The invention as defined by claim 1 wherein said detector circuit means comprises a quadRature detector.
Claim 4
Dependent Claim
45 words
The invention as defined by claim 2 wherein said variable RF frequency source comprises a frequency synthesizer and said sweep generator comprises a saw-tooth generator for varying the frequency output of said synthesizer linearly over a predetermined frequency range as determined by said digital computer.
Claim 5
Dependent Claim
17 words
The invention as defined by claim 2 and wherein said spectrum analyzer comprises a digital wave analyzer.
Claim 6
Dependent Claim
28 words
The invention as defined by claim 4 wherein said second circuit means comprises a digital voltmeter providing an output to said computer comprising a binary coded decimal signal.
Claim 7
Dependent Claim
43 words
The invention as defined by claim 5 and additionally including an IF signal power divider coupled to the output of said RF mixer, having a first and a second output branch and wherein said first branch is coupled to said frequency limiter means.
Claim 8
Dependent Claim
42 words
The invention as defined by claim 6 and additionally including RF detector means coupled to said second output branch of said power divider and including circuit means coupling the output of said RF detector means to the input of said digital voltmeter.
Claim 9
Dependent Claim
32 words
The invention as defined by claim 6 and additionally including an AM detector coupled to said second output branch and including circuit means for being selectively coupled to said digital wave analyzer.
Claim 10
Dependent Claim
62 words
The invention as defined by claim 8 and additionally including a first signal shaping filter and a first amplifier means coupled between the output of said quadrature detector and the input to said digital wave analyzer, and a second signal shaping filter and a second amplifier coupled between the output of said AM detector and said input to said digital wave analyzer.
Claim 11
Dependent Claim
47 words
The invention as defined by claim 1 and additionally including a digitally controlled signal attenuator coupled between the unit under test and said RF mixer and additionally including means coupled to said digital computer for being controlled thereby to step the attenuator in selective increments of attenuation.
Claim 12
Dependent Claim
57 words
The invention as defined by claim 1 wherein said voltage controlled frequency source comprises a voltage controlled crystal oscillator and wherein said phase lock loop circuit includes amplifier means coupled between the output of said detector circuit means and the crystal oscillator whereby the output of said amplifier means applies a control voltage to said crystal oscillator.
Claim 13
Dependent Claim
66 words
The invention as defined by claim 1 wherein said spectrum analyzer means comprises a digital wave analyzer including a circuit connection back to said computer interface apparatus for being controlled by said digital computer, and additionally including threshold detector means coupled to the output of said digital wave analyzer, being adapted to provide an output signal upon detecting a predetermined amplitude signal from said wave analyzer.
Claim 14
Dependent Claim
124 words
The invention as defined by claim 1 and additionally including: a circuit connection between said digital computer and said unit under test through said interface apparatus for varying the output frequency of said unit under test over a predetermined frequency range; and a zero crossover detector having a circuit connection from said digital computer through said interface apparatus for being activated by said computer simultaneously with the signal applied to the unit under test for varying its output frequency, said zero crossover detector additionally being coupled to the output of said detector circuit means to couple a signal back to said computer through said interface apparatus corresponding to the number of zero counts produced over the frequency range output of said unit under test.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-19 | 1976-03-20 | 1976-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-19 | 1980-03-20 | 1980-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-19 | 1984-03-20 | 1984-09-19 | $7700.00 | Window Closed / Lapsed |