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 second-order and third-order nonlinearities. With the sum or difference of any two correlated signal frequencies fi'', fi'''' in the two noise bands equal to a primary beat frequency F1 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 second-order nonlinearity of that test circuit throughout the signal band. The superposition of a pilot oscillation of frequency G3 (lying within the pass band of the test circuit) upon the primary beat frequency F1 gives rise to a secondary beat frequency F2 F1 + OR - G3 whereby the amplitude of another output signal, having this frequency F2, is a measure of third-order nonlinearity of the test circuit.
Inventors
👤 Dietrich-Ekkehard Alker
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-06 17:40
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/28
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
179 words
A system for determining the nonlinearity of a signaltransmitting circuit, comprising a source of random frequencies spread over a predetermined test band; a supply of at least one fixed reference frequency; modulating means connected to said supply and said source for deriving from the output of the latter 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 primary beat frequency upon intermodulation thereof in a nonlinear transmission path; summing means for combining said correlated test bands; supply means for delivering to said summing means a pilot oscillation whose fixed frequency is transmissible by a test circuit connected to said summing means for energization thereby; and frequency-selective indicator means connected to the output of said test circuit for ascertaining the amplitudes of a first output signal at said primary beat frequency and of a second output signal at a secondary beat frequency due to intermodulation of said primary beat frequency with said pilot oscillation.
Claim 2
Independent Claim
179 words
A system for determining the nonlinearity of a signaltransmitting circuit, comprising a source of random frequencies spread over a predetermined test band; a supply of at least one fixed reference frequency; modulating means connected to said supply and said source for deriving from the output of the latter 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 primary beat frequency upon intermodulation thereof in a nonlinear transmission path; summing means for combining said correlated test bands; supply means for delivering to said summing means a pilot oscillation whose fixed frequency is transmissible by a test circuit connected to said summing means for energization thereby; and frequency-selective indicator means connected to the output of said test circuit for ascertaining the amplitudes of a first output signal at said primary beat frequency and of a second output signal at a secondary beat frequency due to intermodulation of said primary beat frequency with said pilot oscillation.
Claim 3
Dependent Claim
32 words
A system as defined in claim 1 wherein said indicator means comprises separate indicator circuit for said first and second output signals and switchover means for alternately rendering said indicator circuit effective.
Claim 4
Dependent Claim
40 words
A system as defined in claim 2, further comprising switch means between said supply and said summing means for feeding said pilot oscillation to said summing means only during periods of effectiveness of the indicator detecting said second output frequency.
Claim 5
Dependent Claim
26 words
A system as defined in claim 1 wherein said modulating means includes filter means for suppressing said reference frequency in the input of said summing means.