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研究生:劉志傑
研究生(外文):Chi-JayLiu
論文名稱:基於多通道媒體播放系統之多點同步實現
論文名稱(外文):Realization of synchronization system based on multimedia player
指導教授:楊中平楊中平引用關係
指導教授(外文):Chung-Ping Young
學位類別:碩士
校院名稱:國立成功大學
系所名稱:資訊工程學系碩博士班
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2012
畢業學年度:100
語文別:英文
論文頁數:83
中文關鍵詞:IEEE 1588規範時脈同步時間同步系統
外文關鍵詞:IEEE 1588Clock SynchronizationTimekeeping system
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經過調查顯示,聆聽動聽的音樂是每個家庭中最普遍的娛樂且也是每個房間不可缺少的服務。多通道輸出之多點同步多媒體播放系統可透過雲端服務取得處理過的音樂資訊,使得每一個節點都能扮演不同的樂器並且協奏出美麗的樂章。所以在此情況下,必須去考慮每個聲道是不是可以同步的播出聲音。因此這篇論文主要目的是實現適用於多點同步媒體播放系統之多點同步系統。IEEE 1588是目前最被廣泛使用之時間同步標準,在有硬體的支援下時間同步精確度可達次微秒等級且移植性非常高,適用於分散式網路嵌入式系統。但是IEEE 1588在沒有硬體支援的情況下,IEEE 1588的精確度則會大幅地降低,原因在於IEEE 1588只能解決時脈偏移所造成的時間差但無法解決時脈偏移所導致的時鐘速度偏移,因此關於IEEE 1588在沒有硬體支援下所衍成的同步問題不斷被討論,解決時脈偏移所造成的時鐘速度偏移變成影響IEEE 1588時間同步精確度的關鍵。然而,IEEE 1588標準將對於時脈偏移的補償並沒有規範,並且交由系統實作者自行設計,因此我們實現多點同步系統於Creator Xscale PXA270嵌入式平台,系統由兩個子系統組成,PPS system負責Grand Master之時脈補償與NTP校時,IEEE 1588 system負責Slaves之時脈補償與同步。透過這兩個系統讓Slaves與Grand Master對於GPS receiver之rate error維持在4 微秒以內,並讓Slaves對於Grand Master之time error維持在10 微秒以內。此外並將Pulse Per Second 整合至IEEE 1588中來降低Master端之時鐘速度偏移所造成的影響,並間接提高整個系統之時間同步精確度。另外我們也提出同步啟動機制,讓各個節點間能同時輸出訊號。最後除了探討造成訊號輸出時刻延遲之抖動來源也將同步啟動機制實做於Creator PXA270 嵌入式開發平台進行驗證。

Listening to beautiful music is a general and necessary entertainment in our lives. Multichannel multimedia player system could obtain the processed digital music data from the cloud server so that different instruments could be played by different nodes. Under this situation, whether or not each node could play songs in synchronous way has to be considered. Thus, the main purpose of this thesis is to implement the synchronize system of the multichannel multimedia player system. IEEE 1588 standard is used broadly in time synchronization, its accuracy could achieve sub-microsecond under the hardware support and it is portable so that IEEE 1588 could be used in distributed network embedded system.But without hardware support, the accuracy of IEEE 1588 would be degraded from sub-microsecond order to millisecond order. Because IEEE 1588 standard only could calculate the time offset caused from clock skew. The way to control the clock with the calculated time offset is out of the scope of the standard. Hence there are many studies regarding to clock controlling without hardware support and clock skew correction becomes essential in increasing the accuracy of IEEE 1588. However, IEEE 1588 standard has not specified the compensation of clock but hand over this part to implementers. Therefore, the author implemented the synchronize system on the Creator Xscale PXA270 embedded system platform. The system is consisted of PPS system and IEEE 1588 system. PPS system is used to compensate the clock of grand master and get UTC time from NTP server. IEEE 1588 system is used to synchronize the slaves to grand master. Through these two systems, the rate error of grand master and slaves could be maintained in 4 microseconds, and the time error could be maintained in 10 microseconds. The author also integrated RFC2783 into IEEE 1588 to correct the clock skew of grand master and increase the time accuracy of the system indirectly. In addition, a start point mechanism was presented for the nodes to produce signals simultaneously. Finally, the source of jitter which could delay the output will be discussed and this mechanism will be implemented on the Creator Xscale PXA270.

