Very good point...It is a new oscillator that has been sitting in a box for 10-15 years. I'll give it a few weeks to settle in. The other very interesting thing I noticed was the variability in the oscillator control voltage before and after installing the new Heol Design GPS. The moving average of the standard deviation of the oscillator control voltage before and after installing the Heol Design gps was striking. The variability of the control voltage for the Heal Design is nearly 1/3 of that for the original Trimble gps. That suggests that the pps signal from the new gps module has 1/3 the variability vs the original gps module. I did consider that this could be due to the new oscillator aging but when I do a linear regression on the standard error of the control voltage before replacing the gps module the p-value for the slope of the line is about 0.5 suggesting that the null hypothesis, that the slope is actually zero, cannot be rejected. Therefore, one would need to conclude that there is no change if control voltage variability vs time prior to the installation of the new gps module and, consequently, there was no change in the stability of the new oscillator (since everything else remained unchanged).
Unfortunately, I do not have sufficient run time on the new gps module to reach any meaningful conclusion of variability vs time. If anything it still appears to be dropping at this point. I can further update once I get additional run time. I also noted a very marked improvement in the satellite signal strength reported by the TS-2100. While I don't have any statistically sound data my observation is that the signal strengths are significantly higher and there are always more viable satellites in view. In the past I would never see more that 6-8 with 4-6 having sufficient signal strength. Now I routinely see 10 with 6 - 8 having sufficient signals strength. [image: Inline image 1] Note: The straight lines represent the mean value and are not linear regression although the linear regression and the mean line are very nearly the same for the original GPS data. I suspect the same will happen once I get some run time with the new GPS. Both imply that there is little time dependence, in the short term, on control voltage variability. Gerhard R Wittreich, P.E. On Tue, Jun 9, 2015 at 8:59 AM, Esa Heikkinen <[email protected]> wrote: > Gerhard Wittreich kirjoitti: > > Once locked I did notice >> something interesting but maybe not important. The control voltage to the >> oscillator (timing > util > tfp 0) went from a very consistent 0xba6f to a >> 0xbb02. That's about 0.2% of scale. I'll watch it over the next few days >> to see where it settles in. >> > > Sounds like oscillator aging to me, sometimes they do larger jumps, stay > there for a while and then again... Also it would not be suprising that > this would happen just after the power was off and oven was cooled down for > a moment. > > Also, brand new oscillators seem to age more rapidly at start and then > settles down when older but the effects of aging will never stop > completely. But they seem to get better and better when aging. > > I'm also waiting my MTI OCXO to arrive... > > -- > 73s! > Esa > OH4KJU > > _______________________________________________ > 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. >
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