[time-nuts] RC TIC linearity correction?

Bob Camp lists at rtty.us
Wed Mar 26 17:47:04 EDT 2014


Having done this - it gets really boring to sit there for 10,000 seconds and collect data. Best to automate the process. 

In reality you want to run three groups of 10,000 samples and see how they relate to each other. With some approaches you can find some disturbing things going on.


On Mar 26, 2014, at 1:22 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:

> A random source will need a lot more samples in each bucket to reduce the noise to an acceptable level.
> To determine the relative bucket width with a 10% error requires at least 100 samples per bucket.
> For 1% error at least 10,000 samples per bucket.
> All thats really required is a sufficiently noisy oscillator that isn't phase locked to your clock.
> Bruce
> Stanley wrote:
>>>> I hadn't given any thought to correcting the linearity of the TIC I
>>>> built, but my PLL plots tell me I should do it now.
>> One method would be to calibrate with a series of  buckets that you fill by sampling a random source, the more samples in a bucket the more range in phase for that bucket. For example 1 1 1 2 2 2 3 2 2 1 0 samples sum equal 17 so each unit equal 17/(total range of  TIC) and the bucket with 3 samples would be 3 * 17/(total range of TIC).
>> Stanley
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