Showing papers on "Phase noise published in 1974"

A Method for Estimating the Frequency Stability of an Individual Oscillator

Abstract: A method is given for estimating the intensity of random noise frequency modulation of an individual oscillator, using data obtained by comparing it with two or more other osci l la tors . This method is appropriate even if the oscillators available for comparison are less stable than the oscillator being evaluated, but their frequency fluctuations must be independent. The statistical uncertainty of the resul ts i s d iscussed briefly.

Integrated source and channel encoded digital communication system design study

Abstract: The results of several studies Space Shuttle communication system are summarized These tasks can be divided into the following categories: (1) phase multiplexing for two- and three-channel data transmission, (2) effects of phase noise on the performance of coherent communication links, (3) analysis of command system performance, (4) error correcting code tradeoffs, (5) signal detection and angular search procedure for the shuttle Ku-band communication system, and (6) false lock performance of Costas loop receivers

Microcycle spectral estimates of 1/f noise in semiconductors

Abstract: Many physical occurrences are characterized by extremely low spectral variations, the measurement and estimation of which has been invariably difficult. An estimate of the density of the power spectrum of very‐low‐frequency semiconductor 1/f noise is experimentally obtained from 10−6.3 to 1.0 cps with a greater accuracy than that achieved in previous similar attempts; it is concluded that the spectrum is 1/fα with α approximately 1.3 over most of the frequency range, but appearing to have a value of about 1.0 in the lowest decade. A peculiar form of stationarity seems to distinguish 1/f noise from other noise in semiconductors. Ten independent noise sources were time multiplexed and their spectral estimates were subsequently averaged. If the sources have similar spectra, this reduces the necessary data‐taking time by a factor of 10 for a given accuracy. An estimator is derived for optimal spectral estimation based on a number of statistically independent noise sources. Other related topics considered are ...

Characterization of Frequency Stability: A Transfer Function Approach and Its Application to Measurements via Filtering of Phase Noise

Abstract: Frequency stability of high-quality signal sources is characterized in the Fourier frequency domain by the spectral density Sy(f) of the fractional instantaneous frequency deviation y(t), and in the time domain by the Allan variance ?y2(?). Two well-known types of measuring apparatus used to evaluate these parameters are analog spectrum analyzers and digital electronic counters, respectively. A detailed analysis of the structure of the relation between ?y2(?) and Sy(f) shows that it is possible to define a variance, i.e., a time-domain measure, by its transfer function in the Fourier frequency domain, even when no corresponding measurement sequence exists in the time domain. Two different kinds of variance are then defined, which possess different properties for white and flicker phase noises. One of these variances is an estimate of the Allan variance. These variances may be measured by a suitable filtering of phase noise at the output of a phase detector.

Measurements and interpretation of low-frequency noise in FET's

Abstract: Equivalent gate-noise voltage magnitudes of MOSFET's and JFET's have been measured by a direct method for the frequency range of 20 Hz-9 kHz. Results of a number of theoretical analyses of MOSFET flicker noise have been combined to yield a generalized expression for the drain-noise current. Experimental results showing the bias, temperature, and frequency dependence of the noise have been presented and carefully examined in cognizance with the divergent nature of various theories and relevant published experimental data.

Noise in IMPATT-diode oscillators at large-signal levels

Abstract: A theory is formulated which describes the noise properties of IMPATT-diode oscillators operating at large-signal levels. This theory is based directly on the work of Convert [17] and Hines [18]. The theory takes into account the signal dependence of the noise generation process, and also the intermodulation effects occurring between the various frequency bands. The equations are conveniently arranged in matrix form; such a formulation provides physical insight and facilitates the obtaining of quantitative results in terms of measurable noise parameters. The AM, FM, and low-frequency noise of low-Q IMPATT-diode oscillators operating at high output power levels has been measured and compared with the values predicted by this theory. Si p+-n, Si n+-p, and n-GaAs S.B. IMPATT diodes have been used. Agreement between the measured and theoretically predicted values is good. Special experimental evidence for the signal dependence of the noise-generating mechanism is obtained by considering the ratio of the AM and FM noise. The Comparatively few measurements published on the correlation between AM, FM, and low-frequency noise have been compared with our theoretical results; as far as can be judged, the trends are similar. Finally, an experiment is described in which a Si n+-p diode was used in a high-Q Kurokawa circuit. The experimental value of the rms frequency deviation of 0.8 Hz in a 100-Hz bandwidth was found to be in reasonable agreement with the present theory, extended with an equivalent circuit describing the high-Q circuit.

Sensitivity of Doppler RADAR with Sell-Detecting Diode Oscillators

Abstract: The behavior of Doppler RADAR with self-detecting diode oscillators is described. Conditions for the frequency deviation to contain only the first harmonic of the Doppler shift frequency are given. The conversion gain and the signal-to-noise (S/N) ratio includlng both intrinsic LF and RF noise are calculated. An equivalent LF circuit is obtained. The shape of the I-V characteristic of the oscillating diode is shown to be important for the design of a Doppler module.

Measurement of Frequency Stability in Time and Frequency Domains via Filtering of Phase Noise

Abstract: A recently developed theoretical analysis has shown that it is possible to measure the Allan variance (a time-domain measure of frequency instability) without any statistical treatment of data from an electronic counter. The measurement is made via high-pass filtering of phase noise with a test set similar to the one used for frequency-domain measurements. The unique test set described in this paper relies on this principle and is capable of measuring the short-term frequency instability of the best quartzcrystal oscillators in both time and frequency domains.

FFT Analysis of a Space Magnetometer Noise

Abstract: Measurements of the intrinsic noise of a second harmonic flux-gate magnetometer have been performed in the 0 Hz to 5 Hz bandwidth. The digital Fourier analysis technique was adopted to extend the spectrum analysis to the very low frequency range. The dependence of the r.m.s. noise on drive current and the frequency spectrum of the noise at the operating drive level have been studied.

Digital phase comparators

Abstract: In a phase comparison radio navigation system in which phase-locked signals of the same frequency are radiated in succession from spaced stations and are compared in phase at a receiver, instead of locking an oscillator or oscillators at the receiver to received signals to provide simultaneously available signals for phase comparison, each received signal is compared in turn in digital phase comparison means with a free-running oscillator, two successive comparisons of the oscillator with one received signal being used to determine the phase error rate of the oscillator and this error rate being used to correct the other phase determinations.

Temperature fluctuations and flicker noise in p-n junction diodes

Abstract: A simple and elementary calculation is carried out which shows that microscopic temperature fluctuations produced by the shot-noise nature of the p-n junction diode current can cause 1/f-flicker noise.

Theory of LDV Tracking Systems

Abstract: The application of frequency-tracking systems to the analysis of laser doppler velocimeter (LDV) signals degraded by background noise has been studied both theoretically and experimentally. Expressions are derived for both the correlation function and the expected value of the phase derivative in the general case of noise off center from the Doppler frequency, and these results are specialized to specific cases of practical interest. Laboratory measurements of output signal-to-noise ratio (SNR) and dc error, for varying input SNR and noise center frequency offset, show good agreement with the theoretical predictions.

Low noise rf signal generator

Abstract: A signal generator for generating a high power low noise RF signal is disclosed. The generator includes a low noise crystal control oscillator for generating a relatively low power, low noise RF signal. The output signal of the oscillator is coupled to a high power RF amplifier which amplifies this signal to generate the low noise high power RF signal. The low frequency noise of the oscillator is reduced by a low frequency negative feedback loop in the oscillator circuit. Noise induced into the oscillator circuit by load changes in the power amplifier is reduced by designing the amplifier such that its input impedance is substantially constant for all phase angles of the RF signal.

Thermally induced FM noise in Gunn oscillators and jitter in Gunn-effect digital devices

Abstract: By considering the starting-time fluctuation of domain formation and the fluctuation of domain-formation time caused by thermal noise, the front-edge fluctuation of the output current pulse of a Gunn device is obtained. Taking the Fourier transform of the output current-pulse train with these front-edge fluctuations, we obtain the equivalent noise-current source due to the thermal noise of Gunn oscillators. Solving Kurokawa's oscillator equation including this equivalent noise-current source, an expression for thermally induced FM noise in Gunn oscillators is derived. The result is in good agreement with experimental data. These results are applied to estimate thermally induced jitter in Gunn-effect digital devices.

Phase comparison radio navigation system receiver having phase memory oscillators for phase locking to time-sequentially received transmissions

Abstract: In a phase comparison radio navigation system in which spaced transmitters radiate phase-locked signals in a time-shared sequence, in order to enable a receiver to be operated on any selected one of a large number of different frequencies, a phase memory in the receiver for giving a continuous output representative of the phase of an intermittently received signal, comprises a controlled oscillator giving an output of a frequency much higher than the received frequency, a frequency divider providing a first sub-multiple of the oscillator frequency, a frequency synthesizer providing a heterodyne signal at a second sub-multiple and a phase comparator providing an output controlling the oscillator in accordance with the phase relation between the divider output and the output of a mixer mixing the received signal with a heterodyne signal.

Masking with narrow‐band FM noise

Abstract: Masked thresholds were measured for signal frequencies below, within, and above two 190‐Hz noise bands centered arithmetically at 1125 Hz. One noise band was computer synthesized and had amplitude fluctuations characteristic of analog noise bands typically used in masking experiments. The other noise band, matched in spectrum and level to the synthesized noise band, was generated by a frequency modulation (FM) process. The resulting waveform was free of envelope fluctuations. Masked thresholds in the FM noise were 5–10 dB lower than in the synthetic noise in the flat portions of the spectra. Synthesized noise resulted in trapezoidal appearing audiograms. The FM noise audiogram tended to be unimodal. Results are discussed with reference to envelope detection hypotheses.

On the Mean Frequency Measurement System Using Correlation Detection

Abstract: This paper is concerned with the problem of measuring the mean frequency of the power spectrum of a zero-mean, stationary, narrowband Gaussian random signal in the presence of additive Gaussian noise. Signal-to-noise ratios at the output of the mean frequency measurement system using correlation detection are analyzed in terms of input signal-to-noise ratio, input signal and noise bandwidths, and integration time. The results obtained are verified experimentally, and a comparison with a conventional zero-crossing detector is also made.

Spectral and Short Term Stability Measurements

Abstract: The noise performance of an oscillator can be given either in the spectral or in the time domain. Two types of apparatus are generally necessary to measure these noise characteristics, spectral analyzers and frequency counters. The system described uses spectral density to time domain conversion and measures both the short term frequency stability and the phase spectral density of an oscillator. Bias functions, depending on the spectral density, are calculated. They are used to determine systematic errors introduced by the apparatus.

AM and FM Noise of BARITT Oscillators

Abstract: AM, FM, and baseband noise of a BARITT diode oscillator in the range 100 Hz-50 kHz off the carrier has been measured under various operating conditions. A simple calculation has been made, relating the baseband noise to the oscillator AM and FM noise via measured amplitude and frequency modulation sensitivities and the results have been compared with the noise measured. It is shown that, depending on the bias current applied, both AM and FM noise performance can be degraded by up-conversion. Complete removal of up-converted noise requires a high-impedance low-noise bias supply since both the diode noise and bias supply noise at baseband frequencies may be significant when up-converted. Even with all modulation suppressed, the AM and FM noise has a flicker component almost completely correlated with the diode flicker noise at baseband frequencies. The RF power dependence of the AM and FM noise has also been investigated. It is shown that the BARITT oscillator noise compares very favorably with that of IMPATT's and TEO's. Values of -142 dB/100 Hz (AM noise) and 3.5 Hz/(100 Hz)/sup 1/2/ for Q/sub ext/ = 200 (FM noise) have been measured at 30 kHz off the carrier.

Synthesis of Low-Frequency Noise for Use in Biological Experiments

Abstract: A simple technique is described for the generation of white noise having sufficient power below 10 Hz to be useful in biological experiments.

Effect of Nonlinearity on Noise Propagation

Abstract: : A previous study of plane waves of noise has been followed up by extending the analysis to the problem of noise propagation in open media. Several different aspects of the problem were examined. First, our plane wave analysis was extended to cover spherically and cylindrically spreading waves. Then scaling rules concerning the effects of frequency and amplitude were determined. Consideration of the unique properties of the random sawtooth wave led to the conclusion that the spectrum of very intense noise has a high frequency rolloff that approaches 6 dB/octave. The role played by phase of the noise signal was investigated by computing the distortion of several noise signals having the same spectrum but different phase characteristics. Phase was found to be relatively unimportant for the cases studied. Finally, distortion computations were made using a particular example of actual jet noise, noise of not very high intensity from the British-French Concorde. In this particular case nonlinear effects did not prove to be very important. (Author)

Magnetic control thyristor chopper equipment for battery vehicle

Abstract: The following three major advantages were observed by adopting a magnetic phase shifter for gate control of a thyristor. 1) A single magnetic phase shifter can compare and amplify multiple signals in an insulated status. 2) At the same time, simplified current detection greatly reduces the number of parts required. 3) It is barely susceptible to the influences of noise. These facts imply that a magnetic phase shifter constitutes a highly reliable and low-cost control device. Especially, using this as a control unit for a chopper offers a substantial advantage with respect to the antinoise margin. By utilizing a balanced half-wave type magnetic phase shifter (capable of operating with a dc power source by combining with a switching transistor), we have developed a gate controller that is free from the influences of noise and allows control of current duties ranging from a minimum value to 100 percent maximum with a greatly simplified circuit.

