Found this link on the Yourdon forum today:

http://www.house.gov/science/rhodes_051299.htm

It's testimony on GPS, which is used for a variety of things in the power biz. Good discussion - check it out.

-- Anonymous, May 20, 1999

Answers

Even if GPS is lost for a while the (more expensive) clocks have built in "flywheels" that keep the time accurate for a long long time. We've conducted tests on the accuracy of the clocks when GPS is lost and it is within 500 micro-seconds for a week.

It should be noted that the accuracy standard for time synch (for the Western Grid) is + or - two seconds.

-- Anonymous, May 20, 1999

What if the problem is, not that GPS is "lost", but either that GPS transmitters send the "wrong" time or that ground receivers get (calculate) the "wrong" time (as in neglect of week-counter rollover)?

-- Anonymous, May 20, 1999

I live in North Dakota where our population does not justify the most expensive equipment. An electrical engineer for a telephone company told me that a less expensive telephone system would begin to lose its synchronization within about a day. He said it would denegrate data communications first and then voice communications.

-- Anonymous, May 23, 1999

If you set the calendar on your watch to the wrong date you can still set the time correctly. They are independent functions. If you dont fix the week roll over counter you could still have the correct time from the clock (depending on the clock). The rest of the questions are what ifs? Why should they send the wrong time? You cant have a reasonable debate when you just say what if everything goes wrong. What if the chips were made badly and they all failed the day after tomorrow? What if another errant rocket launch causes several of the satellites to be hit, spinning them out of orbit. Some of these are as (or as not) probable as some Y2K arguments.

As for the comment from North Dakota. I cant say if that is true or not. It would seem strange that they would buy such cheap equipment but..? On the other hand what did the engineer mean by loose synchronization. The question should be to what tolerance? Nanosecond, Microsecond, millisecond? And it does make me wonder how they had voice communication before GPS or Atomic Clocks? The voice, and even a primitive data network, was around long before those systems.

-- Anonymous, May 24, 1999

The Engineer wrote:

> The voice, and even a primitive data network, > was around long before those systems.

Yes, that is true. And we did a lot of stuff before GPS came around. How many people do you think there are on the face of the planet right now that have, and know how to use properly, a sextant, and can deal with the math of reducing sights, and figure out exactly where they are?

The fallacy of your argument is that you assume we can go back to previous techniques. Sometimes you can, but most times, the knowledge and equipment to do that is long gone.

We can build cars without computers, but I don't imagine any of the big three would be able to stay in business long if their modern computerized robotic manufacturing plants didn't work.

I don't know where the electrical industry stands on this issue. I do know that dismissing problems like GPS because "50 years ago we did it a different way" is silly. How we did things 50 or even 20 years ago doesn't help one iota if the equipment is *only* set up to do things the "modern" way, or if there aren't enough knowledgeable, experienced people to do it the "old" way.

Jon

-- Anonymous, May 24, 1999