Back to results
US 4,365,777 AGranted
Train approach detector
AssigneeModern Industries Signal Equipment, Inc.
InventorWillard L. Geiger
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeModern Industries Signal Equipment, Inc.
InventorWillard L. Geiger
Estimating the term…
A train approach detector uses frequencies in the audio spectrum to activate grade crossing protection devices in advance of and during the presence of railroad trains at grade crossings. The detector is completely solid state, and includes one transmitter and one receiver each connected to the tracks so that transmitted and received track signals, which are partially pulse modulated for optimum filtering and signal coupling and minimum third harmonic radiation, appear on opposite sides of the crossing. The section of track between the transmitter and receiver is designated as a crossing island and sections of rail outside of the island are known as approaches. In addition to its basic train movement detection function, the detector contains additional features that are designed to provide operation under a variety of application conditions, including automatic ballast compensation, loss of shunt, low signal/low gain condition, high signal/broken rail condition, delayed pick-up, delayed drop-out and reverse switch override, and bi-directional motion detection.
A circuit for developing an AC output signal, comprising input means for providing an input AC signal, plural channel means for dividing such input AC signal into plural respective AC signals, modulating means for modulating one of such respective AC signals, combining means for summing such modulated AC signal and at least another one of such respective AC signals to obtain a combined AC signal, filter output means for filtering such combined AC signal to produce such AC output signal, and coupling means for coupling such AC output signal to a track and detector means also coupled to such track for responding to changes in such AC output signal as an indication of at least one of the passing of a vehicle on the track and the condition of the track.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, and receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such a vehicle, and output means responsive to such detector means for producing output information indicative of such vehicle on such track, said transmitter means including input means for providing an AC input signal, plural channel means for dividing such input AC signal into plural respective AC signals having a common frequency, modulating means for modulating one of such respective AC signals at a lower frequency than such common frequency, combining means for summing such modulated AC signal and at least another one of such respective AC signal to obtain a combined AC signal which is not modulated to zero at such lower frequency, and filter output means for filtering such combined AC signal to produce such track signal.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, and receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such a vehicle, and output means responsive to such detector means for producing output information indicative of such vehicle on such track, said transmitter means including input means for providing an AC input signal, plural channel means for dividing such input AC signal into plural respective AC signals having a common frequency, modulating means for modulating one respective AC signal at a lower frequency than such common frequency, combining means for combining such modulated respective AC signal and at least one such other respective AC signal to obtain a combined AC signal which is not modulated to zero at such lower frequency, and filter output means for filtering such combined AC signal to produce such track signal, said filter output means comprising slow recovery filter means for passing such combined AC signal at such common frequency, whereby since such combined AC signal is not modulated to zero at such lower frequency third harmonic distortion is minimized.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, and receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such a vehicle, and output means responsive to such detector means for producing output information indicative of such vehicle on such track, said transmitter means including input means for providing an AC input signal, plural channel means for dividing such input AC signal into plural respective AC signals having a common frequency, modulating means for modulating one respective AC signal at a lower frequency than such common frequency, combining means for combining such modulated respective AC signal and at least one such other respective AC signal to obtain a combined AC signal which is not modulated to zero at such lower frequency, filter output means for filtering such combined AC signal to produce such track signal, combining level control means responsive to the magnitude of the received track signal by said receiver means for adjusting the gain of said receiver means and for correspondingly adjusting the gain of said transmitter means to try to maintain such magnitude substantially constant, coupling means for coupling said transmitter means and said receiver means at tie points to the track, and clamp means for limiting the rise of such received track signal in said detector means in response to a vehicle on the track leaving such tie points.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, and receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such a vehicle, and output means responsive to such detector means for producing output information indicative of such vehicle on such track, said transmitter means including input means for providing an AC input signal, plural channel means for dividing such input AC signal into plural respective AC signals having a common frequency, modulating means for modulating one respective AC signal at a lower frequency than such common frequency, combining means for combining such modulated respective AC signal and at least one such other respective AC signal to obtain a combined AC signal which is not modulated to zero at such lower frequency, and filter output means for filtering such combined AC signal to produce such track signal, further comprising combined level control means responsive to the magnitude of the received track signal by said receiver means for adjusting the gain of said receiver means and for correspondingly adjusting the gain of said transmitter means to try to maintain such magnitude substantially constant, means for stopping further adjustment of gain when the magnitude of the received track signals drops below a predetermined value, and further comprising low signal detector means for sensing when the magnitude of such track signal received at said receiver means drops below such predetermined value, including control means responsive to such low signal detector means for effecting production of output information when the magnitude of such track signal drops below such predetermined value.