Agreed. My consideration was general but, yes, money is necessary so a decision is a must to properly allocate the financial resources.
On Tue, Apr 3, 2012 at 1:10 PM, Jim Lux <[email protected]> wrote: > On 4/3/12 12:49 AM, Azelio Boriani wrote: > >> Yes, but nonetheless why not develop more stable primary clock sources? We >> can always take care of the dissemination in the meantime and try to >> develop a more precise time transfer method. >> >> On Tue, Apr 3, 2012 at 2:39 AM, beale<[email protected]> wrote: >> >> Having read this NIST review paper by Thomas E. Parker, "The uncertainty >>> in the realization and dissemination >>> of the SI second from a systems point of view" >>> http://tf.boulder.nist.gov/**general/pdf/2564.pdf<http://tf.boulder.nist.gov/general/pdf/2564.pdf> >>> >>> ...it seems that any potential improvement in frequency standards (Cs >>> fountain -> optical clocks) will not benefit most time/frequency users, >>> because existing long-range time-transfer methods (TWSTFT and GPS carrier >>> phase) are still limited to at best 2E-16 for 30-day averaging, and there >>> is no generally practical way to improve them currently in sight. (Laser >>> ranging of satellites being considered not generally practical). Just >>> curious what people think, is this too pessimistic a view, or is it fair >>> to >>> say that having a 10x improved primary standard would not improve >>> stability >>> or accuracy for anyone outside of stabilized optical-fiber distance from >>> such a standard? >>> >>> >>> > > In general, as a technology developer, I agree with you, but the sources > of money with which to develop technology often have a slightly different > view. > > If one has limited resources, there's a desire to spend the resources > where they will produce something that is usable. Since there are more > things to spend money on than there is money to spend, the money has to get > allocated, and that allocation process cannot be done in a truly objective > way. > > In my own field of space telecommunications, it seems self evident to me > that faster data links are better, but from the perspective of a national > funding source, they have to decide where to spend their money: faster > telecom; new science instruments; precision pinpoint landing, etc. So > what they do is look for places to spend money that are "enabling" new > science. > > there is a sort of circular argument.. you need scientists to stand up and > say "I need communication technology Y to do my science" (creating what is > known as a "validated requirement"), but, on the other hand, the scientists > have a very strong incentive to say "I can do my science with existing > communication technology X", because that makes their mission proposal > lower risk (or, at least, reduces the risk in "infrastructure" sorts of > ways. That is, they'd rather spend their risk budget on the science > measurement, not on getting the data back to Earth. > > > So, the comment from Parker is quite relevant. If you have no way to > distribute your incredibly precise time, there's no way to get it to users, > so it's not clear whether you should spend your money getting the precise > time, or spend your money on trying to figure out a way to distribute it, > first. Or, should you make your really accurate clock small and portable, > so you can effective distribute it by making lots of them (they are > *primary* standards, after all) > > This is why there is interest in a 1kg, 1 liter Hg+ ion clock for > spacecraft, of course. And you too can have a demonstration of one in > space for around $100M. > > http://www.nasa.gov/mission_**pages/tdm/clock/clock_**overview.html<http://www.nasa.gov/mission_pages/tdm/clock/clock_overview.html> > > > > > ______________________________**_________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/** > mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
