IEEE 1588 moves into new fields
Martin Rowe, Senior Technical Editor -- Test & Measurement World, 2/1/2009 2:00:00 AM
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The IEEE 1588 standard protocol synchronizes time and frequency in networked measurement and factory-automation systems. The LXI Consortium adopted the clock-synchronization protocol into its instrumentation standard, and because of its nanosecond timing, IEEE 1588 is moving into other areas as well. Telecom networks, military systems, financial systems, and many other Ethernet networks may soon use the protocol.
Enhancements adopted in IEEE 1588 v2 let time-synchronization packets, called “transparent clocks,” pass through switches and routers. Previously, the protocol could operate within a LAN only.
As wireless telecom carriers move from synchronous protocols to packet-based protocols, engineers at these carriers are considering IEEE 1588 as an inexpensive way to synchronize cellular base stations. Operators of wireline networks are looking into the protocol for delivering synchronized audio and video.
“Telecom network operators can reduce costs by moving to packet-based networks,” said Kevin Hsu, VP of marketing for telecom at Symmetricom. “But they lose synchronization. With IEEE 1588, nodes on packet-based networks can be synchronized in both frequency and time. The protocol will let base stations pass calls to one another while keeping calls synchronized.”
 This Ethernet PHY IC has IEEE 1588 clock and control functions implemented in silicon.. Courtesy of NationalSemiconductor. |
Jon Waters, applications engineer at IXXAT Automation, a producer of IEEE 1588 protocol stacks, noted that in rural areas, a cellular base station might use the GPS as a master clock, then use IEEE 1588 to synchronize other base stations in its area.
Home-based wireless networks can use femtocells to connect cellphones through Internet connections in homes with weak wireless signals. Hospitals and colleges may use small cells to provide communications and to locate personnel. As a result, IXXAT’s protocol stack is finding its way into DSPs (digital signal processors) and NICs (network interface cards) for use in these products.
Ethernet PHY interface ICs from National Semiconductor now have embedded IEEE 1588 (figure). Alex Tan, product manager at the company, noted that these devices can be used in energy-automation systems: “Electrical substations can use the GPS to obtain a clock, then use IEEE 1588 to distribute it to other stations.”
“IEEE 1588 may also replace IRIG-B for synchronizing clocks in military systems,” said John Eidson of Agilent Labs. Eidson, who wrote the book on IEEE 1588 (Ref. 1), sees it eliminating the clock-synchronization wires that IRIG-B requires.
Waters also pointed out that IXXAT has received inquiries from people interested in using IEEE 1588 for timing of financial systems. “In these economic times, a financial institution must process millions of transactions a second. Networks need to know the precise order at which transactions are received. Current desktop computers synchronized with NTP [Network Time Protocol] can provide 1-ms resolution at best, so it’s impossible to tell which orders came in first. IEEE 1588’s nanosecond resolution solves that problem.”
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| 1. Eidson, John C., Measurement, Control, and Communication Using IEEE 1588, Springer Science+Business Media, 2006. www.springer.com. 2. Rowe, Martin, “IEEE 1588 Keeps Time in Sync,” May 5, 2005. www.tmworld.com/article/CA529830.html. 3. Eidson, John C., Measurement, Control, and Communication Using IEEE 1588, Springer Science+Business Media, 2006. www.springer.com. For further information: “Introduction to IEEE 1588,”ieee1588.nist.gov. Eidson, John C., “Implementing IEEE 1588 in LXI,” LXI Consortium, www.lxistandard.org/about/events/pastEvents/Implementing_IEEE_1588_in_LXI.pdf. |
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