US3740550A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pulse coded railway signal system
Assignee: HARMON INDUSTRIES Inc
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Filing: 1971-01-11
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Granted: 1973-06-19
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Expires: 1991-01-11
Abstract
Abstract A railway crossing signalling system using coded digital signals impressed on the tracks for actuation of a crossing relay, the presence of a train at the crossing location causing shunting of the signals and an indication from the relay which operates in a fail-safe configuration. In each signal circuit first and second tone oscillators provide carrier signals which are modulated in a specific digital pattern and applied to the tracks. A tone sensitive receiver separately detects the carrier signals and provides pulse train outputs which are decoded in a binary counter and coincidence gate circuit for ascertainment that the correct digital code pattern has been received. Signals are developed for energization of an oscillator, the output of the latter being amplified for direct actuation of the crossing relay. More than one signal circuit can be employed on common tracks for separate or overlapping signal control by the selection of different pairs of operating frequencies, readily accommodated by plug-in filter substitution.
Inventors
- 👤 W Geiger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:52
CPC Classifications
B; B61; B61L; B61L29/00; B61L29/24; B61L29/28; B61L29/282
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
121 words
Railway crossing signaling apparatus comprising means for developing a train of digital signals of specific character at a first location, means for coupling said digital signals into the railroad track, receiver means at a second location along the track for detecting said digital signals, decoder means for sensing the specific character of such digital signals and for providing a control signal indicative thereof, means responsive to such control signal for providing an indication at the crossing location, said digital signal developing means comprising a dual frequency signal generator for providing a train of pulses of at least two frequencies, and said receiver means being operative to sense such signals for production of a digital signal for application to said decoder means.
Claim 2
Dependent Claim
121 words
Railway crossing signaling apparatus comprising means for developing a train of digital signals of specific character at a first location, means for coupling said digital signals into the railroad track, receiver means at a second location along the track for detecting said digital signals, decoder means for sensing the specific character of such digital signals and for providing a control signal indicative thereof, means responsive to such control signal for providing an indication at the crossing location, said digital signal developing means comprising a dual frequency signal generator for providing a train of pulses of at least two frequencies, and said receiver means being operative to sense such signals for production of a digital signal for application to said decoder means.
Claim 3
Dependent Claim
67 words
Apparatus as set forth in claim 1 wherein said digital signal developing means comprises an independent oscillator for determining the rate of occurrence of pulses in the digital pulse train, a binary counter coupled to said oscillator for providing plural gating signals, and a gate array enabled by said gating signals and said oscillator, said gate array having a pair of output terminals providing pulse trains thereon.
Claim 4
Dependent Claim
45 words
Apparatus as set forth in claim 2 wherein said digital signal developing means further comprises switching means operative in response to the pulse trains on said pair of output terminals and said dual frequency generator to provide two digitally encoded and synchronized trains of pulses.
Claim 5
Dependent Claim
52 words
Apparatus as set forth in claim 2 further including means for combining said pulse trains for application to the track circuit, and a power amplifier for boosting sUch signals, said power amplifier having a transformer coupled output, the secondary winding being a relatively low impedance winding adapted for connection to said tracks.
Claim 6
Dependent Claim
56 words
Apparatus as set forth in claim 1 wherein said receiver means comprises first and second filters having pass bands corresponding respectively to the two frequencies of said signal generator, said filters being coupled in common to said tracks, and further including means for demodulating the outputs of said filters to provide pulse signals for control purposes.
Claim 7
Dependent Claim
41 words
Apparatus as set forth in claim 5 wherein said demodulating means comprises plural amplifier stages for boosting the signal level, a discriminator and envelope detector circuit for producing DC pulses, and means for referencing the pulses to a zero voltage level.
Claim 8
Dependent Claim
56 words
Apparatus as set forth in claim 5 wherein said decoder means comprises a binary counter, means for combining the digital signals for application to said binary counter, and means for detecting the receipt of a sync pulse in a predetermined relation with respect to said digital signals, said detecting means being coupled to said binary counter.
