Showing papers on "Phase noise published in 1972"

Phase Noise and Transient Times for a Binary Quantized Digital Phase-Locked Loop in White Gaussian Noise

Abstract: Digital phase-locked loops of the type employing discrete phase adjustments form an interesting class for which both steady-state and transient performance may be determined in the presence of additive white Gaussian noise. A general technique for obtaining this analysis is presented. A class of "sequential filters" is described that appears to be well suited to this type of loop. Their performance is characterized by a variable number of inputs per output (depending upon the input sequence) and the use of coarse quantization. Two specific examples are discussed. The closed-loop transient analysis shows these loops to have effectively a slew-rate limited phase adjustment, indicating that they are decidedly nonlinear. A digital loop "quasi-bandwidth" measure is defined in terms of this transient response. This definition allows the comparison of digital loops on a basis of equal signal-to-noise ratios within the loop bandwidth and, to a limited extent, makes possible a similar comparison of the digital loops with linear loops. Performance of the digital loops is found to be similar to that of the first-order linear phase-locked loop model for low loop bandwidth signal-to-noise ratio but reaches a limiting minimum phase error due to quantization of the phase adjustments for high signal-to-noise ratio. This limit, however, can be set as low as desired by choosing a small enough phase-correction quantum. The digitalloop bandwidth is found to vary with the signal energy per noise spectral density ratio rather than with the signal amplitude as in the case of the linear analog model.

Experimental Evaluation of Noise Parameters in Gunn and Avalanche Oscillators

Abstract: Equations are presented that express noise-to-carrier ratio and rms frequency deviation of a negative-resistance oscillator with a multiple-resonant circuit in terms of effective available noise power densities of both 1/f and white-noise sources, an effective saturation factor, and an appropriate Q/sub L/ of the oscillator. Experimental evaluation of the noise parameters in Gunn and avalanche oscillators by use of these equations is described. AM and FM noise measurements have been made on X-band Gunn oscillators and Si and GaAs avalanche oscillators for frequency off carriers extending from 1 kHz to 10 MHz. Both 1/f and white noise have been observed in these oscillators. The validity of the above equations has been verified for Gunn oscillators from the dependence of the noise spectra on Q/sub L/. For Gunn oscillators and Si and GaAs avalanche oscillators, the effective noise-temperature ratio for white noise, N/kT/sub 0/, has been found to be 23~29, 41~51, and 38~44 dB, and the effective saturation factor to be 2~2.9, 0.5~2.4, and 2, respectively. An increase of N/kT/sub 0/ with the RF voltage across the diode has been observed in Si avalanche oscillators. Parameters for 1/f noise have also been evaluated approximately.

A model for flicker frequency noise of oscillators

Abstract: A stationary statistical model is proposed for oscillator frequency fluctuations, leading to a flicker power spectral density for frequency fluctuations and to the corresponding time domain frequency instability (logarithmic behavior).

A general analysis of noise in Gunn oscillators

Abstract: Starting with Kurokawa's oscillator equations, it is shown that the two components of a Gunn oscillator's noise spectrum may be derived by considering flicker noise as equivalent bias fluctuations and thermal noise as a microwave frequency current source. The results are in agreement with expressions previously deduced from experiment.

Comparative Performance of Twin-Channel and Single-Channel Optical-Frequency Receivers

Abstract: This paper describes a theoretical comparison of the noise immunity of direct-detection binary single-channel with direct-detection binary twin-channel optical digital communication systems. The conclusion is that a simple ON-OFF single-channel system is usually superior to twin-channel systems (such as polarization modulation and differentially coherent phase-shift systems) in noise immunity as well as simplicity. This result is quite different from the radio frequency case where twin-channel systems exhibit up to 6-dB advantage relative to single-channel systems.

Lamp Acoustical Noise and the Reverse Phase Controlled Dimmer

Abstract: The standard SCR dimmer, like all phase controlled dimmers, produces a distorted output waveform. When this waveform is applied to an incandescent lamp, the lamp emits an audible hum that in certain applications is intolerable. To reduce lamp acoustical noise, most lighting control manufacturers place a large inductor in series with the lamp. An alternate approach is the reverse phase controlled dimmer. Instead of inductors, it utilizes auxiliary commutated SCR with capacitor commutation circuitry to limit lamp noise. Two advantages are offered by this approach. First, eliminating the large inductor allows the dimmer to be greatly reduced in size. Secondly, elimination of the inductor makes more power available to the load. The cause of lamp acoustical noise, the design of the reverse phase controlled dimmer, and methods for measuring lamp noise are described.

Large-signal noise, frequency conversion and parametric instabilities in impatt diode networks

Abstract: IMPATT diodes exhibit a number of unique nonlinear effects when strongly driven as an amplifier or self-excited oscillator. The avalanche zone behaves as a highly nonlinear inductor, causing parametric effects such as frequency conversion with gain and spurious oscillations in some network configurations. At high drive levels, noise output is enhanced and the spectral distribution is affected by intermodulation. These effects have been studied theoretically using the Read diode model. Using a perturbation technique, equations are derived for the multiple-frequency responses to an applied small signal in the presence of a large signal excitation at another frequency. The equations have also been analyzed for stability against spurious "parametric" oscillations. Theoretical expressions have also been obtained for noise generation at high signal levels and for the noise spectral distribution as affected by intermodulation. Computed curves have been derived for a number of these effects.

Analysis of large-signal noise in read oscillators

Abstract: A large-signal noise theory to second order in the r.f. amplitude is developed for the noise generator of an IMPATT oscillator of Read-type. The coefficient for the second order term in the noise spectrum is calculated as function of frequency. The large-signal noise measure is shown to increase less than 3 dB from the small-signal noise measure for avalanche current modulations of J 1 J 0 = 1 , where J0 is the bias current. Good noise performance is predicted when the operating frequency is a factor of 1·4 higher than the avalanche frequency.

Noise cancelling self mixing doppler radar

Abstract: A noise cancelling self-mixing Doppler type microwave motion detector with greater detecting range and/or lower false alarm rate than prior art self-mixing techniques using equal radiated power is described. The device includes a three terminal microwave oscillator/mixer and a wave guide launched dielectric antenna in a single triaxial structure and a dual input signal processor that provides improved signal to noise ratio as a result of effective signal enhancement and noise cancellation. Separate, out of phase, Doppler output signals are derived from both the emitter and the base of the oscillator/mixer transistor and processed by a balanced amplifier which rejects in-phase noise components.

Spectral density measurements of gyro noise

Abstract: Power spectral density (PSD) was used to analyze the outputs of several gyros in the frequency range from 0.01 to 200 Hz. Data were accumulated on eight inertial quality instruments. The results are described in terms of input angle noise (arcsec 2/Hz) and are presented on log-log plots of PSD. These data show that the standard deviation of measurement noise was 0.01 arcsec or less for some gyros in the passband from 1 Hz down 10 0.01 Hz and probably down to 0.001 Hz for at least one gyro. For the passband between 1 and 100 Hz, uncertainties in the 0.01 and 0.05 arcsec region were observed.

A circuit for generating a high power rf signal having low am and fm noise components

Abstract: An RF signal generator is disclosed which has low AM and FM noise and high power output. The output signal of the RF signal generator is a variable over an octave in response to a tuning voltage signal. The RF signal generator includes a low noise RF oscillator coupled to a limiter circuit through a first buffer amplifier. A second buffer amplifies the output of the limiter circuit to produce a high level RF output signal. The FM noise is reduced to a low value by a high Q resonant circuit which determines the frequency of the oscillator and by the use of components in the oscillator circuit which have low noise characteristics. The AM noise is further reduced by the limiter and the output of the limiter is amplified by a second buffer to produce a high power low noise RF signal.

The Accuracy of AM and FM Noise Measurements Employing a Carrier Suppression Filter and Phase Detector (Short Papers)

Abstract: The accuracy of a commonly used noise-measuring system at microwave frequencies is calculated under actual measuring conditions. Serious deviations are shown to occur, which impose a lower and upper frequency limit on "double-channel" AM and FM noise measurements, respectively.

Generalized Analysis of Phase-Sensitive Detection-Circuit Operating Characteristics at the Signal Detection in the Presence of Noise

Abstract: A new generalized analysis is presented of operating characteristics of phase-sensitive detector circuits, assuming that the input signal and the reference wave are in the presence of independent, stationary, and additive Gaussian noise The generalized criteria are determined for the detector optimum operating conditions and for minimization of the detector characteristic essential nonlinearities by means of computer-aided analysis, using high-density discrete value calculations The results of the analysis are given in normalized form and can be directly applied to evaluate in detail the detector-circuit performance and characteristic essential nonlinearities over a wide dynamic range of operating conditions Furthermore, particular emphasis is laid on the determination of optimum detector-circuit operating conditions in contemporary instrumentation systems

Two-Stage Self-Limiting Series Mode Type Quartz Crystal Oscillator Exhibiting Improved Short-Term Frequency Stability

Abstract: A simplified model of the transistor sustaining stage employed in common quartz-crystal oscillators is presented. Examination of the model, including associated noise sources, provides an explanation for general differences observed in the output-frequency spectra of several types of widely used self-limiting crystal oscillator circuits. A self-limiting quartz-crystal oscillator circuit configuration is described that has been specifically designed to exhibit simultaneously each of the three important circuit characteristics necessary for improved oscillator short-term frequency/phase stability: large value of oscillator resonator loaded Q, adequate suppression of 1/f flicker-of-phase type noise, and improvement in oscillator ultimate signal-to-noise ratio. Several models of the oscillator circuit have been constructed employing high quality third overtone 5-MHz AT- and BT-cut quartz resonators. Measurement of oscillator short-term frequency stability using conventional phase lock and sampling techniques confirm attainment of substantial improvement in oscillator short-term frequency stability when compared to conventional self-limiting oscillator circuits.

Noise spectra of a CW silicon TRAPATT oscillator

Abstract: Noise measurements on a double-sided silicon TRAPATT oscillator have been made and show that the noise is comparable to that of the silicon IMPATT oscillator

A wideband Gaussian noise generator utilizing simultaneously generated pn-sequences.

Abstract: A digital system has been constructed for the generation of wideband Gaussian noise with a spectrum which is flat to within plus or minus 0.5 dB from 0 to 10 MHz. These characteristics are substantially better than those of commercially available analog noise generators, and are required in testing and simulation of wideband communications systems. The noise is generated by the analog summation of thirty essentially independent binary waveforms, clocked at 35 MHz, and low-pass filtered to 10 MHz.

Frequency-modulation noise in feedback oscillators

Abstract: A system is described which measures the f.m. noise in a feedback oscillator. In this method, the oscillator's own frequency-determining network is made to function as the passive reference for a transmission-filter noise-measurement system with no degradation of sensitivity.

Noise suppression by time exposure oscilloscope photography.

Abstract: We describe a simple and inexpensive means of enhancing repetitive signals obscured by noise with roughly equal amplitude. The signal and noise are displayed on an oscilloscope, and we perform a time average over many traces by time exposure photography. If the oscilloscope triggering is synchronous with the signal, the result is a significant suppression of the offending noise.

Innate oscillator noise determination

Abstract: A calibrated noise generator is coupled through a circulator to an oscillator circuit which contains the active negative resistance device having innate noise characterized by Mo. The oscillator is coupled through the circulator to an FM receiver whose output is directed to a frequency bandpass filter. The frequency bandpass filter is coupled to a power measuring meter. A measurement of the output power of the oscillator waveform after it is processed through the FM receiver and frequency bandpass filter is made with essentially no external noise power applied to the oscillator circuit. The noise signal from the noise generator is then increased until the output power meter reading is double the initial measurement. At this point the innate noise, Mo, of the active negative resistance device is known.

Threshold-Extended FM Demodulator for Black and White Video Signal

Abstract: In frequency demodulation threshold noise appears in the form of pulses of various amplitude and width. When a TV signal is transmitted these pulses can be detected at the outputs of a line-by-line subtractor, since their amplitude is in general much greater than the amplitude of the noise and of the residual video signal. Based on this principle a threshold noise suppressor (TNS) has been applied at the output of a phase-lock loop (PLL) demodulating a video signal. The TNS consists of two 64-μs delay lines and a simple logic that detects the spikes and substitutes for the signal the average between the previous and following line when a spike is present. The major and practically unique limit to the operation of the TNS is due to spikes interference, i.e., the simultaneous appearance of two pulses at the input of either line-by-line subtractor. The comparison could be made in principle between more lines with better results. However with the device consisting of only two delay lines the original threshold is lowered at least 3 dB. The same principle is also applicable to a color video signal. In the paper, details of the theory, the implementation, and the limits of the TNS are given together with experimental results.

Noise effect in oscillators using multiple active devices connected in series or in parallel

Abstract: The effect of noise in an IMPATT or Gunn diode oscillator on a phase or frequency fluctuation can be reduced when the oscillator is constructed of multiple diodes connected in series, compared with the oscillator using a single diode.

of Noise Parameters in Gunn and Avalanche Oscillators

Abstract: Equations are presented that express noise-to-carrier ratio and rms frequency deviation of a negative-resistance oscillator with a multiple-resonant circuit in terms of effective available noise power densities of both I/j and white-noise sources, an effective saturation factor, and an appropriate Q~ of the oscillator. Experi- mental evaluation of the noise parameters in Gunn and avalanche oscillators by use of these equations is described. AM and FM noise measurements have been made on X-band Gunn oscillators and Si and GaAs avalanche oscillators for frequency off carriers extending from 1 kHz to 10 MHz. Both 1/f and white noise have been observed in these oscillators. The validity of the above equations has been verified for Gunn oscillators from the dependence of the noise spectra on Q~. For Gunn oscillators and Si and GaAs avalanche oscillators, the effective noise- temperature ratio for white noise, N/k TO, has been found to be 23w29, 41 N51, and 38N44 dB, and the effective saturation factor to be 2=2.9, 0.5-2.4, and 2, respectively. An increase of N/kTO with the RF voltage across the diode has been observed in Si ava- lanche oscillators. Parameters for I/j noise have also been evaluated approximately.

Error rate for p.s.k. and d.p.s.k. in the presence of source noise

Abstract: The analysis of error rate in 2-level p.s.k. and d.p.s.k. systems has been extended to include the effects of source phase noise. Curves are presented for channel S/N ratios up to 6 dB and source phase deviations up to 0.6 rad r.m.s.