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] Measure GPSDO stability with minimum resources?

j99har...@gmail.com said: > Unless the oscillator is still warming up, 5 minutes or even 60 is way too > short a time to look at aging. For aging, you will want to look at the > change in DAC values over several days at least. I think it's worse than that. You have to hold the temperature

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] Measure GPSDO stability with minimum resources?

Hi Jim, I'm using an interpolated RC/ADC TIC to measure the time interval between the 1PPS from the receiver to the next OCXO pulse.  I also count the OCXO pulses between 1PPS ticks to make sure I'm on 10 MHz. I've been developing and improving this GPSDO for over 2 years now, so I have a good

Re: [time-nuts] Need Time Help

There was a time when HAMs where the ones pushing radio technology forward. Maybe these guys are doing that and building a digital EME network on VHF? We don't know. We can guess but typically when you start wanting precise time synchronization it is because of something like TDMA (time

Re: [time-nuts] Measure GPSDO stability with minimum resources?

On Wed, Oct 5, 2016 at 6:46 PM, Bob Stewart wrote: > What I'm really looking for is a way to do everything in the PIC. I've > been experimenting with saving the DAC value in a circular queue every 20 > seconds for 60 minutes, and plotting the difference value between the head >

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] time-nuts Digest, Vol 147, Issue 13

Re: TNS-BUF Amplifier --Jim Robbins wrote: Many thanks for your helpful TN work to John A. , Dr. Bruce and John M. Ordered 3 pieces. -- I second the thanks and ordered 2 pieces --Jim Stone On Wed, Oct

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?

In that case, have you taken the time to look at the math of the sawtooth vs measured phase?  If you like, you can send me 20 or 30 sequential data samples that contains what appears to be good as well as the bad to look at?  And which receiver are you using for this? Bob 

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?

Hi Nick, Are you applying sawtooth correction to your phase measurement?  If not, are you merely seeing a hanging bridge that dissolves into at a normal sort of tick-tock movement? Bob From: Nick Sayer via time-nuts To: Discussion of precise time and frequency

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

> On Oct 5, 2016, at 4:52 PM, Bob Stewart wrote: > > Hi Nick, > > Are you applying sawtooth correction to your phase measurement? Yes, these are post-correction observations. I have some confidence that my corrections are scaled appropriately for the ADC values because of

[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

Re: [time-nuts] Need Time Help

First off you are right, NTP does not run well as it can with only a single reference. But that is a general statement and assumes there is some error in a reference clock. Certainly if using Internet pool servers as reference clocks you want to have 5 to 7 of them. But GPS is so darn good

Re: [time-nuts] Measure GPSDO stability with minimum resources?

I just noticed that my reply didn't go to the list so... Thanks for the reply.  What I'm really looking for is a way to do everything in the PIC.  I've been experimenting with saving the DAC value in a circular queue every 20 seconds for 60 minutes, and plotting the difference value between the

Re: [time-nuts] Need Time Help

Hi Given that this is for intermittent EME use, it’s not a system that has uber reliability as a requirement. Once you get the antenna up in a reasonable location a GPS is going to be pretty stable and reliable. If you have an EME array running, adding a GPS antenna to it probably not a big

Re: [time-nuts] Measure GPSDO stability with minimum resources?

On Wed, Oct 5, 2016 at 1:37 PM, Bob Stewart wrote: > For my GPSDO, I need to calculate the OCXO aging for holdover projection > purposes as well as get some figure of merit for the recent past of the > OCXO stability. Do you have a serial port or some way of generating a

Re: [time-nuts] GPSDO Sigma Tau at large observation times

On Wed, Oct 5, 2016 at 11:01 AM, Tom Van Baak wrote: > Hello again Estanislao, > > Nice set of questions. The short answer is that for a GPSDO, > - The left side of the ADEV plot will show the difference between the quality > of the local oscillator, in your case TCXO vs.

[time-nuts] cleanup

Clearing and cleaning. Have stuff fs, pickup, very cheap. 5370a's 5370b, 3-5320A all with precision osc's 3325a fcn gen, Kode 3100, all working 5335a counts 1/2, plain xtal, and two J Seamon beaglebones for 5370's, unused. BB's are not for sale separately. Pick it all up here,I'm only 2 mi of

Re: [time-nuts] GPSDO Sigma Tau at large observation times

On Wed, 5 Oct 2016 11:01:36 -0700 "Tom Van Baak" wrote: > Nice set of questions. The short answer is that for a GPSDO, > - The left side of the ADEV plot will show the difference between the quality > of the local oscillator, in your case TCXO vs. OCXO vs. Rb. > - The

Re: [time-nuts] Need Time Help

I agree that the built in Microsoft tools are SNTP only and will not work at the 15ms level. I have had excellent success with Windows PC's of many vintages, from XP through Windows 10, using Meinberg NTPD and the "pool.ntp.org" timeservers. Tim N3QE On Tue, Oct 4, 2016 at 12:41 AM, Larry Hower

Re: [time-nuts] Need Time Help

Yo Bob! On Wed, 5 Oct 2016 07:14:30 -0400 Bob Camp wrote: > If you buy a GPS receiver and get it set up for timing …. just use > it. Then there is no need for NTP at all…. Assuming your GPS never farts and always has a good lock. A pretty good assumption, but not a perfect one.

