US3911478A
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Method and apparatus for processing test signals which convey information as to gain and delay distortions of T.V. systems
Assignee: Tektronix Inc
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Filing: 1972-04-05
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Granted: 1975-10-07
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Expires: 1992-04-05
Abstract
Abstract A modulated sine-squared test signal processing technique and an electronic apparatus are employed provide information as to the gain and delay distortions of T.V. broadcast systems, particularly the relative chrominance-to-luminance distortions of T.V. broadcast color transmission systems. A test signal, which is a modulated sine-squared pulse of a desired half-amplitude duration containing both a low-frequency component and the side bands of a carrier at or very near the color subcarrier frequency, is applied to a specially designed frequency-selective filter for separating the low-frequency component from the side bands. Then these separated sideband signals components are applied to two detector circuits, which together with associated low-pass filters, detect the positive and negative envelopes of the modulated side bands and linearly adds the low-frequency component to each envelope. The peak amplitude of the resulting waveform is the low-frequency component plus the positive envelope, and the baseline part of the waveform is the lowfrequency component plus the negative envelope, conveys all information contained in the test signal as to gain and delay distortions. This information is suitable for automated measurement, or it can be measured directly with a generalpurpose oscilloscope.
Inventors
- 👤 Charles W Rhodes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 09:29
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03D; H03D1/00; H03D1/08; H03D1/10; H04; H04N; H04N17/00; H04N17/02
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
94 words
The method of processing a modulated sinesquared test signal, comprising: separating said modulated sine-squared test signal into a lowfrequency component and a high frequency component; splitting the high-frequency component into a first signal having a positive polarity and a second signal having a negative polarity; detecting the positive envelope of said first signal and the negative envelope of said second signal; and adding the separated said low-frequency component linearly to each such positive and negative envelopes of said first and second signals recovered from detection of said high-frequency component to form two measurement waveforms.
Claim 2
Independent Claim
94 words
The method of processing a modulated sinesquared test signal, comprising: separating said modulated sine-squared test signal into a lowfrequency component and a high frequency component; splitting the high-frequency component into a first signal having a positive polarity and a second signal having a negative polarity; detecting the positive envelope of said first signal and the negative envelope of said second signal; and adding the separated said low-frequency component linearly to each such positive and negative envelopes of said first and second signals recovered from detection of said high-frequency component to form two measurement waveforms.
Claim 3
Dependent Claim
23 words
The method according to claim 1 wherein said low-frequency component of said modulated sine-squared test signal corresponds substantially to the luminance frequency spectrum.
Claim 4
Dependent Claim
23 words
The method according to claim 1 wherein said high-frequency component of said modulated sine-squared test signal corresponds substantially to the chrominance frequency spectrum.
Claim 5
Independent Claim
103 words
The apparatus for processing modulated sine-squared test signals, comprising: separation means for separating said modulated sine-squared pulse into a low-frequency component and a high-frequency component; split means for splitting the high-frequency component into a first signal having a positive polarity and a second signal having a negative polarity; detector means for detecting the positive envelope of said first signal and the negative envelope of said second signal; and addition means for adding the separated said low-frequency component linearly to each such positive and negative envelopes of said first and second signals recovered from detection of said high-frequency component to form two measurement waveforms.
Claim 6
Independent Claim
103 words
The apparatus for processing modulated sine-squared test signals, comprising: separation means for separating said modulated sine-squared pulse into a low-frequency component and a high-frequency component; split means for splitting the high-frequency component into a first signal having a positive polarity and a second signal having a negative polarity; detector means for detecting the positive envelope of said first signal and the negative envelope of said second signal; and addition means for adding the separated said low-frequency component linearly to each such positive and negative envelopes of said first and second signals recovered from detection of said high-frequency component to form two measurement waveforms.
Claim 7
Dependent Claim
52 words
The apparatus According to claim 4 wherein said separation means for separating said modulated sine-squared pulse into a low-frequency component and high-frequency component comprises a series combination of a resistor and a parallel-tuned tank circuit including a capacitor and a first inductor for producing said low-frequency and said high-frequency components thereacross respectively.
Claim 8
Dependent Claim
46 words
The apparatus according to claim 5, wherein said split means for splitting the high-frequency component into a first signal having a positive polarity and a second signal having a negative polarity comprises a center-tapped second inductor magnetically coupled to said first inductor to form a transformer.
Claim 9
Dependent Claim
33 words
The apparatus according to claim 6 wherein said detection means for detecting the positive and negative envelopes of said high-frequency component includes a bridge rectifier circuit and an associated pair of low-pass filters.
Claim 10
Dependent Claim
88 words
The apparatus according to claim 7 wherein said addition means for adding the separated low-frequency component linearly to each such positive and negative envelopes of said first and second signals recovered from detection of said high-frequency component to form two measurement waveforms comprises connecting the low-frequency component to the center tap of said second inductor via a delay thereby causing said second inductor and said bridge rectifier to move with the low-frequency component such that the two measurement waveforms with respect to a fixed reference are linearly added.
