Hi Gar: Interesting. I just tried a 30 minute power down, and again the ALIGN light in on. So I guess it's an overnight power down to get it reset.
More tomorrow, Brooke NE8S wrote: >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 > > > > -- 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
