Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of EWKehren@aol.com Sent: Thursday, January 12, 2012 10:43 AM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Mechanical Question Bringing out the C field in my estimation does not effect long or short term.

from "The Allan variance is intended to estimate stability due to noise processes and not that of systematic errors or imperfections such as frequency drift or temperature effects" ws ******************** ----- Original Message ----- From: "John Ackermann N8UR" Subject: Re: [time-nuts] Update on Rb Performance

Was the jitter estimation I made for the single Rb correct? Fabio. P.S. The micro's adc is charachterized for total unadjusted error of +-2LSB Max at 25°C, 12bit total. It's s-h is 8pF with 1kohm in series, probably I can sync the sampling to open just before the pulse, and close after the fact.

> http://www.vk2hmc.net/blog/wp-content/uploads/2013/04/z3805-flash.rar Assuming that the Z3801A and Z3805A ROM contents is somewhat similar (1x512k = 4x128k), let's take a look at the entropy of the data: $ cat z3801a.bin | xz --stdout | wc -c 110020 $ cat z3805-*.bin | xz --stdout | wc -c 60436 This rough estimate on the amount of non redundant data

Another thing, the frequency detector phase history may need to be unwrapped prior to subtraction in order to make sure the frequency estimate becomes correct. > Turning on the "D" term in a PID with a prefilter is mostly not > recommended, They tend to just cancel each other.

In C mode, you get one output every 2 seconds, each of which is an estimate from 100 seconds of measurement, but 98 seconds of that data was also part of the previous output and only 2 seconds of new data is included). What does the data returned by the counter actually look like?

. > > >I also disagree with your estimate of the CR5 zener current. [...] > >[...] > >the CR5 diode current must be (12.2195 - 4.2456 mA) = 7.9739 mA. > > Good point. > > >That's > >pretty close to the zero temperature coefficient current for the 1N938 > >you describe.

2015 13:03:02.350, >clock=d9b79169.f52bbe6f Thu, Oct 1 2015 13:03:05.957, peer=33608, tc=4, reftime is the last ref clock time used - clock is just the current time >mintc=3, offset=0.000, frequency=-27.210, sys_jitter=0.043, offset=0.000 says the system time is not yet set - should be low us frequency=-27.210 has to stay within 1ppm for it to be an accurate estimate

The gear is fairly easy to take care of and to estimate. The “how long will the learning curve be” part is often the biggest issue. Bob > On Nov 26, 2015, at 5:12 AM, Thomas Allgeier wrote: > > Hello Tom, > > One of the problems here (embarrassingly) is that we have a lack of kit in this particular respect.

I challenge your cost estimate! :-) My guestimate on the cost for a Rb vapor cell standard would be somwhere in the region of 2000€ to 5000€, per unit. If you add some experimentation it might become something like 10k€ for the first unit. How do I come to this number? A vapor cell is quite cheap, 300-500€ can buy you an off the shelf cell.