Patent US4935692A successfully refreshed from Google Patents.
US4935692A
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Vector ammeter having digital signal processing unit
Assignee: Agilent Technologies Inc
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Filing: 1988-11-30
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Granted: 1990-06-19
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Expires: 2008-11-30
Abstract
Abstract An improved type of vector impedance measuring instrument is disclosed. The vector impedance is a vector current relative to (or normalized to) a pertinent voltage. A transducer for converting the impedance to corresponding current and voltage includes a digital signal processing unit. The vector value of the current is derived from parameter values set in the digital signal processing unit. This configuration eliminates a conventional vector ratio detector, which conventionally followed the transducer, saves cost, reduces size, and achieves high performance. Also, algorithms implemented in the digital signal processing unit are easily modified for a variety of transfer functins phase compensation, and corrections.
Inventors
- 👤 Tomio Wakasugi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:04
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
203 words
A vector ammeter comprising: a source for producing an AC reference signal; means for coupling the AC reference signal to a device being measured to produce an AC measurement signal; an amplifier having an input to which the AC measurement signal is applied; an analog-to-digital converter having an input connected to an output of the amplifier; digital signal processing means having an input connected to an output of the analog-to-digital converter, the digital signal processing means for decomposing the AC measurement signal into two quadrature components corresponding to the real and imaginary parts of the AC measurement signal; at least one digital-to-analog converter having an input connected to an output of the digital signal processing means; the amplifier, the analog-to-digital converter, the digital signal processing means, and the digital-to-analog converter being connected in cascade to constitute a forward amplification portion; and a feedback circuit inserted between an output of the forward amplification portion and the input of the amplifier; the real and imaginary parts of the AC measurement signal reduced by the digital signal processing means comprising data for determining one of a ratio of the AC measurement signal to the AC reference signal and a vector voltage across the device being measured.
Claim 2
Dependent Claim
203 words
A vector ammeter comprising: a source for producing an AC reference signal; means for coupling the AC reference signal to a device being measured to produce an AC measurement signal; an amplifier having an input to which the AC measurement signal is applied; an analog-to-digital converter having an input connected to an output of the amplifier; digital signal processing means having an input connected to an output of the analog-to-digital converter, the digital signal processing means for decomposing the AC measurement signal into two quadrature components corresponding to the real and imaginary parts of the AC measurement signal; at least one digital-to-analog converter having an input connected to an output of the digital signal processing means; the amplifier, the analog-to-digital converter, the digital signal processing means, and the digital-to-analog converter being connected in cascade to constitute a forward amplification portion; and a feedback circuit inserted between an output of the forward amplification portion and the input of the amplifier; the real and imaginary parts of the AC measurement signal reduced by the digital signal processing means comprising data for determining one of a ratio of the AC measurement signal to the AC reference signal and a vector voltage across the device being measured.
Claim 3
Dependent Claim
140 words
The vector ammeter of claim 1 wherein the digital signal processing means comprises: a pair of digital phase-sensitive detectors having respective inputs connected to the output of the analog-to-digital converter; means for applying a digital cosine wave to another input of one of the digital phase-sensitive detectors; means for applying a digital sine wave to another input of the other digital phase-sensitive detector; the respective phase-sensitive detectors for calculating the product of the respective cosine and sine waves and the output from the analog-to-digital converter; a pair of accumulators having respective inputs connected to respective outputs of the digital phase-sensitive detectors, the accumulators for digitally integrating signals at the respective outputs of the digital phase-sensitive detectors; and a pair of gain adjusters having respective inputs connected to respective outputs of the accumulataors, the gain adjusters for setting a selectable gain.
Claim 4
Dependent Claim
36 words
The vector ammeter of claim 2 wherein there is a pair of digital-to-analog converters and respective outputs of the gain adjusters of the digital signal processing means are connected to respective inputs of the digital-to-analog converters.
Claim 5
Dependent Claim
49 words
The vector ammeter of claim 3 wherein the digital-to-analog converters are quadrant multiplication type digital-to-analog converters and wherein the digital-to-analog converters receive the AC reference signal for energizing the device being measured and a signal shifted in phase by 90 degrees with respect to the AC reference signal, respectively.
Claim 6
Dependent Claim
44 words
The vector ammeter of claim 4, further comprising a 90-degree phase shifter connected between the source of the AC reference signal and one of the digital-to-analog converters for producing the signal shifted in phase by 90 degrees with respect to the AC reference signal.
Claim 7
Dependent Claim
23 words
The vector ammeter of claim 3, further comprising a timing generator for producing a timing signal in synchronism with the AC reference signal.
