Showing papers on "Electronic filter published in 1987"

Harmonic suppressing device

Abstract: A harmonic suppressing device provided in a power system such as, for example, a transmission and distribution system or a power generating system, to filter higher harmonic currents generated by a higher harmonic current source of the power system such as, for example, a cycloconverter. The harmonic suppressing device comprises, as the principal components thereof, a passive filter serving as a high-order higher harmonic filtering unit for filtering higher harmonic currents of comparatively high order among those generated by the higher harmonic current source, and an active filter serving as low-order higher harmonic filtering unit for filtering higher harmonic currents of comparatively low orders among those generated by the higher harmonic current source. The active filter comprises: a main active filtering circuit comprising a plurality of switching transistors, rectifying diodes combined with the switching transistors, respectively, a capacitor, and a reactor; an operating circuit which calculates controlling data for controlling the commutating action of the main active filtering circuit on the basis of the detected values of the higher harmonic currents that flows into the power source side of the power system and the detected values of the output voltage of the higher harmonic current source; and a control circuit which gives control signals such as, for example, pulse width modulating signals to the main active filtering circuit. The harmonic suppressing device is capable of filtering higher harmonic currents in a wide frequency band.

Adjustable electronic filter and method of tuning same

Abstract: An adjustable electronic filter apparatus is disclosed comprising a dielectric block having one or more through-holes and having a conformal conductive coating substantially over all outside surfaces as well as each through-hole therein. Each through-hole so plated forms a resonator from a transmission line which includes an open portion, for providing capacitive reactance at a first end, and a short-circuited end as a base, for providing an associated distributed inductance at a second end thereof. A unique method of tuning the adjustable electronic filter, whether a single resonator, a plurality of resonators, or a plurality of intercoupled multi-resonator filters, is disclosed that permits bi-directional tuning for at least one resonator in each of the above exemplary embodiments. By selectively adjusting an inductive portion of the plating at the base of each resonator so tuned, a resonator is quickly and accurately adjusted to a desired frequency. The selective adjusting may be accomplished by subtractive processes, such as abrasion or laser trimming, or by an additive process, such as by adding conductive paint for partially filling in a removed or absent portion of the plating at the base of a resonator.

Multidriver loudspeaker apparatus with improved crossover filter circuits

Abstract: A loudspeaker system includes at least two loudspeaker drivers, together with an electrical crossover network having filter circuits with at least two separate mutually exclusive frequency passbands. The filter circuits comprising the crossover network each possess brick-wall amplitude responses, i.e., passbands with very high band-edge amplitude vs. frequency response slops, on the order of 100 dB/octave in the better embodiments. The high passband band-edge slopes, which are realized by the inclusion of transmission zeros in the separate crossover filter transfer functions, takes together with further appropriate crossover filter transfer function synthesis causes the separate loudspeaker drivers comprising the loudspeaker system to function independently of one another in their contribution to total system acoustic output. It is shown that the loudspeaker system permits an accurate approximation to the ideal delay function in acoustic space, while minimizing acoustic wave interference among drivers operating in adjacent frequency band, and also reducing overall system nonlinear distortion.

Design of low–loss saw filters employing distributed acoustic reflection transducers

Abstract: As a means to reduce the loss in an SAW filter, the IDT (interdigital transducer) called the internal reflection-type transducer has been studied extensively recently. This IDT is believed to be useful as a filter for video and broadband data transmission since it is simple in structure and has low loss over a broadband while its fabrication process and external circuit are simple. So far, the filter constructed with this IDT has had a large ripple in the passband due to a large spurious reflection. To alleviate this problem, a new distributed acoustic reflection transducer is proposed as an internal reflection type IDT in which suppression of the unwanted spurious reflection is possible over a broad frequency range. Next, the operation mechanism of this IDT is investigated and a first-order design method is presented. It is pointed out that a low-loss filter with an insertion loss less than 10 dB and spurious reflection suppressed by more than 45 dB can be realized with this IDT over a broad frequency range.

Switching supply with pulse width and rate modulation

Abstract: A switching type power supply is described which employs pulse width and rate modulation. Enhanced control range is achieved by controlling a frequency determining circuit to increase operating frequency as a function of power switch pulse width. The power switch controls the switching of primary current in a transformer whose secondary supplies the output via a rectifier/filter circuit.

