Showing papers on "Phase noise published in 1977"

Phase Noise in Oscillators: A Mathematical Analysis of Leeson's Model

Abstract: This paper is devoted to one aspect of the study of phase noise in oscillators: how an oscillator reacts to internal noise that occurs in the active element. The following theoretical analysis will lead us to express the Leeson's model in a more general form.

Current Developments in SAW Oscillator Stability

Abstract: The results reported were obtained with two port delay lines and resonators used in a simple feedback oscillator. The feedback oscillator employed inherently operates with the amplifier in a saturated condition and, therefore, the AM noise is suppressed. Consequently the dominant noise is FM. Generally, it can be concluded that for very narrow-band, or fixed-frequency applications, the resonator-type oscillator will give the best noise performance. For applications where tunability and linearity are important, the delay-line-type oscillator may give the best performance. There have been no significant improvements in oscillator temperature stability. The only two demonstrated materials for temperature stable SAW oscillators are ST-cut quartz and the SiO2/LiTaO3 overlay structure. Aging tests have been going on for the past two-and-a-half years and it has become obvious that the observed aging rates are largely related to cleaning and packaging.

The Measurement of Noise in Microwave Transmitters

Abstract: A tutorial review of the basis for transmitter noise measurements shows that noise is best described and measured as AM and FM noise. The determination of RF spectrum is done by calculation after the AM and FM noise are known. The contribution of AM noise to RF spectrum shape is determined by the power spectral density shape of the AM noise. The contribution of FM noise to RF spectrum is to make the shape that of an RLC circuit resonant response rather than a delta function with a sideband structure. The measurement of AM noise is done with a direct detector diode. The measurement of FM noise for frequencies above 5 GHz is done with a discriminator based on a one-port cavity resonator. The measurement of FM noise below 5 GHz is done with an improved transmission line discriminator which is described in detail. Measurement of low-power low-noise signal sources is made posbible with an injection-locked oscillator for a preamplifier to the discriminator. The most widely used baseband analyzer is the constant bandwidth superhetdrodyne wave or spectrum analyzer. Most differences in measurement results are resolved by understanding the baseband analyzers. At least the baseband spectrum analysis of transmitter noise measurements can be automated with worthwhile savings in time and improvement of documentation.

Heterodyne phase lock system

Abstract: A heterodyne phase lock system is disclosed having a plurality of oscillator circuits, a similar plurality of heterodyne (mixer-filter) circuits representing an input circuit, and a similar plurality of heterodyne circuits representing a control circuit, at least one of the oscillator circuits being a voltage controlled oscillator (VCO) circuit. The heterodyne circuits of the input circuit are cascaded, i.e., linked each to the other, successively, and the heterodyne circuits of the control circuit are likewise cascaded. Each oscillator is linked to a pair of heterodyne circuits, i.e., to one heterodyne circuit in the input circuit and to one heterodyne circuit in the control circuit, and applies a common output signal to said pair of heterodyne circuits. The control circuit includes a phase lock circuit, and is responsive to an applied reference signal for adjusting the output of the VCO and correcting for or substantially cancelling frequency drift, residual FM, and phase noise introduced into the system by the oscillators. This manner of linking oscillators to both heterodyne input and control circuits in a system so as to be able to correct, by adjusting a single oscillator, for frequency drift, residual FM, and phase noise from all of the oscillators in the system, is applicable to receiver and generator type systems alike. The system also includes an offset oscillator for tuning the system.

Phase locked detector

Abstract: A microwave or ultrasonic detection system is disclosed which has a voltage controlled transmitter oscillator. The output of the transmitter oscillator is transmitted into a designated area from a transmit antenna and is reflected by objects in the area and received by means of a second antenna. The reflected signal is phase compared to the output of the transmitter oscillator. A phase error signal is generated that varies with the phase difference, and this signal is input to the transmitter oscillator to cause the frequency of the oscillator to vary in such a way to produce a null phase difference. When the position of an object which reflects the transmitted signal is changed, the length of the propagation path for the signal changes which produces a phase error signal. This phase error signal in turn causes the transmitter oscillator to shift frequency. Thus, either the output of the phase comparator or a change in the frequency of the output of the transmitter oscillator indicates a change in position of objects in the field of the transmitted signal. Range to the object is measured by phase locking at two ranges which differ by a known distance.

Spectral Analysis of Synthesized Signals in the mm Wavelength Region

Abstract: In this paper some experimental results on the spectral purity along a multiplier chain from 5 MHz up to 600 GHz are reported. The measured points are compared to the numerical data which can be obtained from simple calculations considering the phase noise spectrum of the crystal oscillators used to drive the multiplier chains.

