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.

Internal oscillator circuit including a ring oscillator controlled by a voltage regulator circuit

Abstract: An oscillator circuit residing internally to a semiconductor device for generating a clock signal for use by digital circuits. The oscillator circuit includes a voltage regulator circuit responsive to frequency selection signals for selecting a predetermined frequency and a supply voltage. The voltage regulator circuit is operative to generate a voltage reference signal having a voltage level being adjusted to compensate for variations due to temperature, process and supply voltage variations. The oscillator circuit further includes a ring oscillator circuit responsive to the voltage reference signal for generating a clock out signal having a particular frequency based upon the voltage level of the voltage reference signal. Wherein the frequency of the clock out signal remains substantially constant despite temperature, process and supply voltage variations in the semiconductor circuit.

Frequency Stabilization of Microwave Oscillators

Abstract: Two electronic circuits for frequency stabilization of electronically tunable microwave oscillators are described and discussed. One of these uses a microwave circuit equivalent to the lowfrequency discriminator, in conjunction with a d.c. amplifier, to control the oscillator frequency at the frequency of a cavity resonator. The other circuit obtains frequency control of the oscillator by the cavity through a circuit operating almost entirely at an intermediate frequency. With both systems, frequency modulation of a highly degenerative type is provided. The resulting stability over long periods is essentially that of the cavity. The stability over short periods is such that the signal obtained occupies a band of less than 1 part in 108in width. The practical limit to the stabilization obtainable with given components is estimated, and several applications are suggested.

A Kalman Filter Clock Algorithm for Use in the Presence of Flicker Frequency Modulation Noise

Abstract: The National Physical Laboratory (NPL) has developed a Kalman filter based algorithm for combining measurements from its three active hydrogen masers. The algorithm is designed to produce a near optimal composite clock when the dominant noise process of at least one of the masers is flicker frequency modulation (FFM), and significant linear frequency drift is exhibited. The FFM is modelled approximately by a linear combination of Markov noise processes. Each Markov process is included in the Kalman filter and contributes an additional component to the state vector. Both the validity of the model and the effectiveness of adding these additional components are examined. The performance of the new algorithm is investigated when applied to simulated measurements and also to measurements obtained from NPL's hydrogen masers.

Improving short and long term frequency stability of the opto-electronic oscillator

Abstract: For the first time, the high Q components of the optoelectronic oscillator, i.e. the optical fiber, and the narrow pass band microwave filter in the oscillator loop were thermally stabilized to improve the oscillator short- and long-term frequency stability. In our design, the temperature of these elements is kept above ambient and stabilized with the help of resistive heaters and temperature controllers. With this scheme the free running oscillator demonstrates a short-term frequency stability of 0.02 ppm and frequency vs. temperature slope of -0.1 ppm//spl deg/C (at 20-30/spl deg/C) with an exceptional spectral purity (-143 dBc/Hz at 10 kHz offset frequency). Locking the opto-electronic oscillator to a standard reference oscillator, oscillating at 100 MHz further stabilized the 10 GHz microwave carrier frequency.

Ultrastable laser with average fractional frequency drift rate below 5 × 10 −19 /s

Abstract: Cryogenic single-crystal optical cavities have the potential to provide high dimensional stability. We have investigated the long-term performance of an ultrastable laser system that is stabilized to a single-crystal silicon cavity operated at 124 K. Utilizing a frequency comb, the laser is compared to a hydrogen maser that is referenced to a primary caesium fountain standard and to the Sr87 optical lattice clock at Physikalisch-Technische Bundesanstalt (PTB). With fractional frequency instabilities of σy(τ)≤2×10−16 for averaging times of τ=60 s to 1000 s and σy(1 d)≤2×10−15 the stability of this laser, without any aid from an atomic reference, surpasses the best known microwave standards for short averaging times and is competitive with the best known hydrogen masers for longer times of 1 day. The comparison of modeled thermal response of the cavity with measured data indicates an average fractional frequency drift below 5×10−19/s, which we do not expect to be a fundamental limit.