Showing papers on "Phase noise published in 1985"

Estimating the frequency of a noisy sinusoid by linear regression (Corresp.)

Abstract: The estimation of the parameters of a sinusoid from observations of signal samples corrupted by additive noise is investigated. At high signal-to-noise ratios the additive noise is viewed as an equivalent phase noise, suggesting frequency and phase estimation by linear regression on the signal phase. The variances of the regression estimates are shown to achieve the Cramer-Rao bounds. A formula for the variance of the regression frequency estimator is derived in terms of the noise power spectrum. A simple formula for the variance with 1/f^{2} phase noise is presented.

Coherent lightwave communications

Abstract: The chief objective of this paper is to develop a fundamental understanding of the effects of laser phase noise on the performance of coherent lightwave communication systems. A comprehensive treatment applicable to a wide variety of coherent receiver designs under a broad range of conditions is provided. Our models and analytical tools are developed in sufficient detail to encompass a broad range of applications. Formulas are derived for the bit error rate in homodyne and heterodyne Phase Shift Keying (PSK), Differential Phase Shift Keying (DPSK), Frequency Shift Keying (FSK) and on-off keying. Estimates are provided of the penalties accrued due to phase noise. Based on detailed mathematical analysis and estimates, we made several findings. Near quantum-limited receiver sensitivity can be achieved with PSK using homodyne detection only at signaling rates 3000 times greater than the laser linewidth. A receiver sensitivity 3 to 6 decibels poorer than the quantum limit can be achieved with heterodyne rather than homodyne detection. DPSK, for example, can operate at rates only 300 times greater than the laser linewidth. At lower rates, FSK is an attractive candidate. It can be designed to be extremely tolerant of phase noise by using wide frequency deviations.

Quantum noise and excess noise in optical homodyne and heterodyne receivers

Abstract: A parallel development of the semiclassical and quantum statistics of multispatiotemporal mode direct, homodyne, and heterodyne detection using an ideal (except for its subunity quantum efficiency) photon detector is presented. Particular emphasis is placed on the latter two coherent detection Configurations. The primary intent is to delineate the semiclassical theory's regime of validity and to show, within this regime of validity, how the quantum theory's signal quantum noise, local oscillator quantum noise, the quantum noise incurred because of subunity detector quantum efficiency, plus (for heterodyning only) image band quantum noise produce the quantitative equivalent of the semiclassical theory's local oscillator shot noise. The effects of classical fluctuations on the local oscillator, and the recently suggested dual-detector arrangement for suppressing these fluctuations, are treated. It is Shown that previous studies of this arrangement have neglected a potentially significant noise contribution.

Theory of laser phase noise in recirculating fiber-optic delay lines

Abstract: Optically driven recirculating delay lines, often used in fiber-optic signal processors, convert the source phase noise to spectrally structured intensity noise at the loop output. This spectrum is characterized by deep notches at zero frequency as well as at other multiples of 1/(loop delay). An expression is derived for the power spectral density of the output noise. The formulae obtained, are then used to investigate the dependence of the magnitude and shape of this noise on the source coherence time, the coupling ratio, the coupler and loop losses, and the fiber birefringence.

Analysis of Noise Upconversion in Microwave FET Oscillators

Abstract: The upconversion of Iow-frequency noise in microwave FET oscillators is investigated. The theoretical analysis is presented in two forms, a general and a simplified one. The latter version yields closed-form expressions for amplitude and phase noise, which are discussed wfth regard to the physics of the upconversion process. Application of the method is demonstrated with an example.

Signal Recovery from Noise in Electronic Instrumentation

Abstract: Low-pass filtering and visual averaging multiple time averaging and drift phase-sensitive detector methods spectral view of signal recovery 1/F noise frequency response calculations frequency-domain view of the phase-sensitive detector digitation and noise magnitude determination for transient signals of known shape and timing measurement of the time of occurrence of a signal transient.

Squeezing of classical noise by nondegenerate four-wave mixing in an optical fiber

Abstract: Nondegenerate four-wave mixing in an optical fiber is shown to attenuate one quadrature of random sideband fluctuations created by external modulators. A theory of the nonlinear interaction that includes nonlinear dispersion fits the results. Analogous experiments on quantum noise inputs should prove successful.

Observation of modulation speed enhancement, frequency modulation suppression, and phase noise reduction by detuned loading in a coupled-cavity semiconductor laser

Abstract: Simultaneous direct modulation response enhancement, phase noise (linewidth) reduction, and frequency modulation suppression are produced in a coupled‐cavity semiconductor laser by the detuned loading mechanism.

Design of Microwave Oscillators and Filters Using Transmission-Mode Dielectric Resonators Coupled to Microstrip Lines

Abstract: A more detailed model for the transmission-mode dielectric resonator coupled between microstrip lines is given. Novel design approaches for parallel feedback oscillators and bandpass filters are discussed. For oscillators, the design mainly takes into account zero phase shift loop considerations, as in the classical low-frequency approach. Oscillators of this type may offer low phase noise. For filters, the spatial separation between dielectric resonators favors multipole designs. Using the same microstrip layout, different shapes and bandwidths may be obtained by simple tuning.

Spectral Degradation in VHF Crystal Controlled Oscillators Due to Short-Term Instability in the Quartz Resonator

Abstract: Significant degradation and variation in the output signal phase noise sideband spectra of VHF crystal controlled oscillators has been observed. The spectral degradation. which occurs for carrier offset frequencies extending to several hundred kilohertz, has been traced to short-term stability in the fifth overtone AT-cut and the third overtone SC-cut quartz resonators used in the oscillators. The spectral degradation is characterized by flicker-of-frequency noise for f, 5 10 kHz and noise "peaks" at the location of prominent resonator anharmonic spurious responses. Up to 25 dB AM and PH spectral variation has been measured for identically fabricated crystals. The degradation is independent of oscillator type or circuit configuration. For "high noise" crystals the variation is drive-dependent. No correlation has been observed between resonator short- term stability and either drive, stress, or temperature coefficients. Oscillator signal phase noise levels appear influenced by crystal instability even when the lowest noise crystals are used. Details of the resonator stability measurement apparatus are described, and examples of correlation observed between short-term instability in the oscillator output signal and oscillator resonators are given for both single and dual crystal oscillator designs. Simple screening tests, that do not require sophisticated or expensive instrumentation, are now available for incorporation into crystal purchase part drawings associated with low noise oscillator designs.

Reduction of noise in signal from charge transfer devices

Abstract: The noise in the output signal from the floating diffusion output stage of a charge transfer device is reduced. Reset noise can be reduced by resetting the floating diffusion to an in-channel potential, rather than to the reset drain potential. Flicker noise or "1/f" noise in the electrometer stage following the floating diffusion is suppressed by high-pass or band-pass filtering the output signal samples, after which the filtered signal is synchronously detected against a harmonic of the clocking frequency of the charge transfer device to obtain full bandwidth output response. The filtering not only suppresses flicker noise or "1/f" noise, but also suppresses smear that afflicts output signal samples originating from a floating diffusion reset to an in-channel potential. High frequency peaking of the full bandwidth output response can be obtained with reduced noise, using synchronous detection which does not suppress response to input signal components other than the sidebands of the harmonic of the clocking frequency used as switching carrier frequency. The filtering of the charge transfer device output signal, previous to synchronous detection, is allowed to pass high frequency components from bands outside the harmonic spectrum being synchronously detected. This provides for augmenting the high frequency components of the full bandwidth output response with high frequency components without correlation of their respective attendant noise components.

Phase-locked-loop analysis for pilot carrier coherent optical receivers

Abstract: The optimum phase-locked-loop bandwidth which exists when shot and phase noise sources are present at the receiver is derived. This is then used to show beat linewidth to bitrate ratios smaller than 0.05% are needed for PSK homodyne/heterodyne systems.

Direct measurement of the nonlinear phase shift between the orthogonally polarized states of a single-mode fiber.

Abstract: We measure the phase shift induced by the optical Kerr effect between the two orthogonally polarized states of a birefringent single-mode fiber. The associated noise, which can arise whenever amplitude fluctuations of the source are present, is discussed.

Stable Microwave Source Using High Overtone Bulk Resonators

Abstract: The high overtone bulk acoustic resonator (HBAR) provides the basis for stable microwave sources. The HBAR's high Q, closely spaced, periodic resonances provide stabilization for multiple frequency microwave sources. Recently an L-band source with 5 MHz channels has been developed. This HBAR source has phase noise performance equivalent to that of sources based on low frequency quartz crystal stabilization and multiplication, but it requires only a fraction of the hardware.

