Showing papers on "Voltage-controlled filter published in 1969"
Patent•
03 Jun 1969TL;DR: In this paper, the authors describe a series of three BIthis paperRINGENT ELEMENTS of varying thickness with two wave delay ELEMENTS to create an OPTICAL FILTER, which is placed in the light path between an object and a projected image.
Abstract: THE OPTICAL APPARATUS USED IN A TELEVISION SYSTEM, FOR EXAMPLE, INCLUDES A SERIES ARRANGEMENT OF THREE BIREFRINGENT ELEMENTS OF DIFFERENT THICKNESS INTERSPERSED WITH TWO QUARTER WAVE DELAY ELEMENTS TO CONSTITUTE AN OPTICAL FILTER. THE FILTER IS PLACED IN THE LIGHT PATH BETWEEN AN OBJECT AND THE IMAGE FORMED AT THE PHOTOSENSITIVE ELEMENT OF A CAMERA TUBE. THE SPATIAL FREQUENCY BANDWIDTH OF THE LIGHT PASSING THROUGH THE FILTER IS CONTROLLABLE IN ONE OR MORE DIRECTIONS AND IN THE SAME OR DIFFERENT AMOUNTS IN A PLURALITY OF DIFFERENT DIRECTIONS BY SUITABLE DIMENSIONING OF THE BIREFRINGENT ELEMENTS AND/OR BY APPROPRIATE ROTATIONAL POSITIONING OF THE ENTIRE FILTER ABOUT THE OPTICAL AXIS.
32 citations
Patent•
03 Sep 1969
Abstract: A weighing system comprising a transducer operatively connected to a load supporting structure for producing a DC analogue signal voltage having an amplitude which represents a weight condition of a load applied to the structure, at least one signal utilization device, and a circuit for transmitting the DC signal voltage to the signal utilization device and including an electrical filter for attenuating undulating voltage superimposed to the DC signal voltage. The filter includes an amplifier and is characterized by a variable impedance connected to the input of the amplifier for selectively varying the time response of the filter without altering the DC gain thereof. The damping coefficient of the filter is a function only of a preselected value of the percentage by which the filter output voltage initially overshoots its steady state value when the transducer voltage is applied as a step input to the filter.
20 citations
Patent•
17 Mar 1969TL;DR: In this paper, a voltage-regulated converter and a filter supplying a load circuit with relatively smooth unipolarity voltage of desired magnitude are stabilized by connecting rate feedback means to its output for deriving a negative feedback signal.
Abstract: In electric power apparatus including a voltage-regulated converter and a filter supplying a load circuit with relatively smooth unipolarity voltage of desired magnitude, the filter is stabilized by connecting rate feedback means to its output for deriving a negative feedback signal that dominates the dynamic response of the regulator to source or load disturbances.
14 citations
TL;DR: In this paper, it was shown that if a switching technique is used to scale the bandwidth of a lowpass filter, the resultant circuit has some of the characteristics of an N-path filter.
Abstract: It is shown that, if a switching technique is used to scale the bandwidth of a lowpass filter, the resultant circuit has some of the characteristics of an N-path filter. The consequence of this is that the signal frequency must be bandlimited to avoid spurious responses at the switching frequency and its harmonics.
10 citations
TL;DR: Tuneable adjustable solid state bandwidth filter using N path system for low pass to bandpass filter transformation as discussed by the authors, which can be used for both low pass and bandpass filtering.
Abstract: Tuneable adjustable solid state bandwidth filter using N path system for low pass to bandpass filter transformation
9 citations
TL;DR: A special-purpose computer organization of a time-shared digital filter suitable for real-time applications is described, organized in functional modules so that the order of the filter, the coefficients, the programming form, and the multiplexing scheme for the filter are readily adaptable to system needs.
Abstract: A special-purpose computer organization of a time-shared digital filter suitable for real-time applications is described. The computer is organized in functional modules so that the order of the filter, the coefficients of the filter, the programming form of the filter, and the multiplexing scheme for the filter are readily adaptable to system needs.