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, including means for producing an AC signal and modulating means for modulating at least part of such AC signal to produce such track signal, receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such vehicle, output means responsive to such detection of such a vehicle by said detector means for producing output information indicative of such vehicle on such track, and modulating signal producing means directly electrically coupled to both said transmitter means and said output means independently of such track for producing a modulating signal output to control said modulating means to modulate such AC signal and to enable said output means to respond to such detection and to disable said output means upon termination of such modulating signal output.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, including means for producing an AC signal and modulating means for modulating at least part of such AC signal to produce such track signal, receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such vehicle, output means responsive to such detection of such a vehicle by said detector means for producing output information indicative of such vehicle on such track, and modulating signal producing means coupled to both said transmitter means and said output means for producing a modulating signal output to control said modulating means to modulate such AC signal and to enable said output means to respond to such detection and to disable said output means upon termination of such modulating signal output, said modulating signal producing means comprising means for producing such modulating signal output as two pulse trains, and connecting means for connecting one pulse train to said modulating means and the other to said output means.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, including means for producing an AC signal and modulating means for modulating at least part of such AC signal to produce such track signal, receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such vehicle, output means responsive to such detection of such a vehicle by said detector means for producing output information indicative of such vehicle on such track, modulating signal producing means coupled to both said transmitter means and said output means for producing a modulating signal output to control said modulating means to modulate such AC signal and to enable said output means to respond to such detection and to disable said output means upon termination of such modulating signal output, said modulating signal producing means comprising means for producing such modulating signal output as two pulse trains, connecting means for connecting one pulse train to said modulating means and the other to said output means, sensing means for sensing whether such track signal is received by said receiver means, said output means comprising combining means for combining information from said sensing means and such other pulse train to enable said output means when both such track signal is received and such other pulse train is produced and when either or both are not received or produced to disable said output means, said receiver means comprising converting means for converting such received track signal to a substantially DC signal value with ripple pulses impressed thereon, and said sensing means comprising means for sensing such ripple pulses.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, including means for producing an AC signal and modulating means for modulating at least part of such AC signal to produce such track signal, receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such vehicle, output means responsive to such detection of such a vehicle by said detector means for producing output information indicative of such vehicle on such track, and modulating signal producing means coupled to both said transmitter means and said output means for producing a modulating signal output to control said modulating means to modulate such AC signal and to enable said output means to respond to such detection and to disable said output means upon termination of such modulating signal output, said modulating signal producing means comprising means for producing such modulating signal output as two pulse trains, and connecting means for connecting one pulse train to said modulating means and the other to said output means and further comprising sensing means for sensing whether such track signal is received by said receiver means, said output means comprising combining means for combining information from said sensing means and such other pulse train to enable said output means when both such track signal is received and such other pulse train is produced and when either or both are not received or produced to disable said output means, said receiver means comprising converting means for converting such received track signal to a substantially DC signal value with ripple pulses impressed thereon, and said sensing means comprising means for sensing such ripple pulses, and amplifier means for amplifying such ripple pulses and trigger means for producing a square wave pulse train in response to receipt of such amplified pulses.
In an apparatus for detecting a vehicle on a track, including transmitter means for transmitting a track signal and receiver means for receiving such track signal for monitoring a parameter thereof, said receiver means including output means for producing an output indicative of the excursion of such monitored parameter beyond at least one of predetermined limits, the improvement comprising:
Apparatus for detecting an approaching object, comprising transmitter means for transmitting a transmitted signal capable of attenuation by such an approaching object, receiver means for receiving such transmitted signal, including detector means for monitoring such attenuation of such transmitted signal for detecting such approaching object, level control means for automatically adjusting the gain of at least one of said transmitter means and receiver means, and clamp means for temporarily limiting maximum rise of such transmitted signal in said receiver means when such object begins receding.
