Signal system for determining the presence of a train vehicle
Abstract
Abstract AUDIO FREQUENCY SIGNALS, OPERATIVE WITH TRACK CIRCUITS FOR THE PURPOSE OF SENSING THE PRESENCE OF A TRAIN VEHICLE IN ANY SIGNALING BLOCK CIRCUIT, ARE MODULATED FOR FAIL-SAFE SPEED CONTROL OF TRAIN VEHICLES AND FOR TRAIN OPERATION INFORMATION TRANSMISSION. THE TRAIN TRACK IS DIVIDED INTO SIGNALING BLOCKS OF PREDETERMINED LENGTH, WITH A VERY LOW IMPEDANCE SHORT CIRCUIT CONNECTION PLACED ACROSS THE TRACK RAILS AT THE ENDS OF EACH SUCH BLOCK. A SIGNAL TRANSMITTER OPERATING AT ONE OF SEVERAL AUDIO CARRIER FREQUENCIES, WITH ITS OUTPUT MODULATED AT A SUBAUDIO RATE, IS COUPLED TO THE RAILS ACROSS THE SHORT CIRCUIT CONNECTION AT ONE END OF EACH BLOCK. ONE OR MORE COOPERATIVE SIGNAL RECEIVERS ARE COUPLED TO THE SHORT CIRCUIT CONNECTION AT THE REMOTE END OF EACH BLOCK, INTERMEDIATE RECEIVERS ARE COUPLED TO THE RAILS AS REQUIRED FOR DESIRED TRAIN CONTROL.
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Bibliographic Details
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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) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |