Re: [time-nuts] more of a time distribution question

[Bob Darlington]

I'm happy to run a group buy for just the 8736.My last quote from the
vendor was just a bit under $27 each, and that does not come with the board
connector.  I picked these boards for compatibility with Motorola
footprint, but also because it doesn't insist on goofy 3.0 volt power and
logic levels for communication.   It's happy with and rated for 3.3 volts
which is desirable.

I'll start a new thread for a group buy with details once I get a fresh
quote from the vendor.

-Bob
N3XKB

On Fri, Mar 31, 2017 at 12:45 PM, Bob Camp  wrote:

> Hi
>
> The 8736 is a very nice part. I think some sort of group buy would be a
> good idea.
>
> Bob
>
> Sent from my iPhone
>
> > On Mar 31, 2017, at 12:14 PM, Bob Darlington 
> wrote:
> >
> > I guess it's time for me to finish up that NTP cape for the BeagleBone.
> > I'm using a Furuno GT-8736 ( http://www.furuno.com/en/
> > products/gnss-module/GT-8736 )
> >
> > I built up a prototype about two years ago but... got married very
> shortly
> > after that and haven't played with it since.
> >
> > Is there any interest in something like this?   As with past group buys,
> I
> > never charge a penny of profit and sell at cost.   I want to say the
> brand
> > new GT-8736 boards are $26 a pop (my cost) from the vendor.
> >
> > Is there a better board from Furuno for timing applications?
> >
> > -Bob
> > N3XKB
> >
> > On Fri, Mar 31, 2017 at 1:03 AM, David J Taylor <
> > david-tay...@blueyonder.co.uk> wrote:
> >
> >> From: Hal Murray
> >>
> >> That should work.  I haven't found a GPS with PPS for the beaglebone.
> What
> >> level of accuracy do you want?  If you only need 100 ms or so, then a
> >> normal
> >> junk GPS (no PPS) on USB should work.
> >> ==
> >>
> >> This works with the BeagleBone:
> >>
> >> https://www.adafruit.com/product/746
> >>
> >> Cheers,
> >> David
> >> --
> >> SatSignal Software - Quality software written to your requirements
> >> Web: http://www.satsignal.eu
> >> Email: david-tay...@blueyonder.co.uk
> >> Twitter: @gm8arv
> >> ___
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> >> and follow the instructions there.
> >>
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Re: [time-nuts] more of a time distribution question

[Bob Camp]

Hi

The 8736 is a very nice part. I think some sort of group buy would be a good 
idea. 

Bob

Sent from my iPhone

> On Mar 31, 2017, at 12:14 PM, Bob Darlington  wrote:
> 
> I guess it's time for me to finish up that NTP cape for the BeagleBone.
> I'm using a Furuno GT-8736 ( http://www.furuno.com/en/
> products/gnss-module/GT-8736 )
> 
> I built up a prototype about two years ago but... got married very shortly
> after that and haven't played with it since.
> 
> Is there any interest in something like this?   As with past group buys, I
> never charge a penny of profit and sell at cost.   I want to say the brand
> new GT-8736 boards are $26 a pop (my cost) from the vendor.
> 
> Is there a better board from Furuno for timing applications?
> 
> -Bob
> N3XKB
> 
> On Fri, Mar 31, 2017 at 1:03 AM, David J Taylor <
> david-tay...@blueyonder.co.uk> wrote:
> 
>> From: Hal Murray
>> 
>> That should work.  I haven't found a GPS with PPS for the beaglebone.  What
>> level of accuracy do you want?  If you only need 100 ms or so, then a
>> normal
>> junk GPS (no PPS) on USB should work.
>> ==
>> 
>> This works with the BeagleBone:
>> 
>> https://www.adafruit.com/product/746
>> 
>> Cheers,
>> David
>> --
>> SatSignal Software - Quality software written to your requirements
>> Web: http://www.satsignal.eu
>> Email: david-tay...@blueyonder.co.uk
>> Twitter: @gm8arv
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
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Re: [time-nuts] more of a time distribution question

[Bob Darlington]

I guess it's time for me to finish up that NTP cape for the BeagleBone.
I'm using a Furuno GT-8736 ( http://www.furuno.com/en/
products/gnss-module/GT-8736 )

I built up a prototype about two years ago but... got married very shortly
after that and haven't played with it since.

Is there any interest in something like this?   As with past group buys, I
never charge a penny of profit and sell at cost.   I want to say the brand
new GT-8736 boards are $26 a pop (my cost) from the vendor.

Is there a better board from Furuno for timing applications?

-Bob
N3XKB

On Fri, Mar 31, 2017 at 1:03 AM, David J Taylor <
david-tay...@blueyonder.co.uk> wrote:

> From: Hal Murray
>
> That should work.  I haven't found a GPS with PPS for the beaglebone.  What
> level of accuracy do you want?  If you only need 100 ms or so, then a
> normal
> junk GPS (no PPS) on USB should work.
> ==
>
> This works with the BeagleBone:
>
>  https://www.adafruit.com/product/746
>
> Cheers,
> David
> --
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/m
> ailman/listinfo/time-nuts
> and follow the instructions there.
>
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Re: [time-nuts] more of a time distribution question

[David J Taylor]

From: Hal Murray

That should work.  I haven't found a GPS with PPS for the beaglebone.  What
level of accuracy do you want?  If you only need 100 ms or so, then a normal
junk GPS (no PPS) on USB should work.
==

This works with the BeagleBone:

 https://www.adafruit.com/product/746

Cheers,
David
--
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv 


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Re: [time-nuts] more of a time distribution question

[John Hawkinson]

Hal Murray  wrote on Thu, 30 Mar 2017
at 13:43:34 -0700 in 
<20170330204334.18a8d406...@ip-64-139-1-69.sjc.megapath.net>:

> That should work too.  I don't know much about the Mac environment.  If it's 
> running a normal-enough ntpd it is already a server and you don't have to do 
> anything.  If not, you will have to build/install your own and/or poke holes 
> in the firewall rules.

It is worth noting that the ntpd that Apple ships is kind of bizarre,
and it does not actually adjust the clock on the Mac. (Instead it
writes to the drift file -- or at least it is supposed to -- and an
Apple process called "pacemaker(8)" readthe drift file and tries to
maintain the systme clock. In my experience (only through Yosemite --
10.10) this mechanism was horribly broken and did not maintain my
laptop's system clock in any useful way.)

This probably doesn't actually affect the intended use (as the goal is
to keep machines in sync, not to keep them accurate), but anyone who
messes with ntpd under OS X should be aware that it is "weird."

Building the stock ntpd under OS X works just fine, and I recommend that
for anyone who wants to tinker with ntp under OS X.

--jh...@mit.edu
  John Hawkinson
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Re: [time-nuts] more of a time distribution question

[jimlux]

On 3/30/17 1:11 PM, Majdi S. Abbas wrote:

On Thu, Mar 30, 2017 at 09:37:50AM -0700, jimlux wrote:

Running NTP (in some flavor) would be the obvious approach, but I'm in an
environment where there's no "outside" connectivity.. Could I make one of
the beaglebones be the NTP server, and the others be the clients?


Disciplining them all to a specific free-running host would
require the use of the LOCAL reference clock:

http://doc.ntp.org/4.1.2/driver1.htm

However, the LOCAL refclock is deprecated, and it is recommended
that you use orphan mode instead, which is its intended replacement:

https://www.eecis.udel.edu/~mills/ntp/html/orphan.html

http://support.ntp.org/bin/view/Support/OrphanMode

Orphan mode is designed for your use case, and allows for more
redundancy than making them all clients of a single host.  I'd go that
route.



That's exactly what I was looking for.  Didn't think about googling for 
"orphan"  (and really, this is a group of orphans)







(I've seen some "add a GPS to a Rpi to make a NTP server" projects, and I
could probably leverage that)


You could do that, but you don't really have to -- you can keep
them synchronized at least to each other reasonably well this way.


I've also got a laptop (a mac, as it happens).. what's involved in making
*that* be a NTP server (e.g. the Mac might get its time from a NTP server at
some higher stratum, and then it propagates it down).


OSX already runs ntpd; you should just need to tweak their
default configuration.



Yes, I got that figured out, although I need to figure out some network 
routing issues now (independent of NTP...), since it was bridging (via 
NAT) my pack of beagles to the outside world... I was going "from mac TO 
beagle" with ssh, but I've got a problem going "from beagle to mac, 
instead of big world"


But that's straightfoward to solve.