Accurate Measurements of Spectral Density of Phase Noise in Devices

Abstract: Systematic errors larger than 10 dB can occur in the measurement of the spectral density of phase unless considerable caution is exercised. Some potential problems due to the shape of the analyzer passband and the Fourier frequency dependence of mixers are discussed. Three measurement systems are analyzed to determine the conditions under which they may be used to make spectral density measurements with an accuracy of 0.2 dB.

Measurement of Static AM-PM Conversion in Frequency Multipliers

Abstract: The generation of very narrow spectral lines in the far-infrared by frequency synthesis from VHF precision sources requires very stringent specifications on the spectral purity of the source and on the phase noise introduced by the synthesizer. The dc measurements of the AM-PM conversion in different multiplier stages are presented in this paper: stages employing transistors, varactors and step-recovery diodes are examined. The results show that a few degrees per dB of input level variation are typical for the AM-PM conversion reported to the input in a simple, carefully built and well tuned multiplier stage employing any of the mentioned solid state devices. This value is shown to be unlikely to degrade more than the expected n2 factor the spectral purity of a signal with AM noise as low with respect to PM noise as it is in the output of a good quartz crystal controlled oscillator; however, such a conversion could become a source of phase noise, with degradation of the spectral purity, for a signal with a slightly worse AM noise.

A phase-locking technique for estimating the ensemble average of time-series data

Abstract: A digital method employing Fourier analysis is presented, which in the absence of any external synchronizing signals can, with certain restrictions, 1) reduce random noise from repetitive frames of sampled input data; and 2) average waveforms which may differ in shape and which may occur in the presence or absence of random noise. The restrictions refer to the ability to select a window width which will each time encompass all of the aperiodic waveforms or one period of a periodic waveform. There is no restriction as to where in the window any waveform may appear. The new method is called the phase-locked time (PLT) average and should prove useful in a variety of situations.

Improving linear prediction analysis of noisy speech by predictive noise cancellation

Abstract: The analysis of speech using Linear Prediction is reformulated to account for the presence of acoustically added noise and a technique is presented for reducing its effect on parameter estimation. The method, called Predictive Noise Cancellation (PNC), modifies the noisy speech autocorrelations using an estimate of present background noise which is adaptively updated from an average all-pole noise spectrum. The all-pole noise spectrum is calculated by averaging autocorrelations during non-speech activity. The method uses procedures which are already available to the LPC analyzer, and thus is well suited for real time analysis of noisy speech. Preliminary results show signal to noise improvements on the order of 10 to 20 db.

Circuit aspects of the noise performance of microwave oscillator modules

Abstract: An extension of Kurokawa's noise analysis for determining the form of the noise characteristics of broad-band negative-conductance oscillators is described. The method employs a full large-signal experimental characterisation of the active device, and is applicable to any oscillator structure. Some simple oscillator models are used to illustrate the technique. An investigation of the role of particular circuit elements on the noise characteristics of a commonly used oscillator structure is described which indicates the power of the method in the design of oscillator modules.

The Counting Phase Detector with VLF Atmospheric Noise

Abstract: The counting detector offers a simple means of making and averaging digital measurements of signal phase. However, use of the averages can lead to erroneous estimates if the signal has a low carrier-to-noise ratio. How to overcome this problem by using multiple counters is shown here. Characteristics for both Gaussian and impulsive noise are derived, and algorithms for estimating both phase and carrier-to-noise ratio are presented.

Phase Noise Measurements in the Frequency Domain

Abstract: This paper describes two measurement systems used to measure phase noise of sources in the frequency domain at Fourier frequencies from 10 hertz to 13 megahertz from the carrier. One system measures the combined phase noise characteristics of two sources. The two source signals are applied in quadrature to a phase sensitive detector (double balanced mixer), the voltage fluctuations analog to the phase fluctuations are measured at the detector output. One measurement system is designed to measure the phase noise characteristics of a single oscillator. The single-oscillator measurement system is designed using delay lines to form an FM discriminator. Voltage fluctuations analog to the frequency fluctuations are measured at the detector output.

Digital noise generating apparatus

Abstract: A digital noise generator, wherein pseudo-random rapidly changing analog input voltages to a voltage controlled oscillator are used to generate corresponding rapidly changing discrete frequency outputs, is disclosed. Means are provided to delay the oscillator output by an amount at least equal to the rise time between each frequency change. The delayed and non-delayed oscillator outputs are electrically coupled through a switch that operates at times and at a rate to eliminate the rise time between frequency changes and thus improve the frequency spectrum.

