Patent US3586993A successfully refreshed from Google Patents.
US3586993A
Expired / Lapsed
US
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Testing instruments for telecommunication systems
Assignee: Marconi Instruments Ltd
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Filing: 1969-08-11
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Granted: 1971-06-22
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Expires: 1989-08-11
Abstract
Abstract In a ''''while noise'''' test set a mixer is fed from a source of white noise via a narrow band-stop filter and from a variable frequency oscillator, a predetermined band of frequencies from the output of the mixer being fed to a second mixer with oscillators from a fixed frequency oscillator. The arrangement is such that the output from the second oscillator consists of a noise frequency band including a narrow ''''silent slot,'''' the position of which is variable over said band by varying the frequency of the variable frequency oscillator.
Inventors
- 👤 William Alex Buck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 19:32
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/46; H04B3/487
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
162 words
A so-called ''''white noise'''' test set comprising a source of white noise; a narrow band band-stop filter fed with output from said source; a first mixer having one input fed with output from said band-stop filter and another input fed with output from a variable frequency oscillator which is variable over a predetermined frequency range; and a second mixer having an input fed with predetermined band of frequencies selected from the output of the first mixer and another input fed with oscillations from a fixed frequency oscillator, the frequency range of the variable frequency oscillator, the frequency of the fixed frequency oscillator and the band selected from the output of the first mixer being so chosen that the output from the second mixer consists of a noise frequency band extending up to a predetermined upper frequency and including a narrow slot the position of which, within said band, is variable over said band by varying the frequency of the variable freQuency oscillator.
Claim 2
Dependent Claim
162 words
A so-called ''''white noise'''' test set comprising a source of white noise; a narrow band band-stop filter fed with output from said source; a first mixer having one input fed with output from said band-stop filter and another input fed with output from a variable frequency oscillator which is variable over a predetermined frequency range; and a second mixer having an input fed with predetermined band of frequencies selected from the output of the first mixer and another input fed with oscillations from a fixed frequency oscillator, the frequency range of the variable frequency oscillator, the frequency of the fixed frequency oscillator and the band selected from the output of the first mixer being so chosen that the output from the second mixer consists of a noise frequency band extending up to a predetermined upper frequency and including a narrow slot the position of which, within said band, is variable over said band by varying the frequency of the variable freQuency oscillator.
Claim 3
Dependent Claim
101 words
A test set as claimed in claim 1 wherein the variable frequency oscillator is variable over a frequency range extending upwards from a lower frequency limit equal to twice the highest useful frequency from the noise source; the band selected from the output of the first mixer is half the width of the band of the useful frequencies from the noise source and extends upwards from a lower frequency limit equal to three-halves of the highest useful frequency from said noise source; and the frequency of the fixed frequency oscillator is equal to the lower frequency limit of said selected band.
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) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |