Showing papers on "Total harmonic distortion published in 1971"

Harmonic Generation in the Trumpet

Abstract: Various possible mechanisms for the generation of harmonics in the tone of the trumpet were investigated. By sounding the trumpet with a mechanical valve utilizing a sinusoidally varying opening, it was shown that nonsinusoidal motion of the player's lips is not an important mechanism for harmonic generation. Nonlinear behavior of the air column of the instrument due to high sound pressures was also shown not to be important by four different methods: (1) by a theoretical estimate of the amount of second‐harmonic distortion to be expected; (2) by measuring the input resistance of the trumpet at resonance frequencies and finding that it did not vary significantly with sound pressure in the air column; (3) by measuring the intermodulation distortion produced when the air column was excited at two resonance frequencies simultaneously; and (4) by direct measurement of harmonic distortion produced in the trumpet output by different levels of excitation at the mouthpiece. It was found that the mechanism primarily responsible for harmonic generation is the relationship between the input impedance of the trumpet and the time‐varying impedance of the player's lip opening during a cycle. Curves of mouthpiece pressure calculated on this basis showed good agreement with observed waveforms.

Quality judgments of hearing aid transduced speech.

Abstract: Frequency range, harmonic distortion, intermodulation distortion, and transient response measurements were made on five aids which manifested varying amounts of each property. Effects of these prop...

A new technology for high-power IC

Abstract: The paper describes a new fabrication technology for a monolithic high-power linear IC. It is based on a novel process for controlling the epitaxial growth of single crystal regions and very fine polycrystalline regions on an IC substrate essentially in accordance with the specified mapping of the IC pattern. Polycrystalline regions are used in areas of isolation and collector lead paths which must be diffused deeply, and contribute to the most important characteristics required for the high-power IC, i.e., higher breakdown voltage and lower saturation resistance. A power capability far beyond any known in this field has been achieved. A typical example of the output power rating for an IC designed for use in a low-frequency SEPP-type power amplifier is 20-watts rms continuous service, and the total harmonic distortion content is less than 8 percent at 1 kHz at 40-volts source voltage.

Reduction of harmonic distortion

Abstract: Harmonic distortion generated in signal processors is reduced by pre-emphasizing the processor input signal and de-emphasizing the processor output signal.

Distortion Performance of the Abrupt-Junction Current-Pumped Varactor Frequency Converter

Abstract: Intermodulation distortion in abrupt-junction current-pumped varactor frequency converters is usually attributed to gain compression effects. In the present work an analytical procedure is formulated in which distortion generation and gain saturation effects are seen to arise as a consequence of the interaction of signals, pump, and generated products with the nonlinear capacitance of the varactor. Good agreement is demonstrated between predicted distortion levels and those measured in an experimental upper-sideband up-converter operating at VHF with low gain and high level drive to minimize gain compression effects.

Performance of Individual Hearing Aids Utilizing Microphone and Induction Coil Input.

Abstract: Physical measurements of gain, maximum power output, frequency response, and harmonic distortion were made on each of two body-type hearing aids on both the microphone and induction coil settings. ...

A cyclotron-wave rectifier for S-band and X-band

Abstract: A device for converting microwave power into either dc power or low-frequency ac power has been investigated both theoretically and experimentally. Rotational energy is stored in an electron beam by a Cuccia coupler, then converted to longitudinal energy by interaction with a space-dependent dc magnetic field, and finally recovered as electric energy by a depressed collector. A simple kinematic analysis demonstrates that the Cuccia coupler can convert large amounts of microwave power into electron beam rotation. Limits on the electric field strength and asynchronism between signal frequency and cyclotron frequency are established for both classical and relativistic coupler operation. Efficiency analyses of the process of conversion from orbital energy to dc electric energy, both classical and relativistic, indicate that the efficiency exceeds 95 percent for a particular range of operating conditions. As an ac power supply, the device responds to the modulating frequency of the signal. Theory predicts near-negligible harmonic distortion as well as flatness of frequency response from dc to about 1.0 MHz modulating frequency. Four tubes and a prototype (with "artificial" coupler) were tested experimentally. The first three tubes exhibited efficiencies up to 22 percent, being hindered by reflection of electrons into the coupler. Certain design changes were tested on the prototype, where efficiencies from 36 percent to 75 percent were obtained. Incorporating these design changes into the fourth tube yielded measured efficiencies up to 34 percent, or when corrected to disregard unusually large cavity losses, up to 59 percent. Experimental tests of the tube as an ac converter yielded excellent frequency response and about 20 percent second-harmonic distortion. It is concluded that the theoretical foundation of efficiency predictions has thus far been based on too optimistic assumptions.

