Brooke, Now that you mention it, I did power down at first for 45 minutes. After this initial power-up sequence, the same prevailed. I then decided on the 24 hour down period for the oscillator and cesium ovens to fully recycle.
Gar ----- Original Message ----- From: "Brooke Clarke" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <[email protected]> Sent: Monday, March 06, 2006 11:54 AM Subject: Re: [time-nuts] FTS4060 Continuing Saga > Hi Gar: > > OK. It's time to pull the plug and leave it out for awhile. > I tried pulling the plug for 10 seconds, but that may not have been long > enough to get the oven cooled down. > > More later, > > Brooke > > NE8S wrote: > >>Brooke, >> >>One of my FTS4060's behaved the same way during a power interrupt. It was >>the only one that was not on a UPS. After many attempts to reset the logic >>while powered up, I finally brought the clock down and 24 hours later, >>powered it back up again. As a result, it performed its normal power-up >>sequence and the control logic seemed to have reset itself properly. It >>this >>point, it was back to normal. It has been fine ever since. >> >>First time it has happened to me. I am mainly an HP man and very much >>prefer >>the HP clocks and their digital logic structure and methods. >> >>Hope this helps a little. >> >>Kind regards, >> >>Gar Ko >>NE8S >>CsUTC Observatory >>Bio-Nucleonics Laboratory >> >>----- Original Message ----- >>From: "Brooke Clarke" <[EMAIL PROTECTED]> >>To: "Tom Van Baak" <[EMAIL PROTECTED]>; "Discussion of precise time and >>frequency measurement" <[email protected]> >>Sent: Monday, March 06, 2006 10:58 AM >>Subject: Re: [time-nuts] FTS4060 Continuing Saga, GPS rain >> >> >> >> >>>Hi Tom: >>> >>>I think the problem is related to the FTS4060. During the brown out my >>>computer and the SR620 counter reset, but the two green LEDs on the 4060 >>>stayed on, at the time my thought was "cool". But the yellow "Align" >>>light behind the door has turned on and so far I have not been able to >>>get it to turn off. But after trying a bunch of stuff the jitter value >>>is now back in the 9 ns area. I have not been able to find anything in >>>the manual about operation with the "Align" light on and with the "Lock" >>>and "AC Pwr" LEDs on. Does anyone have any ideas about it? >>> >>>On the rain thing. I think the key parameter of water that matters is >>>the dielectric constant which is about 80. The propagation constant is >>>proportional to 1 / SQRT( e ) or about 11% of what it is in air. If >>>it's 1 ns per foot in air then it's 8.9 ns per foot in water >>> >>>I haven't figured out how to calculate the total volume of water in the >>>column between the satellites and the receiving antenna. I did find a >>>web page that shows the terminal velocity of rain and it varies from >>>0.02 MPH for small drops to 20 MPH for big drops. But this would need >>>to be coupled with the rate of rain fall (inches/hour) to determine how >>>much water was in the column. Assuming big drops (20 MPH = 352 IPS) and >>>0.1 IPS rain rate says that the rain takes up 1 part in 3520. If the >>>height of the rain is 20,000 feet then there's 5.6 feet of rain for a >>>delay of 50.5 ns??? >>> >>>Have Fun, >>> >>>Brooke >>> >>>Tom Van Baak wrote: >>> >>> >>> >>>>>Rain should have an effect on the timing of the signal, since the >>>>>propagation speed of radio waves through water is different from that >>>>>through air. It will also attenuate the signal, causing worse S/N >>>>>ratio which would cause the lower-elevation satellites to not be seen. >>>>> >>>>> >>>>> >>>>> >>>>David, >>>> >>>>Maybe we can figure this out. First, the refractive >>>>index of water is about 1.3. So I think this means >>>>the propagation speed of radio waves in water is >>>>down to about 0.75 c, right? >>>> >>>>Then, how much water are the GPS signals traveling >>>>through? Let's assume the typical amount of rain in >>>>a heavy storm is a couple of inches. All that water is >>>>either puddles already on the ground, drops on their >>>>way down, or moisture still in the clouds waiting to >>>>come down. >>>> >>>>The total amount of water in a cross section column >>>>of the atmosphere that the GPS signals travel though >>>>is thus a couple of inches total, max. Let's assume >>>>a worst case -- 6 inches. >>>> >>>>So, those GPS signals go through 20,000 km of >>>>empty space and atmosphere containing a total of >>>>6 inches of water; in which it slows down by 30%. >>>>At a ns/foot, this comes to 25 ps per inch of water >>>>content in the air; a total of 150 ps in my worst-case >>>>example above. >>>> >>>>My conclusion is that rain or snow, light or heavy, >>>>has no effect, even at the ns level. Can someone who >>>>really knows double check this back of the envelope >>>>calculation? >>>> >>>>Thanks, >>>>/tvb >>>> >>>> >>>> >>>>_______________________________________________ >>>>time-nuts mailing list >>>>[email protected] >>>>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>>> >>>> >>>> >>>> >>>> >>>> >>>-- >>>w/Java http://www.PRC68.com >>>w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml >>>http://www.precisionclock.com >>> >>>_______________________________________________ >>>time-nuts mailing list >>>[email protected] >>>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> >>> >> >> >>_______________________________________________ >>time-nuts mailing list >>[email protected] >>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> >> >> >> > > -- > w/Java http://www.PRC68.com > w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml > http://www.precisionclock.com > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
