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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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Patent
10 Jun 2004
TL;DR: In this paper, a method for calibrating an on-chip non-precision oscillator is presented, where the oscillator's period is measured as a function of the time base.
Abstract: Method and apparatus for calibration of a low frequency oscillator in a processor based system. A method for calibrating an on-chip non-precision oscillator. An on-chip precision oscillator is provided having a known frequency of operation that is within an acceptable operating tolerance. The on-chip precision oscillator is used as a time base and then the period of the on-chip oscillator is measured as a function of the time base. The difference between the measured frequency of the on-chip non-precision oscillator and a desired operating frequency of the on-chip non-precision oscillator is then determined. After the difference is determined, the frequency of the on-chip non-precision oscillator is adjusted to minimize the determined difference.

47 citations

Proceedings ArticleDOI
02 Jun 2008
TL;DR: The result of the experiments show that the technique can effectively improve the frequency stability of an inexpensive uncompensated crystal 5 times with the potential for even higher gains in future implementations.
Abstract: Time synchronization is an essential service in distributed computing and control systems. It is used to enable tasks such as synchronized data sampling and accurate time-of-flight estimation, which can be used to locate nodes. The deviation in nodes' knowledge of time and inter-node resynchronization rate are affected by three sources of time stamping errors: network wireless communication delays, platform hardware and software delays, and environment-dependent frequency drift characteristics of the clock source. The focus of this work is on the last source of error, the clock source, which becomes a bottleneck when either required time accuracy or available energy budget and bandwidth (and thus feasible resynchronization rate) are too stringent. Traditionally, this has required the use of expensive clock sources (such as temperature compensation using precise sensors and calibration models) that are not cost-effective in low-end wireless sensor nodes. Since the frequency of a crystal is a product of manufacturing and environmental parameters, we describe an approach that exploits the subtle manufacturing variation between a pair of inexpensive oscillators placed in close proximity to algorithmically compensate for the drift produced by the environment. The algorithm effectively uses the oscillators themselves as a sensor that can detect changes in frequency caused by a variety of environmental factors. We analyze the performance of our approach using behavioral models of crystal oscillators in our algorithm simulation. Then we apply the algorithm to an actual temperature dataset collected at the James Wildlife Reserve in Riverside County, California, and test the algorithms on a waveform generator based testbed. The result of our experiments show that the technique can effectively improve the frequency stability of an inexpensive uncompensated crystal 5 times with the potential for even higher gains in future implementations.

47 citations

Patent
30 Sep 1997
TL;DR: In this article, a global positioning system (GPS) receiver and high accuracy low power time source (HAL) are disclosed, which includes an oscillator adapted to provide an uncompensated frequency signal at a desired frequency.
Abstract: A global positioning system (GPS) receiver and high accuracy low power time source (HAL) are disclosed. The HAL provides a time source having an accuracy which is high enough for the receiver to achieve fast direct Y-code acquisition. The HAL includes an oscillator adapted to provide an uncompensated frequency signal at a desired frequency. Frequency conversion circuitry receives the uncompensated frequency signal and a control signal as inputs, and provides as an output a compensated frequency signal having an average compensated frequency which is closer to the desired frequency than is the average uncompensated frequency. A temperature sensor provides an output indicative of a temperature of the oscillator. Frequency error determining circuitry determines an error value, as a function of the temperature sensor output, which is indicative of a quantity of frequency error over time in the uncompensated frequency signal. The frequency error determining circuitry generates the control signal as a function of the determined quantity of frequency error in the uncompensated frequency signal. A counter receives the compensated frequency signal from the frequency conversion circuitry and provides as an output a digital representation of a time period based upon the compensated frequency signal.

46 citations

Journal ArticleDOI
TL;DR: In this article, an X-band microwave oscillator incorporating a room temperature thermoelectric stabilized sapphire resonator operating at 9.00000 GHz with a Galani type stabilization scheme was measured.
Abstract: The authors report on an X-band microwave oscillator incorporating a room temperature thermoelectric stabilized sapphire resonator operating at 9.00000 GHz. With a Galani type stabilization scheme they have measured a reduced single sideband phase noise of about -124 dBc/Hz at 1 kHz with a f/sup -3/ dependence. The measurement was limited by the flicker noise of the phase detector in the feedback electronics. The frequency stability was also measured; at an integration time of 0.1 seconds a /spl delta/f/f of about 10/sup -11/ with a /spl tau//sup 0.7/ dependence was measured. The frequency drift strongly correlated with ambient temperature fluctuations. >

46 citations

Proceedings ArticleDOI
23 Aug 1999
TL;DR: In this paper, an on-chip oscillator with small frequency variation in a digital 0.6 /spl mu/m CMOS technology is described, which utilizes a bias technique to compensate for the influences on the oscillation frequency caused by both temperature and process variations.
Abstract: An on-chip oscillator with small frequency variation in a digital 0.6 /spl mu/m CMOS technology is described. The oscillator utilizes a bias technique to compensate for the influences on the oscillation frequency caused by both temperature and process variations. No external components are needed in the oscillator. Simulation results show that the frequency of the proposed oscillator has a peak variation of /spl plusmn/6.8% for all process corners and a temperature range of 120/spl deg/C. The oscillator is measured to operate at a center frequency of 680 kHz and have a peak variation of /spl plusmn/4.7% over 29 sample chips in two different lots and a temperature range of 35/spl deg/C to 115/spl deg/C. As a comparison, a conventional inverter chain oscillator is made on the same chip. The frequency variation of the conventional inverter chain is /spl plusmn/14.6%.

46 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20237
202217
202150
202059
201963
201887