US4250484A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alarm system for detecting a plurality of different alarm conditions
Assignee: MARINE ELECTRIC RAILWAY PRODUCTS DIVISION Inc A CORP OF NEW YORK
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Filing: 1977-11-21
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Granted: 1981-02-10
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Expires: 1997-11-21
Abstract
Abstract An alarm system, particularly for use on a train, responsive to a plurality of different alarm conditions for providing outputs for indicating which one or ones of the alarm conditions have been detected. A signal having at least as many frequency components as there are alarm conditions is generated on a transmission line which runs the length of the area over which the conditions are to be detected. Alarm sensing switches are connected to taps of the transmission line, and each switch is connected to a frequency dependent impedance means which is resonant and has a low impedance at one of the frequencies. A filter is provided for each alarm condition to be detected, each such filter having a band pass at one of said resonant frequencies. The presence of an alarm condition causes an alarm switch to change state, which causes one of the impedance means to short circuit a frequency which otherwise would have been passed by one of the filters, thus indicating the presence of an alarm condition.
Inventors
- 👤 Harry G. Parke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:14
CPC Classifications
B; B61; B61L; B61L15/00; B61L15/0018; B61L15/0036; B61L15/0081; G; G08; G08B; G08B25/00; G08B25/01; G08B25/04
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
230 words
An electrical system for detecting a change in state of a switch means which is in one of a plurality of groups of switch means and for providing an indication of the group to which the switch means which has changed state belongs, each group of switch means including one or more switch means, comprising, an electrical transmission line, means for generating a signal on said transmission line having a plurality of frequency components at least equal in number to the number of said groups of switch means, each frequency component corresponding to one of said groups, a plurality of filter means in circuit connection with said line, each filter means being associated with a different group and comprising a means for passing the frequency component corresponding to that group, a plurality of frequency dependent variable impedance means at least equal in number to the number of said groups, each said means being associated with a group and comprising a means responsive to the change in state of a switch means in that group for attenuating the frequency component which is passed by the filter means associated with that group, and means responsive to the attenuation of said frequency component beneath a predetermined level for providing an indication of the group corresponding to the attenuated frequency component which is the group which includes the switch means which has changed state.
Claim 2
Dependent Claim
230 words
An electrical system for detecting a change in state of a switch means which is in one of a plurality of groups of switch means and for providing an indication of the group to which the switch means which has changed state belongs, each group of switch means including one or more switch means, comprising, an electrical transmission line, means for generating a signal on said transmission line having a plurality of frequency components at least equal in number to the number of said groups of switch means, each frequency component corresponding to one of said groups, a plurality of filter means in circuit connection with said line, each filter means being associated with a different group and comprising a means for passing the frequency component corresponding to that group, a plurality of frequency dependent variable impedance means at least equal in number to the number of said groups, each said means being associated with a group and comprising a means responsive to the change in state of a switch means in that group for attenuating the frequency component which is passed by the filter means associated with that group, and means responsive to the attenuation of said frequency component beneath a predetermined level for providing an indication of the group corresponding to the attenuated frequency component which is the group which includes the switch means which has changed state.
Claim 3
Dependent Claim
27 words
The system of claim 1 wherein said electrical system is an alarm system and wherein each of said switch means comprises an alarm condition sensing switch means.
Claim 4
Dependent Claim
29 words
The system of claim 1 wherein said means for generating comprises means for generating a non-sinusoidal periodic signal, the Fourier series of which includes said plurality of frequency components.
Claim 5
Dependent Claim
49 words
The system of claim 2 wherein each of said groups of switch means includes a plurality of alarm condition sensing switch means and wherein all of said switch means of any one group sense the same alarm condition while the switch means of different groups sense different alarm conditions.
Claim 6
Dependent Claim
76 words
The system of claim 4 for detecting a set of different alarm conditions at each of a plurality of different general areas which are spaced along said transmission line, a set of switch means comprised of switch means from different ones of said groups being disposed at different locations within any one such general area, and the different means of any one of said groups being disposed at locations within different ones of said general areas.
Claim 7
Dependent Claim
53 words
The system of claim 5 wherein said transmission line is disposed along the length of a train which is made up of a plurality of cars, and wherein some of said sets of switch means are disposed at locations in different ones of said cars than others of said sets of switch means.
Claim 8
Dependent Claim
32 words
The system of claim 2 wherein said frequency dependent variable impedance means comprise tuned circuits which are resonant at the frequency corresponding to the group with which the impedance means is associated.
Claim 9
Dependent Claim
21 words
The system of claim 7 wherein each of said tuned circuits is in direct circuit connection with a said switch means.
Claim 10
Dependent Claim
22 words
The system of claim 8 wherein each of said tuned circuits is in series connection with only one of said switch means.
Claim 11
Dependent Claim
77 words
The system of claim 2 wherein said filter means are connected in parallel across said signal generating means, and wherein when an alarm condition is detected a said frequency dependent variable impedance means is also switched into parallel connection across said signal generating means by an alarm condition sensing switch means in the group with which the impedance means is associated, which attenuates the frequency component which is passed by the filter means associated with that group.
Claim 12
Dependent Claim
41 words
The system of claim 8 wherein said filter means are connected in parallel across said signal generating means, and wherein when an alarm condition is detected a said tuned circuit is also switched into parallel connection across said signal generating means.
Claim 13
Dependent Claim
15 words
The system of claim 2 wherein said signal generating means is a current generating means.
Claim 14
Dependent Claim
60 words
The system of claim 12 further including fail safe means for detecting if said transmission line becomes open circuited, said transmission line being terminated by a resistance means, and said fail safe means comprising voltage level detection means connected to the output of said current generating means for detecting when the voltage at said output rises above a predetermined level.
Claim 15
Dependent Claim
20 words
The system of claim 13 wherein said level detecting means includes a zener diode in circuit connection with a transistor.
Claim 16
Dependent Claim
35 words
The system of claim 4 wherein said means responsive to the attenuation of said frequency component comprises a plurality of switching means, each switching means being connected in series with one of said filter means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-10 | 1984-08-11 | 1985-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-10 | 1988-08-11 | 1989-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-10 | 1992-08-11 | 1993-02-10 | $7700.00 | Window Closed / Lapsed |