Abstract: A direct current motor power controlling chopper apparatus is disclosed which determines the operational speed of one or more traction motors propelling a passenger vehicle along a track. The speed of the motor is established by changing the ON and OFF conduction ratio or duty cycle relationship of a thyristor switch device to determine the field current and the armature voltage of that motor. The present apparatus can provide a greater controlled range of motor speeds including a lower minimum OFF operation and a full ON capacity. In addition, the present apparatus provides greater reliability due to less thermal stress on the thyristor switch devices and fewer circuit elements required to provide an improved motor current control operation.

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.

Abstract: The present invention relates to a train vehicle speed control apparatus which recognizes a change in one of the acceleration rate or the deceleration rate of a train moving along the track and the control of the train velocity in relation to what distance will be required for a desired operation of the train such as a predetermined decrease in the train speed or a stopping of the train. If the deceleration rate has changed, for example, the fixed physical system limits what control can be exercised and the velocity of the train can be modified to adjust the actual stopping distance used by the train or with a fixed stopping distance desired then the permitted train velocity can be changed.

Abstract: There is disclosed a programmed microprocessor control apparatus and method for a transit vehicle electric motor through operation of a chopper apparatus. The microprocessor program controls the motor braking effort in brake mode through operation of the brake resistors and the motor tractive effort in the power mode through the motor field shunt operation.

Abstract: There is disclosed a programmed microprocessor control apparatus and method for determining the electric brake current build-up for regenerative braking effort with a series motor. The microprocessor program determines the current build-up by controlling the chopper operative with the electric motor of a transit vehicle.

Abstract: A signal amplifier and clipper apparatus is disclosed including two four terminal capacitors and an operational amplifier to obtain fail-safe voltage gain which will not increase due to the failure of any element of the apparatus. A signal clipping operation is provided by the saturation of the operational amplifier output at the supply voltages, such that a maximum output signal level is provided by a fail-safe attenuator operation that will not decrease.

Abstract: A signal bandpass filter apparatus is disclosed wherein a direct short circuit between input and output is prevented and the loss of the ground reference of the filter is detectable and fail-safe in operation.

Abstract: A signal decoder is disclosed for use in a transportation vehicle control system in which vehicle control signal information bits are transmitted according to a multiple message frequency, FM, PSK, or FSK, comma-free binary coded command signal. The disclosed invention uses selective receiver channels for each command signal message frequency to detect information bits according to the selected message frequency. The detected information bits of each receiver channel are separately stored to comprise a separate information history for each message frequency and these information bit histories are then individually decoded. The decoded signals are compared to detect a discrepancy between any of the decoded signals due to component failures, signalling system noise, or component transient conditions. For any discrepancy between the decoded signals, a fail-safe comparator reduces the decoded signal to a more safe condition.

Abstract: An inverting amplifier apparatus is disclosed, which provides, in a failsafe manner, a predetermined initial gain that decreases linearly over a known range of frequencies. The disclosed inverting amplifier apparatus includes an amplifier whose feedback impedance contains a four terminal capacitor in parallel with a feedback resistor. The use of a four terminal capacitor as a feedback element makes the amplifier failsafe by preventing a failure mode of the amplifier in which the opening of the feedback element results in infinite AC gain of the amplifier. A virtual ground is provided at the junction of an input resistor, the feedback resistor, and one terminal of the four terminal capacitor, so the amplifier apparatus may simultaneously accommodate multiple input signals thereby permitting the amplifier apparatus to perform summing operations.

Abstract: In a transportation vehicle control system, a signal is detected from a transposed cable to determine the vehicle position relative to a predetermined speed control zone. This position data, along with other manual and/or automatic inputs, is fed into a profile function generator whose output is a predetermined singular function of the position and other inputs. While the vehicle is within the speed control zone, the output of the profile function generator is converted from digital form into analog form and then used to limit the vehicle speed.

Abstract: A receiver is disclosed which is used in a transportation vehicle detection system to compare logic conditions in signals which are transmitted from a first vehicle pathway location, with logic conditions which are detected from signals received at a second vehicle pathway location. When first and second enable signals correspond, the signal from an oscillator is transmitted through two pairs of fail-safe AND gates and applied, through a fail-safe OR gate, to a latch circuit which signals the transportation system speed controller that no vehicle is present between the first and second pathway locations. When the first and second enable signals do not correspond, the signal from the oscillator is not transmitted through both pairs of fail-safe AND gates, there is no signal applied to the fail-safe OR gate, and no signal is applied to the latch circuit which signals the transportation system speed controller that a vehicle is present between the first and second pathway locations.

Abstract: A signal bandpass filter apparatus is disclosed wherein a direct short circuit between input and output is prevented and the loss of the ground reference of the filter is detectable and fail-safe in operation.