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 -- [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.
