- Overview
- Configuration
- NTP4 Plug-In
- Hardware
- RFC 868
- RFC 2030
-
RFC 1305
- RFC 1305
- 1. Introduction
- 1.1 Related Technology
- 2. System Architecture
- 2.1 Implementation Model
- 2.2 Network Configurations
- 3. Network Time Protocol
- 3.1 Data Formats
- 3.2 State Variables and Parameters
- 3.2.1 Common Variables
- 3.2.2 System Variables
- 3.2.3 Peer Variables
- 3.2.4 Packet Variables
- 3.2.5 Clock-Filter Variables
- 3.2.6 Authentication Variables
- 3.2.7 Parameters
- 3.3 Modes of Operation
- 3.4 Event Processing
- 3.4.1 Notation Conventions
- 3.4.2 Transmit Procedure
- 3.4.3 Receive Procedure
- 3.4.4 Packet Procedure
- 3.4.5 Clock-Update Procedure
- 3.4.6 Primary-Clock Procedure
- 3.4.7 Initialization Procedures
- 3.4.7.1 Initialization Procedure
- 3.4.7.2 Initialization-Instantiation Procedure
- 3.4.7.3 Receive-Instantiation Procedure
- 3.4.7.4 Primary Clock-Instantiation Procedure
- 3.4.8 Clear Procedure
- 3.4.9 Poll-Update Procedure
- 3.5 Synchronization Distance Procedure
- 3.6 Access Control Issues
- 4. Filtering and Selection Algorithms
- 4.1 Clock-Filter Procedure
- 4.2 Clock-Selection Procedure
- 4.2.1 Intersection Algorithm
- 4.2.2. Clustering Algorithm
- 5. Local Clocks
- 5.1 Fuzzball Implementation
- 5.2 Gradual Phase Adjustments
- 5.3 Step Phase Adjustments
- 5.4 Implementation Issues
- 6. Acknowledgments
- 7. References
- Appendix A
- Appendix B
- Appendix C
- Appendix D
- Appendix E
- Appendix F
- Appendix G
- Appendix H
- Appendix I
- Time Tools
- NTP Auditor
- About
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Windows Time Server
Standard Deviation Statistical FilterStandard Deviation is a statistical measure of variance in a sample set. It is calculated from the square root of the variance of the sample set as shown below :
where n is the number of data samples
and
denotes the arithmetic mean of the sample set.
The standard deviation of time measurements is important to PresenTense Time Server because it reflects the quality of the network connection to the legal source of Coordinated Universal Time and therefore reflects the quality of the time measurements themselves. As the quality of service on the internet is subject to variation, the standard deviation is computed for every set of measurements. If the standard deviation is excessively large or varies substantially from previous measurements, the affected measurements are marked as discarded.