Putting GPS To Work
"When will it all happen?"
Although GPS is well-known for navigation, tracking, and mapping, it's also used to disseminate precise time, time intervals, and frequency. Time is a powerful commodity, and exact time is more powerful still. Knowing that a group of timed events is perfectly synchronized is often very important. GPS makes the job of "synchronizing our watches" easy and reliable.
There are three fundamental ways we use time. As a universal marker, time tells us when things happened or when they will. As a way to synchronize people, events, even other types of signals, time helps keep the world on schedule. And as a way to tell how long things last, time provides and accurate, unambiguous sense of duration.
GPS satellites carry highly accurate atomic clocks. And in order for the system to work, our GPS receivers here on the ground synchronize themselves to these clocks. That means that every GPS receiver is, in essence, an atomic accuracy clock.
Astronomers, power companies, computer networks, communications systems, banks, and radio and television stations can benefit from this precise timing. One investment banking firm uses GPS to guarantee their transactions are recorded simultaneously at all offices around the world. And a major Pacific Northwest utility company makes sure their power is distributed at just the right time along their 14,797 miles of transmission lines.
Time Can Buy Money
One large, international investment banking firm has given new meaning to "synchronize your watches". They've started using a Trimble Palisade NTP Synchronization Kit to synchronize their computer networks so that transactions at their London, New York, and Tokyo offices will be recorded simultaneously. To date, the firm has one Acutime and plans to get more. The GPS receiver serves as the time reference for the transactions happening on several thousand UNIX host machines and even more PC's.
According to their spokesman, the precision of GPS timing technology provides the firm with:
High-Energy Transmission with High-Precision GPS Time
- A constant source of market-time information,
- An inarguable reference time source for all transactions, and
- The ability to accurately synchronize log files for the ordering of transactions.
For most of us, the only time we think about the systems that supply our electrical power is when they fail us. Street lights winking off, the clock flashing 12:00, or flicking a switch with no result are a few ways we're reminded that there's a fallible organization responsible for providing our energy.
Given the amount of power a power company supplies, the number of customers they service, and the high-precision timing that the generation and transmission of electricity requires, it's surprising that power doesn't fail more often. Increasingly, GPS is becoming the tool that is used to provide that timing.
Since 1988, the Bonneville Power Administration in the U. S. Pacific Northwest has been integrating GPS technology into its operations. As an integral part of any electrical operations system, timing is the technology on which many of its functions are based. Generation and power transfers are planned in advance. Utilities coordinate with each other by making adjustments on a GPS timed schedule. Outages for maintenance are scheduled to ensure that they do not interrupt reliable power delivery. Disturbance records are aligned with recorded GPS time tags for analysis and comparison with related information. Price varies with demand, so even billing is based on time. Advanced applications like locating power line faults (short circuits) and real-time phase measurement require continuous timing with high precision. And bad timing can throw a monkey wrench into all these operations.
BPA administrator, Kenneth Martin puts it all in perspective. "With help from GPS we are finding ways to develop a comprehensive system that meets the needs of new applications while continuing to serve existing systems. In short, we have found that GPS is the universal answer for power system timing, meeting all requirements of accuracy, reliability, coverage, and cost."
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