Claim 9
Dependent Claim
35 words
Apparatus as set forth in claim 7 wherein said detecting means comprises a coincidence circuit enabled by said binary counter and adapted for transmission of a sync pulse at a specific state of said counter.
Claim 10
Independent Claim
147 words
A system for protection of railroad crossings and the like, comprising: a. first and second transmitters located on opposite sides of a railway crossing and coupled to the railroad tracks, each said transmitter comprising a dual signal generator for producing an output signal having at least two frequencies, b. first and second receivers coupled to said tracks more closely adjacent the crossing than said transmitters and on opposite sides of the crossing from the respective transmitters to provide a signal overlap in the region of the crossing, each of said receivers comprising means for accepting a single pair of said frequencies to be responsive to a single transmitter, c. relay means energized by said first and second receivers to provide a crossing indication, whereby said transmitters have different frequencies of operation to avoid crosstalk and are adapted to produce digitally coded signals distinctive of each said transmitter.
Claim 11
Independent Claim
147 words
A system for protection of railroad crossings and the like, comprising: a. first and second transmitters located on opposite sides of a railway crossing and coupled to the railroad tracks, each said transmitter comprising a dual signal generator for producing an output signal having at least two frequencies, b. first and second receivers coupled to said tracks more closely adjacent the crossing than said transmitters and on opposite sides of the crossing from the respective transmitters to provide a signal overlap in the region of the crossing, each of said receivers comprising means for accepting a single pair of said frequencies to be responsive to a single transmitter, c. relay means energized by said first and second receivers to provide a crossing indication, whereby said transmitters have different frequencies of operation to avoid crosstalk and are adapted to produce digitally coded signals distinctive of each said transmitter.
Claim 12
Dependent Claim
36 words
The system as set forth in claim 9 wherein said first and second receivers comprise digital signal decoders for energizing said relay means only in response to a predetermined digital code received from the respective transmitters.
Claim 13
Dependent Claim
34 words
The system as set forth in claim 10 wherein said first and second receivers are interconnected to provide a common indication for the crossing, only when a shunting medium is detected within the crossing.
Claim 14
Independent Claim
188 words
A system for protection of railroad crossings and the like, comprising first and second transmitters located on opposite sides of a railway crossing and coupled to the railroad tracks, first and second receivers coupled to said tracks more closely adjacent the crossing than said transmitters and on opposite sides of the crossing from the respective transmitters to provide a signal overlap in the region of the crossing, relay means energized by said first and second receivers to provide a crossing indication, said transmitters having different frequencies of operation to avoid crosstalk and adapted to produce digitally coded signals distinctive of each said transmitter, said first and second receivers comprising digital signal decoders for energizing said relay means only in response to a predetermined digital code received from the respective transmitters, said first and second receivers being interconnected to provide a common indication for the crossing, only when a shunting medium is detected within the crossing, each said first and second transmitter comprising dual signal generators of differing frequency, and said receivers comprising means for accepting a single pair of said frequencies to be responsive to a singlE transmitter.
Claim 15
Independent Claim
188 words
A system for protection of railroad crossings and the like, comprising first and second transmitters located on opposite sides of a railway crossing and coupled to the railroad tracks, first and second receivers coupled to said tracks more closely adjacent the crossing than said transmitters and on opposite sides of the crossing from the respective transmitters to provide a signal overlap in the region of the crossing, relay means energized by said first and second receivers to provide a crossing indication, said transmitters having different frequencies of operation to avoid crosstalk and adapted to produce digitally coded signals distinctive of each said transmitter, said first and second receivers comprising digital signal decoders for energizing said relay means only in response to a predetermined digital code received from the respective transmitters, said first and second receivers being interconnected to provide a common indication for the crossing, only when a shunting medium is detected within the crossing, each said first and second transmitter comprising dual signal generators of differing frequency, and said receivers comprising means for accepting a single pair of said frequencies to be responsive to a singlE transmitter.
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) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |