Showing papers on "Electronic filter published in 1984"

Design of Nonradiative Dielectric Waveguide Filter

Abstract: An efficient design technique of nonradiative dielectric waveguide filter circuits for use at millimeter wavelengths is developed. A 3-pole, 0.1-dB Chebyshev ripple bandpass filter with 2-percent bandwidth at center frequency of 49.5 GHz was designed and fabricated with Teflon dielectric according to this theory. The calculated and measured filter responses agree quite well, and the excess insertion loss is found to be as small as 0.3 dB.

Design of Nonradiative Dielectric Waveguide Filters (Short Papers)

Abstract: An efficient design technique of nonradiative dielectric waveguide filters for use at millimeter wavelengths is developed. Filter stuctures considered here are a gap-coupled type and an altenating-width type. According to present theory, 3-pole, 0.1-dB Chebyshev ripple bandpass filters with a 2-percent bandwidth at a center frequency of 49.5 GHz were designed and fabricated with Teflon dielectric. Calculated and measured filter responses agree quite well, and excess insertion losses are found to be as small as 0.3 dB for both types of the fabricated filter circuits.

Controller for providing PWM drive to an A.C. motor

Abstract: A controller for providing PWM drive to an inductive load incorporating an input rectifier bridge (24) the output of which is filtered by capacitors (106, 108) and which includes input impedance (116, 118) for limiting start-up current surges. A by-pass network (124) controlled from a high voltage sensor circuit (32) controls the by-pass network. The sensor circuit also provides an enablement signal (40) to a pulse width modulation circuit (42). A low voltage power supply (36) is coupled with the output (26) of the rectifier and filter function (24) to supply isolated power to the discrete driver networks of a driver circuit (48). The driver networks are controlled from the pulse width modulation circuit which, in turn, is controlled from a microprocessor (68). The drivers provide drive to three, phase designated transistor pairs of an inverter switching bridge (50) which is supplied power from the rectifier and filter circuit (24).

A history of network synthesis and filter theory for circuits composed of resistors, inductors, and capacitors

Abstract: This paper is an informal history of the birth and growth of network synthesis and filter theory, as it was developed for RLC circuits. It includes events, experiences, and anecdotes which are not all well documented but may make interesting reading. Other papers in this issue are histories of other aspects of circuit theory; for the most part descended from the RLC theory.

Adaptive comb filter.

Abstract: Various filter circuits for a processing digitized color television signals are disclosed. Particularly, there are disclosed several embodiments of a luminance/chrominance signal separating filter (11) with which separated, digitized luminance and chrominance signals are derived with a minimum amount of interference therebetween by determining the direction from a given point in which there is a minimum amount of change in the digitized image signal. Also, there is disclosed a subnyquist sampling filter which operates upon this same principle.

Rotation control apparatus for a motor

Abstract: A rotation control apparatus for a motor comprises a motor for rotating or moving a recording medium, a circuit for generating first and second reference signals, a circuit for passing a signal which is obtained by comparing phases of the first reference signal and a synchronizing signal through a filter circuit thereof so as to produce a first error signal therefrom, a circuit for producing a second error signal which is obtained by comparing phases of the second reference signal and the rotation detection signal, and a control circuit for controlling first and second switching circuits. The control circuit supplies a specific signal having a level dependent on the level of the second error signal to a capacitor of the filter circuit through the second switching circuit and selectively passes the second error signal through the first switching circuit when the motor rotates at a rotational speed which is not near a steady state rotational speed. The control circuit blocks the supply of the specific signal to the capacitor by the first switching circuit and selectively passes the first error signal through the first switching circuit when the motor rotates at a rotational speed which is approximately equal to the steady state rotational speed.

Echo canceller device for data transmitter

Abstract: PURPOSE:To decrease the required bit number of an operation processing circuit by combining a processing pre echo canceller and an adaptive type digital processing echo canceller and eliminating a part of an echo signal from an input signal of the latter in advance so as to narrow the dynamic range of an A/D converter. CONSTITUTION:A transmission signal from a transmitter 2 is given a specific frequency characteristic by a filter circuit 22 in a pre echo canceller 21 and attenuated properly by an attenuation circuit 23, then subtracted from a reception signal including an echo signal incoming through a terminal 6 and a hybrid transformer 5 by a subtraction circuit 24. When the frequency characteristic of the filter 22 and the attenuation of the attenuation circuit 23 are decided properly, the absolute amount of the echo signal included in the signal inputted to the digital processing adaptive type echo canceller 13 is decreased, the number of bits required for an A/D converter 7 is reduced and the number of bits of the operation processing circuit is reduced.

System Design Considerations In Bar-Code Laser Scanning

Abstract: The unified transfer function approach to the design of laser barcode scanner signal acquisition hardware is considered. The treatment of seemingly disparate system areas such as the optical train, the scanning spot, the electrical filter circuits, the effects of noise, and printing errors is presented using linear systems theory. Such important issues as determination of depth of modulation, filter specification, tolerancing of optical components, and optimi-zation of system performance in the presence of noise are discussed. The concept of effective spot size to allow for impact of optical system and analog processing circuitry upon depth of modulation is introduced. Considerations are limited primarily to Gaussian spot profiles, but also apply to more general cases. Attention is paid to realistic bar-code symbol models and to implications with respect to printing tolerances.

Self-regulating electronic ballast system

Abstract: This invention provides for a self-regulating electronic ballast system (10) which includes a power source (12) for actuating at least one gas discharge tube (66). The self-regulating electronic ballast system (10) includes a filter circuit (11) connected to the power source (12) for maintaining a substantially smooth direct current voltage signal as well as for suppressing harmonic frequencies generated by the electronic ballast system (10). Induction circuitry (15) is coupled to the filter circuit (11) and includes a tapped primary winding (42) for generating a voltage across the gas discharge tube (66) responsive to a regulated current. A switching network (13) which is feedback coupled to the induction circuitry (15) establishes the regulated current and the switching network (13) includes a regulation control circuit (17) for maintaining the power output of the gas discharge tube (66) at a predetermined and substantially constant value.

Tuner for communications equipment

Abstract: An tuner unit is provided for communications receivers with automatic self-balancing of the individual high frequency filter circuits. An assigned frequency applied to the desired receiver channel is fed to the antenna input during the automatic balancing process. The voltage of this assigned frequency picked up at the output of the filter circuits changes according to a stepwise increase of a tuning voltage controlled by a microprocessor. The tuning voltage is applied to the filter circuit to be balanced via a digital-analog converter and via a switching means controlled by the microprocessor. The automatic balancing is provided by switching the switching means successively to connect to the individual filter sections.

Alternating-current filter circuit arrangement

Abstract: In this three-phase filter circuit system for static converter systems and particularly high-voltage direct-current short ties, at least two high-pass filters are provided which are connected in parallel. Each high-pass filter consists of a choke connected in parallel with a resistance and, in series with both, a capacitor and can be individually connected to the three-phase busbar via a switch. The filter circuits are used not only for reducing harmonics but also as compensating devices, which can be switched in steps, for the reactive power requirement of the static converters so that in the lower partial load range of the system one of the filter circuits is disconnected for reasons of reactive power balance. In order to improve the filtering effect in this lower partial load range, a bus-coupler switch connecting in each case the common junctions of capacitor, resistance and choke of the high-pass filters is closed. When the switch is closed, this widens the band width of the filter circuit which is in operation and increases the resonance frequency, and individual distortions, the total distortion and telephone interference factors on the busbar are reduced.

Television SAW/VSB filter incorporating receiver equalizer

Abstract: A visual exciter for use in a television broadcasting system is disclosed. The exciter includes a surface acoustic wave (SAW) filter for vestigial sideband filtering of an RF carrier signal amplitude modulated with a video signal. The SAW filter has a time delay versus frequency characteristic which is designed to compensate for a complementary delay characteristic of a TV receiver. The need for a separate receiver equalization circuit is therefore eliminated.

A security system

Abstract: A security system for a vehicle comprises a crystal oscillator circuit with a crystal (10) which is located inside the vehicle and removable by the driver, a filter circuit (Fig. 2) tuned to the frequency of the oscillator circuit 1 and means such as a solenoid (Fig. 4) or relay (Fig. 8) for preventing starting of the vehicle except upon receipt of a signal from the oscillator circuit via the tuned filter circuit. The technique described may be used generally to disable apparatus against unauthorised use.

Optical multiplex circuit

Abstract: PURPOSE:To constitute inexpensively an optical multiplex circuit of high multiplexing, by constituting the titled circuit with an optical wavelength multiplex circuit and an optical frequency filter circuit discriminating full-optically a modulating frequency of a light subjected to intensity modulation. CONSTITUTION:A signal having frequencies P11-P1N is inputted respectively to N sets of modulators 303 via N sets of signal input lines 300, a light having a wavelength lambda1 is modulated, added by an adder 309 via an optical fiber 306, and the added output is inputted to a wave synthesizer 316 via an optical fiber 312. Similarly, the input signal having frequencies P21-P2N, P31-P3N- is inputted respectively to N sets of modulators 304, 305, where the light of wavelengths lambda2, lambda3- is modulated, the modulated output is added 310, 311 and inputted to a wave synthesizer 316. The output of the synthesizer is inputted to a branching filter 318 via an optical fiber 317. The light is branched at wavelengths lambda1, lambda2- by a branching filter 318 and inputted respectively to optical branching filters 323-325. The output of each optical branching filter is discriminated to each signal frequency PiN by a filter circuit 329 of an optical filter circuit network group 330 and outputted.

Reference signal waveform shaping circuit device

Abstract: PURPOSE:To decide on a threshold level on the basis of only one pulse of a reference signal and to improve transient responsibility, by generating a charging signal according to the reference signal corresponding to the angle of rotation of an engine and holding the peak value of the reference signal. CONSTITUTION:A filter circuit 21 reduces the level of noises superposed upon a crank reference signal (a) obtained from a rotation angle sensor 1 to suppress the peak value of the signal level within some range. A threshold level generating circuit 22 holds the peak value of the reference signal (b) passed through the filter circuit 21 every time a reference signal pulse arrives to decide on the threshold level. A crank reference signal level comparing circuit 23 compares the signal (c) with the threshold level determined by the circuit 22 to generate a waveform-shaped crank reference signal (c).

Small ripple surface acoustic wave filter with low insertion loss

Abstract: A surface acoustic wave (SAW) filter is disclosed which exhibits both low insertion loss and small ripple in the passband, requirements which were considered mutually exclusive in the prior art. In accordance with the present invention, apodized group-type recessed electrodes are utilized to form the transducers. The grouping of the electrodes functions to reduce reflection between electrodes and apodization of the electrodes functions to increase the sideband rejection. However, merely combining these techniques is inadequate since the apodization process produces additional ripple between adjacent electrodes, thus increasing the passband ripple. By recessing the apodized groups of electrodes, this reflection is minimized and a SAW filter formed in accordance with the present invention is thus capable of providing both low insertion loss and small ripple with high sideband rejection.

Single electrode, multiple frequency plasma apparatus

Abstract: O Plasma processing is accomplished with an improved single electrode reactor apparatus. High and low frequency power supplies are coupled to the single electrode by way of a multi-stage passive filter network which performs the functions of coupling both power supplies to the electrode, isolating the low frequency power supply from the high frequency power supply, and attenuating the undesired frequencies produced by mixing of the two frequencies in the non-linear load presented by the reactor.

Harmonic Current Interruption Phenomena In ARC Furnace Filter Circuits

Abstract: The current interruption phenomenon in arc filter circuit containing harmonic current was experimented in the field and analyzed by TNA (Transient Network Analyzer) and numerical analysis to calculate the recovery voltage. The recovery voltage when the filter circuit contains harmonic current becomes greater than that obtained in the IEC-specified test using a small leading current.

CMOS Digital Signal-Processing Codec Filter with High Performance and Flexibility

Abstract: A novel approach for a monolithic Codec Filter is presented, which provides results for the dynamic range and the signal-to-noise ratio which exceed the CCITT requirements considerably and in addition offers very comfortable programming possibilities. Progress in circuit design simulation techniques and advanced CMOS technology made it possible to integrate the analog part and the fully digital, programmable signal processor on a single chip in an economic way. Compared to conventional Codec Filter circuits, the presented solution may further profit from the continuing reduction in feature size of VLSI technology in terms of power consumption and chip area.

New general biquadratic active RC and switched-capacitor filters

Abstract: An active RC filter capable of realising a general biquadratic transfer function, using two operational amplifiers with grounded noninverting inputs, is described. Its application to the realisation of SC filters using 'p-transformation' is also discussed.