Surface acoustic wave filter

Abstract: PROBLEM TO BE SOLVED: To attain a SAW filter which is small-sized, low in cost and loss and has one input and two outputs or two inputs one outputs. SOLUTION: A SAW filter Fil1 which has a central frequency of a pass-band is f1 is connected to a SAW resonator Reso1 which has a frequency f1 as a resonance frequency. A SAW filter Fil2 which makes a frequency f2 a resonance frequency is connected to by a SAW resonator Reso2 which makes the frequency f2 a resonance frequency. Part of the SAW resonator Reso1 and the Reso2 are commonly connected and connected to an impedance matching circuit 10. The SAW filters Fil1 and Fil2, the SAW resonators Reso1 and Reso2 and a capacitor of the impedance matching circuit 10 are formed on a single SAW chip.

Integrated electric filter with adjustable RC parameters

Abstract: An integrated electrical filter includes resistors (R10-12) and capacitors (C10-12). The capacitors are controllable in value by means of a control circuit (100-109) and are formed by a binary weighted array of capacitor elements which are selectively connectable in parallel. A controlled oscillator (103) or a controlled phase shifting network (113) includes a capacitor of the same form as the filter capacitors. The oscillator (103) or phase shifter (113) form part of a phase locked loop (101, 104, 105, 107) which produces a digital code as its control signal at the output of an up/down counter (107). This digital code is latched in a register (109) to provide a control signal for the filter capacitors and also is used directly to control the capacitor(s) in the controlled oscillator or phase shifter.

Crystal Filters: Design, Manufacture, and Application

Abstract: Quartz-Crystal Resonators. Transformers and Coils. Filter Circuit Theory. Discrete Crystal Filters. Mechanical Design and Manufacture of Discrete Crystal Filters. Monolithic Crystal Filters. Cascaded Monolithic Crystal Filters. Applications of Crystal Filters. Specification and Testing of Assembled Crystal Filters. Using Crystal Filters. Appendix. Index.

Ultrasonic continuous wave blood flowmeter using Doppler effect analysis

Abstract: An ultrasonic continuous wave blood flowmeter using Doppler effect analysis includes a filter having a cut-off frequency determined in part by a manually selected zero shift value. A tranducing device, in the flowmeter includes a transmission element and a reception element, the transmission element transducing an electric transmission signal into an ultrasonic signal to irradiate a living body and the reception element transducing a reflected ultrasonic signal into an electric reception signal. A detecting circuit is operatively connected to the transducing device for orthogonally detecting the electric reception signal and outputting a Doppler detection signal. A filter circuit is operatively connected to the detecting circuit for cutting high frequency components of the Doppler detection signal based on the cut-off frequency and outputting an analog signal. A converting circuit is operatively connected to the filter circuit for converting the analog signal of the filter circuit to a digital signal based on a Doppler sampling frequency having a continuous wave. A transforming circuit is operatively connected to the converting circuit for analyzing the digital signal and obtaining a Doppler frequency spectrum based on a Fourier transform method. A control circuit is operatively connected to the filter circuit for controlling the cut-off frequency based on the Doppler sampling frequency and the zero shift value.

Real-time self-tuning deconvolution filter and smoother†

Abstract: A new self-tuning deconvolution filter/smoother is presented. The algorithm runs in real time on a TMS32010 microprocessor. The filter/smoother employs a moving average of the innovations sequence to estimate the required signal. An application to speech processing and to the channel equalization problem is described.

1.86 GHz SAW Filter

Abstract: Using the third order harmonic wave of Sezawa-mode which propagates in ZnO films epitaxially deposited on R-plane sapphire, high performance filter which is a low insertion loss of 9 dB at 1.86 GHz has been realized.

A Study of the Effects of Apodized Structure Geometries on SAW Filter Parameters

Abstract: Apodization is the most common- ly used weighting technique for defining the impulse response of SAW filters. This work presents the results and compares the parameters of six of the most commonly used transducer apodization geometries. Parameters are presented for the six apodization implementations of a low shape factor filter design example. The parame- ters compared are apodization loss, frequency dependent transducer acoustic conductance and susceptance, transducer group delay and filter passband response. Fast and efficient track modeling ap- proaches are presented. The results show the importance of anticipating the effects of structure geometry when designing apodized low loss SAW filters. Results of the modeling are verified for the case of a low shape factor slant centered apodized transducer SAW filter.

