Railroad crossing motion sensing system
AssigneeSaftran System Corporation
InventorsJames E. Moe, Richard V. Peel, Richard E. Smith
Life of this patent
Estimating the term…
Abstract
An apparatus for detecting an approaching train within a track section utilizes a transmitter coupled to the rails at a feed point for applying a current to the track section. There is a receiver coupled to the track section for producing a signal representative of the impedance of the track section. There are devices for utilizing the received signal for detecting train motion, abnormally low impedance and abnormally high impedance of the track section. A normalizer circuit is connected to the receiver for increasing or decreasing the received signal gain within predetermined limits in accordance with variation in impedance of the track section.
Claims24
An apparatus for detecting an approaching train within a track section between a feed point and at least one low impedance connection across the rails, said apparatus including:
- transmitter means coupled to the rails at the feed point for applying a current to the track section,
- receiver means coupled to the track section for producing a first signal representative of the impedance of said track section,
- means for utilizing said first signal for detecting train motion, abnormally low impedance and abnormally high impedance,
- The improvement comprising a normalizer circuit connected to said receiver means for increasing or decreasing said first signal within predetermined limits in accordance with variations in impedance of said track section.
An apparatus for detecting an approaching train within a track section between a feed point and at least one low impedance connection across the rails, said apparatus including:
- transmitter means coupled to the rails at the feed point for applying a current to the track section,
- receiver means coupled to the track section for producing a first signal representative of the impedance of said track section,
- the improvement comprising means for changing the level of said transmitted current for a limited period of time during a predetermined time frame, differentiator means coupled to said receiver means for producing a signal representative of the rate of change of said first signal, integrator means coupled to said differentiator means, and a threshold detector connected to said integrator means for use in determining when said rate of change signal represents train motion.
An apparatus for detecting an approaching train within a track section between a feed point and at least one low impedance connection across the rails, said apparatus including:
- transmitter means coupled to the rails at the feed point for applying a current to the track section,
- receiver means coupled to the track section for producing a signal representative of the impedance of said track section,
- normalizer means connected to said receiver means for increasing or decreasing said signal within predetermined limits in accordance with variations in impedance of said track section,
- motion decision means connected to said normalizer circuit for determining when said signal represents train motion,
- and track-occupied detector means connected to said motion decision means and having an output connected to said normalizer circuit.
An apparatus for detecting an approaching train within a track section between a feed point and at least one low impedance connection across the rails, said apparatus including:
- transmitter means coupled to the rails at the feed point for applying a current to the track section,
- receiver means coupled to the track section for producing a signal representative of the impedance of said track section,
- means for utilizing said signal for detecting train motion, abnormally low impedance and abnormally high impedance,
- a normalizer circuit connected to said receiver means for increasing or decreasing said signal within predetermined limits, in accordance with variations in impedance of said track section, and a track-occupied detector connected to the means for utilizing said signal for detecting train motion having its output connected to said normalizer circuit.
An apparatus for detecting an approaching train within a track section between a feed point and at least one low impedance connection across the rails, said apparatus including:
- transmitter means coupled to the rails at the feed point for applying a current to the track section,
- receiver means coupled to the track section for producing a first signal representative of the impedance of said track section,
- means for changing the level of said transmitted current for a limited period of time during a predetermined time frame, differentiator means coupled to said receiver for producing a signal representative of the rate of change of said first signal, integrator means coupled to said differentiator means, and a threshold detector connected to said integrator means for use in determining when said rate of change signal represents train motion,
- and a track-occupied detector connected to the output of said integrator means.
Dependencies are inferred from the claim text.