摘要.............................I
Abstract...............III
Acknowledgement...............V
List of Figures................IX
List of Tables.............XI
Chapter 1 Introduction...........1
1.1 Motivation.........1
1.2 Introduction......2
1.3 Organization................3
Chapter 2 Background Knowledge.........5
2.1 Multi-channel multimedia system.................5
2.2 Basic Concept of Time Synchronization................6
2.2.1 Definitions.....................6
2.2.2 Traditional Time Synchronization Approaches.....................10
2.3 IEEE 1588 Introduction..........................13
2.4 Overview of the Standard.............................15
2.5 A Detailed Analysis of IEEE 1588.....................17
2.5.1 Boundary Clock and Ordinary Clock.......................17
2.5.2 Protocol State machine...........................18
2.5.3 Best Master Algorithms........................21
2.5.4 State decision algorithm....................... 21
2.5.5 Data set Comparison.....................24
2.5.6 Precise Time Protocol in IEEE 1588..................24
2.5.7 PPS Signal synchronization..................26
Chapter 3 Related works...............27
3.1 The Challenge of IEEE 1588................27
3.1.1 Clock Characteristic...................27
3.1.2 Delay Asymmetry Clock Synchronization In IEEE 1588..........29
3.1.3 Time Stamp Points in Clock Synchronization.............31
3.2 The Mechanism of Adjusting clock.............35
3.2.1 Two state clock model......................35
3.2.2 Controller of Native Feedback System.....................37
3.2.3 The system Integration............39
Chapter 4 Implementation...............40
4.1 Hardware Architecture.....................40
4.1.1 Creator PXA270 platform..........40
4.1.2 ICP-DAS GPS721.............42
4.2 System Architecture Overview.............44
4.2.1 System architecture in hardware level.................44
4.2.2 System architecture in software level...........45
4.3 Synchronization of Start Point...................46
4.4 IEEE 1588 System Implementation..................48
4.5 PPS System Implementation.............................52
4.5.1 The PPS Clock Servo Algorithm...............................53
4.5.2 The PPS System Implementation Architecture..........................55
4.5.3 PPS Life Cycle......................57
4.5.4 UTC Time Emulation.............................58
4.5.5 The High Frequency Noise.............................59
4.6 The Implementation of RFC2783..........................60
4.6.1 Overview of Implementation................60
4.6.2 Implementation.................................61
4.7 The Implementation of simple multi-channel media player....................65
Chapter 5 Experimental Results................68
5.1 Experimental Scenario..........................68
5.2 The Experimental architecture.......................69
5.3 At Grand Master......................71
5.4 At the slave side.........................72
5.5 Case study......................76
Chapter 6 Conclusion and Future work.........................80
6.1 Conclusion.......................80
6.2 Future works.....................80
Reference.........................82
[1]H. C. Kuo, Time Synchronization for ZigBee-based Wireless Sensor Networks, Master Thesis, Department of Computer Science and Information Engineering, National Cheng Kung University, 2005.
[2]G. Welch and G. Bishop, Introduction to IEEE 1588 [Online]. Available: http://www.nist.gov/el/isd/ieee/intro1588.cfm
[3]IEEE Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems, IEEE 1588-2002, 2002.
[4]J. C. Eidson, Measurement, Control and Communication Using IEEE 1588, 2006.
[5]J. Mogul, D. Mills, and J. Brittenson, Pulse-Per-Second API for Unix-like Operationg Systems,Version 1.0, in RFC 2783, 2000.
[6]NI-Sync User Manual [Online]. Available: http://digital.ni.com/manuals.nsf/websearch/B20C3BAA8A3F301286257887004FAB27.
[7]W. Ye, IEEE1588 Clock Servo Algorithm, in Electronic Measurement and Instruments (ICEMI), 2009 International Conference on, vol. 1, pp. 341-344, 2009.
[8]H. Weibel and D. Bechaz, IEEE 1588 Implementation and Performance of Time Stamping Techniques, in IEEE 1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems, 2004 International Conference on, vol. 1, pp.24-38, 2004.
[9]N. Simanic, R. Exel, P. Loschmidt, T. Bigler and N. Kero, Compensation of Asymmetrical Latency for Ethernet Clock Synchronization, in Precision Clock Synchronization for Measurement Control and Communication (ISPCS), 2011 International IEEE Symposium on, pp. 19-24, 2011.
[10]G. Giorgi and C. Narduzzi, Performance Analysis of Kalman Filter-based Clock Synchronization in IEEE 1588 Networks, in Precision Clock Synchronization for Measurement, Control and Communication (ISPCS), 2009 International Symposium on, pp. 6-11, 2009.
[11]G. Bishop and G. Welch, An Introduction to the Kalman Filter, 2006.
[12]N. Barendt, K. Correll, and M. Branicky, Design Considerations for Software Only Implementations of the IEEE 1588 Precision Time Protocol, in IEEE 1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems, 2005 International Conference on, 2005.
[13]D. Mills, A Kernel Model for Precision Timekepping, in RFC 1589, 1994.
[14]GPS-721 User Manual v2.0 [Online]. Available: http://www.icpdas.com/products/GSM_GPRS/wireless/gps-721.htm
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