Method of and apparatus for generating three-phase sinusoidal voltages

Abstract: A method and apparatus are provided for inverting input unidirectional source voltage to generate substantially sinewave, three-phase, line-to-line output voltages. In the apparatus, most of the power transfer from the unidirectional source to the load conductors is effected through flat-top ''''power center'''' portions of line-to-neutral generated voltages. A minor proportion of the power to the load is supplied by an ascending and descending voltage generator which, in the threephase system, produces alternate pairs of stepped ascending and descending voltages at a frequency equivalent to at least three times the fundamental frequency of the substantially sinusoidal output voltages. The ascending and descending voltages are selectively switched to complement the power center voltage of each phase voltage to complete the line-to-neutral waveforms. The respective line-to-neutral voltages are phase displaced 120* in relation to each other and are combined to form three-phase, line-to-line voltages characterized by a high fundamental frequency content and low harmonic distortion. In accordance with one preferred form of the method and apparatus of this invention, the waveform of the line-to-neutral voltages outboard the flat power center is based on a departure from the line-to-neutral fundamental in such fashion that higher fundamental content, more nearly sine-wave, line-to-line voltages are obtained than would be obtained from line-to-neutral voltages having less harmonic distortion. Further, in accordance with an additional preferred form of the method and apparatus of this invention, the flat-top voltage portions are generated by a square-wave inverter operated in slaved relation to the ascending and descending voltage generator through the medium of reverse voltage commutating pulses, to the square-wave generator, introduced into the respective line-to-neutral voltages by the ascending and descending voltage generator.

Certain non-algebras in harmonic analysis

Abstract: Given qo ∈ [1, 2), functions and are constructed such that fgqAq for every q ∈ [1, qo]. In particular, if p ∈ (1, 2), AP is not an algebra.

Multi-frequency analysis of switching diode modulators under high-level signal conditions

Abstract: Distortion products of intermodulation, cross-modulation and harmonic types can be calculated in switching modulator circuits by evaluating the coefficients of the multiple Fourier series resulting from the interaction of many signals of differing frequencies with a bi-linear diode characteristic. An analysis of this type is developed in order to establish the range of signal levels for which approximate predictions of distortion product magnitudes are accurate and to demonstrate that under conditions where approximate techniques cannot be justified, satisfactory and rapidcalculation of distortion performance is possible using straightforward computer procedures without recourse to general non-linear circuit analysis techniques.

A Solution to the Second Harmonic Interference in Acoustically Coupled Data Sets

Abstract: The difficulties encountered by acoustically coupled 103 compatible data sets are considered. In particular the limitations introduced by the harmonic distortion generated by the nonlinearity of the telephone's microphone are analyzed. It is shown that interference between the second harmonic of the transmitted signal and the received signal restricts the application of acoustic coupling to lines of relatively low attenuation. A method of cancelling the second harmonic by adding a third harmonic component to the transmitted signal is described, and shown to be independent of the microphone's nonlinearities. The effect of handset placement on the microphone's performance is also analyzed and experimental results are given. Incorporating the described method of reducing second harmonic distortion and choosing the optimal handset placement allow Applied Digital Data Systems acoustic coupler to transmit at full power and to communicate reliably in full duplex on lines of up to 30-dB attenuation.

Peak harmonic distortion due to quantization

Abstract: In this thesis, the problem of quantization noise 1s presented, and recent efforts 1n this area are reviewed. With the motivation for further Investigation Into the problem explained, the purpose of this thesis 1s stated to be the determination of peak harmonic distortion due to quantization for predominantly single frequency Inputs. Two cases were examined with pure sinusoid and sine wave plus Gaussian bandllmlted white noise. The method used was to simulate the quantization process on the computer, and to use a Fast Fourier Transform algorithm to analyze the spectra of the quantized signals. For pure sinusoidal Inputs, the location of the peak harmonic distortion 1n the quantization noise spectrum was found to be very sensitive to the degree of loading of the quantizer. However the magnitude of the peak distortion when plotted as a function of the number of bits totally used by the Input was fitted very well with a straight line of slope -6dB/b1t. Moreover the largest component 1n the quantization noise spectrum was observed to be about 4dB above the average noise spectral density across the entire frequency band of observation. The addition of noise to the sine wave was anticipated to have a smoothing effect on the quantization noise spectrum. This phenomenon was observed for a specific set of Input noise samples but the results are not conclusive, becuase after further investigation of the noise generation mechanism, the statistical properties of the synthesized noise signal were found to be unsuitable for analysis of power spectra. However since the pure sinusoidal inputs represent the worst case condition for harmonic distortion due to quantization, the measured peaks

Distortion of a phase-shift discriminator employing all-pass network

Abstract: A phase-shift discriminator employing an all-pass network and suitable for fabrication in microminiature circuit form is discussed. By expanding its transfer function into Taylor's series the harmonic distortion of the discriminator is analyzed.

Analysis of semiconductor diodes with multifrequency input signal

Abstract: In this paper a closed form expression for the intermodulation output power from a semiconductor diode driven by an arbitrary number of "small-level" input signals is obtained. The effect of the intrinsic resistance of the diode material is taken into consideration through the use of the modified exponential function for the diode characteristic. It has been found that the relative harmonic distortion depends on the bias voltage, which agrees with the experimental observations. This dependence would not have been obtained had the intrinsic resistance been neglected. Also, the calculated intermodulation output power shows good agreement, for small input signal, with the published experimental results.