The so-called 1/Δf noise

Abstract: A sinusoidal ac current of frequeencyfc generates an excess noise in many solidstate conductors. The power spectrum of this noise is calculated starting from the autocorrelation function of the stochastic process. Besides a 1/Δf term the spectrum includes another contribution varying with 1/(fc+f). In the low frequency range there is white noise.

New Microwave Frequency Synthesizers that Exhibit Broader Bandwidths and Increased Spectral Purity

Abstract: A superior microwave-frequency synthesis technique is treated in this paper, emphasizing improved spectral purity with octave bandwidths in the microwave region. The microwave-frequency synthesizer is discussed in two sections each corresponding to a system unit. The driver unit specifications are analyzed in the first section, showing its voltage-controlled crystal oscillator (VCXO) L(f ) output to be -130 dBc/Hz at 10 kHz. In the second section, the driver VCXO output is translated in the microwave unit to the final X-band frequency by means of a phase-locked loop. An analysis of this phase-locked loop, as described in this paper, shows the final L(f ) equal to -101 dBc/Hz at 10 kHz. Since a worst case situation was assumed, the final L(f ) is quite superior for octave bandwidth microwave-frequency synthesizers.

HF and VHF Source Stabilization Technique Incorporating Q-Multiplied Quartz Crystal Resonator

Abstract: A new approach is described for the desiga of HF/VHF crystal-controlled frequency sources exhibiting theoretical short-term stability unattainable through the use of conventional quartz oscillator design. The signal generator design uses the concept of AFC stabilization of a conventional quartz oscillator (VCXO) by means of a crystal-controlled highly selective active frequency reference. The AFC reference is a phase-shift type frequency discriminator that employs a product detector and an active Q-multiplied quartz crystal resonator. The extremely selective transmission response, large group delay, and power gain exhibited by the resonator, together with resonator phase noise levels comparable to that exhibited by the oscillator-maintaining circuit, provide the principal means for prediction of superior output signal spectral purity. Models of the resonators have been designed and constructed at 30 and 80 MHz, exhibiting 3-dB bandwidths of 30 and 160 Hz, respectively. Based on actual measurement of VHF Q-multiplied crystal resonator performance characteristics, approximately 16 dB improvement in VHF crystal-controlled frequency source spectral purity at low and moderate modulation rates is possible, compared to that attainable using the best available VHF quartz oscillator circuit designs.

Near carrier noise in TWT amplifiers

Abstract: Near carrier amplitude and phase noise modulations have been measured for low noise (receiving type) and medium power (20 w) TWT amplifiers at 6 GHz. The measured noise is greater than predicted by the noise figure measured 30 MHz from the carrier. Below 20 kHz, at least part of the excess can be accounted for by phase modulation products coherent with the power line frequency.

Low-noise, integrated, millimeter-wave receiver

Abstract: A low-noise, hybrid-integrated, millimeter-wave receiver that consists of a local oscillator and a downconverter on a silica substrate is described in this paper The source for the local oscillator is a Gunn diode, and the mixer element is a beam-leaded Schottky barrier diode A novel filter circuit is used to combine the local oscillator and the signal with low insertion loss in the signal path The single-sideband noise figure of the receiver at 30 GHz is 55 dB, including 08-dB contribution of the if amplifier, and the rms FM frequency variation resulting from the local oscillator is 168 Hz/√KHz

Parameter Estimation for an Adaptive Instrumentation of Hall's Optimum Receiver for Digital Signals in Impulse Noise

Abstract: Newton's method for root finding is shown to be an effective algorithm for computing maximum likelihood estimates of the bias parameter in Hall's optimum receiver for digital singals in impulse noise. Use of a bias estimator allows the receiver to be adaptively instrumented. A simulation indicates that the number of independent samples of the impulse noise, as modeled by Hall, should be around 20 000 for satisfactory parameter estimates.