US4939446A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Voltage transmission link for testing EMI susceptibility of a device or circuits
Assignee: ELECTRONIC DEVELOPMENT Inc A CORP OF MI
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Filing: 1988-03-30
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Granted: 1990-07-03
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Expires: 2008-03-30
Abstract
Abstract The performance of a device under test is observed with and without the presence of controlled EMI fields. Voltage signals from the device under test are transmitted to an oscilloscope by overdamped conductors, a hybrid electrical/optical transmitter, a fiber optic cable, a receiver and a conductor cable. The overdamped conductors are transparent to the EMI fields and the current in those conductors is kept very small by the use of a very high input impedance in the transmitter. The hybrid transmitter may be an analog or a digital transmitter.
Inventors
- 👤 Wesley A. Rogers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:41
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/001
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
132 words
An electromagnetically transparent voltage transmission link for determining the susceptibility of a device under test to EMI over certain frequencies of interest, by monitoring voltages of said device, comprising: conduction means, having first and second ends, said conduction means being electrically overdamped along its length for said frequencies of interest, the first end of said conduction means adapted to be connected to said device under test and exposed to said EMI, and a transmission device having very high impedance input port to which the second end of said conduction means is connected, for receiving at least one first signal from said device under test by way of said conduction means and for transmitting at least one second signal, related to said first signal, to a location remote from said device under test.
Claim 2
Dependent Claim
132 words
An electromagnetically transparent voltage transmission link for determining the susceptibility of a device under test to EMI over certain frequencies of interest, by monitoring voltages of said device, comprising: conduction means, having first and second ends, said conduction means being electrically overdamped along its length for said frequencies of interest, the first end of said conduction means adapted to be connected to said device under test and exposed to said EMI, and a transmission device having very high impedance input port to which the second end of said conduction means is connected, for receiving at least one first signal from said device under test by way of said conduction means and for transmitting at least one second signal, related to said first signal, to a location remote from said device under test.
Claim 3
Dependent Claim
20 words
An electromagnetically transparent voltage probe in accordance with claim 1 wherein said conduction means comprises at least two overdamped conductors.
Claim 4
Dependent Claim
31 words
An electromagnetically transparent voltage probe in accordance with claim 1 wherein said conduction means comprises a thread core impregnated with fine conducting particles and an insulating layer surrounding said thread core.
Claim 5
Dependent Claim
19 words
An electromagnetically transparent voltage probe in accordance with claim 3 wherein said thread core is a monofilament plastic thread.
Claim 6
Dependent Claim
19 words
An electromagnetically transparent voltage probe in accordance with claim 3 wherein said fine conducting particles are composed of carbon.
Claim 7
Dependent Claim
24 words
An electromagnetically transparent voltage probe in accordance with claim 1 wherein said conduction means has a series resistance which is distributed along its length.
Claim 8
Dependent Claim
25 words
An electromagnetically transparent voltage probe in accordance with claim 6 wherein said conduction means exhibits a series resistance of several thousand ohms per foot thereof.
Claim 9
Dependent Claim
23 words
The electromagnetically transparent voltage probe of claim 1 wherein said conduction means has a capacitance and inductance which is distributed along its length.
Claim 10
Dependent Claim
23 words
An electromagnetically transparent voltage probe in accordance with claim 1 wherein said first end of said conduction means comprises a short conductive clip.
Claim 11
Dependent Claim
25 words
An electromagnetically transparent voltage probe in accordance with claim 9 wherein said short conductive clip is less than or equal to one centimeter in length.
Claim 12
Dependent Claim
34 words
An electromagnetically transparent probe in accordance with claim 10, wherein said short conductive clip is protected from impinging electric fields with electrically isolated silver paint or metal foil on the surface of the housing.
Claim 13
Dependent Claim
22 words
An electromagnetically transparent voltage probe in accordance with claim 1 wherein said second end of said conductor means comprises a BNC connector.
Claim 14
Dependent Claim
19 words
The electromagnetically transparent voltage probe of claim 1 wherein the high impedance port comprises a FET input operational amplifier.
Claim 15
Dependent Claim
50 words
The electromagnetically transparent voltage probe of claim 1 wherein said very high input impedance port comprises the non-inverting input of a FET input operational amplifier, the output of which is re-applied to its inverting input, to provide an input impedance on the order of approximately ten gigohms (10 10 ohms).
Claim 16
Dependent Claim
32 words
The electromagnetically transparent voltage probe of claim 1 wherein said transmission device converts an electrical signal at its input port to a related optical signal for optical transmission to the remote location.
Claim 17
Dependent Claim
58 words
The electromagnetically transparent voltage probe of claim 15 wherein said conduction means has two signal leads and one ground lead, and said transmission device functions to reject common mode signals, and amplify differential signals on said signal leads, said amplified differential signals controlling the application of a driving voltage to an LED, to produce said related optical signal.
Claim 18
Independent Claim
134 words
A method for testing the susceptibility of a device under test to EMI fields over certain frequencies of interest by monitoring voltages of said device, comprising: attaching the first ends of at least two conductors to at least two points of interest in a device under test, the conductors being electrically overdamped along their length for said frequencies of interest, attaching the other ends of said conductors to respective high impedance input ports on a transmission device, transmitting a signal related to the voltages at said points of interest to a location remote from said device under test, selectively applying controlled EMI fields to said device under test and to at least a portion of said conductors, and monitoring the effect of said EMI fields on said device under test at said remote location.
Claim 19
Independent Claim
134 words
A method for testing the susceptibility of a device under test to EMI fields over certain frequencies of interest by monitoring voltages of said device, comprising: attaching the first ends of at least two conductors to at least two points of interest in a device under test, the conductors being electrically overdamped along their length for said frequencies of interest, attaching the other ends of said conductors to respective high impedance input ports on a transmission device, transmitting a signal related to the voltages at said points of interest to a location remote from said device under test, selectively applying controlled EMI fields to said device under test and to at least a portion of said conductors, and monitoring the effect of said EMI fields on said device under test at said remote location.
Claim 20
Dependent Claim
56 words
The method of claim 17 wherein the step of monitoring the effect of said EMI fields on said device under test further comprises the step of comparing said signal related to the voltages at said points of interest during the selective application of controlled EMI fields to said signal during the absence of said EMI fields.
References Cited (Backward Citations)
US3743925A
Cited
US3991397A
Cited
US4328461A
Cited
US4425542A
Cited
US4510468A
Cited
US4647844A
Cited
US4737708A
Cited
US4704596A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-02 | 1994-01-01 | 1994-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-02 | 1998-01-01 | 1998-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-02 | 2002-01-01 | 2002-07-03 | $7700.00 | Window Closed / Lapsed |