To the Issue of Frequency Band and Frequency Measurement Accuracy

2019 ◽  
Author(s):  
Igor Yu. Blinov ◽  
Yuri S. Domnin ◽  
N. Kosheliaevskii
Keyword(s):  
Frequency Band ◽  
Measurement Accuracy ◽  
Frequency Measurement

Error Analysis and Improvement of Equal Precision Frequency Measurement

2014 ◽  
Vol 687-691 ◽  
pp. 841-846 ◽  
Author(s):  
Rong Xiang Wang ◽  
Xia Zhang
Keyword(s):  
Error Analysis ◽  
Measurement System ◽  
Measurement Accuracy ◽  
Frequency Measurement ◽  
Frequency Count ◽  
Frequency Multiplication ◽  
Circuit Performance ◽  
Standard Frequency ◽  
Synchronization Signal ◽  
Precision Frequency

In accordance with the principle of equal precision frequency measurement and theory of errors, in this paper, the problems are discussed that the equal precision frequency measurement eliminates the standard frequency count error. In order to reduce the relative error and improve the measurement accuracy, a method is proposed for phase coincide detection between standard frequency multiplication and measurement frequency demultiplication to open or shut the gate, at the same time, a signal selector is also used to improve circuit performance. This method can effectively solve the problem that the frequency can not be detected without the synchronization signal and improve the performance of the frequency measurement system.

scholarly journals Experimental study on improving the accuracy of marine gravimetry by combining moving-base gravimeters with GNSS antenna array

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Zhimin Shi ◽  
Junjian Lang ◽  
Xinghui Liang ◽  
Zhibo Zhou ◽  
Aizhi Guo ◽  
...  
Keyword(s):  
Antenna Array ◽  
Real Time ◽  
Frequency Band ◽  
Antenna Arrays ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Tectonic Activity ◽  
Gravity Measurement ◽  
Vertical Position ◽  
Point Positioning

AbstractThe gravity field is one of the Earth’s basic physical fields. The geoid can be calculated and the tectonic activity underground can be inversed by gravity anomaly. With the development of various ship-borne gravimeters and navigation technology, including the Global Navigation Satellite System (GNSS) and Strapdown Inertial Navigation System (SINS), the precision of marine gravimetry has been significantly improved (achieve or better than 1mGal). Errors arising from calculations of the correction term have become the main source of gravity measurement errors. At present, the traditional approach is to deploy a GNSS antenna, connect the GNSS antenna to the gravimeter, record the real-time position through data acquisition software, and then use this position to calculate the gravity correction item afterward. Two errors are inevitable. (1) The GNSS antenna position error is large. The pseudorange point positioning method is generally used to obtain real-time GNSS antenna positions, and the positioning accuracy is poor compared with that of precise point positioning. (2) The position coordinates of the gravimeter contain systematic errors related to the ship’s attitude. In this paper, a joint experiment including GNSS antenna arrays and ship-borne gravimeters was designed to evaluate the measurement accuracy via repeat lines on the same ship. The experimental results show the following: (1) attitude accuracies of 0.0299° for the yaw angle, 0.0361° for the pitch angle, and 0.1671° for the roll angle can be obtained at baseline lengths of 25 and 4 m. (2) The GNSS antenna array has an obvious role in determining the point acceleration in the low-frequency band (0–0.01 Hz) and the point position and velocity in the high-frequency band (0.01–1 Hz). (3) The vertical position eccentricity causes an absolute error of 1 mGal and a relative error of $${10}^{-1}$$ 10 - 1 mGal in gravity measurements and can be corrected by the GNSS antenna array method. (4) Using a GNSS antenna array can obviously improve the measurement accuracy of an instrument with a precision equaling or exceeding 1 mGal, but cannot obviously improve that to an instrument with poor precision (2 mGal or below).

scholarly journals Attitude Angle Compensation for a Synchronous Acquisition Method Based on an MEMS Sensor

Sensors ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 483 ◽  
Author(s):  
Huanhuan Tian ◽  
Yixiao Liu ◽  
Jiqin Zhou ◽  
Ying Wang ◽  
Jing Wang ◽  
...  
Keyword(s):  
Measurement Accuracy ◽  
Inertial Sensor ◽  
Measuring Method ◽  
Frequency Measurement ◽  
Process Time ◽  
Navigation Systems ◽  
Micro Electro Mechanical Systems ◽  
Mems Sensor ◽  
Attitude Angle ◽  
Aircraft Navigation

As a new type of micro-electro-mechanical systems (MEMS) inertial sensor, the Quartz Vibrating Beam Accelerometer (QVBA) is widely used in intelligent sweeping robots, small aircraft, navigation systems, etc. For these applications, correcting and compensating the attitude angle with the result of acceleration plays an important role to improve the measurement accuracy. The synchronization error between the measurement of the accelerometer and gyroscope attitude angle has an adverse impact on the accuracy of the attitude angle. In this paper, a synchronous acquisition scheme of the accelerometer and gyroscope attitude angle in a strapdown inertial navigation system (SINS) is proposed. At the same time, to improve the sampling accuracy and the conversion speed of QVBA, an improved equal-precision frequency measuring method is also implemented in this paper. The hardware float point unit (FPU) is used to accelerate the calculation of the frequency measurement value. The long-term cumulative error of the frequency measurement value is less than 10 − 4 . The calculation process time from sampling to attitude angle compensation calculation is reduced by 40.8%. This work has played a very good role in improving the measurement accuracy and speed of the SINS.

Based on SoC Technology Frequency Measurement Meter

2014 ◽  
Vol 556-562 ◽  
pp. 2974-2977
Author(s):  
Wei Zhang
Keyword(s):  
Embedded System ◽  
Measurement Accuracy ◽  
New Technology ◽  
Frequency Measurement ◽  
Integrated System ◽  
Logic Device ◽  
Core Technology ◽  
Slow Type ◽  
The Embedded System ◽  
On Chip

SoC is the ASICS (ApplieationSpeenIetgratdeCierulst) design methodology of the new technology, refers to the embedded system as the core technology used in PI-based, set of software and hardware in one, and the pursuit of products inclusive of the largest integrated system chip. The article in-depth exploration into the complexity of using VHDL language and system programmable logic device (CPLD) to develop "system-on-chip (SoC)" - such as adaptive frequency measurement accuracy of the basic methods to overcome the system of the previous frequency measurement accuracy is not high , measuring the accuracy of the process of change, approaching the speed of slow-type shift shortcomings.

scholarly journals High-Resolution Multi-Channel Frequency Standard Comparator Using Digital Frequency Measurement

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5626
Author(s):  
Bo Xiao ◽  
Ya Liu ◽  
Xiaohui Li ◽  
Zhifeng Deng ◽  
Yanrong Xue
Keyword(s):  
Measurement Method ◽  
Measurement Accuracy ◽  
Frequency Standard ◽  
Frequency Measurement ◽  
Low Noise ◽  
Measurement Technology ◽  
Zero Crossing ◽  
Noise Floor ◽  
Digital Frequency ◽  
Atomic Frequency

The rapid improvement accuracy of the atomic frequency standard puts forward higher requirements for the measurement resolution of the atomic frequency standard comparison system. To overcome the defect that the single zero-crossing point detection is sensitive to noise in the traditional dual mixer time difference measurement method, a digital frequency measurement method is proposed. This method combines sinusoidal beat technology, multi-channel synchronous acquisition technology, and digital frequency measurement technology, and uses differential compensation of system error to realize the precision measurement of atomic frequency standard. The frequency measurement accuracy is less than 2.5 × 10−14 and the noise floor is better than 6.5 × 10−15/τ = 1 s. The system has a high frequency measurement accuracy and a low noise floor, which can realize the precise measurement of a highly stable frequency source.

Methods for Restricting Maximum Exposure Rate in Computerized Adaptative Testing

Methodology ◽  
2007 ◽  
Vol 3 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Juan Ramon Barrada ◽  
Julio Olea ◽  
Vicente Ponsoda
Keyword(s):  
Measurement Accuracy ◽  
Computerized Adaptive Testing ◽  
Computation Time ◽  
Adaptive Testing ◽  
Exposure Rate ◽  
Control Parameters ◽  
The Impact ◽  
Two Alternatives ◽  
Selection Of ◽  
Maximum Exposure

Abstract. The Sympson-Hetter (1985) method provides a means of controlling maximum exposure rate of items in Computerized Adaptive Testing. Through a series of simulations, control parameters are set that mark the probability of administration of an item on being selected. This method presents two main problems: it requires a long computation time for calculating the parameters and the maximum exposure rate is slightly above the fixed limit. Van der Linden (2003) presented two alternatives which appear to solve both of the problems. The impact of these methods in the measurement accuracy has not been tested yet. We show how these methods over-restrict the exposure of some highly discriminating items and, thus, the accuracy is decreased. It also shown that, when the desired maximum exposure rate is near the minimum possible value, these methods offer an empirical maximum exposure rate clearly above the goal. A new method, based on the initial estimation of the probability of administration and the probability of selection of the items with the restricted method ( Revuelta & Ponsoda, 1998 ), is presented in this paper. It can be used with the Sympson-Hetter method and with the two van der Linden's methods. This option, when used with Sympson-Hetter, speeds the convergence of the control parameters without decreasing the accuracy.

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