Study on Aerospace Layering Time Synchronization Architecture and Time Synchronization Algorithm

2012 ◽  
Vol 546-547 ◽  
pp. 1614-1619
Author(s):  
Fei Jiang Huang ◽  
Xiao Chun Lu ◽  
Jun Yang ◽  
Qing Xiao Shan ◽  
Yong Bin Zhou
Keyword(s):  
Time Synchronization ◽  
Rapid Development ◽  
Frequency Standard ◽  
High Accuracy ◽  
Time Frequency ◽  
Aerospace Application ◽  
Visual Model ◽  
Application Systems ◽  
Synchronization Algorithm ◽  
Time And Frequency Standard

The rapid development of various kinds of aerospace application systems requires the appropriate high-accuracy time and frequency standard. This problem can be effectively solved by establishing suitable time and frequency standard in aerospace. Based on the establishment of aerospace satellite visual model, the simulation of satellite visual time on 3-layer constellation structure, including GEO satellite, IGSO satellites and MEO satellites, has been conducted. The visual features of this constellation have been gained. Combining with the major influencing factors of satellite clock correction error, aerospace time synchronization architecture on the basis of layering has been proposed. The time synchronization algorithm in line with this architecture has been researched. The results show that aerospace time frequency standard established based on this layering time synchronization architecture can meet the demand on high-accuracy time frequency of future aerospace application systems.

scholarly journals A Novel Ultrasonic TOF Ranging System Using AlN Based PMUTs

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 284
Author(s):  
Yihsiang Chiu ◽  
Chen Wang ◽  
Dan Gong ◽  
Nan Li ◽  
Shenglin Ma ◽  
...  
Keyword(s):  
Clock Cycle ◽  
High Accuracy ◽  
Ultrasonic Waves ◽  
Oxide Semiconductor ◽  
Average Error ◽  
Cmos Process ◽  
Clock Frequency ◽  
Time Frequency ◽  
Range Finding ◽  
Wide Range

This paper presents a high-accuracy complementary metal oxide semiconductor (CMOS) driven ultrasonic ranging system based on air coupled aluminum nitride (AlN) based piezoelectric micromachined ultrasonic transducers (PMUTs) using time of flight (TOF). The mode shape and the time-frequency characteristics of PMUTs are simulated and analyzed. Two pieces of PMUTs with a frequency of 97 kHz and 96 kHz are applied. One is used to transmit and the other is used to receive ultrasonic waves. The Time to Digital Converter circuit (TDC), correlating the clock frequency with sound velocity, is utilized for range finding via TOF calculated from the system clock cycle. An application specific integrated circuit (ASIC) chip is designed and fabricated on a 0.18 μm CMOS process to acquire data from the PMUT. Compared to state of the art, the developed ranging system features a wide range and high accuracy, which allows to measure the range of 50 cm with an average error of 0.63 mm. AlN based PMUT is a promising candidate for an integrated portable ranging system.

Fuzzified time-frequency method for identification and localization of power system faults

2021 ◽  
pp. 1-13
Author(s):  
Pullabhatla Srikanth ◽  
Chiranjib Koley
Keyword(s):  
Power System ◽  
High Accuracy ◽  
Fuzzy Decision ◽  
Frequency Method ◽  
Time Frequency ◽  
Novel Approach ◽  
S Transform ◽  
Different Types ◽  
Power System Faults ◽  
Frequency Magnitude

In this work, different types of power system faults at various distances have been identified using a novel approach based on Discrete S-Transform clubbed with a Fuzzy decision box. The area under the maximum values of the dilated Gaussian windows in the time-frequency domain has been used as the critical input values to the fuzzy machine. In this work, IEEE-9 and IEEE-14 bus systems have been considered as the test systems for validating the proposed methodology for identification and localization of Power System Faults. The proposed algorithm can identify different power system faults like Asymmetrical Phase Faults, Asymmetrical Ground Faults, and Symmetrical Phase faults, occurring at 20% to 80% of the transmission line. The study reveals that the variation in distance and type of fault creates a change in time-frequency magnitude in a unique pattern. The method can identify and locate the faulted bus with high accuracy in comparison to SVM.

A Multi-Source Dynamic Determination Algorithm for Digital Synchronization Equipment

2014 ◽  
Vol 654 ◽  
pp. 370-373
Author(s):  
Bin Zhang ◽  
Bao Ren Chen ◽  
Yue Zhuo ◽  
Guang Cai Wang ◽  
Yi Jie Ding
Keyword(s):  
Time Synchronization ◽  
Weighted Average ◽  
Reference Source ◽  
Time Frequency ◽  
Output Performance ◽  
Synchronization Signal ◽  
Dynamic Source ◽  
Security And Reliability ◽  
Multiple Reference ◽  
Synchronization Accuracy

In order to improve the security and reliability of digital synchronization network, digital synchronized equipment mostly uses reference source design and ensure the output performance in abnormal situation by redundancy back-up of multiple reference sources. The paper not only describes the concept of time-frequency equipment reference source and its judgment index, but also details a multi-source dynamic determination algorithm for digital synchronization equipment. A multi-component weighted average approach is designed the multi-source dynamic source selected processes by the study of several time sources of anomaly detection to improve the accuracy of the synchronization signal. The algorithm with simple structure can help keeping the high synchronization accuracy of multi-source time synchronization system.

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