In an apparatus for detecting a vehicle on a track, including transmitter means for transmitting a track signal in the track, receiver means receiving such track signal for responding to the character thereof upon the presence of such vehicle to indicate such vehicle, said receiver means including monitor means for monitoring such track signal, the improvement comprising:
In an apparatus for detecting a vehicle on a track, including transmitter means for transmitting a track signal, receiver means receiving such track signal for monitoring at least one parameter thereof, and output means for producing a prescribed output in response to such parameter attaining a prescribed condition as monitored by such receiver means, the improvement comprising
In an apparatus for detecting a train on a track, including transmitter means for producing a track signal, receiver means for receiving such track signal, coupling means for coupling said transmitter means and receiver means to such track at respective spaced-apart tie points defining an island therebetween, the improvement comprising
Apparatus for detecting a vehicle on a track, comprising transmitter means for producing a track signal, receiver means for receiving such track signal, coupling means for coupling said transmitter means and receiver means at tie points to such track, said receiver means including circuit means for producing from such received track signal a characteristic signal having a magnitude capable of varying according to the proximity of a vehicle on such track to such tie points, output means responsive to a parameter of such characteristic signal for producing output information indicating the presence of a vehicle on such track, and clamp means for limiting the rise of such characteristic signal for a predetermined time in response to a vehicle leaving such tie points.
Apparatus for detecting a vehicle on a track, comprising transmitter means for producing a track signal, receiver means for receiving such track signal, coupling means for coupling said transmitter means and receiver means at respective tie points to such track defining an island therebetween, said receiver means including circuit means for producing from such received track signal a characteristic signal having a magnitude capable of varying according to the proximity of a vehicle on such track to such tie points, output means responsive to a parameter of such characteristic signal for producing output information indicating the presence of a vehicle on such track, and level control means for adjusting the gain of said receiver means in an effort to maintain the magnitude of such characteristic signal at a predetermined value, and wherein such parameter is the downward rate of change of such characteristic signal in response to approaching movement of a vehicle, and said output means comprising means for sensing when such downward rate of change exceeds a predetermined value, thereby to detect the approaching motion of such vehicle, and further comprising holding means for controlling said level control means to hold such gain at a substantially constant level when the magnitude of such characteristic signal drops below a predetermined value before the motion of such approaching vehicle has been detected.
Apparatus for detecting a train on a track, comprising transmitter means for transmitting a track signal, receiver means for receiving such track signal, coupling means for coupling said transmitter means and receiver means at tie points to the track, output means responsive to a parameter of such received track signal for producing information indicative of whether or not a train is detected on such track, and reverse switch override means for consistently temporarily preventing said output means from producing information indicative of a detected train while at least one of said receiver means and output means stabilize when a track switch in such track is thrown to permit entry of a train onto the track in a direction away from such tie points.
In an apparatus for detecting a vehicle on a track, including transmitter means for transmitting a track signal, receiver means for receiving such track signal, and including movement detector means responsive to changes in such track signal for detecting approaching motion of a vehicle on the track, low signal detector means for sensing excursions of such track signal below a predetermined low signal level, and high signal detector means for sensing excursions of such track signal above a predetermined high signal level, the improvement comprising output circuit means for producing one output signal when no approaching movement of a vehicle has been detected and the magnitude of such track signal is within a window between such high and low signal levels and a second output signal when approaching motion is detected or such track signal is outside such window, said output circuit means including circuit means for producing an AC output signal when approaching motion is not detected and a DC signal when approaching motion is detected, plural series gates connected to pass such AC output signal when such track signal is within such window and to block such AC output signal when such track signal is outside such window.
In a train approach detector including transmitter means for transmitting a track signal, receiver means for receiving such track signal, said receiver means including output means for producing output information indicative of detection of a train, motion detecting means for detecting a change in such track signal representative of an approaching train, coupling means for coupling said motion detecting means to said output means to cause the latter to produce such output information when said motion detecting means detects an approaching train,
In a train approach detector including transmitter means for transmitting a track signal, receiver means for receiving such track signal, said receiver means including output means for producing output information indicative of detection of a train, motion detecting means for detecting a change in such track signal representative of an approaching train, coupling means for coupling said motion detecting means to said output means to cause the latter to produce such output information when said motion detecting means detects an approaching train,
In a train approach detector including transmitter means for transmitting a track signal, receiver means for receiving such track signal, said receiver means including output means for producing output information indicative of detection of a train, motion detecting means for detecting a change in such track signal representative of an approaching train, coupling means for coupling said motion detecting means to said output means to cause the latter to produce such output information when said motion detecting means detects an approaching train, connecting means for connecting said transmitter means and receiver means to such track at respective tie points to define an island therebetween, said receiver means including island detector means for detecting the presence of a train in such island, the improvement comprising delayed pick-up means for preventing termination of such output information caused by detection of an approaching train for a predetermined time period commencing with the time at which said motion detecting means loses detection of such approaching train, and cancel means responsive to a train entering such island for cancelling operation of such delayed pick-up means.
