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Reference Number: AA-02285// Views: AA-02285// Created: 2024-03-06 10:00:21// Last Updated: 2024-03-07 16:24:02 Q&A Q&A - Time Synchronization methods DescriptionThis article outlines different time synchronization protocols such as IRIG-B, PTP, PPS, NTP. Information about standards such as C37.118, and C37.118.1 are documented. IRIG-BIRIG-B stands for "Inter-Range Instrumentation Group Time Code format B". It is a time code format commonly used in applications where precise time synchronization is required, such as in aerospace, defense, telecommunications, and power systems. IRIG-B time code is transmitted using pulses over a communication link, typically a coaxial cable or an optical fiber. It encodes time information such as hours, minutes, seconds, and fractions of seconds, allowing synchronized timekeeping across multiple devices or systems.
The IRIG-B time code format includes various subformats, such as IRIG-B001, IRIG-B002, etc., each with specific characteristics and encoding methods. IRIG-B is often used in conjunction with GPS (Global Positioning System) to provide highly accurate time synchronization across distributed systems. How does IRIG-B work?IRIG-B time synchronization works by transmitting a one-way signal from a master clock to slave devices without feedback from the slave. To enable synchronization, additional fields are added to the IRIG-B code to allow the slave devices to align their time with the master clock1. This method is commonly used to synchronize devices like breakers, relays, switches, and other components in various applications2. What does IRIG-B000 DCLS mean?IRIG-B000 DCLS refers to a specific variant of the IRIG-B time code format. In the context of IRIG-B, "IRIG-B000" is a designation used to specify the format and characteristics of the time code, while "DCLS" stands for Differential Coherent Level Shift. IRIG-B time code formats are used for precise time synchronization in various industries, including aerospace, defense, telecommunications, and power systems. The "000" designation typically refers to the basic format or version of the IRIG-B time code, while additional letters or numbers may be appended to indicate specific variations or encoding methods. Differential Coherent Level Shift (DCLS) is a modulation technique used in some implementations of IRIG-B time code. In DCLS modulation, the time code signal is encoded by shifting the amplitude of the carrier signal between two levels in a coherent manner, where the transitions between levels encode the time information. This modulation scheme offers advantages such as improved signal-to-noise ratio and robustness against noise and interference. In summary, IRIG-B000 DCLS refers to a variant of the IRIG-B time code format that uses Differential Coherent Level Shift modulation for encoding time information. PTPPTP
stands for Precision Time Protocol. It is a protocol used for synchronizing
clocks in a network of computers or devices with high precision. PTP is
particularly important in applications where accurate and synchronized timing
is critical, such as in telecommunications, industrial automation, power
systems, and audio/video production.
PTP operates by exchanging timing messages between the master and slave clocks, allowing the slave clocks to adjust their local time to match the master clock's time with high precision. This enables synchronized operation of devices and systems within the network, facilitating tasks that require precise timing, coordination, and synchronization. PPSPPS stands for Pulse Per Second. A PPS signal is a timing signal that generates a precisely timed pulse once per second. It is often used as a reference for clock synchronization in various applications, particularly in systems where accurate timing is critical. The PPS signal is typically generated by a highly accurate timekeeping device, such as a GPS receiver or an atomic clock. These devices use satellite signals or other highly precise time references to generate the PPS signal, ensuring that the pulse occurs at the exact beginning of each second according to Coordinated Universal Time (UTC). PPS signals are commonly used in:
Overall, PPS signals play a crucial role in ensuring accurate and synchronized timing in a wide range of applications, helping to maintain the reliability and efficiency of various systems and processes. NTPNTP protocol stands for Network Time Protocol. It is an internet protocol used to synchronize computer clock time sources in a network, allowing the synchronization of system clocks from desktops to servers1, 2. NTP has been in operation since before 1985 and is one of the oldest Internet protocols still in use today, enabling clock synchronization between computer systems over packet-switched, variable-latency data networks3. The protocol plays a crucial role in ensuring accurate timekeeping across networks and systems, contributing to efficient operations and data consistency4. C37.118C37.118 packets refer to the data packets used in the IEEE C37.118 standard, which specifies the communication protocol for synchrophasor measurements in power systems. These packets are used to transmit synchrophasor data from Phasor Measurement Units (PMUs) to data concentrators or other devices in a power system communication network. The IEEE C37.118 standard defines the format and structure of these packets, including the information required for synchronized phasor measurements, such as voltage, current, frequency, and phase angle. These packets typically contain synchronized phasor measurements sampled at a high rate, along with metadata such as timestamps, quality flags, and device identifiers.
C37.118 packets are crucial for wide-area monitoring, control, and protection of power systems, as they enable real-time monitoring and analysis of the grid's dynamic behavior. They are transmitted over communication networks using various protocols such as Ethernet, UDP (User Datagram Protocol)1, or TCP (Transmission Control Protocol)2, depending on the specific implementation and requirements of the power system communication infrastructure. C37.118.1The term C37.118.1 refers to the IEEE standard that defines the normative synchrophasor measurement requirements. Specifically, IEEE C37.118.1-20111 outlines the necessary specifications for synchrophasor measurements, playing a crucial role in ensuring accurate and standardized synchronization of phasor measurements across different systems and locations. This standard is part of the broader IEEE C37.118 standard, which is widely used for synchrophasor data exchange both in the United States and internationally2. |