9 citations
Patent•
23 Apr 1969
TL;DR: In this paper, a very high frequency filter for use with a high frequency radio transmitter which prevents transmission of harmonics is described, which includes an absorptive filter which eliminates spurious passbands resulting from interaction of components.
Abstract: Disclosed is a very high frequency filter for use with a high frequency radio transmitter which prevents transmission of harmonics. The filter includes an absorptive filter which eliminates spurious passbands resulting from interaction of components. The absorptive filter includes highpass filters arranged in an L-network.
6 citations
TL;DR: In this article, a simple algorithm for nonlinear filtering of a time series composed of a gaussian component, pulses and steps is presented, where the main advantage is a scheme for adaptation of the filter parameters.
Abstract: A simple algorithm is presented for nonlinear filtering of a time series composed of a gaussian component, pulses and steps. The method used is a combination of simple statistical techniques. The main advantage is claimed to be a scheme for adaptation of the filter parameters.
6 citations
TL;DR: In this article, an active RC circuit is described, which can be used as a second-order bandpass or high-pass filter, and its sensitivity is independent of the Q factor and very low.
Abstract: An active RC circuit is described, which can be used as a second-order bandpass or highpass filter. Its sensitivity is independent of the Q factor and very low.
5 citations
Patent•
31 Jan 1969
TL;DR: In this article, an amplifier is coupled to a filter and connected to the frequency-measuring indicator of a frequency meter, where the amplifier is a transistor and has a current amplification factor which is highly dependent upon the instantaneous working point of the amplifier.
Abstract: An amplifier is coupled to the filter and connected to the frequency-measuring indicator of a frequency meter. A coupling circuit couples the filter to the amplifier. The amplifier is a transistor and has a current amplification factor which is highly dependent upon the instantaneous working point of the amplifier whereby the equivalent effect of the filter and the amplifier is a function of the direct current component output of the filter, and the filter and amplifier function as a filter with an automatically controlled filtering effect.
TL;DR: An improved method for introducing self-tuning features in an active filter for detection of weak signals in a noisy background is described, which was able to detect a sinusoidal signal in a 10kHz-bandwidth background noise.
Abstract: An improved method for introducing self-tuning features in an active filter for detection of weak signals in a noisy background is described. The filter, which works at low frequencies (100Hz-10kHz), is provided with facilities for search and tracking. During an experiment, the filter was able to detect a sinusoidal signal of 1mV r.m.s. in a 10kHz-bandwidth background noise of 3mV r.m.s.
Patent•
18 Sep 1969
TL;DR: A range-gated doppler filter with a balanced input switch with cancelling feedback supplied to the switch from a following lowpass filter section is described in this article. But it is not suitable for low-pass filters.
Abstract: A range-gated doppler filter having a balanced input switch with cancelling feedback supplied to the switch from a following lowpass filter section
TL;DR: In this article, a double quadrature-modulation realisation of lowpass and high-pass filters was described, where the output frequencies are not required to be identical to the input frequencies, this filter also uses fewer modulators.
Abstract: Double quadrature-modulation realisations of lowpass and highpass filters were described recently by Saraga. Extensions to these methods lead to the design of an octave filter using one carrier oscillator rather than the two needed for an equivalent filter designed by the technique referred to above. If the output frequencies are not required to be identical to the input frequencies, this filter also uses fewer modulators. By employing two carrier oscillators, any desired bandwidth may be obtained; the bandwidth and passband position may then be independently varied.
TL;DR: This paper proposes a method for synthesizing digital filters in the time domain based on the assumption that the pulsed transfer function of the digital filter is a ratio of two rational polynomials.
Abstract: In designing digital systems, one often faces the task of replacing a given analog filter by an equivalent digital filter. This paper proposes a method for synthesizing such digital filters in the time domain. It is assumed that the pulsed transfer function of the digital filter is a ratio of two rational polynomials. The coefficients are then determined by least-square fitting the digital filter to the analog filter's sampled input and output data. The resulting equations for computing the coefficients are linear. It is shown that the digital filter is essentially related to the analog filter, the sampling time, and the power spectrum of the signal being processed. If the signal is band-limited and the sampling frequency is sufficiently high, the digital filter can then be simply approximated by the Z transform of the analog filter multiplied by the sampling period.