Smart clock: a new time

Weiss, Marc; Allan, David W.; Davis, D. D.; Levine, Judah

doi:10.1109/19.199433

Cited by 6 publications

(7 citation statements)

References 6 publications

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“…The wristwatches will show different times from each other by at least a few seconds. A group of cesium clocks can also be measured using the same method, and the time difference will be small, nanoseconds instead of seconds, but again, the clocks would not keep the perfect similar time [12]- [14].…”

Section: A Public Timekeepingmentioning

confidence: 99%

“…According to the results in Table IV, respondents who calibrate their timekeeping devices have better accuracy compared with the respondents who did not calibrate their timekeeping devices. This accuracy difference may be explained by the fact that the calibration of a timekeeping device may slow the process of clock drift although it could never eliminate the error continuously [14].…”

Section: Calibration Of Public Timekeeping Devicesmentioning

confidence: 99%

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How is Your 8 O‘clock Different from Mine? The Accuracy of Public Timekeeping

2019

IJITEE

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Public timekeeping devices such as analogue watch, digital watch and smart watch give several of accuracy as there are differences between the public time and the standard time. The consequence of having various accuracies in timekeeping is there will be difficulties in having reasonable agreement with other timekeeping devices when it involves public time-reference applications such as attendance system, car parking system, prayer timekeeping as well as making appointments and meetings. In this paper, public timekeeping accuracy has been determined. The data for this study is collected using questionnaire survey, in which the respondents are asked about the information of their timekeeping devices and accuracy. One-way analysis of variance and independent t-test are used to determine the factors of that impact on public timekeeping accuracy. Our results show that type of timekeeping devices, gender differences and calibration of the devices have significant impacts on public timekeeping accuracy. The findings also indicate that public timekeeping accuracy for this study is 2.07 min (S.D. ± 2.20 min). Differences ranged from -8.12 to +10.07 minutes, with a median of 1.18 minutes. Overall, this study provides evidence that it is difficult for the public to perfectly match their time with the Malaysian Standard Time. With these findings in mind, policy makers should consider timekeeping accuracy among the public in order to define acceptable range in time-compliance.

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Section: A Public Timekeepingmentioning

confidence: 99%

Section: Calibration Of Public Timekeeping Devicesmentioning

confidence: 99%

How is Your 8 O‘clock Different from Mine? The Accuracy of Public Timekeeping

2019

IJITEE

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“…The advantages of using multiple sensors over a single sensor to improve the accuracy of acquired information about an object have been recognized and employed by many engineering disciplines ranging from applications such as a medical decision-making aid system to a combined navigation system (Lam et al, 2004). Weis and Allan (1992) presented a high-accuracy clock with a monthly error of one second, by combining three inexpensive wrist watches with monthly errors of 40 seconds. Actually, this technology used heterogeneous sensor data fusion to improve the accuracy.…”

Section: Introductionmentioning

confidence: 99%

“…Weis and Allan (1992) presented a high-accuracy clock with a monthly error of one second, by combining three inexpensive wrist watches with monthly errors of 40 seconds. Actually, this technology used heterogeneous sensor data fusion to improve the accuracy.…”

Section: Introductionmentioning

confidence: 99%

Optimal Redundant Sensor Configuration for Accuracy and Reliability Increasing in Space Inertial Navigation Systems

Jafari¹,

Roshanian²

2012

J. Navigation

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A redundant Inertial Measurement Unit (IMU) is an inertial sensing device composed of more than three accelerometers and three gyroscopes. This paper analyses the performance of redundant IMUs and their various sensor configurations. The inertial instruments can achieve high reliability for long periods of time only by redundancy. By suitable geometric configurations it is possible to extract the maximum amount of reliability and accuracy from a given number of redundant single-degree-of-freedom gyros or accelerometers. This paper gives a general derivation of the optimum matrix which can be applied to the outputs of any combination of three or more sensors to obtain three orthogonal vector components based on their geometric configuration and error characteristics. Certain combinations of four or more instruments are able to detect an instrument malfunction, and combinations of five have the additional capability of isolating that malfunction to a particular sensor. Finally, this paper offers a major improvement in reliability, although the improvement in accuracy is minor.

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“…Weis and Allan presented a high-accuracy clock with a month error of one second through combining three inexpensive wrist watches with month errors of 40 seconds in 1992 [4]. This new time technology was named 'smart clock'.…”

Section: Introductionmentioning

confidence: 99%

An Integrated MEMS Gyroscope Array with Higher Accuracy Output

Chang

Xue

Qin

et al. 2008

Sensors

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Abstract:In this paper, an integrated MEMS gyroscope array method composed of two levels of optimal filtering was designed to improve the accuracy of gyroscopes. In the firstlevel filtering, several identical gyroscopes were combined through Kalman filtering into a single effective device, whose performance could surpass that of any individual sensor. The key of the performance improving lies in the optimal estimation of the random noise sources such as rate random walk and angular random walk for compensating the measurement values. Especially, the cross correlation between the noises from different gyroscopes of the same type was used to establish the system noise covariance matrix and the measurement noise covariance matrix for Kalman filtering to improve the performance further. Secondly, an integrated Kalman filter with six states was designed to further improve the accuracy with the aid of external sensors such as magnetometers and accelerometers in attitude determination. Experiments showed that three gyroscopes with a bias drift of 35 degree per hour could be combined into a virtual gyroscope with a drift of 1.07 degree per hour through the first-level filter, and the bias drift was reduced to 0.53 degree per hour after the second-level filtering. It proved that the proposed integrated MEMS gyroscope array is capable of improving the accuracy of the MEMS gyroscopes, which provides the possibility of using these low cost MEMS sensors in high-accuracy application areas.

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Smart clock: a new time

Cited by 6 publications

References 6 publications

How is Your 8 O‘clock Different from Mine? The Accuracy of Public Timekeeping

How is Your 8 O‘clock Different from Mine? The Accuracy of Public Timekeeping

Optimal Redundant Sensor Configuration for Accuracy and Reliability Increasing in Space Inertial Navigation Systems

An Integrated MEMS Gyroscope Array with Higher Accuracy Output

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