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Regards, David Partridge -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bob Camp Sent: 17 October 2010 16:09 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] New (refurbished) LPRO-101 GPSDO Hi The antenna should do fine just sitting on the roof. It will do better sitting over a ground plane. Does the antenna have a clear view of the sky to the south? Bob On Oct 17, 2010, at 10:15 AM, David McClain wrote: > Well, not exactly an urban jungle here, but there could be multipath off the > neighbor's home... Thanks for that suggestion. I will try moving the antenna > about. > > When I first deployed it, the GPS would go solid reception for a while, and > it actually claimed to lock, after only an hour or so. But it kept losing the > birds and would go back into hunt mode after about 20 minutes of lock time. I > wasn't sure that I could trust the lock indication after so short a time. And > I didn't like the sporadic lock conditions. > > So I tried duct taping the antenna to the roof tiles that I could reach and > got solid GPS reception, but no lock. > > The antenna is a little black hockey puck with a magnetic base. I wonder if > it would do better affixed to a metal ground plane? > > First time user of a GPSDO and so I don't know what to expect. But I'm also > beginning to understand better that a GSPDO probably is more than was > warranted for the needs of a solid reference oscillator for radios. Now that > I'm learning more about Rb and GPSDO's in general, I probably could have got > by quite well with just a bare LPRO. And I am also beginning to understand > that GPSDO's don't necessarily have internal Rb references -- looks like the > T'Bird is just a really good OCXO with a GPS discipline. And everyone is > raving about T'Birds... The LPRO has an internal Rb reference and an untamed > VCXO. > > Thanks for all the advice! > > Dr. David McClain > Chief Technical Officer > Refined Audiometrics Laboratory > 4391 N. Camino Ferreo > Tucson, AZ 85750 > > email: [email protected] > phone: 1.520.390.3995 > web: http://refined-audiometrics.com > > > > On Oct 17, 2010, at 06:07, mike cook wrote: > >> >> >> Le 17/10/2010 11:55, David McClain a écrit : >>> >>> I just received my LPRO-101 with a GPSDO control on it, from TenMhz.com. >>> After fiddling with getting a good placement for the GPS antenna, so that >>> it doesn't keep losing the satellites, I have been attempting to discipline >>> the oscillator for more than 24 hours. >>> >>> At this point, the LED has been toggling red / green for the past 24 hours >>> which indicates solid GPS acquisition and < 5e-8. But it isn't locked to >>> NIST until it turns solid green which indicates < 5e-11. >>> >>> Since this is a first deployment at my location, is it reasonable behavior >>> for it to take longer than 24 hours to lock to NIST through GPS? Or do you >>> think something may be wrong with the device. >>> >> I don't have this box or an LPRO, but if the manafacturer says 24hrs is OK, >> then I guess that should be enough. You may need to give them a call. >> However am wondering if you are getting reflected path GPS signals. You said >> that you had to fiddle with the antenna placement. Are you in an urban >> jungle? I have a situation where I can see satellites at all times, but once >> or twice a day I am getting strong reflected signal which is disturbing the >> GPS 1PPS. It is due to buidings opposite my north facing office where the >> antenna sits. The issue is seen with my TBOLT, Z3801A and independent >> Oncore GPS engines all of which are not the latest hardware. That would >> cause the PLL to be constantly chasing a moving target. >>> I already know by comparison to WWV that I'm within a few mHz of >>> being aligned, but noise in the measurements, human impatience, and >>> wander in the soundcard clock, prevents me knowing any better than >>> this. So already I'm < 5e-10. But that's about all I know until I >>> see it lock. (If it ever does...) >>> >>> eh? >>> >>> Dr. David McClain >>> Chief Technical Officer >>> Refined Audiometrics Laboratory >>> 4391 N. Camino Ferreo >>> Tucson, AZ 85750 >>> >>> email: [email protected] >>> phone: 1.520.390.3995 >>> web: http://refined-audiometrics.com >>> >>> >>> >>> On Oct 15, 2010, at 16:00, Magnus Danielson wrote: >>> >>>> On 10/16/2010 12:08 AM, Bob Camp wrote: >>>>> Hi >>>>> >>>>> It's a crazy world when it comes to self signed certs. >>>>> >>>>> You have at least 5 OS's you need to consider (MS, Linux/FBSD, OS-X, >>>>> I-OS, Android). You need to think about both browsers and mail clients. >>>>> Each of those come from a half dozen sources on each platform. Then you >>>>> have configuration options on each. That's a lot of combinations. >>>>> >>>>> Each combo seems to have a different idea of what not to do when they see >>>>> a self signed cert. If you want to be able to handle all of them, even >>>>> "real" certs may have issues. There are indeed several common combo's >>>>> that are a major pain with a self signed cert. >>>>> >>>>> No, I didn't write any of the code with the problems in it. I also don't >>>>> want to get into the details of what and where. This really isn't the >>>>> forum for that sort of thing. I'm not out to bash any particular >>>>> solution, only to point out that there are indeed issues. >>>> >>>> Do handle part of the mess, we have setup our local root cert at the >>>> computer club, and then sign our server certs to that. I did a major >>>> overhaul on the infrastructure for that. It is still not "real" safety >>>> routines, but ah well. We provide a cert download which quickly solves the >>>> cert issue with most browser. >>>> >>>> Seems to work for our myriad of server and client OSes and clients. >>>> >>>> There is various ways to get "real" root certs, but depending on degree of >>>> uhm... safety... it may be argued of their capabilities. There is efforts >>>> to build a chain of trust for a stable free root cert, but it is so far >>>> nog included in any major browsers. >>>> >>>> Essentially it's a mess. I'm only scratched the surface here. >>>> >>>> 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. _______________________________________________ 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.
