Abstract: A method for generating a digital sine wave signal having a predetermined sampling rate includes generating a pulse train with an alternating or constant amplitude sign, at a sampling frequency having a predetermined sampling rate frequency divided by 2.sup.n. An envelope curve is generated. The sampling rate is doubled. The doubling of the sampling rate is repeated until generation of a desired sine wave signal in an unfiltered spectrum of the generated signal. Undesired frequency components are filtered out. The sampling rate is optionally re-increased by oversampling a previously generated signal. A circuit configuration for carrying out the method includes a unit for generating digital sampling values. A filter for generating an envelope curve is connected downstream of the unit for generating digital sampling values. Units for raising a sampling frequency are connected downstream of the filter for generating an envelope curve. A digital filter filters the generated digital sampling values.

Abstract: A circuit for the filtering of a pulse signal comprises means to detect an output pulse upon the detection of an input pulse, the shape of this output pulse being based on elementary delays obtained by the charging and discharging of capacitors. During the generation of the output pulse, no new input pulse can be taken into account.

Abstract: A control system having a source of control signals and a multi-window electrical signal tracking filter. The signal tracking filter includes an operational amplifier operating in the non-inverting mode as a high impedance load, with a plurality of input stages cascaded at the input to the operational amplifier, each input stage having both a frequency determining filter portion and an amplitude determining threshold detecting portion. Each input stage defines a "window" of operation, such that the portion of a control signal or the like inputted to the filter which falls within the "window" will be filtered or attenuated thereby, while the portion of the control signal which falls outside of the "window" will pass unaffected through the filter. Cascading of the input stages allows one to customize the portions of the signal to be filtered for any particular application.

Abstract: A soft switching circuit gradually connects an audio signal to zero reference level to mute the audio signal, or connect a filter to enable the filter. A MOSFET is connected between the audio signal and the zero reference level. A resistor-capacitor circuit is connected to the gate of the MOSFET and receives the MUTE or FILTER* signal from the computer system. When the MUTE or FILTER* signal changes condition, the RC circuit provides a signal to the MOSFET gate that changes relatively gradually. Consequently, the drain-to-source resistance of the MOSFET also changes from short circuit to open circuit or vice versa relatively gradually.

Abstract: An electronic device comprises, for example, a portable device or a signal receiver mounted on a vehicle for opening and closing the doors of the vehicle in response to telecontrol signals from a remote source. The device comprises two stages arranged in cascade with respect to the input signal, with the polarising terminals of the two stages being connected in series across the supply.

Abstract: A method for processing electrical signals includes the steps of: storing a plurality of first data signals, each representative of an instantaneous amplitude of a first input signal in a memory; selecting one of the first data signals in response to a second input signal; combining the selected one of the first data signals with a second data signal representative of a subsequent instantaneous amplitude of the first input signal, to produce a difference signal; producing a first output signal in response to the difference signal; and combining the difference signal and the selected first data signal to produce a modified data signal and for replacing the selected one of the first data signals with the modified data signal in the memory. The method can be performed by an equalizer in a circuit for compensating for amplitude variations in a radio frequency signal or by a comb notch filter.

Abstract: A highly DC accurate filter network capable of implementing a transfer function of arbitrary complexity is disclosed herein. The filter network includes a differential integration and summation network having a first input port connected to an input terminal of the filter network, a second input port, and an output port. A filter circuit having a predefined transfer function is connected between the output port and an output terminal of the filter network. In addition, a feedback path connects the output terminal to the second input port of the differential integration and summation network. During operation of the filter network the filter circuit cooperates with the differential integration and summation network so as not to affect the amplitude of the DC component of an input signal applied to the input terminal. This results in high DC accuracy even if the filter circuit is implemented using, for example, active components.

Abstract: An impulse noise canceler includes circuitry which recognizes, locates, and cancels impulse noise when it occurs in an incoming signal. Impulse noise is characterized by a shape, an amplitude, and an arrival time, any or all of which may be unknown. In one implementation, adaptive circuitry is deployed to estimate the amplitude when it is the only unknown, and a replica of the impulse noise is generated and used to cancel the impulse noise in the incoming signal. In another implementation, both the arrival time and amplitude are estimated when they are unknowns, and a replica is again generated to cancel the original impulse noise. In yet another implementation, the shape, amplitude, and arrival time are all estimated of the impulse noise to produce the replica to cancel the original impulse noise.

Abstract: In a noise canceler, a pilot-canceling signal without noise is applied to the inverting input of a subtracter via a first MOS transistor. When a noise signal is present, a pilot signal and noise signal passing through a capacitor are applied to the inverting input port of the subtracter via a second MOS transistor to cancel the noise signal contained in the composite input signal. In the canceler, external noise may be digitally converted and the inverted noise thereof stored in a memory. When a noise signal detector detects the external noise, inverted data corresponding to the external noise is output from the memory. The detector enables an address generator to continuously generate addresses. The memory reads out inverted noise patterns which are converted into analog form and transmitted via a speaker, thereby canceling noises produced by various electrical and electronic appliances as well as nearby automobiles and aircraft.

Abstract: A real-time tracking filter circuit (10) that exhibits accurate zero placement is implemented in a monolithic structure by incorporating a three-input summing circuit (24) and a two-input summing circuit (28). The input signal (12) and a feedback signal (30) are summed and converted to a first current. The first current is integrated for providing a first integrated voltage (18). The first integrated voltage and an amplified input signal (40) and the feedback signal are summed and converted to a second current. The second current is integrated for providing a second integrated voltage as the feedback signal. The second integrated voltage and the amplified input signal are summed for providing the filtered output signal (36). Integration capacitors (20, 32) are grounded to remove parasitic effects that impact the pole-zero frequency response of the tracking filter output.

Abstract: A vortex flow transmitter has a filtering circuit receiving a noise contaminated input signal representative of the flow and which has a fundamental frequency varying responsively to flow. The filter filters the input signal using one of a family of HP filter characteristics to produce a filtered signal having a frequency representative of the physical parameter. Each member of the family of HP filters has varying corner frequencies, each filter having a unique switchup and a unique switchdown value assigned to it. Adaptive response element select a current HP filter for use in the filter. Adaptive circuitry uses one selection method when the flow is increasing and another selection method when the flow decreases. Finally, output circuitry converts the signal from the filter into a transmitter output, typically a 4-20 mA current or a frequency output representative of the flow.