| 摘要 |
A non-contact, distance traveled measurement system (DTMS) to calculate speed and distance traveled by a vehicle over rails—more specifically, by trains traveling on standard railroad tracks. Preferably, a pair of short range (near field) microwave-based transmitters/sensors (transceivers) are mounted on the underside of the train and used to key on rail-bed features such as cross ties or tie plates. Preferred embodiments also include infrared sensors as a redundant channel that is less sensitive to moisture in the track bed. Data from the sensors is correlated to determine the time delay between the first and second sensors' passage over objects on the rail bed such as cross-ties or tie-plates. From this time delay, nearly instantaneous velocity can be computed at each given target such as a tie plate (metal target) or a tie (dielectric contrast target). Velocity versus time curves can be integrated over time to derive distance traveled.
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