Claim 8
Dependent Claim
79 words
The vector ammeter of claim 2 wherein the digital signal processing means further comprises: a pair of demodulating digital modulators having respective inputs connected to respective outputs of the gain adjusters; and a digital adder having respective inputs connected to respective outputs of the demodulating digital modulators; an output of the adder being connected to the digital-toanalog converter, the digital-to-analog converter for converting the signal produced by the adder into an AC signal proportional to a reference DC signal.
Claim 9
Dependent Claim
23 words
The vector ammeter of claim 7, further comprising a timing generator for producing a timing signal in synchronism with the AC reference signal.
Claim 10
Dependent Claim
116 words
A vector ammeter comprising: a forward amplifier chain which cascades: (a) amplifier means to which is input an AC current; (b) analog-to-digital converter means; (c) digital signal processing means; (d) digital-to-analog converter means; and (e) feedback circuit means connected between an output of the digital-to-analog converter means and the input of the amplifier; and characterized in that the digital signal processing means orthogonally decomposes the AC input current into real and imaginary components; the real and imaginary components of the AC input current comprising data for determining one of a ratio of the AC input current to an AC reference current and a voltage across a device being measured through which the AC input current flows.
Claim 11
Dependent Claim
116 words
A vector ammeter comprising: a forward amplifier chain which cascades: (a) amplifier means to which is input an AC current; (b) analog-to-digital converter means; (c) digital signal processing means; (d) digital-to-analog converter means; and (e) feedback circuit means connected between an output of the digital-to-analog converter means and the input of the amplifier; and characterized in that the digital signal processing means orthogonally decomposes the AC input current into real and imaginary components; the real and imaginary components of the AC input current comprising data for determining one of a ratio of the AC input current to an AC reference current and a voltage across a device being measured through which the AC input current flows.
Claim 12
Dependent Claim
140 words
The vector ammeter of claim 9 wherein the digital signal processing means comprises: a pair of digital phase-sensitive detectors having respective inputs connected to an output of the analog-to-digital converter; means for applying a digital cosine wave to another input of one of the digital phase-sensitive detectors; means for applying a digital sine wave to another input of the other digital phase-sensitive detector; the respective phase-sensitive detectors for calculating the product of the respective cosine and sine waves and the output from the analog-to-digital converter; a pair of accumulators having respective inputs connected to respective outputs of the digital phase-sensitive detectors, the accumulators for digitally integrating signals at the respective outputs of the digital phase-sensitive detectors; and a pair of gain adjusters havino respective inputs connected to respective outputs of the accumulators, the gain adjusters for seeking a selectable gain.
Claim 13
Dependent Claim
39 words
The vector ammeter of claim 10 wherein the digital-to-analog converter means comprises a pair of digital-to-analog coverters and respective outputs of the gain adjusters of the digital signal processing means are connected to respective inputs of the digital-to-analog converters.
Claim 14
Dependent Claim
49 words
The vector ammeter of claim 11 wherein the digital-to-analog converters are quadrant multiplication type digital-to-analog converters and wherein the digital-to-analog converters receive the AC reference current for energizing the device being measured and a signal shifted in phase by 90 degrees with respect to the AC reference current, respectively.
Claim 15
Dependent Claim
45 words
The vector ammeter of claim 12, further comprising a 90 degree phase shifter connected between a source of the AC reference current and one of the digital-to-analog converters for producing the signal shifted in phase by 90 degrees with respect to the AC reference current.
Claim 16
Dependent Claim
23 words
The vector ammeter of claim 11, further comprising a timing generator for producing a timing signal in synchronism with the AC reference current.
Claim 17
Dependent Claim
81 words
The vector ammeter of claim 10 wherein the digital signal processing means further comprises: a pair of demodulating digital modulators having respective inputs connected to respective outputs of the gain adjusters; and a digital adder having respective inputs connected to respective outputs of the demodulating digital modulators; an output of the adder being connected to the digital-to-analog converter means, the digital-to-analog converter means for converting the signal produced by the adder into an AC signal proportional to a reference DC signal.
Claim 18
Dependent Claim
23 words
The vector ammeter of claim 15, further comprising a timing generator for producing a timing signal in synchronism with the AC reference current.
References Cited (Backward Citations)
US4481464A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-06-18 | 1993-12-18 | 1994-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-18 | 1997-12-18 | 1998-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-18 | 2001-12-18 | 2002-06-19 | $7700.00 | Window Closed / Lapsed |