Re: [time-nuts] Need Time Help

Yo Chris! On Wed, 5 Oct 2016 10:19:10 -0500 "Chris Caudle" wrote: > On Wed, October 5, 2016 6:14 am, Bob Camp wrote: > > If you buy a GPS receiver and get it set up for timing, just use it. > > Then there is no need for NTP at all. > > Is there another way to get

Re: [time-nuts] TNS-BUF High Isolation, Low Noise Buffer Amp Available

It's possible we may have some bare boards, but no guarantees at this point. On 10/5/2016 2:04 PM, Dan Rae wrote: For those of us who aren't scared of surface mount stuff, and maybe even prefer it, will there be any bare boards available? Dan - ac6ao

Re: [time-nuts] TNS-BUF High Isolation, Low Noise Buffer Amp Available

For those of us who aren't scared of surface mount stuff, and maybe even prefer it, will there be any bare boards available? Dan - ac6ao ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to

Re: [time-nuts] Need Time Help

On 2016-10-05 10:22 , Jay Grizzard wrote: Because NTP normally never actually sets you clock to match a server's clock. It adjusts the RATE of your clock so the it cruises on the middle of the pack of vetted servers. To be nitpicky, it doesn't actually track towards the median, it tracks

Re: [time-nuts] GPSDO Sigma Tau at large observation times

Hello again Estanislao, Nice set of questions. The short answer is that for a GPSDO, - The left side of the ADEV plot will show the difference between the quality of the local oscillator, in your case TCXO vs. OCXO vs. Rb. - The middle of the ADEV plot will show the difference in the choice of

[time-nuts] Measure GPSDO stability with minimum resources?

For my GPSDO, I need to calculate the OCXO aging for holdover projection purposes as well as get some figure of merit for the recent past of the OCXO stability.  The latter is so that I can determine that the PLL has (or soon will have) a good lock.  I'm developing on a dfPIC33FJ128MC802, and

Re: [time-nuts] Need Time Help

In practice I'm not convinced the timing requirements for the JT modes in question are even more than a single order of magnitude more severe than the when I have been timing 15 second sequences on my wrist watch during manual non computer aided weak signal operations. To recap if some one has

Re: [time-nuts] Need Time Help

If you are working "real" EME where you, and not a computer plus lookup table, are coping the signals, none of these precise timing issues exist. Wes N7WS On 10/5/2016 6:18 AM, Peter Torry via time-nuts wrote: I must admit to being rather puzzled at the sub microsecond timing requirement as

Re: [time-nuts] Need Time Help

On Wed, October 5, 2016 6:14 am, Bob Camp wrote: > If you buy a GPS receiver and get it set up for timing, just use it. > Then there is no need for NTP at all. Is there another way to get computer system time set from a GPS receiver other than NTP? In the case that the system clock is controlled

[time-nuts] TNS-BUF Amplifier

Many thanks for your helpful TN work to John A. , Dr. Bruce and John M. Ordered 3 pieces. 73, Jim Robbins N1JR ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and

Re: [time-nuts] Need Time Help

Yes I'd be curious in knowing more about this as well. I've often observed time differences from other stations of several tenths of a second when running the JT modes on HF. Although I am beginner at EME I have made a couple of EME (earth moon earth) JT65 contacts on VHF without taking any

[time-nuts] TNS-BUF High Isolation, Low Noise Buffer Amp Available

I've previously mentioned a high performance buffer amplifier called the "TNS-BUF" that I built based on a design by Dr. Bruce Griffiths with further input from John Miles. Key numbers are: * Phase noise -140dBc/Hz at 1 Hertz offset, noise floor -175dBc/Hz. (PN plot attached) * Reverse

Re: [time-nuts] Need Time Help

I must admit to being rather puzzled at the sub microsecond timing requirement as I use ntp to set the W7 clock in my computer and have not had any issues. In fact less than one second is OK for the usual two minute periods that are required to allow for the Faraday rotation. Although I use a

Re: [time-nuts] Need Time Help

For the group. This ham is trying to work EME. Earth-Moon-Earth propagation path. Aka, "moonbounce." He is trying to time synchronize a system, where the other station he is communicating with can be any other place on the Earth that can also see the Moon. So the system time sync is for a little

Re: [time-nuts] ntp and asymmetric delays

On 10/05/2016 01:48 PM, Attila Kinali wrote: On Tue, 4 Oct 2016 18:05:16 -0700 Chris Albertson wrote: The problem, I think with your Internet sync's NTP servers is you are only using one server S. The most common practice is to use 3 to 5 with 5 being about the

[time-nuts] ntp and asymmetric delays (was: Need Time Help)

On Tue, 4 Oct 2016 18:05:16 -0700 Chris Albertson wrote: > The problem, I think with your Internet sync's NTP servers is you are only > using one server S. The most common practice is to use 3 to 5 with 5 being > about the right number. If you get Ntp enough

Re: [time-nuts] Need Time Help

Hi If you buy a GPS receiver and get it set up for timing …. just use it. Then there is no need for NTP at all…. Bob > On Oct 5, 2016, at 12:33 AM, Chris Albertson > wrote: > > On Tue, Oct 4, 2016 at 6:52 PM, Bob Camp wrote: > >> Hi >> >> If: >>

Re: [time-nuts] Roughtime

albertson.ch...@gmail.com said: > But I use a set of five different servers all controlled by different > organizations and they are geographically distributed. Also some of these > are randomly elected "pool" servers. So even I don't know who I will ask > for time. How could anyone corrupt