Waveform estimation using group delay processing

Abstract: A method of signal waveform estimation from an ensemble of jittered noisy measurements is presented. The method uses group delay functions to perform the ensemble averaging and thus overcomes the difficulty of computing the unwrapped phase function before averaging. We propose a new technique, called group delay processing, to estimate the signal waveform if only a single noisy measurement is available. We demonstrate our group delay averaging and group delay processing techniques through illustrative examples.

Optical source linewidth criteria for heterodyne communication systems with PSK modulation

Abstract: The performance of an optical heterodyne communication system is analysed for the cases of phase-shift keying (PSK) with synchronous electrical demodulation and differential PSK with non-synchronous demodulation. The combined effect on the system performance from the shot noise, quantum phase noise of the optical sources and the pulse shaping are considered. From the results, criteria are given for the maximum linewidth of the transmit and local optical sources to satisfy a given degradation in the optical receiver sensitivity.

A Novel GaAs FET Oscillator with Low Phase Noise

Abstract: A novel GaAs FET oscillator circuit is presented. This circuit is capable of reducing phase noise up to 20 db. A source-coupled pair of GaAs FETs has a balanced characteristic which can eliminate both the reactive and resistive modulation mechanisms which upconvert l/f noise. This circuit is inherently broadband and ideal for monolithic implementations.

Digital noise generator

Abstract: A digital noise generator for use in aeroengine noise testing can accurately and repeatably reproduce a standard noise spectrum so that differing noise analysis systems can be calibrated to a common standard. The noise generator comprises a pseudo-random binary sequence generator which is fed with a low clock frequency derived from a high frequency crystal oscillator. The generator produces a pseudo-random noise single bit signal which is fed to the most significant bit input of a digital to analogue converter, whose other inputs are fed with simulated tone data residing within an EPROM, the pseudo-random and tone noise thereby being digitally summed before conversion to an output analogue signal of desired spectral characteristics.

Principles Governing The Transfer Of Signal Modulation And Photon Noise By Amplifying And Scattering Mechanisms

Abstract: A general analysis is made of the influence of stochastic amplifying and scattering mechanisms on the transfer of signal modulation and photon noise in imaging processes. In this way we quantify the spatial-frequency dependence of signal and noise as they propagate through a multistage imaging system. Whereas by definition the signal structure (or modulation) is transferred via the MTF, the input photon noise is effectively unmodulated signal and as such bypasses the MTF. However, stochastic amplification of photon noise by one stage of an imaging process may produce noise structure that constitutes an effective signal spectrum to the next. Thus, in general, it is necessary to cascade these two components of the noise spectrum separately at each stage.

Phase Locking of Semiconductor Lasers Using Homodyne Detection and Negative Electrical Feedback

Abstract: Investigations of an optical phase locked loop using semiconductor lasers and homodyne detection are reported. The phase noise in the phase locked loop, that is, the fluctuatin of phase difference between the slave and master laser is measured under free running and locked conditins. Strong phase noise reduction has been observed under locked condition. The measured results are in reasonable agreement with calculated results applying the linear transfer function of a phase locked loop.

Measurement and modelling of amplitude and phase scintillations in an Earth–space path

Abstract: This paper gives a complete summary of the theory and experimental results obtained by Portsmouth Polytechnic on the subject of amplitude and phase scintillations on a down-link path through the atmosphere during the Orbital Test Satellite campaign of research at 11.786 GHz and special and emphasis is given to engineering applications. The paper introduces first a brief summary of relevant theoretical studies, inclusive of antenna aperture smoothing, which facilitates the understanding of the scintillation process and the use of the experimental results in system design and planning. The results include chart recording observations, spectra of the scintillations and correlation with meteorological conditions together with results of cumulative distributions of scintillation fade, fade rate and intensity. The subject of propagation-induced phase noise is also dealt with and includes the theoretical estimates of the phase noise due to turbulence and precipitation as well as an outline of the experimental techniques used to measure the f.m. noise of the beacons.

Phase effects for a sine wave masked by reproducible noise

Abstract: A tone‐in‐noise detection task was used to assess the filtering properties of the auditory system. In the first experiment, ten 150‐ms samples of reproducible noise were used as maskers. The signal was a 500‐Hz tone either 20 or 100 ms in duration. The 100‐ms signal was centered temporally in the noise; the 20‐ms signal occurred either at the beginning, center, or end of the noise. The starting phase of the signal was varied from 0°–315° in steps of 45°. Signal thresholds, collected by the method of adjustment, were a cyclical function of starting phase and could be described by an energy model [Green and Swets, Signal Detection Theory and Psychophysics (Krieger, Huntington, NY, 1966/1974)]. A vector description of these data revealed an invariant property of each sample of noise, which we call the ‘‘noise vector.’’ The relationship among the parameters of the noise vectors over the various signal conditions suggest the presence of temporal interactions due to narrow‐band filtering. These relationships ar...

Differential phase shift keying receiver

Abstract: A receiver for demodulating differential phase shift keying data, the data having bit values dependent upon whether the phase of a carrier is inverted or not inverted during a bit interval, the receiver having a phase locked loop oscillator for locking up with the phase of the carrier, a phase detector for sensing differences in phases between the oscillator signal and the incoming data, an oscillator controller for controlling the output phase of the oscillator in response to the phase detector, a phase sense detector which detects whether or not the carrier has been inverted, a data clock responsive to the oscillator and to the phase sense detector for providing a data clock signal defining a bit interval, and a bit detector responsive to the phase sense detector, the data clock and the oscillator for integrating the incoming data.

Optical DPSK heterodyne detection experiments using DBR laser diodes with external optical feedback

Abstract: High receiver sensitivity, with 7 dB improvement over a direct detection system, has been achieved in a 400 Mbit/s optical DPSK heterodyne detection experiment using DBR laser diodes with external optical feedback. The influence of the laser output phase noise was evaluated experimentally in good agreement with theory.

Intrinsic lineshape and FM response of modulated semiconductor lasers

Abstract: A new method for measuring the FM response and the intrinsic linewidth of modulated semiconductor lasers is reported. No additional stochastic line broadening has been observed for direct modulation of buried-heterostructure 1.3 μm lasers with modulation depths of less than 20%. Thus FSK systems employing heterodyne detection are expected not to exhibit any additional phase noise penalty due to direct current modulation.

The Fractal Dimension of Phase and Frequency Noises: Another Approach to Oscillator Characterization

Abstract: An e v a l u a t i o n i s made o f t h e p o s s i b i l i t y o f a p p l y i n g M a n d e l b r o t ' s c o n c e p t o f f r a c t a l s t o t h e c h a r a c t e r i z a t i o n o f no ises and i n p a r t i c u l a r of phase and $requency f l u c t u a t i o n s . Two methods are considered. The f i r s t one c o n s i s t s i n m e a s u r i n g w i t h a gauge t h e appar e n t l e n g t h o f t h e s i g n a l : t h e f r a c t a l d i m e n s i o n o f w h i t e and random walk no i ses a re ca l cu la ted with this method. The second one i s based on the space f i l l i n g a b i l i t y o f t h e s i g n a l . The method i s a p p l i e d t o l / f a noises, which are s imulated on a computer, by superpos i t i o n o f l o r e n t z i a n s p e c t r a , f o r i n t e g e r and m inte g e r v a l u e s o f t h e c o e f f i c i e n t a . The dependence nf the f r a c t a l d i m e n s i o n D as a f u n c t i o n o f t h e spectral dms i t y i s es tab l i shed.

Extraction of helicopter‐radiated noise by frequency domain processing

Abstract: Real data observations of farfield radiated noise from an approaching UH‐1 helicopter revealed that the received time‐domain radiated noise contained impulses. The cited literature attributes these observed impulses to blade slap which is caused by, among other mechanisms, blade vortex interactions. This paper is concerned exclusively with extracting these measured impulses by a frequency‐domain processing method. As is well known, the total radiated noise of a helicopter is quite complex. No attempt is made in the paper to discuss the full complexity of the radiated noise field. However, references are cited in the text which support our findings and give a more general treatment to helicopter‐radiated noise. The method for extracting impulses generated by an approaching helicopter utilizes a nonlinearity implemented in the frequency domain. It is shown with real helicopter‐radiated noise data that autocorrelation estimates of a signal, interfered with by additive helicopter‐radiated noise, can be improv...