Claim 11
Dependent Claim
44 words
The apparatus according to claim 8 wherein said two measurement waveforms correspond identically to each the envelope of the positive peak portion of the modulated sine-squared test signal and the envelope of the negative peak portion, or baseline, of the modulated sine-squared test signal.
Claim 12
Dependent Claim
40 words
The apparatus according to claim 4 wherein said separation means for separating said modulated sine-squared pulse into a low-frequency component and a high-frequency component comprises a parallel pair of frequency-selective filters specifically tuned to pass only the desired frequency component.
Claim 13
Independent Claim
56 words
The method of annulling gain distortion carried by a modulated sine-squared test signal, comprising: processing said modulated sine-squared test signal to obtain two measurement waveforms; obtaining a control signal from the measurement waveform containing substantial information as to gain distortion and; employing said control signal to change a variable attenuator until said gain distortion is annulled.
Claim 14
Independent Claim
56 words
The method of annulling gain distortion carried by a modulated sine-squared test signal, comprising: processing said modulated sine-squared test signal to obtain two measurement waveforms; obtaining a control signal from the measurement waveform containing substantial information as to gain distortion and; employing said control signal to change a variable attenuator until said gain distortion is annulled.
Claim 15
Independent Claim
66 words
The apparatus for annulling gain distortion carried by a modulated sine-squared test signal, comprising: processing means for processing said modulated sine-squared test signal to obtain two measurement waveforms; error recognition means for obtaining a control signal from the measurement waveform containing substantial information as to gain distortion; and correction means for employing said control signal to change a variable attenuator until said gain distortion is annulled.
Claim 16
Independent Claim
66 words
The apparatus for annulling gain distortion carried by a modulated sine-squared test signal, comprising: processing means for processing said modulated sine-squared test signal to obtain two measurement waveforms; error recognition means for obtaining a control signal from the measurement waveform containing substantial information as to gain distortion; and correction means for employing said control signal to change a variable attenuator until said gain distortion is annulled.
Claim 17
Dependent Claim
51 words
The apparatus according to claim 12 wherein said processing means for processing said modulated sine-squared test signal to obtain two measurement waveforms includes a pair of frequency-selective filters, a pair of attenuators, a pair of equal gain impedance matching amplifiers, a transformer, a bridge detector, and a pair of low-pass filters.
Claim 18
Dependent Claim
38 words
The apparatus according to claim 13 wherein said error recognition means for obtaining a control signal from the measurement waveform containing substantial information as to gain distortion includes a detector circuit, an integrator circuit, and a low-pass filter.
Claim 19
Dependent Claim
37 words
The apparatus according to claim 14 wherein said correction means for employing said control signal to change a variable attenuator until said gain distortion is annulled comprises an electric motor to mechanically change the value of attenuation.
Claim 20
Independent Claim
83 words
The apparatus for providing direct readout of gain and delay distortions carried by a modulatEd sine-squared test signal, comprising: processing means for processing said modulated sine-squared test signal to obtain two measurement waveforms; error recognition means for obtaining a control signal from the measurement waveform containing substantial information as to gain distortion; correction means for changing a calibrated variable attenuator until gain distortion is annulled; interpretation means for direct readout of gain distortion; and second interpretation means for direct readout of delay distortion.
Claim 21
Independent Claim
83 words
The apparatus for providing direct readout of gain and delay distortions carried by a modulatEd sine-squared test signal, comprising: processing means for processing said modulated sine-squared test signal to obtain two measurement waveforms; error recognition means for obtaining a control signal from the measurement waveform containing substantial information as to gain distortion; correction means for changing a calibrated variable attenuator until gain distortion is annulled; interpretation means for direct readout of gain distortion; and second interpretation means for direct readout of delay distortion.
Claim 22
Dependent Claim
56 words
The apparatus according to claim 16 wherein said processing means for processing said modulated sine-squared test signal includes passing the signal, through a pair of frequency selective filters, a pair of attenuators, a pair of equal gain impedance matching amplifiers, a transformer, a bridge detector, and a pair of low-pass filters and, a calibrated variable attenuator.
Claim 23
Dependent Claim
31 words
The apparatus according to claim 17 wherein said error recognition means for obtaining a control signal from the measurement waveform containing substantial information as to gain distortion includes an integrator circuit.
Claim 24
Dependent Claim
32 words
The apparatus according to claim 18 wherein said correction means for changing a calibrated variable attenuator until gain distortion is annulled comprises an electric motor to mechanically change the value of attenuation.
Claim 25
Dependent Claim
36 words
The apparatus according to claim 19 wherein said interpretation means for direct readout of gain distortion includes a meter or the like to display an numerical amount of corrective attenuation required to annul said gain distortion.
Claim 26
Dependent Claim
49 words
The apparatus according to claim 20 wherein said second interpretation means for direct readout of delay distortion includes a meter or the like to display a multiple of the percentage of one of said measurement waveforms with respect to the other said measurement waveform when gain distortion is annulled.
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) | 1978-10-06 | 1979-04-07 | 1979-10-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-06 | 1983-04-07 | 1983-10-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-06 | 1987-04-07 | 1987-10-07 | $7700.00 | Window Closed / Lapsed |