摘要:
An alarm or signalling system between a transmitter station and a receiver station either or both of which may be in motion. A signal is selectively radiated from the transmitter station for detection at the receiver station. The receiver station includes processing means for responding to the received signal and producing a new signal indicative of selected physical relationships between the transmitter and receiver stations during the period of signal transmission and reception. The modified signal may indicate approaching or departing relative motion and/or magnitude of separation. One embodiment may incorporate synchronizing signals transmitted from a central control station. This embodiment may include receiver stations with and without the synchronizing equipment.
摘要:
A vital communication system connects an input location to an output location using a non-vital communication link. In addition to transmitting, from the input location to the output location, a word with a bit dedicated to each different input, a system check word is transmitted. Each different input is assigned a unique multi-bit value, and the system check word comprises a linear combination of the unique multi-bit values for each of the inputs in a given binary state. Thus, there is a relationship between the transmitted words with bits dedicated to each input line and the system check word. At the output location, this correspondence is checked for. In addition, a further check is employed which first produces an output check word made up of a linear combination of the unique names for each output which are not in the given binary state. This output check word is then linearly combined with the received system check word. In the absence of a failure, the result of this linear combination of the output check word and the system check word should be constant regardless of the particular condition of different inputs and outputs, so long as the output and inputs actually correspond. Apparatus is provided to check for this constant result.
摘要:
A polarity sensitive relay fabricated of and controlled by, solid state components is provided to produce a more trouble-free and smaller device. The relay may be made in first and second versions, the first of which responds to input signals of a single polarity and the second of which produces first and second output signals in response to input signals of first and second polarities, respectively. The relays include first or second Wiegand modules each of which has a drive coil, an input signal coil and an output signal winding. The Wiegand modules are placed in a steady state magnetic bias and the drive coils pulsed at a predetermined frequency. When two modules are used, the input signal coils are connected in series and in a manner to produce opposite magnetic effects on their associated Wiegand modules. One or the other of the output signal windings will produce a stream of pulses, at the frequency at which the drive coils are driven, in response to a signal of one or the other polarity in the input signal windings. An appropriate magnetic shield is provided to prevent magnetic interference to or from nearby components. A disclosed embodiment is designed to be fail safe meaning that a component failure will not result in an output signal. The relays will not respond to an input signal below a predetermined magnitude.
摘要:
A fail-safe time delay circuit is provided to produce an output a predetermined time, and no less than a predetermined time after an input stimulus. The circuit includes a driving circuit for a pair of relays which are operated at slightly greater than 50% duty cycle and out of phase such that, except when the circuit is de-energized, at least one of the relays is always energized. The contacts of the two relays are employed in a balanced voltage amplifier to produce a bi-polar signal, with the magnitude of both polarities increasing, with the time required for the increase to a defined threshold establishing the time delay. A pair of threshold circuits are coupled to the output of the balanced voltage amplifier such that each threshold circuit (one responding to the positive portion, and the other the negative portion of the bi-polar output) is energized when the respective portion of the bi-polar signal is detected to reach the associated threshold. Each of the threshold circuits provides an input to a vital AND gate such that only when the excursion in the bi-polar signal exceeds the threshold of both threshold circuits will the vital AND gate produce an output to energize a load.
摘要:
A control system for a plurality of vehicles provides for efficient communication while minimizing necessary bandwidth and communication delays. Periodic reports are received from the vehicles by a controlling authority. All vehicles in motion continually receive a permissive GO signal. When the controlling authority determines a vehicle should be stopped, it immediately addresses a STOP command thereto. The addressed vehicle acknowledges the message. Failure of the controlling authority to receive the acknowledgement results in removal of the permissive GO, stopping all vehicles.
摘要:
An improved signal light employing a deep-dish reflector and critically positioned mask or masks for blocking at least some selected light rays having their origin in an external source to reduce, or eliminate, phantom signals. The mask is effective to block out at least a portion of the reflector which reflects light, from an external source, back out of the signal in a direction parallel to the reflector axis. The mask may take the form of a planar ring, a cylindrical surface, a cone or portions thereof. Other shapes may prove expedient or the reflector may be treated in selected and controlled locations to inhibit reflection. The mask may comprise any suitable material such as an opaque material or an electrically controlled optical shutter which is closed when it is desired to inhibit phantom signals and opened to accommodate normal signals.
摘要:
There is disclosed a circuit for energizing a vital relay in response to an input signal that is modulated between two frequencies. A discriminator circuit responds to the modulated frequencies and alternately produces an output patented of one polarity and then a reverse polarity in response to the modulated signals. Coupled between the discriminator and the vital relay is a relay driver which responds to the output of the discriminator and energizes the vital relay. A d.c. power supply is coupled to the relay driver. The vital relay includes two windings. Failure of the modulation, the d.c. source or virtually any circuit element, will result in release of the vital relay. The disclosed embodiment uses photoresistors as switching elements.
摘要:
A vehicle control system monitors vehicle passage at predetermined locations. Each time a vehicle passes a predetermined location a window is created for passage of that vehicle at the next predetermined location. So long as the vehicle actually passes the next location during the window the vehicle is allowed to continue its travel. As a further check each location ensures that safe separation is maintained between vehicles by allowing continued travel only if a minimum time separation is maintained. The system also responds to coupled vehicles by detecting that the time separation is below a predetermined value indicative of coupled vehicles and thus minimum time separation need not be enforced. In one embodiment, passage of a vehicle outside of a time window results in immediate protective action such as by de-energizing the power to each of the vehicles in the system to prevent violation of minimum safe separation rules. In another embodiment, however, vehicle detectors are spaced closely enough such that minimum safe headway requirements will not be violated even if vehicle passes outside a window.
摘要:
A technique for measuring the insulation resistance of an insulated rail joint in the presence of leakage ground resistance (ballast resistance), as well as other track run-around paths, without the use of calibrated meters, such technique characterized by the use of a bridge circuit which includes a leg having the insulated joint therein whose resistance is being measured, the other three legs including a resistor of fixed known value and two variable resistors respectively, such that when the variable resistors are varied to obtain simultaneously both (a) the null of the rail, or ballast, current, and (b) ballast in the bridge circuit, the resistance value of the insulated joint is determined.
摘要:
A microprocessor based vital delay circuit is provided which is arranged to emit an output no less than a predetermined time after an input stimulus. The predetermined time, which corresponds to the delay, is controlled by selecting the relationship between two quantities. A digital processor performs a series of computations on the two quantities, each computation is arranged to take unit time and by selecting the proper relationship between the two quantities, the total series of computations takes a predetermined amount of time. Before the output is allowed to occur, several checks are performed to insure that no hardware or software failures have erroneously generated the result. One novel checking technique insures that the clock frequency has not changed, and this technique is applicable to a wide variety of devices in which digital techniques are employed.