Extremely high speed, real-time background filter for radiation detectors

Abstract: A five stage background filter circuit (10) which is capable of responding to background radiation changes at speeds which are from one to two orders of magnitude faster than conventional prior filter. The invention utilizes a cross can multiplexing technique in combination with filter circuitry depicted in schematic over view in (Fig. 1). Circuit (10) includes a differential amplifier (12), a sample and hold device (14), a responsivity corrector (16), a recursive filter (18), and a background subtractor (20). Output signals (11) from a focal plane array of detectors (Fig. 3) are passed through impedance matching input resistors (12a, b) to an amplifier. A sample and hold circuit (14a) cyclically selects and stores a signal received from first stage (12). The detector outputs are then normalized by responsivity corrector stage (16) which employs a digital-to-analog converter (16a) and random access memory (16c). A threshold band comparison and time-out logic circuit (21) within background subtractor stage (20) controls the operation of recursive filter stage (18) in order to suppress signals due to sensed radiation bursts and to eliminate the unwanted, dynamically varying background radiation portion of the signal present at node (17b). A processed output signal present at node (20i) is then passed to a target detection processor.

Compensation of Diffraction Effects in SAW Filters Using the Uniform Asymptotic Expansion

Abstract: Abstruct-The uniform asymptotic expansion (UAE) previously developed for the calculation of the diffracted SAW beam profile is extended to the calculation of diffraction effects in the frequency response of a SAW filter. The method provides a fast and accurate method of calculating the effects of diffraction in the frequency response of SAW filters even in the very near field region (z < 2.5 A,,). Accuracy and speed comparisons between the UAE and a direct numerical integration algorithm are given. For transducer separations greater than 25 X. the relative difference between the two methods is less than 0.1 dB in the frequency range of interest. In addition, the computation speed of the UAE is greater than that of the numerical integration algorithm by at least a factor of 60 and continues to increase with increasing transducer separation. This technique is used in conjunction with well-known wide-band compensation procedures to design diffraction compensated SAW filters. Experimental results of diffraction compensated SAW filters constructed on 128" rotated Y-cut X-propagating LiNbO, are given.

Gated base‐line restorer without ‘‘droop’’

Abstract: Different configurations of an analog gated base‐line restorer circuit are discussed. An elimination of a ‘‘droop’’ rate is achieved by replacing the analog memory by a digital one. A design employing a digital feedback loop is described.

Band stop type filter circuit

Abstract: PURPOSE:To increase the Q without increasing the shape of a filter circuit by providing an active element coupled in common to plural resonance circuits, operated when the resonance circuits are in the resonance state and causing a negative resistor CONSTITUTION:A transmission filter 12 is formed by series connection between 3-stage of band-pass filters 16 and 4-stage of band-stop filters 18, the band-pass filters 16 are designed for comparatively wide band and its attenuation region is parted greatly from a desired frequency Then an undesired frequency signal is stopped by the band-stop filters 18 A resonator of the band-stop filters 18 is combined with an active element T The resonance circuit R is resonated with the attenuation region of the band-stop filters 18, the active element T is operated to show a negative resistance Thus, energy is supplied from the active element T to the resonance circuit T That is, in adjusting the Qex between the resonance circuit R and the active element T equal to the specific Qo to the resonance circuit R, the apparent Q of the resonance circuit R becomes a very large value

Analysis and design of periodically time varying digital filters

Abstract: This paper describes a type of periodically time varying (PTV) digital filter. Such a filter of period M, simulates the response of a bank of M bandpass filters with their outputs connected to a rotating switch, and requires less multiplications per output sample. A theoretical analysis of the filters is presented, followed by a description of a method of design. A design of a 12-channel filter for use in transmultiplexing is considered.

Mute circuit in aft

Abstract: PURPOSE:To prevent a local oscillation frequency of a tuner circuit from being locked to a microwave signal by inserting a filter circuit eliminating a disturbing wave to the post-stage of an intermediate frequency amplifier circuit CONSTITUTION:A satellite broadcast television signal in 37-42GHz received by an antenna is given to a down-converter, from which the 1st intermediate frequency signal in 430-930MHz is obtained and inputted to a tuner circuit 2, from which the 2nd intermediate frequency signal whose center frequency is 70MHz is obtained The 2nd intermediate frequency signal is amplified by an intermediate frequency amplifier circuit 3 and the result is inputted to a filter circuit 4 When a microwave in a frequency of 60MHz or 80MHz does not exist, a switch 8 is turned on Thus, a signal applied with an AFT as conventionally is fed to a channel selection circuit 11 When the microwave in 60 or 80MHz exists, the switch 8 is turned off and a switch 15 is turned off tentatively Thus, the local oscillation frequency in the tuner circuit 2 is not synchronized with the disturbing wave and controlled to the normal frequency

RF converter employing an SAW filter

Abstract: An RF converter includes a video modulator and a sound modulator. A modulated video signal from the video modulator and a modulated sound signal from the video modulator are mixed and conducted to a surface acoustic wave (SAW) filter constituted as a band pass filter, an RF television signal being the output of this surface acoustic wave filter. A high frequency side of the amplitude characteristic in the pass band of the surface acoustic wave filter is enhanced in comparison with a low frequency side thereof.

