US3876997A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Analog data acquisition system
Assignee: Westinghouse Electric Corp
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Filing: 1973-10-31
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Granted: 1975-04-08
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Expires: 1993-10-31
Abstract
Abstract The invention relates to analog multiplexing systems used in an industrial environment to derive small signals from remote locations. Since the signals received might mask a failure of the sensing devices a bias source is used to generate an anomalous signal when sensing is defective. The bias source is common to all points of measurement. It has a small time constant so that it can be switched at the multiplexing frequency, and it is operative only at the inception of the time interval for signal derivation so that measurement is not affected. Provision is made for purging successively the signal transmitting cables before signal derivation.
Inventors
- 👤 Earl T Farley
- 👤 Andras I Szabo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 13:29
CPC Classifications
G; G08; G08C; G08C15/00; G08C15/06; G08C15/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
139 words
In an analog data acquisition system operative with output terminals for deriving in a multiplex manner respective measurement signals having a predetermined operative range from a plurality of sensing devices with each of said sensing devices being associated with a different pair of transmission lines, the combination of: storing means for providing a test potential having a magnitude substantially different from said predetermined operative range of said measurement signals; switch means for selectively connecting said storing means between a selected one pair of transmission lines and said output terminals for providing a discharge path for said storing means to reduce said test potential to a magnitude within said operative range when the sensing device associated with said selected one pair of transmission lines has electrical continuity; and means operative with said output terminals for detecting a defective sensing device.
Claim 2
Dependent Claim
139 words
In an analog data acquisition system operative with output terminals for deriving in a multiplex manner respective measurement signals having a predetermined operative range from a plurality of sensing devices with each of said sensing devices being associated with a different pair of transmission lines, the combination of: storing means for providing a test potential having a magnitude substantially different from said predetermined operative range of said measurement signals; switch means for selectively connecting said storing means between a selected one pair of transmission lines and said output terminals for providing a discharge path for said storing means to reduce said test potential to a magnitude within said operative range when the sensing device associated with said selected one pair of transmission lines has electrical continuity; and means operative with said output terminals for detecting a defective sensing device.
Claim 3
Dependent Claim
33 words
The analog system of claim 1 with said storing means and the associated discharging circuit having a time constant which is small relative to a measurement time interval defined by said scanning means.
Claim 4
Dependent Claim
31 words
The analog system of claim 2 wherein said storing means includes means operative with said switch means for charging said storing means during a time period following said measurement time interval.
Claim 5
Dependent Claim
99 words
The analog system of claim 3 wherein said sensing devices are divided into groups, each of said pairs of transmission lines of one group being selectively connected to a corresponding pair of group lines, said output terminals being connected to said pairs of group lines, said switch means being operative to connect said storing means with said pairs of group lines and with said output terminals; means being provided for discharging said pairs of group lines after a supply of a measurement signal from a selected pair of transmission lines and before selection of another pair of transmission lines.
Claim 6
Dependent Claim
60 words
The analog system of claim 4 wherein said switch means is operative during a measurement time interval during which said measurement signal is supplied to said output terminals by said selected one pair of transmission lines, and wherein said means for discharging said pairs of group lines is operative during a time period between two consecutively established measurement time intervals.
Claim 7
Dependent Claim
21 words
The analog system of claim 5 wherein said time period is established in response to operation of said means for discharging.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |