Hi all, Just wondering how many people have used John Miles work @ http://www.ke5fx.com/tbolt.htm, or similar, to discipline a rubidium oscillator and if so... 1. what was the RB of choice ? 2.have any measurements of phase noise etc. been published on such a rig ? 3. Are there any published how-to's etc. available ? I'd like to build such a beast as my lab standard so any help appreciated. thanks Tim -- VK2XTT :: QF56if :: BMARC :: WIA :: AMSAT-VK :: AMSAT

On 07/12/11 02:15 AM, Tim Tuck wrote: > Hi all, > > Just wondering how many people have used John Miles work @ > http://www.ke5fx.com/tbolt.htm, or similar, to discipline a rubidium > oscillator and if so... > > 1. what was the RB of choice ? > 2.have any measurements of phase noise etc. been published on such a rig ? > 3. Are there any published how-to's etc. available ? > > I'd like to build such a beast as my lab standard so any help appreciated. > > thanks > > Tim I'm no expert on this, but I believe that the rubidiums have poorer phase noise than crystals, so unless holdover performance is an issue, there is no advantage in using a rubidium over a crystal as long as GPS lock is maintained at all times. The Stanford PRS-10 rubidium looks to be quite nice, as it has a 10 MHz crystal to give good phase noise and also the rubidium for medium term stability. It can be disciplined easily, as it has a 1 pps input. Alas the PRS-10 is not as plentiful (i.e. cheap) as some other rubidiums. There may be better ways, but a PRS-10 and a timing receiver which outputs 1 pps looks to be a relatively easy way to get the short term peformance of a crystal, the medium term performance of a rubidium should the GPS get unlocked and the long term stability of GPS. I'm looking for a lab standard too, so I'd be interested in what other replies you get. For me personally, for a short term solution, I'm thinking of using an undisciplined rubidium. -- A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

Hi David, Just to clear the AIR, all Rubidium frequency standards have a crystal oscillator as the primary signal source within the Rubidium device. The Rubidium portion of the standard is just a very high Q filter whose properties can be controlled such that it's filter's center frequency has extremely small drift. That small drift factor is, typically, way less then the resulting factors that control drift in a Quartz resonator. In order to gain the properties of the Rubidium's longer term stability and the short term noise properties of a very good Quartz oscillator you would need both items. You select a very good Quartz device and phase lock it to a really good Rubidium (with its own Quartz oscillator). You would adjust the loop constants to correct at a very slow pace consistent with the quality of the very good Quartz oscillator. To get to the next level (connection to the Nation's reference), you would discipline the Rubidium against a GPS device with an even slower loop. So, in the end you have two separate loops with three separate devices. This is not your "Nickel & Dime store" plug-and-play set up. It would have to be set up with care and some experimentation to get it right. For a reference on the basic process, you should read the QST article on Brooke Shera's GPS disciplined oscillator system. Contained within it is a description of the loop process I referred to above. To utilize his method would require upgrading his circuit design (some parts not available any longer) and some software upgrading as well to account for those changes. To obtain the QST article go to Shera's web site at http://www.rt66.com/~shera/ Also click on the "more information line" for further reading. Bill....WB6BNQ "Dr. David Kirkby" wrote: > On 07/12/11 02:15 AM, Tim Tuck wrote: > > Hi all, > > > > Just wondering how many people have used John Miles work @ > > http://www.ke5fx.com/tbolt.htm, or similar, to discipline a rubidium > > oscillator and if so... > > > > 1. what was the RB of choice ? > > 2.have any measurements of phase noise etc. been published on such a rig ? > > 3. Are there any published how-to's etc. available ? > > > > I'd like to build such a beast as my lab standard so any help appreciated. > > > > thanks > > > > Tim > > I'm no expert on this, but I believe that the rubidiums have poorer phase noise > than crystals, so unless holdover performance is an issue, there is no advantage > in using a rubidium over a crystal as long as GPS lock is maintained at all times. > > The Stanford PRS-10 rubidium looks to be quite nice, as it has a 10 MHz crystal > to give good phase noise and also the rubidium for medium term stability. It can > be disciplined easily, as it has a 1 pps input. > > Alas the PRS-10 is not as plentiful (i.e. cheap) as some other rubidiums. > > There may be better ways, but a PRS-10 and a timing receiver which outputs 1 pps > looks to be a relatively easy way to get the short term peformance of a crystal, > the medium term performance of a rubidium should the GPS get unlocked and the > long term stability of GPS. > > I'm looking for a lab standard too, so I'd be interested in what other replies > you get. For me personally, for a short term solution, I'm thinking of using an > undisciplined rubidium. > > -- > A: Because it messes up the order in which people normally read text. > Q: Why is top-posting such a bad thing? > A: Top-posting. > Q: What is the most annoying thing in e-mail? > > _______________________________________________ > 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.