Ac signal input/output circuit

Abstract: PURPOSE:To decrease the quantity of terminals, by superposing an AC signal on a DC control signal, inputting and outputting this superposed signal through a single terminal, separating the inputted or outputted superposed signal of the DC control signal and AC signal by means of a filter and supplying the respective components to the corresponding circuits. CONSTITUTION:A control DC voltage CDC is applied to an input/output terminal 16 of an integrated circuit 11. An output from an AC signal generator circuit 17 is superposed on this control DC voltage CDC by an adder 18. The output of the adder 18 is processed by a filter circuit 19 for removing AC signals other than the control DC voltage CDC, and the output from which AC signals have been removed is supplied to a control circuit 12. On the other hand, DC components are removed by a capacitor 20a one electrode of which is connected to the input/output terminal 16 and an AC signal SACOUT is outputted from the other electrode of the capacitor 20a. In this manner, a single input/output terminal can be utilized both for the input of the control DC voltage CDC and the output of the AC signal SACOUT and hence the quantity of terminals used in the integrated circuit 11 can be decreased.

Input filter circuit

Abstract: PURPOSE:To vary the resonance frequency to obtain a trap over a wide range and to prevent the generation of distortion by connecting a coil and two varactor diodes connected in anti-parallel in series between a common and a connecting point between two coils connected in series between input and output terminals. CONSTITUTION:An input terminal 30a is connected to an output terminal 30b via coils L11, L12 constituting an input filter 30 in series. A series circuit comprising a coil L13 and varactor diode D11, D12 connected in anti-parallel is connected between a common and a connecting point of the coils L11, L12. A mixer 13 mixes a signal from the input filter 30 and an oscillation output from a local oscillator 14 to output an intermediate frequency signal. The oscillation frequency of the local oscillator 14 is varied by a channel selection voltage from a channel selection circuit 15 in response to the reception frequency. Thus, a high frequency voltage applied to the varactor diodes is less in level and the generation of distortion is reduced.

Automotive sound system

Abstract: A sound system comprises four channels, each having a low level input for coupling to a source of program material, multiple, independently selectable gyrators providing equalization poles, and an input stage for independently and selectively coupling one or more of the gyrators to the low level input. Each channel further includes an amplifier, a buffer for coupling the selected one or more of the multiple gyrators to the amplifier, and a transducer coupled to the amplifier. A filter is coupled between the buffer and the amplifier. The filter has a variable lower corner frequency and a control input terminal. The sound system further comprises a low-pass filter circuit coupled between the amplifier and the control input terminal of the variable corner frequency filter for generating a feedback signal.

Internal partial discharge detection system of gas insulated switch apparatus

Abstract: PURPOSE:To efficiently remove external noise and to perform measurement based on the voltage waveform of a main circuit by simple constitution, by controlling a corona detection sensor on the basis of the commercial frequency voltage of the main circuit detected from a corona detection terminal. CONSTITUTION:A receiver 30 generates a sensor controlling pulse on the basis of the voltage waveform of a main circuit from a main circuit voltage detection sensor 20 to send the same to corona detection sensors 10a, 10b. The corona signal from a corona detection terminal 5 is sent to a gate circuit 13 through a filter circuit 11 and a detecting and amplifying circuit 12. The light pulse sent from the receiver 30 is photoelectrically converted by an O/E converter 17 to control the gate circuit 13. The corona signal passed through the gate circuit 13 is converted to a light signal by an E/O converter 15 through an A/D converter 14 and transmitted to the receiver 30 through an optical fiber 40.

