Showing papers on "Total harmonic distortion published in 1980"

Nonlinearities of GaAlAs lasers - Harmonic distortion

Abstract: Narrow stripe lasers ( 2-6 \mu m) and transverse junction lasers exhibit excellent linearity. The dependence of relative second-and third-harmonic distortion is investigated as a function of modulation frequency and modulation current. Relative second- and third-harmonic distortion of -50 and -70 dB is observed for an optical signal of 4 mW p-p ( f_{m} = 60 MHz). Intermodulation products are compared with the harmonic distortion and good agreement is obtained between the two quantities when the relations for a simple nonlinearity without memory are used. The measured distortion is in agreement with distortion calculated from rate equations.

Distortion measurement system

Abstract: A type of Total-Harmonic-Distortion (THD) distortion analyzer is described in which the use of the State Variable (SV) circuit in both the oscillator and the filter sections confers several benefits and results in performance superior to previously available analyzers. In the SV oscillator, the traditional compromise in the automatic level control function between settling time, component tolerance and distortion is alleviated by the use of polyphase level detection, made possible by the SV circuit. The doubly-integrated output available from the SV circuit also minimizes distortion, especially that contributed by the level-setting AGC. The other property of the SV circuit, which is particularly valuable, is the connection of frequency-setting elements to virtual-ground points, which allows great simplification of wide-range tuning circuitry. Exploitation of this property is described both for manual and programmable cases. The SV circuit is also superior to many previously employed circuits in its tolerance of component inaccuracies. The simultaneous presence of high-pass, band-pass and low-pass outputs from the SV filter is shown to be advantageous also for its use as the filter on a distortion analyzer.

Band pass filter

Abstract: PURPOSE:To eliminate the phase change, by the circuit constitution consisting of two sets of band pass filters and frequency multipliers or demultipliers. CONSTITUTION:When a sinusoidal wave of V1 is entered to the input, the amplitude and phase are shifted respectively A1 and theta1 with the band pass filter 51. Next, they are respectively further shifted by A2 and theta2 with the band pass filter 52. On the other hand, the output of the filter 51 is branched into the frequency multiplier or demultiplier 53 and thd output of the filter 52 is fed to the frequency multiplier or demultiplier 54. Taking that the ratio of the output frequency to the input frequency of the multipliers or demultipliers 53 and 54 is respectively m and n. The output of the multipliers or demultipliers 53 and 54 is fed to the frequency converter 55 and the frequency component of difference is picked up as the output. Taking that the delay time in the pass band of the filters 51 and 52 are r1 and r2, the output without phase shift can be obtained by satisfying the relation of m/n r2/r1+1.

Apparatus for harmonic oscillation analysis

Abstract: Apparatus for harmonic oscillation analysis includes a detector for taking up, as electric oscillation, mechanical vibration generated during the operation of a rotary machine system, a comb filter for extracting from the detector's output signal having a composite periodic oscillation wave form only fundamental wave component of a determined fundamental frequency fo and its harmonic wave component, and a clock pulse generator for generating clock pulses to drive the comb filter by the clock pulse having the fundamental frequency fo and a discriminator for evaluating abnormality of the rotary machine system depending upon the particular signal components extracted through the comb filter.

Precise Differential-Phase Generator

Abstract: A sinewave differential-phase standard of high accuracy and repeatability has been developed for the frequency range "zero frequency" to 200 kHz. The potential accuracy is better than (0.000 36 × F) degrees, where F is in kilohertz, throughout the range. Particular attention has been given to the purity of the output sinewave and a theoretical study has been undertaken with a view to minimizing harmonic and intermodulation distortion and at the same time optimizing the digital circuit.

Wavelength response of harmonic distortion in AC-bias recording

Abstract: Wavelength response of harmonic distortion in ac-bias recording is analyzed. The wavelength response is affected in both the record and playback processes. In the record process tape nonlinearity and magnetization phase shift, which is dependent on signal-field intensity, are taken into account. In the playback process, tape thickness, tape-to-head spacing, gap length, etc. axe taken into account. An approximate expression for the third-harmonic distortion is derived. The experimental data show quantitative agreement with theory.

Electrical energy storage type filter

Abstract: The invention is an electrical energy storage type filter which is useful for attenuating harmonic distortion, modulation at high frequencies, line voltage transient sags and surges The invention structurally consists of a inductance capacitance tank circuit having resistive components and with a resistive element connected in series with the tank circuit The circuit is tuned to include in its bandwidth the fundamental frequency of the power source and includes in its design consideration of the reactance of the source

Harmonic Distortion of a PLL FM Demodulator for Periodic Signals

Abstract: This paper presents a method which evaluates the harmonic distortion of the phase-locked FM demodulator in the absence of noise. An approach of the harmonic-balance method with the digital Fourier transform is described, and then it is applied to the phase-locked loop in order to calculate the steady-state phase error and harmonic distortion.

Distortion in sinusoidal oscillators

Abstract: A theoretical analysis is given of the origins and fundamental limits of harmonic distortion in oscillators with a variety of frequency-selective networks and amplitude-control system; other sources of distortion are also considered.

Unsolved theoretical problem in design of optimal low-pass filter for harmonic suppression in radio-transmitter output

Abstract: The author offers to cooperate in development of an optimal harmonic-suppression output filter for power amplifiers. The commonly used elliptic-function filter is not optimal for this purpose: less attenuation is needed at higher frequencies in the stopband. An improved design should provide a value of A_{\min} that varies with frequency as the harmonic output of the amplifier varies with frequency.

Volt drop compensation for output transducer - uses positive feedback from primary winding to input amplifier and negative feedback to inverting input of operational amplifier

Abstract: The primary winding of the transducer is excited by an operational amplifier and the object of the proposed circuit modification is to keep the primary winding voltage exactly proportional to the amplifier input voltage. Non-linearities occur due to primary winding chmic resistance and distortion introduced by the presence of a magnetic core. A positive feedback resistor is added between the primary winding and the reference voltage, and a connection taken to the non-inverting input of the amplifier. The values of the inputresistor, negative feedback resistor, and positive feedback resistor are chosen such that for k = Rn/Re = k'. Rc/Rxthe value of k' lies between 1 and 1.1. In this range almost complete compensation for resistance volt drop and harmonic distortion is achieved.

A volume and frequency response control IC for audio

Abstract: A dual channel DC controllable tone, volume, and balance control IC is described. A novel variable response filter, combined with a time constant control technique, makes it possible to integrate all functions into a 16-pin package. The chip, requiring very few external components, has an 80 dB gain controlling range and less than 0.2 percent total harmonic distortion.

Optical multiplex transmission system

Abstract: PURPOSE:To realize the transmission system very useful and excellent to the multiplex transmission without being affected with the dispersion of semiconductor laser characteristics, by eliminating the distortion caused by the non-linearity of the current versus light output characteristics of semiconductor laser by means of filter. CONSTITUTION:A plurality of carriers mixed inputted to the terminal 1 are branched with the branch unit 2 and electric-photo conversion is made by inputting to the semiconductor laser 3 different in the emitted spectrum wave length. The light output signal in intensity modulation is coupled with the fiber 4 and mixed in the photo synthesizer 5 and transmitted with one transmission fiber 6. The photo signal transmitted is branched with the photo branch unit 7 and photo-electric conversion is made with the respecitve photo detector 9. The signal converted with the photo detector 9 and having distortion, is eliminated for harmonic distortion with the mixer 10 constituted with the band pass filter and the electric signal only with the fundamental waves is obtained at the terminal 11.

Electronic filter for generating a third harmonic signal

Abstract: An integratable third harmonic signal generator comprises an amplitude limiting amplifier, a linear amplifier, and a signal combining network. A sinusoidal input signal is coupled to the limiter and linear amplifiers. The limiting amplifier generates a square wave signal containing a first harmonic (fundamental) component at the frequency of the input signal, and higher order odd harmonics including a desired third harmonic frequency. The signal gain of the linear amplifier is set so that the magnitude of the output signal from the linear amplifier is sufficient to cancel with the first harmonic of the square wave output signal from the limiter amplifier, when these output signals are combined in the combining network. A resulting signal developed at the output of the combining network contains the desired third harmonic component, as well as higher order harmonics at acceptably reduced levels relative to the third harmonic component, to the substantial exclusion of the first harmonic component.

A novel three-phase stepped-wave inverter using eight thyristors

Abstract: The three-phase stepped-wave inverter is based on a new method of synthesizing waveforms The proposed system comprises a 120° conduction type three-phase bridge inverter and a single-phase triple-frequency square-wave inverter The triple-frequency inverter need for wave-shaping is of low power and is used in the neutral circuit of the three-phase inverter A special complementary impulse commutation circuit realizes the above system with only eight thyristors The output voltage waveform has three steps per quarter cycle and has a total harmonic distortion of 151% The kVA ratings of the wound components are derived The experimental results are presented and discussed

Temperature dependence of storage time in silicon p+-n-n+ switching diodes and reduction of harmonic distortion

Abstract: Using the reverse-recovery technique, storage times in p+-n-n+ diodes have been measured as a function of temperature. In all cases the effective lifetime for injected charge increases with increasing temperature within the interval 0 to 180°C. This result was found to reduce second-harmonic distortion in p+-n-n+ switches by as much as 6 dB at 2.5 MHz.

Thyristor current source with an improved power factor

Abstract: This paper describes the steady state and dynamic characteristics of a microprocessor controlled current source. The source is based on an 8-thyristor phase commutated bridge which gives an improved power factor and decreased harmonic distortion. Limiting curves for the tridge continuous conduction are presented together with line and thyristor currents in a Δ-y input transformer bank. System's salient characteristics, such as an equidistant firing scheme, a line variation compensator and the elimination of a filter in the current feedback loop are described. The transfer function of the current source, with the thyristor switching delays included, is derived and is verified experimentally. It is practically demonstrated that a very fast response is attainable even with microprocessor controlled inner current loop.

Driving-stress waveform and the determination of rock internal friction by the stress—strain curve method

Abstract: Summary Harmonic distortion in the stress—time function applied to rock specimens affects the measurement of rock internal friction in the seismic wave periods by the stress—strain hysteresis loop method. If neglected, the harmonic distortion can cause measurements of rock internal friction to be in error by 30 per cent in the linear range. The stress-time function therefore must be recorded and Fourier analysed for correct interpretation of the experimental data. Such a procedure would also yield a value for internal friction at the higher harmonic frequencies.

Distortion fluctuation phenomena in audio magnetic heads

Abstract: Fluctuations exist in the harmonic distortion of audio magnetic heads, presumably due to the "magnetizing curve disaccommodation" of the head core material. The fluctuations are most pronounced when the signal field intensity is suddenly varied. This behavior was experimentally investigated by using simple distortion measuring methods. The fluctuation is observed in both record and playback heads. Although the measuring methods may not indicate absolute distortion, the differences among various kinds of head core material are clearly shown.

Minimizing harmonic distortion apparatus

Abstract: An apparatus is provided to minimize harmonic distortion in a microwave circuit which is used with a velocity measuring system. The apparatus is particularly applicable where at least two Doppler signals are generated at substantially the same time from two different targets whose velocity is being measured. The apparatus includes a microwave circuit which transmits a microwave energy signal directed to each of the targets. The microwave circuit also receives the signals reflected by the targets and produces Doppler signals. A control circuit responds to the Doppler signals outputted by the microwave circuit by providing a control signal corresponding to the greatest in amplitude of the Doppler signals. The control signal is fed back to the microwave circuit to control the Doppler signals so that a predetermined amplitude thereof is not exceeded and, as a consequence, harmonics of the Doppler signals are not generated.

Monolithic minimum phase CCD channel filter for a PCM codec employing overlapping-double-split-electrode technique

Abstract: A monolithic CCD channel filter consisting of transmit-and-receive filters for a PCM codec was fabricated using a triple-layer polysilicon gate and NMOST process. This filter employed both a minimum phase design with a greatly reduced number of taps and newly developed overlapping-double-split-electrode (ODSE) structure in order to minimize chip area and eliminate excess capacitances at all of the sensing nodes. Improved filter performance, such as negligible degradation in frequency response, reduced power dissipation, a significantly small common mode signal, and consequently, much improved signal-to-noise ratio are discussed. Frequency responses, harmonic contents, and noise spectral densities are presented as experimental results. Signal-to-noise ratio was measured to be 84 dB with a total harmonic distortion of less than 0.4 percent.

An improved three-phase stepped-voltage inverter

Abstract: The paper Presents an improved method of generating a three-phase stepped-voltage waveform using ten thyristor power switches. In the proposed method, it is possible to generate one step for every 20 ° of the voltage waveform on all the phases. The waveform has a total harmonic distortion of about 10% and the Predominant harmonies are the 17th and 19th. This is possible by a unique method of magneticcoupling betweena 120° conduction three-phase bridge inverter and a triple frequency single phase bridge inverter. The theoretical results are in close agreement with experimental results.

Amplitude limiting circuit

Abstract: PURPOSE:To suppress the phase change and the secondary harmonic distortion of output due to amplitude change in the input signal with a simple constitution, by using the differential amplifier in cascode connection of two sets of transistors. CONSTITUTION:With the cascode connection of grounded-emitter-grounded-base consisting of transistors Tr1a, 9a in the differential amplifier, the capacitance between the collector and the base of Tr1a giving effect to the input signal from the terminal 4 is equivalently made smaller. Further, with the cascade connection of grounded-emitter-granded-base consisting of Tr1b, 9b, the collector base capacitance of Tr1b giving effect on the input signal from the terminal 5 is equivalently smaller. Thus, since the capacitance between the collector and base is equivalently made smaller, even in use at the harmonics serveral MHz or more, the phase change of output and secondary harmonic distortion due to amplitude change of input signal can easily be suppressed.