Hi Bob, So, to use this as a phase reference for testing my unit, I'd have to get the phase error out each second and correct for that? Or is it a matter of the OCXO getting happy over the next few weeks and it will settle down? In my mind's eye, I see its DAC moving on a slope just like mine is, as the OCXO ages in.
It looks like I need to put a shelf on the wall and give this a permanent home. At the very least, that would get it out of my way so I can do other work. All things considered, it's a good problem to have. =) Bob From: Bob Camp <kb...@n1k.org> To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Saturday, October 25, 2014 11:12 AM Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup Hi If the Z3810/11/12 is like the other HP / Symmetricom boxes (and I’d bet it is): 1) It will go into survey and sync relatively slowly compared to some of the other units. 2) It’s got a less sensitive / lower channel count receiver than stuff like Said’s new part. 3) It will take a *long* time to get to it’s best stability operating point. Think weeks / months not hours. 4) It has pretty good environmental rejection. You won’t see much (as in any) benefit in a normal basement / always locked installation. 5) It’s phase noise isn’t as good as some units. (like a TBolt ) 6) Lady Heather does not play well with one :( My guess is that the Z3805 has pretty much the same “stuff” in it. They both come from the same era and (may) have the same MTI OCXO in them. Bob > On Oct 25, 2014, at 11:24 AM, Bob Stewart <b...@evoria.net> wrote: > > Hi Bob, > > During the first hour it reported poor geometry a number of times. Then it > seemed to get its act together and was solidly into survey mode. A few hours > later and it was satisfied with life and went into hold mode, with TFOM=3, > FFOM=0. > > This morning, I see that there is some phase tracking difference of opinion > between my GPSDO and this one WRT the 10MHz signal out from REF-0. > > http://evoria.net/AE6RV/GPSDOe/Z3812A.10.25.png > > The green is the phase difference plot, and the red is the ADEV. Given this > is the first time I have done this against another GPSDO, I don't know > whether this is good or bad. Looking at the phase plot on my unit, it > wanders around a bit but not 100ns. > > http://evoria.net/AE6RV/GPSDOe/GPSDO.10.25.png > > Sorry the plot is so busy with debug traces. You can easily spot the same > phase difference line as in the one above. The blue squiggle is my phase > error. The red is my DAC. The phase in this plot is in hundreds of ps. I > have shut the unit down numerous times recently, and the OXCO has been > subjected to different thermal environments. Right now the case is closed, > there are no vent holes, and the temperature in the box on my PCB is just a > bit over 99 degrees F. > > Bob > > From: Bob Camp <kb...@n1k.org> > To: Bob Stewart <b...@evoria.net>; Discussion of precise time and frequency > measurement <time-nuts@febo.com> > Sent: Saturday, October 25, 2014 7:09 AM > Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup > > Hi > > One of the interesting things about these little receiver modules is that > they don’t all report the same survey location. There are NIST papers with > examples. You could probably spend a lot of time on the “why”. > > If you are getting “poor geometry” errors, either you have an antenna issue, > or your receiver is in trouble some other way. It should go into survey mode > and stick there. It should be solidly into the survey after about 10 minutes > power on. > > Bob > > > > > On Oct 24, 2014, at 9:46 PM, Bob Stewart <b...@evoria.net> wrote: > > > > Sorry if these comments are a bit naive, but this is my first exposure to a > > Z38xx. > > > > I've got mine powered on and connected to the antenna. After referring to > > Stewart's original post (once again) I've managed to download HP's SATSTAT > > and get it running. When I connected to the REF-1 unit (with the receiver) > > all I get is comms errors. But when I connect to REF-0, Satstat seems > > quite happy. It's reporting the unit as a Z3812A. Is REF-0 the only one > > you can connect to, or is REF-1 mute till it's happy with the GPS receiver? > > > > The mode says "Power-Up: GPS Acquisition", so I guess that's OK. I think > > things are progressing. It's attempting to survey, but reporting > > "Suspended: poor geometry". I suppose with a little more time this will > > work itself out? It seems to be slowly tracking more sats, as it's now up > > to 5. > > I wonder if there's a way to shortcut the survey process using Satstat? > > I've got a 48 hour survey done on this antenna with the LEA-6T, so I should > > be able to input those figures, right? I'll see if I can find anything in > > a Satstat manual I found. > > > > Bob - AE6RV > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.