Calculation of the suppression of signals and intermodulation noise when multiple unequal carriers are amplified by a TWT

Abstract: Weak signals are suppressed and intermodulation noise is generated when a number of carriers having different amplitudes are amplified by a TWT. These effects are analyzed using an extension of a method which has been described previously2 and which is simpler to use than other methods in current use4,5,6,7. This paper describes the calculations and includes a comparison of the results with experimental observations. The results are useful in the design of a satellite communications system in which a TV signal and multiple radio or two-way voice signals are present in one satellite transponder. The calculations show that for each 1 dB signal suppression of the small carriers due to the presence of a large carrier at saturation, the suppression of intermodulation noise is by more than 2 dB. Based on these results, it would be advantageous to operate with a single carrier saturating the transponder when multiple unequal carriers are present.

Frequency Domain Adaptive Correlator

Abstract: A specific configuration of an adaptive process, called a Frequency Domain Adaptive Correlator, is analyzed and simulated. The processor is used to de tect narrowband signals in broadband noise. The pro- cessor is shown to be slightly superior to conventional processors under ideal noise conditions, and signifi- cantly superior for practical noise conditions.

Optimum waveform design and its effect on the peak shift compensation

Abstract: An equalization method of reducing peak shift caused by the intersymbol interference is presented to obtain high density digital magnetic recording First, a new ideal frequency characteristic is determined to get an impulse response free from peak shift Then, using the equalizer that gives this response, the extent of the peak shift compensation is simulated with a computer When a 2200BPI (FM) disk unit is used to double the bit density with MFM, it is found that the peak-shift in the worst case is only 84% of the full phase margin Here, other parameters such as RPM, remain constants However, as the application of the equalizer increases the noise power, signal to noise ratio of the input signal is required to be sufficiently high When the equalizer is applied to a 4040BPI (MFM) disk unit at the same density, phase margin for data separation increases, because the decrease in peak shift seems to be greater than the increase in the noise power

X Band Bulk-Wave Delay Line Stabilized Oscillator

Abstract: A low noise X band oscillator, stabilized by a microwave delay line discriminator has been designed for Doppler RADAR applications. It uses a Gunn varactor VCO and a bulk-wave. 5 mu s delay line. The measured phase noise of this source is Single Sideband dBC of -90 dB in a 1 kHz band at 100 kHz from the Carrier, in fairly good accordance with calculated figures.

A digital noise and sine-wave generator

Abstract: A circuit is described that will digitally generate three kinds of signal useful in auditory research: broad-band pseudorandom noise, low-pass-filtered Gaussian noise, and low-distortion sine waves. This digital circuit has two advantages over its analog counterparts, ease of calibration and adaptation to computer control.

Synchronous marker for measuring phase in the presence of noise

Abstract: A circuit has been constructed to mark the phase of a sinusoidal signal even when it is obscured by noise. The time jitter of the marker signal due to the noise can be reduced as much as desired in trade for slowed response time of the circuit. A theoretical description of the performance of the circuit and an error analysis are presented. Results of tests on the circuit agree approximately with the theoretical description.

Longitudinal Bunch Dilution Due to RF Noise

Abstract: The effect of phase noise on a tightly bunched proton beam is investigated taking into account the frequency spread in the beam, the wall impedance and the phase feedback loop. Under normal conditions the measured dilution rates in the ISR correspond typically to a doubling of the bunch length in one to a few hours, and are consistent with the measured noise spectra. Amplitude noise is not investigated.

Spectra of a.c.-induced noise in resistors

Abstract: Noise-spectra measurements are reported on flat carbon-film linear resistors with sinusoidal excitation. In addition to the expected I/Δf noise, 1/f spectra were observed at low frequencies and also paired spectra at harmonics of the excitation frequency. An analogue circuit model is proposed and shown to be consistent with the observations on the additional spectra.

Measurement of crystalline faults in magnetic material - uses analysis of noise signal generated by Barkhausen effect

Abstract: A method of measurement of faults of application generally to magnetic materials (ie ferromagnetic, antiferromagnetic, ferrimagnetic and antiferrimagnetic) is based on the analysis of the noise signal generated by the Barkhausen effect Factors controlling the generation of the noise signal are frequency and amplitude of the applied magnetic field, the phase of the magnetising cycle (point on the hysteresis curve) at which the noise is measured and the inherent damping of the noise signal in the material (eddy current damping) Analysis of the character of the noise signal yields information on lattice faults such as dislocations, precipitates, inclusions and cracks Analysis may be based on the pulse amplitude, length or repetition rate, or the autocorrelation function of the noise signal