Capacitor type converter

Abstract: PURPOSE:To compensate for nonlinearity effectively, by using a pair of variable capacitors, whose capacity is differentially varied in correspondence with the quantity to be measured, and a reference capacitor, whose capacity is constant. CONSTITUTION:A pair of variable capacitors C1 and C2 are constituted by a movable electrode 10, which is displaced in correspondence with the quantity to be measured such as pressure, and fixed electrodes 11 and 12. The capacity of a reference capacitor C3 is constant. A capacity pulse width converting circuit C/P detects the change in capacity of the capacitors and outputs a pulse width signal PW1, whose duty ratio corresponds to the difference in capacities of the capacitors C2 and C1 and a pulse width signal PW1, whose duty ratio corresponds to the difference in capacities of the capacitors C2 and C3. A switch SW2 is driven by the signal PW2 and turns ON and OFF a preset voltage Vr. An integrating circuit IC adds and integrates a voltage, which is obtained by turning ON and OFF the voltage Vr by the switch SW2, an output voltage Vo, and a reference voltage VS1, and obtains the voltage Vr. A filter circuit FC smoothes the voltage, which is turned ON and OFF by a switch SW1 and obtains the output voltage Vo.

Carrier recovery circuit for PSK communication system

Abstract: A PSK carrier recovery system has a frequency multiplier, a filter circuit and a limiter circuit for producing a double frequency signal from the incoming PSK signal. A pair of demodulators are supplied with the double frequency signal and with 0 and 90 degree phased reference signals of the same frequency to produce two output voltages representative of the phase of the incoming PSK signal. The output voltages are supplied through a pair of low pass filters at baseband frequency to a pair of remodulators which are also supplied with the reference signals. The outputs of the remodulators are added and applied to a filter, a limiter, a phase adjuster to compensate for processing delays and to a divide by 2 frequency circuit. The reconstituted signal has a frequency substantially equal to the incoming PSK signal and has a phase equal to one of the phases thereof. The incoming PSK signal is also supplied through a limiter to a demodulator circuit along with the reconstituted signal for demodulation.

Low-pass filter circuit

Abstract: A low-pass filter circuit for suppressing a subcarrier contained in an FM stereo demodulation signal in which the output signal of the circuit is unaffected by magnetic distortion. The FM stereo demodulation signal is applied through a low-pass filter to n sample-and-hold circuits connected in parallel with one another. The outputs of the sample-and-hold circuits are summed to form an output signal in which the subcarrier signal has been suppressed. The n sample-and-hold circuits are driven with a corresponding number of sampling pulse signals of different phases.

Tunig unit for communication apparatus

Abstract: Elektronische Abstimmeinheit fur Nachrichtenempfangsgerate mit automatischem Selbstabgleich der einzelnen HF-Filterkreise (2,1 - 2,n). Electronic tuner unit for receiving messages devices with automatic self-adjustment of the individual RF filter circuits (2.1 to 2, n). Wahrend des automatischen Ableichvorgangs wird an den Antenneneingang (21) eine im gewahlten Empfangskan-al liegende Kennfrequenz gelegt. to the antenna input (21) is placed a need in the selected Empfangskan-al characteristic frequency during the automatic Ableichvorgangs. Die am Ausgang der Filterkreise (2,1 - 2,n) abgenommene Spannung dieser Kennfrequenz andert sich durch von einer Rechnereinheit (4) gesteuerte schrittweise Erhohung einer Abstimmspannung, die uber einen Digital-Analogwandler (11) und einen von der Rechnereinheit gesteuerten Schalter (12) und einen Zwischenspeicher (13) an den abzugleichenden Filterkreis (2) gelegt wird. At the output of the filter circuits (2.1 to 2, n) obtained voltage of this characteristic frequency changes by of a computer unit (4) controlled to gradually increase a tuning voltage (via a digital-to-analog converter (11) and a switch controlled by the computer unit switches 12) and a latch (13) to be matched filter circuit (2) is placed. Der automatische Abgleich erfolgt durch Umschalten des Schalters fur die einzelnen Filterkreise (2,1 - 2,n) nacheinander. The automatic adjustment is carried out by switching the switch for the individual filter circuits (2.1 to 2, n) sequentially.