Here's an app note from NASA on what they did for controlling, or filtering, phase noise, and it can get complicated. http://ipnpr.jpl.nasa.gov/progress_report2/XII/XIIK.PDF Best, Will *********** REPLY SEPARATOR *********** On 7/12/2011 at 1:44 AM WB6BNQ wrote: >Hi David, > >Just to clear the AIR, all Rubidium frequency standards have a crystal oscillator as >the primary signal source within the Rubidium device. The Rubidium portion of the >standard is just a very high Q filter whose properties can be controlled such that >it's filter's center frequency has extremely small drift. That small drift factor is, >typically, way less then the resulting factors that control drift in a Quartz >resonator. > >In order to gain the properties of the Rubidium's longer term stability and the short >term noise properties of a very good Quartz oscillator you would need both items. You >select a very good Quartz device and phase lock it to a really good Rubidium (with its >own Quartz oscillator). You would adjust the loop constants to correct at a very slow >pace consistent with the quality of the very good Quartz oscillator. > >To get to the next level (connection to the Nation's reference), you would discipline >the Rubidium against a GPS device with an even slower loop. So, in the end you have >two separate loops with three separate devices. This is not your "Nickel & Dime >store" plug-and-play set up. It would have to be set up with care and some >experimentation to get it right. > >For a reference on the basic process, you should read the QST article on Brooke >Shera's GPS disciplined oscillator system. Contained within it is a description of >the loop process I referred to above. To utilize his method would require upgrading >his circuit design (some parts not available any longer) and some software upgrading >as well to account for those changes. > >To obtain the QST article go to Shera's web site at http://www.rt66.com/~shera/ >Also click on the "more information line" for further reading. > >Bill....WB6BNQ > > >"Dr. David Kirkby" wrote: > >> On 07/12/11 02:15 AM, Tim Tuck wrote: >> > Hi all, >> > >> > Just wondering how many people have used John Miles work @ >> > http://www.ke5fx.com/tbolt.htm, or similar, to discipline a rubidium >> > oscillator and if so... >> > >> > 1. what was the RB of choice ? >> > 2.have any measurements of phase noise etc. been published on such a rig ? >> > 3. Are there any published how-to's etc. available ? >> > >> > I'd like to build such a beast as my lab standard so any help appreciated. >> > >> > thanks >> > >> > Tim >> >> I'm no expert on this, but I believe that the rubidiums have poorer phase noise >> than crystals, so unless holdover performance is an issue, there is no advantage >> in using a rubidium over a crystal as long as GPS lock is maintained at all times. >> >> The Stanford PRS-10 rubidium looks to be quite nice, as it has a 10 MHz crystal >> to give good phase noise and also the rubidium for medium term stability. It can >> be disciplined easily, as it has a 1 pps input. >> >> Alas the PRS-10 is not as plentiful (i.e. cheap) as some other rubidiums. >> >> There may be better ways, but a PRS-10 and a timing receiver which outputs 1 pps >> looks to be a relatively easy way to get the short term peformance of a crystal, >> the medium term performance of a rubidium should the GPS get unlocked and the >> long term stability of GPS. >> >> I'm looking for a lab standard too, so I'd be interested in what other replies >> you get. For me personally, for a short term solution, I'm thinking of using an >> undisciplined rubidium. >> >> -- >> A: Because it messes up the order in which people normally read text. >> Q: Why is top-posting such a bad thing? >> A: Top-posting. >> Q: What is the most annoying thing in e-mail? >> >> _______________________________________________ >> 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. > >__________ Information from ESET Smart Security, version of virus signature database 5851 (20110206) __________ > >The message was checked by ESET Smart Security. > >http://www.eset.com

Hi Any time you get into something like this, there are a lot of qualifiers on everything. That makes for a number of special cases. Ignoring them and looking at the most likely: 1) Your typical modular Rb will beat your typical good OCXO past a few hundred seconds on short term stability. 2) The same Rb will start to degrade on short term stability past a few thousand seconds. (Curve goes down, levels, and then starts to come back up). 3) GPS it's self starts out pretty awful. It just keeps getting better the longer you look at it. 4) Most good GPS's will get better than most modular RB's between 5,000 and 50,000 seconds. 5) We are talking about radio here. The atmosphere does matter. There are some daily cycles that might push you out past 86,000 seconds for a unit that's stable under all conditions. You could go with an L1/L2 receiver if you have one available. Of course, what matters is "what do the ones I have do" and not what a typical population does. You might select parts that do a bit better than typical. That is likely to involve some measure and adjust cycles. If you toss in a TBolt rather than a simple GPS receiver, it's going to clean up some of the GPS crud for short time intervals. That may or may not help things overall. It's not likely to hurt anything though. That's the overview, there are a whole lot of grubby little details each step along the way. Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Tim Tuck Sent: Monday, July 11, 2011 9:16 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Disciplining a Rubidium with a Thunderbolt. Hi all, Just wondering how many people have used John Miles work @ http://www.ke5fx.com/tbolt.htm, or similar, to discipline a rubidium oscillator and if so... 1. what was the RB of choice ? 2.have any measurements of phase noise etc. been published on such a rig ? 3. Are there any published how-to's etc. available ? I'd like to build such a beast as my lab standard so any help appreciated. thanks Tim -- VK2XTT :: QF56if :: BMARC :: WIA :: AMSAT-VK :: AMSAT _______________________________________________ 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.