Driving method for piezoelectric speaker

Abstract: PURPOSE:To realize the reproducing in a wide band area with making even sound pressure frequency characteristic over the whole area of an audio frequency by area-dividing the electrode of a piezoelectric speaker and driving a diaphragm with inputting a signal having a specified frequency component that is filtered at a filter circuit to each divided electrode area. CONSTITUTION:A diaphragm 11 consists of a sheet of piezoelectric element 12 and an electrode 13 attached on the upper surface of the piezoelectric element 12, and the electrode 13 is area-divided to two area, a large and a small ones, 13a and 13b. And with outputting an amplified signal from an amplifier 14, the signal of all frequency band area that is not filtered is inputted to the small area 13b of the electrode 13, on the other hand, to the large area 13a, only the signal of low frequency component that is filtered at a filter circuit 15 is inputted. Thereby, the area driven with a low frequency is relatively increased and the balance between the low area and the high area of emitting sound pressure is maintained.

A programmable electronic filter

Abstract: A filter including one or more variable resistance components ('R') controllable by variation of control current. Each resistance component comprises a multiplicity of series connected stages, each stage (Fig. 3) including a diode (D). The diode (16, 18,... 20) of successive stages are arranged in alternate sense. The resistance component may include a buffering transistor (14) at its input. The resistance may be made arbitrarily large merely by the design choice of including a sufficiently large number of stages. The filter may include a plurality of variable resistance components. For frequency scaling, these components would be connected in parallel to a common source of control current. Alternatively, for variation of shaping characteristics, they may be controlled independently.

Trolley bus driving device

Abstract: PURPOSE:To enable a trolley bus to travel by a low-pressure battery power source at the time of emergency traveling by providing a change-over switch which changes-over the DC input side of the inverter and a connection change- over means which changes-over the connection of the induction electric motor CONSTITUTION:At the time of normal traveling, DC power is led in from a DC stringing 1 through a trolley pole 2 and the DC power is supplied to a variable voltage variable frequency inverter 6 through a filter circuit consisting of a filter reactor 3 and a filter capacitor 4 and a change-over switch 5 In the case of emergency traveling, with a change-over of the change-over switch 5 to the side of a battery power source 12, an induction electric motor 7A is changed-over from a Y connection to a DELTA connection Hereby, the emergency necessary tractive force characteristics can be satisfied

Active filter circuit

Abstract: An active filter circuit having emitter coupled first and second transmittors and emitter coupled third and fourth transistors, wherein the base and collector electrodes of the third transistor are connected to the base electrode of the first transistor, and the base and collector electrodes of the fourth transistor are connected to the base electrode of the second transistor with a reactance circuit connected to a collector electrode of the second transistor and an output terminal connected by the collector electrode of the second transistor such that the filter circuit has a small number of components and operates over a broad band.

Counting device for number of sheets

Abstract: PURPOSE:To attain counting with high accuracy and exactness by providing a setting apparatus which gives a threshold that decides the stage of an object to be counted, and a counting means which gives the threshold from the setting apparatus to an output signal from a filter circuit, and counts a binarization signal. CONSTITUTION:Only stage displacement signals are taken out at a high-pass filter 19 and a low-pass filter 21, and a signal set so that a stage fluctuation can count the threshold is generated based on a displacement on a sheet of paper due to the overlapping quantity of a printed matter 4 as a reference, with a low-pass filter 20, a detection level setting apparatus 23, and an adder 22. By performing a subtraction between both two signals at a differential amplifier 24, a signal SG2 consisting of only the stage displacement on which the threshold is added can be obtained. And by inputting the signal SG2 to a Schmitt circuit, its output becomes the binarization signal like a signal SG3, and it is counted at a counting circuit 26, and a circuit is constituted as the one having a function to perform the subtraction and the reset of a pulse with a non-paper detection signal SD and a reset switch 27. Based on the count signal, the number of printed sheets are displayed at a count display apparatus 28.

Voice switch device

Abstract: PURPOSE:To increase the suppressing sense of noise with less speech head and speech tail cutoff by providing a filter circuit subjected to insertion and deinsertion control by a voice detection circuit and a switching citcuit. CONSTITUTION:A voice detection circuit 11 detecting the presence of a voice from an input signal, a filter circuit 12 providing the frequency characteristic to the input signal and a switching citcuit 13 outputting an input signal when the voice detection circuit 11 decides it to be sound and outputting an output signal of the filter circuit 12 when the circuit 11 decides to be silent are provided. Thus, when the voice detection circuit 11 detects the silence period of the input signal, the switching circuit 13 applies control to output the output signal of the filter circuit 12, then speech head and tail cutoff is less and the noise suppressing effect is large.