--msa
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Re: [time-nuts] more of a time distribution question

[Hal Murray]

jim...@earthlink.net said:
> I've got a bunch (a pack?) of beaglebones that are connected via  ethernet
> (wired) and I want them to be (roughly) synchronized. 

How rough?

> Running NTP (in some flavor) would be the obvious approach, but I'm in  an
> environment where there's no "outside" connectivity.. Could I make  one of
> the beaglebones be the NTP server, and the others be the clients? 

Yes.  Search for orphan mode.  I've never tried it.  Let e know if you can't 
figure out how to make it work and I'll use that as an excuse to learn more.

> (I've seen some "add a GPS to a Rpi to make a NTP server" projects, and  I
> could probably leverage that)

That should work.  I haven't found a GPS with PPS for the beaglebone.  What 
level of accuracy do you want?  If you only need 100 ms or so, then a normal 
junk GPS (no PPS) on USB should work.

There is at least one GPS+PPS over USB.  The GPS breakout board plus FTDI USB 
2.0 breakout with a few wires gives you PPS with improved accuracy.  (Not 
great, just 8x better than PPS over old/slow USB.)  I got mine from Sparkfun.

> I've also got a laptop (a mac, as it happens).. what's involved in  making
> *that* be a NTP server (e.g. the Mac might get its time from a  NTP server
> at some higher stratum, and then it propagates it down). 

That should work too.  I don't know much about the Mac environment.  If it's 
running a normal-enough ntpd it is already a server and you don't have to do 
anything.  If not, you will have to build/install your own and/or poke holes 
in the firewall rules.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] more of a time distribution question

[Paul]

https://www.eecis.udel.edu/~mills/ntp/html/orphan.html

On Thu, Mar 30, 2017 at 12:37 PM, jimlux  wrote:

>
> Pointers to documentation would be appreciated.
>
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Re: [time-nuts] more of a time distribution question

[Majdi S. Abbas]

On Thu, Mar 30, 2017 at 09:37:50AM -0700, jimlux wrote:
> Running NTP (in some flavor) would be the obvious approach, but I'm in an
> environment where there's no "outside" connectivity.. Could I make one of
> the beaglebones be the NTP server, and the others be the clients?

Disciplining them all to a specific free-running host would 
require the use of the LOCAL reference clock:

http://doc.ntp.org/4.1.2/driver1.htm

However, the LOCAL refclock is deprecated, and it is recommended
that you use orphan mode instead, which is its intended replacement:

https://www.eecis.udel.edu/~mills/ntp/html/orphan.html

http://support.ntp.org/bin/view/Support/OrphanMode

Orphan mode is designed for your use case, and allows for more
redundancy than making them all clients of a single host.  I'd go that
route.

> (I've seen some "add a GPS to a Rpi to make a NTP server" projects, and I
> could probably leverage that)

You could do that, but you don't really have to -- you can keep
them synchronized at least to each other reasonably well this way.

> I've also got a laptop (a mac, as it happens).. what's involved in making
> *that* be a NTP server (e.g. the Mac might get its time from a NTP server at
> some higher stratum, and then it propagates it down).

OSX already runs ntpd; you should just need to tweak their
default configuration.

--msa
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Re: [time-nuts] more of a time distribution question

[Attila Kinali]

On Thu, 30 Mar 2017 09:37:50 -0700
jimlux  wrote:

> Running NTP (in some flavor) would be the obvious approach, but I'm in 
> an environment where there's no "outside" connectivity.. Could I make 
> one of the beaglebones be the NTP server, and the others be the clients?

Yes, you can tell ntpd to use the system clock as reference.
I have in my ntpd.conf:

---schnipp---
# use hw clock in case no servers available
server  127.127.1.0  # local clock
fudge   127.127.1.0 stratum 10  
---schnapp---

That makes the system clock a valid source. The fudge line is there
to prevent ntpd from using the local system clock as reference unless
it's the only source available.

Attila Kinali

-- 
You know, the very powerful and the very stupid have one thing in common.
They don't alters their views to fit the facts, they alter the facts to
fit the views, which can be uncomfortable if you happen to be one of the
facts that needs altering.  -- The Doctor
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