Hi >From the ever useful Wikipedia:
http://en.wikipedia.org/wiki/Parts-per_notation ppt = parts per trillion. A change of one in 1,000,000,000. Just like ppm or ppb, only smaller. In this context at 10 MHz, 10 ppt would be a change of 0.0001 Hz. Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of SAL CORNACCHIA Sent: Thursday, January 21, 2010 10:45 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] LPRO Pressure Sensitivity Hi Bob, Can You explain what 10 PPT stands for. Thank You ________________________________ From: Bob Camp <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Sent: Thu, January 21, 2010 7:50:43 AM Subject: Re: [time-nuts] LPRO Pressure Sensitivity Hi Yes indeed. There really isn't a lot of data out there on pressure on rubidiums. Of course we don't talk about it a lot on our data sheets either ... If you accept that a normal day might have a 100 millibar change, That changes the frequency 10 ppt, if the guess is right. At 10X that level it would be as significant as temperature on a good unit. If it was that big it should get a lot more attention ... Bob On Jan 21, 2010, at 4:53 AM, Magnus Danielson wrote: > Bob Camp wrote: >> Hi >> Has anybody taken any data on LPRO's to see what their pressure sensitivity is? I'm guessing it's ~ 0.1 ppt / millibar. That's only a guess backed up by no data at all .... > > Do you mean 1E-13 per millibar? (I am only guessing) > > Cheers, > Magnus > > _______________________________________________ > 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. > _______________________________________________ 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. _______________________________________________ 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. _______________________________________________ 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.
