Showing papers on "Electronic filter published in 1972"

Hairpin-Line and Hybrid Hairpin-Line/Half-Wave Parallel-Coupled-Line Filters

Abstract: A new class of microwave filters, hairpin-line and hybrid hairpin-line/half-wave parallel-coupled-line filters, is reported. This class of filters is particularly well suited for microstrip and TEM printed-circuit realizations because grounding of the filter resonators is generally not required. Hairpin-line filters have been divided into two types. The first (Type A) is characterized by having its input and output lines open-circuited at their ends. The Type A filter has been found to yield practical impedance levels for narrow to approximately 25-percent bandwidths. The second (Type B) is characterized by having its input and output lines short-circuited at their ends. However, because of space limitations, details of the Type B filter are not presented in this paper. Theoretical background and design equations for Type A bandpass filters are presented. Experimental data for several stripline filters of 5- and 20-percent bandwidths are given. Experimental results for two microwave-integrated-circuit (MIC) filters are discussed.

Active bandpass filtering with bucket-brigade delay lines

Abstract: Bucket-brigade delay lines have been used to build a tunable active bandpass filter. Experimental results showing the dependence of center frequency and bandwidth on the delay-line clock frequency, and the dependence of the center frequency and the Q of the filter on internal gain parameters are presented.

Active controllable filter circuit using variable transconductance amplifier

Abstract: An RC active filter circuit wherein the active elements of the circuit are realized by controllable transconductance amplifiers. The transfer response of the filter circuit is readily variable by altering signals applied to the control terminals of the transconductance amplifiers.

Signal mode converter and processor

Abstract: An analog signal comparator is coupled to provide its output to a data processor which has digital outputs coupled through a digital-to-analog converter to an input of the comparator, for periodically producing in the processor digital representations of samples of another analog signal that is also applied to the comparator. In each sampling period, additional data processing is carried out with respect to the digital representations; and an output circuit coupled to the converter output employs a filter circuit to select only the results of the last-mentioned processing. The additional processing is shown for digital filters featuring single and tandem sections.

Motion detection system

Abstract: An intrusion alarm system for providing an alarm indication in response to the detection of an intruder within a protected area includes Doppler radar apparatus having a transmitter for radiating energy into the protected area, a receiver for receiving Doppler signals provided whenever radiated energy is reflected off a moving body within the protected area and a signal detecting and filter circuit having a lever detector circuit and a low pass digital filter circuit responsive to Doppler signals in excess of a predetermined amplitude and frequency to provide a logic level output indicative of the detection of an intruder within the protected area In addition to the low pass digital filter circuit, there are described a high pass digital filter circuit and a digital band pass filter circuit

Integration and filtration circuit apparatus

Abstract: A digital word serial integrator circuit is disclosed which can be utilized as the basis for various types of filter circuits. The filter circuits all utilize serial digital input words and produce digital output words and in the process provide low and high pass filtration functions as well as multiplication, division, and square root functions.

Control device for filter circuits connected in parallel with each other and tuned to different resonance frequencies

Abstract: A control device for filter circuits connected in parallel with each other and tuned to different resonance frequencies is disclosed. To prevent the occurrence of parallel resonances in the filter circuits connected to an electrical system in the event of sudden load changes or faults in the system, the control device switches the reactive member of these filter circuits in steps to retune the same in accordance with changes in the fundamental frequency of the system. The switching takes place upon reaching predetermined values of frequency deviation and frequency rate of change.

Bucket-brigade tuned sampled data filter

Abstract: A tuned filter circuit having response characteristics of a tuned LC circuit includes bucket-brigade delay lines and gain factor components connected in feedback circuit relationship around a summing amplifier, and in forward circuit relationship. The resonant frequency of the filter is primarily controlled by the frequency of a digital clock input to the bucket-brigade delay lines. The filter Q and the filter transient response are controlled by the gains established by the gain factor components.

Active RC filter circuit

Abstract: A filter circuit is disclosed which uses an operational amplifier and a plurality of resistors and capacitors to obtain a variety of filter transfer functions. By modification of a basic circuit structure, bandpass, high-pass, low-pass notch, high-pass notch, and all-pass filter transfer functions are obtained.

Low pass filter network

Abstract: An electrical filter having a first and second terminals extending from opposite ends of a conductive case and a filter network housed within the conductive case. The filter network comprises at least one capacitor connected between the case and the first terminal and an inductive component connected between the first terminal and the second terminal. The filter network further comprises a tubular high frequency filter carried by and connected between the second terminal and the conductive case. The capacitor may extend axially along or transversely across the conductive case and the inductive component may be provided by an inductor or a ferrite bead associated with a terminal member.