In a train approach detector including transmitter means for transmitting a track signal, receiver means for receiving such track signal, said receiver means including output means for producing output information indicative of detection of a train, motion detecting means for detecting a change in such track signal representative of an approaching train, coupling means for coupling said motion detecting means to said output means to cause the latter to produce such output information when said motion detecting means detects an approaching train, and connecting means for connecting said transmitter means and receiver means to such track at respective tie points to define an island therebetween, said receiver means including island detector means for detecting the presence of a train in such island,
A train approach detector, comprising transmitter means for transmitting a track signal in a track, receiver means for receiving such track signal, said receiver means including monitor means for monitoring at least one parameter of such track signal and output means for indicating such a train in response to a predetermined condition of such parameter occurring in such track signal, and reverse switch override control means for consistently temporarily overriding an indication of a train by said output means when a track switch is thrown at least temporarily causing such predetermined condition of such parameter to occur.
A detector for detecting an approaching vehicle on a track, comprising transmitter means for transmitting a detectable signal capable of attenuation by an approaching vehicle, and receiver means for monitoring changes in the magnitude of such detectable signal, including energy storage means for storing energy in proportion to the magnitude of such detectable signal received by said receiver means, comparison means for comparing the signal value at an output of said energy storage means with an AC comparison signal to produce a first output signal when the energy stored in said energy storage means changes in one polarity direction, which represents a receding vehicle, or remains at a substantially constant energy level, which represents no detected vehicle on the track, and a second output signal when the energy stored in said energy storage means changes in an opposite direction, which represents detection of an approaching vehicle on the track.
In an apparatus for detecting a vehicle on a track, including transmitter means for transmitting a track signal and receiver means for receiving such track signal for monitoring a parameter thereof, said receiver means including output means for producing an output indicative of the excursion of such monitored parameter beyond at least one of predetermined limits, the improvement comprising:
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such vehicle, and output means responsive to such detection of such a vehicle by said detector means for producing output information indicative of such vehicle on such track, said receiver means including converting means for converting such received track signal to a substantially DC signal value with ripple pulses impressed thereon, and sensing means for sensing such ripple pulses as a function of whether or not such track signal is received by said receiver means, said sensing means comprising amplifier means for amplifying such ripple pulses and trigger means for producing a square wave pulse train in response to receipt of such amplified ripple pulses, such ripple pulses comprising an AC signal at one frequency with a higher frequency AC ripple signal impressed thereon, said amplifier means having inverting and non-inverting inputs and an output, gain circuit means connected to said output, to one of said inputs and to a source of reference potential for determining the gain of said amplifier means, such ripple pulses normally being applied to the other of said inputs, and filter means coupled to said gain circuit means for limiting the frequency response of said amplifier means to pass such AC signal while blocking at least a substantial portion of such AC ripple signal.
Apparatus for detecting a vehicle on a track, comprising transmitter means for transmitting an AC track signal in the track, receiver means for receiving such track signal, including detector means for monitoring a parameter of such track signal representative of such vehicle, and output means responsive to such detection of such a vehicle by said detector means for producing output information indicative of such vehicle on such track, pulse train producing means for producing a pulse train indicative of a proper form of such AC track signal being produced by said transmitter means, said receiver means including converting means for converting such received track signal to a substantially DC signal value with ripple pulses impressed thereon, and sensing means for sensing such ripple pulses as a function of whethr or not such track signal is received by said receiver means, said sensing means comprising amplifier means for amplifying such ripple pulses and trigger means for producing a square wave pulse train in response to receipt of such amplified ripple pulses, said output means comprising combining means for combining information from said sensing means and such pulse train to enable said output means when both such track signal is received and such other pulse train is produced and when either or both are not received or produced to disable said output means, said combining means comprising flip-flop means for producing an enabling signal for said output means when both said pulse train and said square wave pulse train are received by said flip-flop means, such ripple pulses comprising an AC signal at one frequency with a higher frequency AC ripple signal impressed thereon, said amplifier means having inverting and non-inverting inputs and an output, gain circuit means connected to said output, to one of said inputs and to a source of reference potential for determining the gain of said amplifier means, such ripple pulses normally being applied to the other of said inputs, and filter means coupled to said gain circuit means for limiting the frequency response of said amplifier means to pass such AC signal while blocking at least a substantial portion of such AC ripple signal.
Dependencies are inferred from the claim text.