Abstract: A continuous input cell for data acquisition circuits, particularly in railway applications. The cell consists of at least two parallel lines of identical elements, and each line includes at least one Zener diode (DZ1 or DZ2), a switch (SW1 or SW2) preferably consisting of an optocoupler (U1 or U2), and an optocoupler (U3 or U4) including an LED.

Abstract: The invention provides for a cab signaling apparatus and method for use on board a railway vehicle propelled on a set of spaced rails by a traction motor. The cab signaling apparatus may reduce a noise component within a signal having a primary cab signal component and reduce a cab signal component within a signal having a primary noise component. The cab signaling apparatus may further include an adaptive filter to cancel the noise component within the signal having a primary cab signal component without specialized tuning of the cab signaling apparatus. The cab signaling apparatus may include a false code monitor for identifying a true cab signal code and a track signal monitor for identifying a true cab signal in the presence of noise.

Abstract: A device for protecting track relays from electrical disturbances originating from a train's traction current. The device has: a control signal generator; a signal inverter, to invert periodically the polarity of the signal emitted; and a receiver for the control signal. A distinguishing circuit is provided downstream from the receiver for assessing the frequencies forming the receive signal and switching the track relay to the "line clear" position only after recognition of the frequencies forming the periodically inverted control signal.

Abstract: A central control system includes a method for monitoring a plurality of trains throughout a transit system having computer for maintaining a train location table tracking the location of the trains throughout the system and for detecting and recording false train occupancy indications. The system is designed to handle a large number of false occupancy designations and to associate each train with a physical track circuit location.

Abstract: A railroad track segment simulator for assessing track signal susceptibility to electric power line interference including a circuit including a series dc resistor, a series inductor, and an inductive network representing characteristic impedance of an electrical R-L transmission line, resistor, inductor, and network being serially connected as a series circuit, a first ballast resistance connected between one end of series circuit and a ground potential, and a second ballast resistance connected between another end of series circuit and a ground potential. The impedance of the segment is expressed as: ##EQU1## where: f=frequency (hz),r.sub.o =effective radius of rail at power line ac frequencies=0.09 m for 132 lb/yd rail,R.sub.dc =dc resistance per kft of track,j=imaginary number,Ln=impedance per track segment.A plurality of segments can be serially connected to simulate any length of line.

Abstract: An arrangement for reliably detecting process states within freely couplable units each controlled by a computer. Each one of n couplable units forms its own internal signal current loop including a controllable current source and at least two current detection members and series connected process contacts actuated by the process. If a plurality of such units are coupled together, the internal signal current loops of these units are electrically separated and common signal current loops are formed for identical processes so as to pass through all units. Each current source belonging to a unit and its current detection members can be bridged by a subloop which can be activated for test purposes by means of a switch, with the position of the switch being monitored with respect to safety by predetermined tests employing additional, position specific current loops.

Abstract: A train detection system is disclosed which works on the axle-counting principle and in which preprocessing units each containing a two-microprocessor system are associated with the individual detection points. Along the track, a major number of preprocessing units are connected with a central evaluation unit which interrogates the preprocessing units for stored counts on a cyclic basis. This interrogation is performed separately for each microprocessor of a preprocessing unit. In addition to containing counts, data telegrams transmitted to the evaluation unit include functional characters which make it possible to check the correct functioning of the detection points and preprocessing units at short intervals.

Abstract: An automatic vehicle testing apparatus in which data representing conditions of units to be controlled are transmitted through optical transmission lines between a central station and terminal stations mounted on vehicles, which may be railroad cars. The central station can be placed in an automatic test mode. A test controller installed at a test location is operated to place the central station in the test mode. A response signal generating unit for operating each of the units in the vehicles and a monitoring unit for monitoring operations thereof are connected between each terminal station and the respective unit to be controlled. The data in the automatic test mode is transmitted through the optical transmission lines.

Abstract: A railway track switch, also known as a switch machine, is controlled by a microprocessor switch lock connected to the electric switch lock of the switch machine and permits the switch machine to be unlocked so that the track switch points may be thrown, as by a hand-throw mechanism, to permit movement of a train between main and secondary tracks. The switch lock is connected to a cut section repeater of the track circuit adjacent to the track switch. An overlay track circuit connected to the main tracks indicates occupancy in the vicinity of the track switch. The microprocessor receives signals from the repeater, the overlay circuit and the electric switch lock of the switch machine indicating track occupancy and requests to unlock the track switch so that the switch points may be moved. Signals are also received from a timer as to specific, selected delay times set by the user before unlocking the switch.

Abstract: Vital transmission checking apparatus is disclosed for a communication channel which transmits quasi-static signals representing several alternative states of a function, e.g., the control function for a signal in a railway control system, one of which states is potentially unsafe. Each function channel transmits a digital signature code of predetermined length which is continuously repeated in a selected form, e.g., non-inverted, inverted, or alternately inverted and non-inverted, to represent the different states of the function. To provide a check of proper transmission, the repeated signature code is periodically corrupted in accordance with a predetermined error pattern which is repeated at a lower repition frequency than the code. The channel receiver is so designed that its output can only be held in the selected state when both the signature code and the error pattern in the received signal are correct. If a fault is detected, the receiver output is shifted to the most safe state of the function.