1000 bit surface-wave matched filter

Abstract: A 1010 bit, biphase-coded, surface-wave matched filter on s.t.-cut quartz is described, and waveforms are shown. The matched filter was designed to operate with a 60 MHz carrier and 10 Mbit/s code rate (0.1 ?s tap spacing). Measurements indicate that the predicted performance is achievable by application of straightforward design procedures and fabrication techniques.

Switching voltage regulator circuit

Abstract: A tapped inductor is utilized in a switching mode voltage regulator, which employs a pass transistor and an associated driver transistor connected in a modified Darlington configuration, for the purpose of allowing these transistors to saturate during switching, thereby substantially increasing the over-all efficiency of the regulator. A filter circuit may be added at the output of the voltage regulator to significantly reduce ripple and to improve the response of the regulator to load transients.

Electronic tremolo effect producing device

Abstract: A tremolo effect producing device, wherein a frequency deviated musical sound signal the frequency of which is shifted higher or lower by as much as an extremely low frequency signal, is tonecolored differently from the tone color of the original signal, and the frequency deviated musical sound signal thus tone-colored and an original musical sound signal are mixed at a predetermined level. The resultant mixed signal presents a repeated change in tone color, which results in a so-called tone color tremolo. A tone coloring circuit for the frequency deviated musical sound signal expediently comprises a filter circuit acting as a filter the value of which changes in response to the level of an extremely low frequency signal applied at a control terminal of the filter circuit.

Easily integrable very-low-sensitivity active RC filter

Abstract: A new easily integrable active RC biquadratic filter, with all the capacitors earthed, is described. The biquads can be directly cascaded without buffer stages. The sensitivities of the Q factor and ω0 to the various passive and active components are very low. Further, the sensitivity of the Q factor with respect to the passive elements can be made zero, making the filter easy to tune. Experimental results which agree with the theory are given for a lowpass Butterworth filter.

Lf amplifier, limiter, and filter system for a receiver of a pneumatic tire low pressure monitoring and warning system

Abstract: An amplifier, limiter, and filter circuit having an improved pass-band and a pneumatic tire low pressure monitoring and warning system using same is provided. The circuit comprises a multiplicity of transistors operatively connected to define stages of amplification, limiting and filter means for attenuating signals on both sides of the pass-band. The circuit includes improved limiters which in combination with the band-pass characteristics of the amplifier serves to restrict the output signals outside the LF pass band to a level which is too low to provide a warning indication. The last downstream transistor has a resistor in a circuit connected to its collector electrode and another resistor connected between its emitter and ground thereby enabling this transistor, serving as an active filter, to provide both amplification and a high pass filtering action.

Frequency filter circuit apparatus

Abstract: Disclosed is a sharp cutoff frequency filter. An alternating input signal derived from a source such as a Doppler detection system is fed to a threshold detector that provides a pulse output of a preselected first level when the alternating input voltage is below a predetermined input level and of a second preselected level during excursions of the alternating input above the predetermined threshold level. The two level pulse signal is next passed to a filter circuit. Within the filter, capacitive integration is provided such that energy is absorbed by a capacitor at a controlled rate when the pulse output is at the second preselected lvel and the capacitor is rapidly discharged when the threshold detector produces the first preselted output level. Thus, the energy stored in the capacitor is a measure of the total time that the second preselected digital output was produced in a particular cycle. A second threshold detector samples the energy stored in the capacitor and produces an output signal when energy in the capacitor exceeds a predetermined level. Thus, an output signal is supplied only if the alternating input signal possesses a minimum wave length and the filter circuit functions as a low pass filter. Another preferred embodiment is disclosed in which the quiescent output from the second threshold detector enables an output circuit to pass the pulse signal. The output circuit is disenabled only in the event that the alternating input signal possesses a wave length greater than a predetermined minimum length. Consequently, this second embodiment functions as a high pass filter. Additional related embodiments disclosed herein function as sharp cutoff notch and sharp cutoff band pass filters.

Preferred active filter forms for bandpass functions

Abstract: The importance of Q sensitivity is shown. Several networks are compared. In many cases adequate stability can be achieved with a single operational amplifier per complex-pole pair.

