US3614418A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Railroad grade crossing protection system
Assignee: Marquardt Industrial Products Co
•
Filing: 1970-02-26
•
Granted: 1971-10-19
•
Expires: 1990-02-26
Abstract
Abstract A railroad crossing warning indicator which predicts the time of arrival of trains to a grade crossing is described. Two voltages are derived from the track reactance magnitude and the impedance magnitude and are both indicative of the distance of the train. By summing the difference between the impedance voltage and the reactance voltage with the impedance voltage, a new distance voltage is obtained whereby errors are reduced due to the nonlinearity of the signals due to ballast resistances in the tracks.
Inventors
- 👤 Richard V Pell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:30
CPC Classifications
B; B61; B61L; B61L29/00; B61L29/24; B61L29/28; B61L29/286
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
174 words
In a system for deriving from railroad tracks information for predicting the time required for arrival at a given location of a distant train which is moving on said track towards said location, comprising: means for applying an AC signal of a constant current level on said track from said location; means for deriving a first voltage proportional to the reactance component across said tracks indicative of the distance of said train from said location; means for providing a second voltage proportional to the impedance component across said tracks; means for providing a voltage developed by the difference between said first voltage and said second voltage; means for combining said difference voltage with said first voltage to provide a linearized distance voltage; means for differentiating said linearized distance voltage to obtain a voltage representative of the instantaneous speed of said train; and means for combining said first voltage and said differentiated voltage to provide a third voltage which is a function of the time required for said train to arrive at said given location.
Claim 2
Dependent Claim
174 words
In a system for deriving from railroad tracks information for predicting the time required for arrival at a given location of a distant train which is moving on said track towards said location, comprising: means for applying an AC signal of a constant current level on said track from said location; means for deriving a first voltage proportional to the reactance component across said tracks indicative of the distance of said train from said location; means for providing a second voltage proportional to the impedance component across said tracks; means for providing a voltage developed by the difference between said first voltage and said second voltage; means for combining said difference voltage with said first voltage to provide a linearized distance voltage; means for differentiating said linearized distance voltage to obtain a voltage representative of the instantaneous speed of said train; and means for combining said first voltage and said differentiated voltage to provide a third voltage which is a function of the time required for said train to arrive at said given location.
Claim 3
Dependent Claim
24 words
The system as defined in claim 1 and further comprising means for utilizing said third voltage for operating a warning device at said location.
Claim 4
Dependent Claim
19 words
The system as defined in claim 1 wherein said means for deriving said first voltage is a quadrature detector.
Claim 5
Dependent Claim
19 words
The system as defined in claim 1 wherein said means for deriving said second voltage is an amplitude detector.
Claim 6
Dependent Claim
17 words
The system as defined in claim 1 wherein said means for differentiating is an operational amplifier differentiator.
Claim 7
Dependent Claim
50 words
The system as defined in claim 1 and further comprising: means for providing a reference voltage; and comparator means responsive to said reference voltage and said thiRd voltage provided by said combining means, said comparator means being adapted to provide an output when said third voltage exceeds said reference voltage.
Claim 8
Dependent Claim
28 words
The system as defined in claim 6 and further comprising means for utilizing the output voltage of said comparator means for operating a warning device at said location.
Claim 9
Dependent Claim
212 words
In a system for predicting the time of arrival of a train on a track comprising: a source of AC signals at a constant current level, said source being coupled across said tracks at a selected location; a quadrature detector adapted to receive signals from said track at said selected location, said quadrature detector being adapted to provide an output voltage proportional to the reactance component across said track; an amplitude detector adapted to receive signals from said track at said selected location, said amplitude detector being adapted to provide an output voltage proportional to the impedance component across said tracks; a first summing amplifier responsive to said amplitude detector and said quadrature detector for providing a voltage difference between the impedance output voltage and the reactance output voltage and adding this difference to the impedance output voltage; a differentiator circuit responsive to the output voltage of said first summing amplifier adapted to provide an output indicative of the instantaneous speed of said train; and a second summing amplifier responsive to the output voltage of said differentiator circuit and the output voltage of said quadrature detector, said summing amplifier being adapted to provide an output voltage which is a function of the time required for said train to arrive at said location.