Abstract: An automatic car carried departure test unit including an integrated circuit code oscillator for generating coded signals and an integrated circuit carrier oscillator for producing a carrier signal which is modulated by the coded signal to produce coded carrier signals. The coded carrier signals drive a current source which directly injects current signals into a pair of series aiding pick-up coils for testing the reception of coded speed command signals by the pick-up coils and the amplifier of the cab signal receiver. An integrated circuit speed oscillator produces simulated speed signals which are logically processed in sequential order to verify the operation of the overspeed functions of the automatic train protection equipment.

Abstract: A facility for fail-safe data transmission between trackside equipment of a guideway and vehicles moving therealong is disclosed which transmits two identical data records held in two independent storage arrangements in the trackside equipment to a data receiver in the vehicle according to fail-safe principles. Error protection of the data is provided by means of a cyclic code. To enable monitoring the transmitting equipment for component failures from the receiving equipment, a special bit group is transmitted whose bits are checked for equivalence in the receiving equipment.

Abstract: A receiver for sensing track currents includes a toroid coupled to the track rails via a single conductor. The toroid has an air gap in which a linear Hall sensor is inserted. The voltage of the Hall sensor is applied to signal processing circuitry including a low pass filter, amplifier and level detectors. In one embodiment of the invention comprising a track occupancy detector, second and third windings coupled to the toroid are selectively energized from a potential source to provide MMF's in the toroid of one and another polarity, and of a level less than the MMF provided by an occupied track section. The amplifier includes first and second channels for amplifying signals of opposite polarities. Each channel of the amplifier is coupled to a pair of level detectors, one of the level detectors in each pair is a vital level detector with the threshold set at about 50% of the threshold of the other level detector in the pair.

Abstract: In order to prevent a false signal being given in a circuit arrangement for detecting the presence of rolling stock on a track section, when a rail is grounded or fractured, a detecting circuit (31) is provided for detecting unbalance of the traction current. The unbalance detecting circuit is for association with a transmitter (20) for transmitting a track circuit current and an associated receiver (21). The unbalance detecting circuit has two current sensors (TA) which are connected to the ends of the rails (1, 2) adjacent to the receiver (21) for transmitting respective signals to the unbalance detecting circuit (31), and the unbalance detecting circuit transmits the track circuit signal to the receiver only when the signals detected by the current sensors are equal or when their difference is such as not to cause undue excitation of the receiver, and a pole change switch (30) for connection between the track circuit current transmitter and the ends of the rails associated therewith.

Abstract: A track circuit receiver is driven by the signal across an impedance bond and operates a relay to disconnect the signal so causing the relay to cycle. In series with the receiver input is a signal from the center tap of the impedance bond, which is normally at earth potential and does not affect the relay cycling. In the event of a rail break a significant output is obtained from the center tap, which either cancels or replaces the original receiver input signal but on a permanent basis uncontrolled by the relay. The relay therefore ceases to cycle in either event and thus provides a break indication.

Abstract: A process for coding track circuits allows particularly information to be transmitted to a vehicle travelling over a railway track divided into a succession of sections each equipped with a track circuit, in which each of the carrier frequencies for energizing the track circuits is frequency modulated by means of a number of modulation frequencies each representing a piece of information to be transmitted. This process includes the steps of comparing the modulation frequency obtained by demodulation of the modulated carrier frequency with another source of modulation so as to check that said modulation frequency is indeed correct, and to allow transmission of the modulated carrier frequency in the corresponding track circuit only when this check is positive. This process and device applies to high-speed railway trains.

Abstract: A vital rate decoder for actuating one of a plurality of output relays in correspondence with the frequency of an input signal applied thereto, comprising a main rate decoding processor for evaluating the frequency and duty cycle of the input signal by establishing permissible rate windows defined by predetermined tolerances such that the output device corresponding to a frequency can be actuated only when the input signal has a rate code falling in a respective rate window with a predetermined duty cycle tolerance. The rate decoding processor produces plural checkwords having predetermined values based on failure-free rate decoding of the input signal. The checkwords are processed by a checking processor which produces a relay actuating signal only if valid checkwords are produced. The checking processor uses the checkwords to select and load predetermined bytes into a pair of vital counting registers which are then successively decremented.

Abstract: A more failsafe signal voltage threshold determining apparatus is disclosed for operation in a train vehicle control system, and which utilizes the forward voltage drop characteristic of an input light emitting diode of an optical isolator device as a train vehicle control signal threshold reference. The detector transistor of the optical isolator device provides an output control signal in response to an input train vehicle control signal applied to the light emitting diode which has a voltage level high enough to overcome the light emitting diode voltage drop.