Topic
Frequency drift
About: Frequency drift is a research topic. Over the lifetime, 5054 publications have been published within this topic receiving 56191 citations. The topic is also known as: chirp rate.
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TL;DR: In this paper, the frequency drift in giant pulse ruby laser was investigated using a photomixing system and it was shown that the drift is due to an inversion dependent change of the polarizability of ruby.
17 citations
Patent•
14 Jul 2011TL;DR: A phase detector for a phase-locked loop includes a phase detector that is configured to become unstable, oscillate and drift rapidly in frequency in a predictable manner when a reference frequency signal is not available.
Abstract: A phase detector for a phase-locked loop includes a phase detector that is configured to become unstable, oscillate and drift rapidly in frequency in a predictable manner when a reference frequency signal is not available. When applied, for example, to a power converter connected to a power distribution grid, the predictable oscillatory and rapid frequency drift behavior when the phase detector is unstable allows very rapid and reliable detection of disconnection from the grid, referred to as islanding.
17 citations
Patent•
04 Aug 1972TL;DR: In this article, the authors propose an approach for synthesizing an adjusted reference signal at a frequency that is controllable to a prescribed value, which performs the programmed addition (or subtraction) of sequential increment of phase shift to the reference signal output of an undisturbed oscillator that has a characteristic frequency of oscillation that is accurately predictable for a significant time period into the future.
Abstract: Apparatus for synthesizing an adjusted reference signal at a frequency that is controllable to a prescribed value performs the programmed addition (or subtraction) of sequential incrementation of phase shift to the reference signal output of an undisturbed oscillator that has a characteristic frequency of oscillation that is accurately predictable for a significant time period into the future. Purposes of the proposed apparatus include (a) the generation and maintaining of small offsets in the frequency of the adjusted output reference signal relative to the nominal or actual frequency of the oscillator, (b) the compensation for the time dependent predictable drift of the source oscillator to maintain the adjusted output signal at the desired frequency even though the source oscillator frequency changes, (c) the operation of precise time and frequency systems with complete coherency between the modulation representing timing and the RF carrier representing frequency, and (d) the ability to calibrate, adjust, and normalize the timing of a clock system operating from the adjusted reference signal both as to location of its epoch(s) and its scale relative to an accepted system primary standard of time.
17 citations
01 Jun 1997
TL;DR: In this article, an extremely low-frequency digital sinusoidal oscillator is proposed and its performance is evaluated, where the difference between two adjacent generated frequencies is shown to be approximately constant over the frequency range of operation.
Abstract: An extremely low-frequency digital sinusoidal oscillator is proposed and its performance is evaluated. The proposed oscillator structure can generate sinusoidal signals with a large number of samples per cycle without the need for increasing the width of the multiplier coefficient. The difference between two adjacent generated frequencies is shown to be approximately constant over the frequency range of operation. The proposed oscillator utilises one multiple-output direct-form digital oscillator together with very simple shift operations. Simulation results are given to verify the analysis and demonstrate the performance as measured in terms of total harmonic distortion.
17 citations
Patent•
10 Dec 2004
TL;DR: In this paper, a method and an arrangement for interference compensation in a phase-locked loop comprising a voltage-controlled frequency generator, wherein the frequency generator is tuned to a nominal frequency by a tuning voltage Vtune and whose actual frequency is compared with a reference frequency by means of a frequency comparison and is re-adjusted if a deviation is detected via the frequency comparison.
Abstract: The invention, which relates to a method and an arrangement for interference compensation in a phase-locked loop comprising a voltage-controlled frequency generator, wherein the frequency generator is tuned to a nominal frequency by a tuning voltage Vtune and whose actual frequency is compared with a reference frequency by means of a frequency comparison and is re-adjusted if a deviation is detected via the frequency comparison, in which case, in the event of interference, the tuning voltage Vtune is changed by an interference voltage Vstor that depends on the interference event, and thus a frequency deviating from the nominal frequency is generated, which deviating frequency is corrected again by the phase locked loop, is based on the object to provide a method and an arrangement for interference compensation in a phase-locked loop comprising a voltage-controlled frequency generator, with which a deviation from a predefined nominal frequency is avoided if known interference events occur. The object is achieved in accordance with the invention in a method whereby, if a known interference event occurs, a voltage Vstor which compensates for the interference voltage Vcomp, is generated in synchronism with this with sign inversion and is superimposed on the interference voltage Vstor.
17 citations