Varyable circuit of frequency characteristics

Abstract: PURPOSE:To ensure the satisfactory operation of the titled circuit with a power supply of low voltage by using a combination of two amplifying elemets, a hig- impedance buffer circuit which serves as an output, a control circuit and a filter circuit respectively. CONSTITUTION:When an input signal is supplied to an input terminal T1, the voltage corresponding to the quantity of a current I1 emerges at both ends of a resistance R2. Then the change of the collector voltage of a transistor TRQ2 is equal to the change of a current I2 and then to the change of the base currents of TRQ2 and Q3. The TRQ3 works at a high speed in response to the base current which is supplied via the TRQ2, and a current IA flows to the TRQ3. While a current IB flows to the TRQ4 only when the frequency is lower than a prescribed level since a filter circuit 1 is provided to the base of the TRQ4. These currents IA and IB are controlled by a control circuit 2. At the same time, a high-impedance buffer circuit 3 is provided between collectors of TRQ3 and Q4. Thus an output signal is obtained through a terminal T2. In such a constitution, no fluctuation is produced with the DC component of the output signal. This ensures the driving with the power supply voltage of a low level.

Equalizer for television relay broadcast equipment

Abstract: PURPOSE:To attain excellent equalization and to improve the grade of picture quality, by detecting various signal changes generated in a relay line propagating path so as to stabilize the level ratio of a video intermediate frequency signal versus sound intermediate frequency signal. CONSTITUTION:A distributor 54, filter circuit 57, sound intermediate frequency signal amplitude modulation component pickup circuit 58, synthesis circuit 56 and a phase shift circuit 55 form an amplitude modulation component suppressing circuit. When an input signal is normal, no output of a synthetic circuit 62 is supplied, the degree of quality of the input signal is kept and the operation is performed so as to attain the objective only when the input signal is failured for attaining the compensation. Thus, the reliability of characteristic of a main signal line is improved, and this suppression circuit means exerts no adverse effect. Since a video intermediate frequency signal and a sound intermediate frequency signal are not treated by separation as shown in Fig. 3, the circuit is operated with a good performance even with the increased band width relating to the sound signal.

Semiconductor laser driver for optical disk device

Abstract: PURPOSE:To avoid the noises generated by the mode transition, etc. by detecting the generation of noises with use of a filter circuit that transmits the frequency component containing no video FM signal, etc. with the reproduction output and switching the optical output of laser among >=2 set levels. CONSTITUTION:The reflected light of an optical disk 15 that emits a semiconductor laser 1 is led to a polarizing surface 12a, a photodetector 17 and a demodulating circuit 18 and converted into video and sound signals respectively. If a mode transition and then noises and generated to the laser 1 at a certain temperature, the noise component is extracted through a filter circuit 22 and compared with the prescribed reference voltage 26 through a comparator 27 after amplification and rectification. A monostable multivibrator 27 is actuated by the output of a comparator 25, and a comparison arithmetic circuit 3 is switched to the reference voltage 30a or 30b by an FF28 and a changeover switch 29 and every actuation of the vibrator 27 and then compared with the output signal of a photodetector 2. Then two levels can be selected with control for the optical output of the laser 1.

Active circuits for flux waveform compensation in ferromagnetic cores

Abstract: Some new schemes using active circuits are proposed for realization of sinusoidal flux in a ferromagnetic core during loss testing. One of the suggested configurations facilitates the loss measurements to be made from the primary side itself. A few filter circuits enable the tests to be carried out on normal supply mains without the need for a calibration generator. Experimental results are reported to confirm the acceptability of the proposed schemes.

Photoelectric transducing device for distance measurement

Abstract: PURPOSE:To attain a photoelectric transducing device for distance measurement which is not affected by a bias current by providing a filter circuit through which only modulation signal components of the output of a bipolar operational amplifying circuit pass. CONSTITUTION:A modulation light is converted to a current signal IA corresponding to the input light by a photoelectric transducer D. The current signal IA is converted to a voltage signal by the first operational amplifying circuit. The filter circuit consisting of a capacitor C1 and a resistance R1 is provided for the purpose of taking out a modulation signal. The output of the first operational amplifying circuit U1 has DC components cut by the capacitor C1 while it passes the filter circuit, and the whole of the modulation signal where VB is added to V0 is taken out. This modulation signal is amplified by the second operational amplifying circuit U2 furthermore and is outputted as VAC. Thus, the photoelectric transducing device which is not affected by the bias current is realized.