A circuit for filtering electrical waveforms in which the useful information is contained in patterns and spacing of zero-voltage crossings is disclosed. Illustratively, a disk memory system is disclosed in which the voltage peaks developed by the disk memory read-transducers are converted into zero-voltage crossing waveforms by differentiation. To eliminate false zero-voltage crossings caused by noise, the digital filter generates a linear ramp waveform whose magnitude is proportional to the time duration between successive zero-voltage crossings. False zero crossings typically have a short time duration between successive crossings. They are eliminated from the integrated ramp waveform by a comparator which only responds when the integrated waveform reaches a predetermined threshold level indicating the time between successive zero-voltage crossing exceeds a minimum time duration. A balanced version of the digital filter circuitry is also disclosed which recovers a limited, filtered version of the original zero-voltage crossing wave form except for a slight delay.
A low pass filter comprises a complementary signal generator circuit for receiving an input pulse signal to output a first and a second signals having phases inverse to each other, a first CR circuit inputted with the first signal, a second CR circuit inputted with the second signal, a flip-flop circuit, a set circuit, and a reset circuit. In the low pass filter, the set circuit detects an output signal of the first CR circuit by the threshold voltage value thereof to set the flip-flop circuit in accordance with a detection result, and the reset circuit detects an output signal of the second CR circuit by the same threshold voltage value to reset the flip-flop circuit in accordance with a detection result.
The present invention describes a circuit for activating a control unit such as an ABS controller in a vehicle by way of a CAN bus, with the ignition turned off, which is in particular characterized by a first input for a logic activation signal for the control unit, an input filter for suppressing disturbing pulses in the activation signal, and a device for producing an output signal (CAN_WU) that activates the control unit when a predeterminable number of activation signals is recorded within a predeterminable duration.
A resistor capacitor (RC) tracking loop includes a parasitic insensitive integrator (211) charged by a buffer (207) with offset compensation. The integrator (211) operates to provide an accurate ramped voltage proportional to a measured RC time constant. A single comparator (213) is used for sensing the voltage ramp rate by detecting two multiplexed reference voltages (V.sub.REFLO V.sub.REFHI). A timer within controller (201) is triggered by the V.sub.REFLO crossing at comparator (213). The timer counts the number of precision reference clock periods (F.sub.REF) that occur between the V.sub.REFLO and V.sub.REFHI crossings and adjusts an accumulator within controller (201) to a value (M). This value (M) is directly used to adjust a resistor and/or capacitor array used in a continuous time filter whose bandwidth and corner frequency can be precisely tuned.
A foundry installation control device is disclosed for causing a rapid cut off of a molten metal flow at the time when a mold is full. Two detectors are provided, one of which collects information concerning the instantaneous rate of metal flow pouring from a ladle into a sprue cup while the other collects information on the level of the molten metal in the cup. An electronic circuit connected to the outputs of the two detectors produces a mold filling signal which undergoes a sharp fluctuation at the precise moment when filling is completed. This signal is compared with an instruction value and causes the generation of a flow cut-off signal which triggers the cessation of pouring by righting of the ladle in the case of a tilting ladle, closing of the stopper in the case of a bottom-pour ladle, or closing the discharge valve in the case of a pressure ladle.
A phase noise reduction circuit for reducing phase noise in an input pulse train consisting of pulses which are all of the same length and which, in the absence of phase noise, have a nominal frequency f, includes a DC removal circuit for removing a DC level from the input pulse train, an integrator for integrating the input pulse train after a DC level has been removed therefrom by the DC removal circuit and a comparator for deriving from the integrated pulse train an output pulse train containing periodic transitions at said nominal frequency. The input pulse train may be derived using a monostable circuit.
