US3619774A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for measuring nonlinearity of a signal-transmitting network
Assignee: Wandel and Golterman GmbH and Co
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Filing: 1969-07-29
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Granted: 1971-11-09
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Expires: 1989-07-29
Abstract
Abstract The output of a random-noise generator is modulated with the aid of two fixed reference frequencies G1, G2 (one of which may be zero) to yield two mutually transposed but correlated noise bands overlapping in a frequency range which substantially coincides with a band of signal frequencies to be transmitted through a test circuit to be examined for nonlinearity. With the sum or difference of any two correlated signal frequencies fi'', fi'''' in the two noise bands equal to a fixed beat frequency F G2 + OR G1, the amplitude of a signal of this beat frequency in the output of the test circuit receiving the two wholly or partly coincident noise bands is a measure of the nonlinearity of that test circuit throughout the signal band. A broadband of signal frequencies may be substituted for the noise frequencies if the system is to be tested in actual operation.
Inventors
- 👤 Franz Josef Landwehr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:22
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/46
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
154 words
A system for determining the nonlinearity of a signaltransmitting circuit, comprising a source of random frequencies spread over a predetermined test band; modulatiNg means including a supply of at least one fixed reference frequency for deriving from the output of said source a pair of two mutually transposed but at least partly overlapping correlated test bands within which any two correlated frequencies, derived from a common frequency in the original test band, give rise to a predetermined beat frequency upon intermodulation thereof in a nonlinear transmission path; summing means for combining said correlated test bands; and frequency-selective indicator means connected to receive said beat frequency from the output of a test circuit connected to said summing means for ascertaining the amplitude of an output signal at said beat frequency as a measure of nonlinearity of said test circuit throughout a signal band substantially coinciding with the region of overlap of said correlated test bands.
Claim 2
Independent Claim
154 words
A system for determining the nonlinearity of a signaltransmitting circuit, comprising a source of random frequencies spread over a predetermined test band; modulatiNg means including a supply of at least one fixed reference frequency for deriving from the output of said source a pair of two mutually transposed but at least partly overlapping correlated test bands within which any two correlated frequencies, derived from a common frequency in the original test band, give rise to a predetermined beat frequency upon intermodulation thereof in a nonlinear transmission path; summing means for combining said correlated test bands; and frequency-selective indicator means connected to receive said beat frequency from the output of a test circuit connected to said summing means for ascertaining the amplitude of an output signal at said beat frequency as a measure of nonlinearity of said test circuit throughout a signal band substantially coinciding with the region of overlap of said correlated test bands.
Claim 3
Dependent Claim
36 words
A system as defined in claim 1 wherein said source includes a random-noise generator and a band-pass filter in the output of said generator, said reference frequency being located beyond the pass band of said filter.
Claim 4
Dependent Claim
28 words
A system as defined in claim 2 wherein said modulating means includes a supply of a second fixed reference frequency located beyond the pass band of said filter.
Claim 5
Dependent Claim
23 words
A system as defined in claim 3 wherein said modulating means further includes additional filter means in the output of said summing means.
Claim 6
Dependent Claim
25 words
A system as defined in claim 4 wherein said additional filter means has a pass band excluding said original test band and said reference frequencies.
Claim 7
Dependent Claim
40 words
A system as defined in claim 5 wherein said reference frequencies are located above said original test band with a mutual separation corresponding to a difference frequency near the lower limit of the pass band of said additional filter means.
Claim 8
Dependent Claim
59 words
A system as defined in claim 1 wherein said source comprises a broadband signal transmitter, said modulating means including mixer means for heterodyning the output of said transmitter with said reference frequency and for transmitting the resulting frequency band to said summing circuit together with the signals from said transmitter but at a lower amplitude level than said signals.
Claim 9
Dependent Claim
40 words
A system as defined in claim 7, further comprising alarm means controlled by said indicator means for interrupting the transmission of said signals through said test circuit in response to an amplitude of said beat frequency exceeding a predetermined level.
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) | 1974-11-08 | 1975-05-10 | 1975-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-08 | 1979-05-10 | 1979-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-08 | 1983-05-10 | 1983-11-09 | $7700.00 | Window Closed / Lapsed |