A Multipurpose Electronic Filter and Integrating Level Detector

Abstract: A multipurpose electronic filter and integrating level detector suitable for electroencephalographic (EEG) and electromyographic recording and analysis is described. It uses solid-state components and is easily constructed. An application of the device in the detection of slow wave sleep (SWS) potentials is given.

Expression control of electronic musical instrument

Abstract: A light-sensitive variable resistor is connected in series between a tone filter circuit and an amplifier of an electronic musical instrument in order to give expression to musical performance by the instrument. In parallel with the lightsensitive variable resistor is connected a gate circuit which normally is nonconductive. Upon failure of a lamp adapted to regulate the electrical resistance offered by the light-sensitive variable resistor to the passage therethrough of the output signal from the tone filter circuit, the gate circuit becomes conductive to provide a bypass for the signal. An alarm lamp may be provided to visually indicate the lamp failure.

Design of elliptic function filters using a double-layer RC distributed-active circuit

Abstract: An active double-layer RC distributed circuit is analyzed. Design charts for realizing a second-order transfer function with real-frequency zeros and a pair of complex-conjugate poles are given using the dominant-pole approach. A fifth-order Cauer-Chebyshev-(CC) type low-pass filter with equiripple passband and stopband characteristics is realized using these charts.

Telephone signaling unit filter circuit

Abstract: An in-band telephone signaling unit of the type useful in carrier trunk systems is disclosed having receive and transmit pulse correction circuits and a band stop/bandpass filter for using an idle channel for supervisory purposes. The transmit pulse correction circuit provides constant length pulses in response to varying length pulses; the receive pulse correction circuit looks for pulses longer than a predetermined length and generates pulses having a constant duty cycle. The bandstop/bandpass filter employs a resonant arm in an active resistance bridge configuration.

Tone generator circuit for electric or electronic musical instruments

Abstract: A tone generator circuit for electric or electronic musical instruments, having a band-pass filter circuit inserted in a transmission line for transmitting an electric sound from an electric sound source to a speaker and knobs for adjusting the upper and lower cutoff frequencies of the band-pass filter circuit, the knobs being slidably mounted on a guide member in such a manner that either one of them may always lie on a predetermined side of the other.

Inductorless filter design using active elements and piezoelectric resonators

Abstract: Inductorless active filters using piezoelectric resonators are described. Because of the excellent frequency stability of piezoelectric resonators (quartz crystals in particular), these filters are more suitable for realizing narrow bandwidth responses than are active RC filters which are restricted to relatively low Q applications by the limited tracking capability of the RC components. In addition, because the filters are active, the inductors and transformers which are often required in passive piezoelectric filters are eliminated.

Load filter network

Abstract: A new and improved filter circuit arrangement wherein the instantaneous current demand from an ON-OFF voltage source is kept below the current requirements of the load by storing energy in the magnetic circuit of the filter inductance during the ON-time of the source and recovering this stored energy and delivering it to the load during the OFF-time of the source and at a lower voltage and higher current level than that at which is was stored. To accomplish this a shunt rectifier device is connected with an intermediate tap of the filter inductance and is poled to block current flow from the source.

The Two-Stage RC Low-Pass Matched Filter

Abstract: In a recent correspondence [1] practical constructions of matched filters for three-pulse signal waveshapes were shown. In each case, the matched filters were realized as a prefilter in cascade with a comb filter utilizing a delay line. The purpose of this correspondence is to present results that demonstrate how closely the simple two-stage RC low-pass filter approximates the matched filters for five different signal pulse shapes.

Electronic band-pass filter or oscillator

Abstract: The disclosure is directed to an electronic band-pass filter having improved characteristics including high band-pass selectivity and a highly amplified output signal. The circuitry used in the filter system is particularly amenable to hybrid and/or monolythic integration, without the need for large external L-C components commonly found in present electronic filters. In the integrated form, the filter is easily adjusted for both selected frequency (fo) and gain and Q (figure of merit).

Problems in Processing of Radar Signals

Abstract: : Contents: Radar signals and the method of their processing; Output signals of filter devices; Detection of signals against a background of interference and other signals; Signal parameter measurements; Signal processor design principles; Methods for the technical realization of signal-processing devices; Analog electronic filters; Digital electronic filters; Optical filters

Series compensation of servodrive resonance

Abstract: The paper considers the effects of the locked-rotor frequency in a range of servodrives. The methods of compensating for the resonance are discussed, and suitable active filters are designed to compensate for the resonance. Practical results of filter circuits are given.