Re: [time-nuts] Three-cornered hat on timelab?

Hi Magnus, Today I started a long run against my PRS-45A.  Maybe this time I won't have a power outage.  I'll see what it tells me in a few days. Bob  From: Magnus Danielson To: Bob Stewart ; Discussion of precise time and frequency

Re: [time-nuts] Three-cornered hat on timelab?

mag...@rubidium.dyndns.org said: > You can fair better if you have a double-frequency GPS setup, as it can > first-degree measure and compensate the ionospheric shifts, which allows > for a benefit over L1 CA only receiver. Are any dual-frequency receivers available at hobbyist prices? What is

Re: [time-nuts] Three-cornered hat on timelab?

Bob, First of all, there is a first degree of compensation from the GPS transmitted Klobuchar ionspheric model. There is a limit to how well those would match the actual values at the time and behavior for your spot on the globe. The GPS models this to a fair fit for the globe. Use of

Re: [time-nuts] Three-cornered hat on timelab?

Hi If you look at Tom’s data, he very definitely has a peak to peak in the 5 to 7 ns range over a 24 hour period. He also gets the expected auto correlation spikes. Bob > On Apr 17, 2017, at 4:38 PM, Bob Stewart wrote: > > Hi Tom, > The reason I express so much confusion

Re: [time-nuts] Three-cornered hat on timelab?

Hi Tom, The reason I express so much confusion over this is because I don't see the wild phase excursions on my GFS units that people insist will happen due to ionospheric effects.  Is this because they are rare events, and I just haven't been saving data during a bad time?  I notice in your

Re: [time-nuts] Three-cornered hat on timelab?

Bob S, Here's an example of a one week GPSDO run: http://leapsecond.com/pages/tbolt-8d/ IIRC, this was a default, untuned, self-surveyed TBolt. You can see some level of daily variations -- probably a mix of sky view, survey error, ionosphere, multi-path, sidereal effects [1], temperature

Re: [time-nuts] HP E1938

Hi Tom: I have some info on this at: http://www.prc68.com/I/HPE1938.shtml -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Original Message I purchased one of these HP E1938 OCXO recently on eBay but have not yet received

Re: [time-nuts] Three-cornered hat on timelab?

Hi Bob, OK, thanks.  I've kicked off a 7 day run of a GFS against the PRS-45A.  That should be long enough to separate out the GFS from the PRS' drift direction from the ionosphere. Bob  From: Bob kb8tq To: Bob Stewart Cc: Discussion of precise time

Re: [time-nuts] Three-cornered hat on timelab?

Hi One way to check what’s going on is to watch for 12 or 24 hour “blips” in the data. Unless you have a very unusual antenna setup, you should see some of them. They aren’t the ionosphere, but they are normally there in most datasets. Bob > On Apr 17, 2017, at 12:33 PM, Bob Stewart

Re: [time-nuts] Three-cornered hat on timelab?

Hi The ionosphere is the culprit in terms of the daily swing. The swing is a function of the goodness of fit between the GPS broadcast data and the ionosphere as it impacts the satellites you are using. There is no rime or reason to it beyond that. If you get “lucky” things don’t move much. If

Re: [time-nuts] Three-cornered hat on timelab?

Hi Bob, Oh, I had completely forgotten about the many runs you gifted us with back then.  Fortunately, I kept all of them in my email archive.  I can't compare like for like, of course, but I think I can work up something that compares at the larger taus where the 5370 doesn't dominate. I'm

Re: [time-nuts] Three-cornered hat on timelab?

Hi The data I have on the KS boxes was posted to the list back when they were.a hot topic. I’m sure it is still in the archives. I’m guessing it’s not quite what you are after. The closer the devices are to each other the better the technique works. A simple way to look at it is as an

[time-nuts] Efratom SLCR-101 vs LPRO-101

Hi, I've recently picked up a couple of SLCR-101s - one working normally, the other sold very cheaply as faulty - it doesn't stay locked for very long. I've not looked at the latter yet in any detail to see what's going on - considering it a side project for now in any case. Unless my

Re: [time-nuts] Re. DIY atomic "resonator"

Hi, On that note we have Rick Karlquists article showing how he replaced the traditional syntheis chain with an oscillator at the target frequency, locked to the lower frequency. Benefit is in the phase-noise. This was from the fine work on the 5071A. This approach can be used for rubidiums

Re: [time-nuts] Three-cornered hat on timelab?

Hi, This problem have since been addressed by Francois Vernotte as I saw in a presentation last year. He addressed the issue somewhat different than the traditional calculations to achieve the same problem. Turns out that correlation eats your noise if I recall things right. Cheers, Magnus

Re: [time-nuts] a link to a explanation of Rb vs Cs?

Hi, On 04/12/2017 01:17 PM, Bob kb8tq wrote: Hi If you take a look at the standard weekly publications, the GPS system runs on Rb’s. There is always one sat that has a Cs turned on. That’s been true as long as they have been running the system. The simple answer for that choice is that the

Re: [time-nuts] OCXO Soft-Start

Hi Scott, On 04/12/2017 11:38 PM, Scott Stobbe wrote: Hello, I wanted to see if I could soft-start a used OCXO (Trimble 34310) during warm-up. By default with an appropriately rated 12 VDC supply, the OCXO starts the heater at about 8 W, and eventually settles down to 2 W for 20-25 degC