Re: [time-nuts] ADC sample voting algorithm?

Hi, You may have already done this, but if you log the same pulses with a counter or actual TDC IC you can view it and see how they compare with your measurements. Then you can look at how to get them closer - or find that it's actually correct and that's just where the pulse is at the time.

Re: [time-nuts] ADC sample voting algorithm?

In message <59ab451c-ca1b-4824-a953-4f0f28b66...@kfu.com>, Nick Sayer via time-nuts writes: >My theory at the moment is that sampling the ADC multiple times in a row might >help, but then what’s the best way to (quickly) pick which sample to use? If you are sampling for noise: Always

Re: [time-nuts] ADC sample voting algorithm?

I always try to calculate things like the standard deviation and peak-to-peak to get some idea if the measurement is valid. A DSO with infinite persistence or envelope mode is great for tracking this sort of thing down during development. Only toy DSOs will lack both. On Wed, 05 Oct 2016

Re: [time-nuts] ADC sample voting algorithm?

time-nuts@febo.com said: > That’s kind of why I’m going down the road of multiple samples - to see if > there’s anything to it. I would hack up some way to grab a clump (say 10) of samples and print them out where you can capture them on a PC and analyze them. I'd start by looking with

Re: [time-nuts] ADC sample voting algorithm?

On Wed, Oct 5, 2016 at 7:45 PM, Nick Sayer via time-nuts wrote: > I notice periodically that the phase measurements seem “noisy.” You can > see that over the course of several seconds the value doesn’t change, then > it jumps a bunch and then comes right back. > Hi Nick,

Re: [time-nuts] ADC sample voting algorithm?

It sounds like once in awhile your sampling something else too. Ground bounce of a 10 MHz buffer, or something coupling onto your phase detector, or running your adc at the edge of a timing spec? How large would the outlier be in mV? On Wednesday, 5 October 2016, Nick Sayer via time-nuts

Re: [time-nuts] ADC sample voting algorithm?

Hi If you are looking at a high impedance source with a “normal” ADC, you need a buffer amp. If you have a signal that decays, it is generally not a good idea to toss all the samples into a single bucket. You probably need to do some sort of slope estimation. The still better solution is

Re: [time-nuts] ADC sample voting algorithm?

> On Oct 5, 2016, at 5:00 PM, Bob Camp wrote: > > Hi > > What does the signal you are sampling look like? The last time I actually looked (it was a while ago), it looked reasonable as closely as I could look, but the ADC resolution is something like 1mV per LSB, and I’m not

Re: [time-nuts] ADC sample voting algorithm?

2016 6:57 PM Subject: Re: [time-nuts] ADC sample voting algorithm? > On Oct 5, 2016, at 4:52 PM, Bob Stewart <b...@evoria.net> wrote: > > Hi Nick, > > Are you applying sawtooth correction to your phase measurement? Yes, these are post-correction observations. I have som

Re: [time-nuts] ADC sample voting algorithm?

Hi What does the signal you are sampling look like? Does it (maybe) have a bit of noise on it? If it is the output of a “normal” TDC, then the answer is to sample once. Bob > On Oct 5, 2016, at 7:45 PM, Nick Sayer via time-nuts > wrote: > > This is tangentially on

Re: [time-nuts] ADC sample voting algorithm?

quency measurement <time-nuts@febo.com> Sent: Wednesday, October 5, 2016 6:45 PM Subject: [time-nuts] ADC sample voting algorithm? This is tangentially on topic, I suppose. It’s for my GPSDO. I notice periodically that the phase measurements seem “noisy.” You can see that over the cours

Re: [time-nuts] ADC sample voting algorithm?

Sayer via time-nuts <time-nuts@febo.com> > To: Discussion of precise time and frequency measurement <time-nuts@febo.com> > Sent: Wednesday, October 5, 2016 6:45 PM > Subject: [time-nuts] ADC sample voting algorithm? > > This is tangentially on topic, I suppose. It’s for my

[time-nuts] ADC sample voting algorithm?

This is tangentially on topic, I suppose. It’s for my GPSDO. I notice periodically that the phase measurements seem “noisy.” You can see that over the course of several seconds the value doesn’t change, then it jumps a bunch and then comes right back. My theory at the moment is that sampling