Ulrich Bangert wrote: > Hi folks, > > first i would like to announce a new version of PLOTTER which can be > downloaded from > > www.ulrich-bangert.de > > The new version can classify data and compute new data columns from > existing ones using a formula interpreter in that you may input a > formula of your own. A lot of mathematic expressions are supported. > > Second, i would like to say thanks to anybody who answered on my > "Frequency processing scheme of HP5065 rubidium vapour standard" thread. > As usual in this group the (s+n)/n of the answers has been high. > Nevertheless I dare to state that the basic question of mine is still > unanswered. I believe that this is due to English not being my natural > language so perhaps i did not manage to make the question really clear > to everybody. Let me try again. > > Rubidium is NOT a PRIMARY frequency standard. Point. This has been well > understood before I put forward my question and a lot of you have > pointed to environmental parameters that may have a influence on the > resonance frequency one may measure with a given physics package. > > The basic question has not been WHY the atomic resonance frequency is > dependend on environmental parameters. The question has been TO WHAT > EXTENT or expressed in other words IN WHICH ORDER OF MAGNITUDE these > environmental parameters have an influence on the resonance frequency. > > This question has a very practical background: > > If you look at the schematics of a Ball-Efratom FRK-L rubidium standard > you will notice that it has a fixed frequency synthesizer stage to > generate the microwave frequency from the 10 MHz OCXO. There is NO > possibility to tune anything concerning the microwave frequency of the > physics package OTHER than the C-field setting. Since the C-field > setting covers a frequency range of +/- 1E-9 relative this seems to be a > strong indication that all efects that you decribe (including a exchange > of the physics package) must be WELL below 10E-9 relative. With the > resonance frequency in the 7 GHz region +/-10E-9 makes abt. +/- 7 Hz > absolute. Note that this +/-7 Hz matches pretty much the way how the > rubidium's frequency is usually specified as x.xxxxxx +/- 4 (7)Hz for > example on TVB's pages. Up to this point I am in harmony with the world. > > Now comes the strange fact: HP's 5065 is equipped with a tuneable > synthesizer to generate the microwave frequency from the OCXO. HP states > that this tuneable synthesizer can be used to generate a number of > different 'time scales' as some of you also have pointed at. I > understand this very well! > > But the STRANGE thing is that HP uses DIFFERENT synthesizer settings > albeit the intended purpose of the tuning ALSO to generate THE SAME time > scale with two different physics packages. > > That is what we found on two different physics packages: > > Physics Package 1 C-Field 7.21 Synth. 8619 - 5.31498914 > Mhz > > Physics Package 2 C-Field 8.24 Synth. 8397 - 5.31503431 > Mhz > > Please note that the two synthesizer setting are different by MORE THAN > 45 Hz. This is just one example, other physics packages may perhaps even > be more apart. We have seen above that there is reason to believe that > all environmental influences are smaller than +/-7 Hz. So where comes > this 45 Hz difference from? > > Cheers > > Ulrich Bangert, DF6JB > > > _______________________________________________ > time-nuts mailing list > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > Ulrich
The manual for the SRS PRS10 states that the combined effects of the buffer gas and the pump lamp spectral profile shift the resonance about 3kHz from the unperturbed natural transition frequency. With a different buffer gas, lamp spectral profile, or buffer gas pressure the resonance shift will be different for different physics packages. Perhaps Efratom relied on the reproducibility of lamp characteristics, buffer gas pressure, buffer gas composition during the manufacturing process whilst HP allowed for variations in these parameters from one physics package to another. Bruce _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
