In a train control signalling system, a wayside signal of an unknown code rate is detected and decoded on board the train to determine the code rate and derive the coded train control intelligence. The code rate is determined by counting the number of cycles of a known higher frequency which occur during one period of the unknown code rate. Before a train command signal is issued, a number of tests are performed to verify that the determination is accurate with no margin for error. The known higher frequency signal is passed through a tuned circuit to verify that it is within predetermined limits of its rated frequency. The counter that counts the cycles of the known higher frequency is tested to verify that it is reset to zero at required intervals. Verification is obtained that one and only one train control signal is obtained. The counting circuits and memory devices are cycled prior to each decoding operation to verify proper functioning. Each train control circuit is tested and none can operate unless the prior one in the chain responded properly. A train control circuit cannot remain operated unless it receives periodic confirmation signals.
A digital tone signal detector having N-path filters eliminates the need for a variable-frequency active filter and makes possible the use of integrated circuits in paging receivers, transceivers, mobile radio equipment and so forth. The tone signal detector comprises a clock pulse generator, an N-path filter (where N is an integer equal to or greater than 2), a low-pass filter, a wave shaping circuit, a gate circuit, a counter and detection circuitry. The clock pulse generator generates clock pulses of a predetermined frequency Fc equal to N times the frequency fo of tone signals. The N-path filter samples and selects the tone signal of the frequency fo according to the output of the clock pulse generator. The low-pass filter converts the sampled tone signal including the clock frequency component into a form close to sine wave to eliminate the clock frequency component. The wave shaping circuit shapes the output of the low-pass filter to produce pulses, and the gate circuit passes the clock pulses in accordance with the output of the wave shaping circuit. The counter is connected to the output of said gate circuit to count the number of the output pulses of the gate circuit. The detection circuitry is connected to the counter to detect whether or not the received tone signals are the designated tone signals by the count accumulated by the counter in a prescribed period of time.
A coke oven machinery positioning and spotting system comprises system characteristics mapped in a process memory and system dynamics controlled by a central processing unit and a sensing mode. The system results in the automatic control of machine travel, positioning and spotting, and interlock against further travel until a command signal is given to start a new sequence.
A numerical vital relay driver serving as an independent arbiter of vital railway (control) system operation constituting a checkword translator for receiving system checkwords from a system processor in the form of "N" bit NISAL parameters and for implementing a hardware algorithm utilizing the checkwords. It also consists of variable waveform data tables, including means for translating the data in the tables into a periodic signal, wherein it is insured that only if the checkwords are present and correct within a specific check period and the operation of the hardware algorithm is correct, will the desired periodic signal be produced.
A system for transmitting initialization information between fixed installations and trains. The system comprises: an initialization loop (bi) physically constituted in the same way as a speed monitoring loop; a speed monitoring coil (cd) which is also used for receiving initialization messages; a source of initialization messages (si) connected to the initialization loop and providing a message in the form of an initialization carrier wave having an initialization frequency modulated by frequency shift keying, with the level of the wave being considerably higher than the level of the carrier wave for speed monitoring; and circuits (di) for detecting initialization information, the circuits being connected to the speed monitoring coil and detecting the frequency shift keying in order to provide a received initialization message under the control of a switching device (ad, dp, sd, ri) which responds to reception of the initialization frequency solely when the frequency is at a level which exceeds a predetermined threshold.
A method is described for testing a train control system configured to control at least two locomotives. The train control system includes a control unit on each locomotive and is configured to control the locomotives using communication links between the control units. The method includes establishing communication between a testing device and a first locomotive control unit, and emulating a second locomotive control unit using the testing device. The testing method allows control system testing to be performed using a hand-held testing device in place of a second locomotive and facilitates testing of repeaters.
