Re: [time-nuts] accurate 60 hz reference chips/ckts

d" <t...@patoka.org> To: "Jeremy Nichols" <jn6...@gmail.com> Cc: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Friday, December 15, 2017 9:41 AM Subject: Re: [time-nuts] accurate 60 hz reference chips/ckts My setup is pret

Re: [time-nuts] accurate 60 hz reference chips/ckts

Yo All! Jeremy wrote: > I'm surprised Vlad is seeing as much as six seconds differential > but maybe I don't understand the experiment. I've done measurements > of the line frequency here in California and never seen much > variation. I live in Central Oregon. Next to the Pacific Intertie

Re: [time-nuts] accurate 60 hz reference chips/ckts

Jeremy wrote: I'm surprised Vlad is seeing as much as six seconds differential but maybe I don't understand the experiment. I've done measurements of the line frequency here in California and never seen much variation. When was the earliest time (year) you started looking seriously at the

Re: [time-nuts] accurate 60 hz reference chips/ckts

Hi It depends a *lot* on just where you are and how the “gird” is managed. Many years ago, we figured out that the local power company corrected things between 4 and 5 PM. It became a habit to fire up WWV and watch them slip seconds one way or the other. A ten second delta was not at all

Re: [time-nuts] accurate 60 hz reference chips/ckts

My setup is pretty simple indeed. This is 9.830400MHZ OCXO which clocking MCU. Then it is Zero-Cross detector which connected to capture timer. The MCU counting the intervals between of each zero-cross event and number of events occurred. if (htim->Instance == TIM5 && htim->Channel ==

Re: [time-nuts] accurate 60 hz reference chips/ckts

I'm surprised Vlad is seeing as much as six seconds differential but maybe I don't understand the experiment. I've done measurements of the line frequency here in California and never seen much variation. Jeremy On Fri, Dec 15, 2017 at 9:02 AM Vlad wrote: > > > I have one of

Re: [time-nuts] accurate 60 hz reference chips/ckts

I have one of my project boxes, which monitor the main freq. Here is graph which reflect the time difference between of RTC (based on number of pulses from OCXO) and the "MAIN TIME" which is based on number of zero-cross events. The observation period is 486 hours. On 2017-12-14 23:13,

Re: [time-nuts] accurate 60 hz reference chips/ckts

On Thu, Dec 14, 2017 at 10:53 PM, Bob kb8tq wrote: > > > Of course this *assumes* an electronic approach. Given that it’s moving > pretty slow and you > only are looking at fractions of a millisecond, one *could* do an electro > mechanical design …... > > Bob > > There is

Re: [time-nuts] accurate 60 hz reference chips/ckts

Hi My guess is that the “best design” would likely do a sample at some specific time of day. Just when would depend a bit on your local grid and how it is fed and loaded. There are definitely “it’s 6 PM and everybody just got home” issues with power line phase. Next question wold be how long

Re: [time-nuts] accurate 60 hz reference chips/ckts

t...@leapsecond.com said: > For GPS and OCXO the choice of time constant is fairly obvious. But the > ADEV for mains frequency isn't quite as pretty. So I'm not sure several > hours would work; maybe more like days or weeks? Here's a sample ADEV for > power line frequency: Has anybody

Re: [time-nuts] accurate 60 hz reference chips/ckts

On Thu, December 14, 2017 8:39 pm, Tom Van Baak wrote: > One can determine the appropriate time constant by looking at the ADEV of > the two clocks It appears that the appropriate design would use a local oscillator which is stable to better than 10^-7 at 5 years and approximately 1200 days time

Re: [time-nuts] accurate 60 hz reference chips/ckts

50.000Hz > > Alan > G3NYK > > - Original Message - From: "Jim Harman" <j99har...@gmail.com> > To: "Discussion of precise time and frequency measurement" > <time-nuts@febo.com> > Sent: Thursday, December 14, 2017 10:08 PM > Subject: Re: [time-nuts]

Re: [time-nuts] accurate 60 hz reference chips/ckts

the frequency be 50.000Hz Alan G3NYK - Original Message - From: "Jim Harman" <j99har...@gmail.com> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Thursday, December 14, 2017 10:08 PM Subject: Re: [time-nuts] acc

Re: [time-nuts] accurate 60 hz reference chips/ckts

Since the power line has the desired long term stability but is poor on the short term, I wonder if a solution might be to use it as the reference for a "power line disciplined oscillator." You would want a filter time constant of several hours in the control loop to smooth out the variations in

Re: [time-nuts] accurate 60 hz reference chips/ckts

apollo...@gmail.com said: > Want to provide an accurate (relatively accurate) 60 hz reference to the > chip. Some room inside for custom modifications. Does a TCXO or similar > exist in a small package that provides 60 hz ticks? I doubt if you will find a TCXO that puts out 60 Hz. But it's

Re: [time-nuts] accurate 60 hz reference chips/ckts

National Semi used to make a chip (MM5369) that was designed specifically for that task, but it's long out of production. I don't know of any off-the -shelf 60Hz generators, but it's pretty easy to build one. Here are a couple of web pages that will generate a 60Hz crystal controlled signal.

Re: [time-nuts] accurate 60 hz reference chips/ckts

Pat, > They drift a few seconds in the course of a few days, and wander back and > forth. Yes, it's normal for AC mains to drift around by a few seconds over a day but it usually stays roughly on-time over weeks and months. Here's an old example of monitoring mains time & frequency for 45