Reduced harmonic switching mode apparatus and method for railroad vehicle signaling

• US 5,507,456 A
• Filed: 05/24/1995
• Issued: 04/16/1996
• Est. Priority Date: 09/26/1994
• Status: Expired due to Term

• Current Assignee: Ansaldo STS SPA
• Original Assignee: Union Switch & Signal, Inc. (Hitachi, Ltd.)
• Inventors: Brown, James P., Bozio, Robert P.
• Primary Examiner(s): Le, Mark T.
• Application Number:
  US08/449,776
• Time in Patent Office: 328 Days
• Field of Search: 246/1 C, 246/62, 246/64, 246/167 R, 246/182 R, 246/191, 246/34 B, 246/175, 246/3, 246/4, 246/5, 246/72, 246/182 A, 246/187 A, 375/17, 370/47, 370/49.5, 340/825.57, 340/825.63
• US Class Current: 246/167.00R
• CPC Class Codes: B61L 1/188 Use of coded current
• CPC Class Codes: B61L 3/00 Devices along the route for controlling devices on the vehicle or train, e.g. to release brake or to operate a warning signal

Abstract

A signaling apparatus that includes a transmitter having a step-square wave generator for generating a signaling waveform, which waveform is composed of a plurality of square wave signals, and which has an information signal encoded thereupon. The apparatus may also include a signaling waveform receiver, disposed on the railcar, and an information signal decoder, connected to the receiver, for extracting the information signal from the receiver. The stepped-square wave generator produces square waves such that a portion of the duty cycle of one of a plurality of square wave signals overlaps at least a portion of the duty cycle of at least one other of the plurality of square wave signals. A method for signaling in which a multi-stepped square waveform is generated, includes a waveform having a series of superimposed square waves, each of which having preselected amplitudes and duty cycles. An information signal can be encoded upon the multi-stepped carrier waveform such that a coded-carrier signal is created.

Claims

1. A signaling apparatus for transmitting information from wayside to a railway vehicle comprising an information signal transmitter having a stepped-square wave generator for generating a stepped-square wave signaling waveform output, said stepped-square wave signaling waveform output, having a plurality of square wave signals, said stepped-square wave signaling waveform output having information encoded thereupon, and said transmitter transmitting said stepped-square wave signaling waveform output onto rails of a track, said railway vehicle receiving said stepped-square wave signaling waveform output thereby.

2. The signaling apparatus of claim 1 wherein said transmitter is a switching-mode transmitter.

3. The signaling apparatus of claim 1 wherein at least a portion of a first preselected duty cycle of at least one of said plurality of square wave signals overlaps at least a portion of a second preselected duty cycle of at least one other of said plurality of square wave signals so that said signaling waveform is generally a stepped-square waveform.

4. A method for signaling, comprising the steps of generating a multi-stepped square waveform having a series of superimposed square waves and at least two waves of said series of superimposed square waves having preselected amplitudes;

injecting said waveform into a railway signaling circuit; and

overlapping the duty cycle of a first of said at least two waves with the duty cycle of a second of said at least two waves, said overlapping producing a multi-step carrier waveform having a single high-amplitude square wave interposed between two lower amplitude square waves.

5. The method of claim 4 further comprising encoding an information signal on said multi-step carrier waveform, creating a coded-carrier signal thereby.

6. The method of claim 5 further comprising injecting said coded-carrier signal into a railway track for providing information to a railway vehicle.

7. A method for signaling, comprising the steps of:

a. generating a plurality of square wave signals, and said plurality of square wave signals having a plurality of predetermined duty cycles;

b. overlapping at least a portion of a first preselected duty cycle of at least one of said plurality of square wave signals with at least a portion of a second preselected duty cycle of at least one other of said plurality of square wave signals so that a stepped-square waveform results therefrom, and said stepped-square waveform having a predetermined frequency;

c. encoding an information signal at a preselected frequency upon at least a portion of said stepped-square waveform; and

d. transmitting said stepped-square waveform having said information signal encoded thereupon into a transmission medium, and at least a portion of said transmission medium being a portion of railroad track.

8. The method of claim 7 further comprising the steps of:

e. receiving said stepped-square waveform having said information signal encoded thereupon from said transmission medium; and

f. decoding said information signal from said stepped-square waveform.