Claim 10
Dependent Claim
212 words
In a system for predicting the time of arrival of a train on a track comprising: a source of AC signals at a constant current level, said source being coupled across said tracks at a selected location; a quadrature detector adapted to receive signals from said track at said selected location, said quadrature detector being adapted to provide an output voltage proportional to the reactance component across said track; an amplitude detector adapted to receive signals from said track at said selected location, said amplitude detector being adapted to provide an output voltage proportional to the impedance component across said tracks; a first summing amplifier responsive to said amplitude detector and said quadrature detector for providing a voltage difference between the impedance output voltage and the reactance output voltage and adding this difference to the impedance output voltage; a differentiator circuit responsive to the output voltage of said first summing amplifier adapted to provide an output indicative of the instantaneous speed of said train; and a second summing amplifier responsive to the output voltage of said differentiator circuit and the output voltage of said quadrature detector, said summing amplifier being adapted to provide an output voltage which is a function of the time required for said train to arrive at said location.
Claim 11
Dependent Claim
28 words
The system as defined in claim 6 and further comprising means for utilizing the output voltage of said summing amplifier for operating a warning device at said location.
Claim 12
Dependent Claim
74 words
The system as defined in claim 6 and further comprising: a reference voltage source adapted to provide an output voltage of a predetermined level; and an amplitude comparator being responsive to the output voltage of the said summing amplifier and to the output voltage of said reference voltage source and being adapted to provide an output signal when the voltage provided by said summing amplifier exceeds the voltage provided by said reference voltage source.
Claim 13
Dependent Claim
37 words
The system as defined in claim 8 wherein said source of AC signals includes: an oscillator adapted to provide an output signal at a predetermined frequency; and a power amplifier coupled between said oscillator and said tracks.
Claim 14
Dependent Claim
25 words
The system as defined in claim 11 and further including a band-pass amplifier coupled between said track and said quadrature detector and said amplitude detector.
Claim 15
Dependent Claim
28 words
The system as defined in claim 12 and further comprising means for utilizing the output voltage of said amplitude comparator for operating a warning device on said location.
Claim 16
Independent Claim
94 words
A system for determining the distance to a vehicle on a railroad track which has an electrical current thereon, including; means coupled to said track for generating a first voltage indicative of the track input impedance; means coupled to said track for generating a second voltage indicative of the reactance component of said track input impedance; means for generating a third voltage proportional to the difference between said first voltage and said second voltage; and means for combining said third voltage with said first voltage to provide a fourth voltage indicative of said distance.
Claim 17
Independent Claim
94 words
A system for determining the distance to a vehicle on a railroad track which has an electrical current thereon, including; means coupled to said track for generating a first voltage indicative of the track input impedance; means coupled to said track for generating a second voltage indicative of the reactance component of said track input impedance; means for generating a third voltage proportional to the difference between said first voltage and said second voltage; and means for combining said third voltage with said first voltage to provide a fourth voltage indicative of said distance.
Claim 18
Dependent Claim
19 words
The system as defined in claim 14 wherein said means for generating said first voltage comprises an amplitude detector.
Claim 19
Dependent Claim
19 words
The system as defined in claim 14 wherein said means for generating said second voltage comprises a quadrature detector.
Claim 20
Dependent Claim
31 words
The system as defined in claim 14 wherein: said means for generating said first voltage comprises an amplitude detector; and said means for generatIng said second voltage comprises a quadrature detector.
References Cited (Backward Citations)
US3246143A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-10-18 | 1975-04-19 | 1975-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-18 | 1979-04-19 | 1979-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-18 | 1983-04-19 | 1983-10-19 | $7700.00 | Window Closed / Lapsed |