[time-nuts] Re: NTP servers

[Gerhard Hoffmann]

Am 23.11.21 um 11:53 schrieb Avamander:

Speaking of Raspberry Pi's as time servers, does anyone here know of a nice
single board computer that supports both Ethernet hardware timestamping and
GPIO PPS input?


It seems the BeagleBoneBlack fits the bill.
I like it because it runs a normal Debian and it has more
I/o-Pins than competing boards, and the 2 PRU-I/O processors
that are completely time-predictable.


< 
https://forum.beagleboard.org/t/does-the-x-15-have-hardware-timestamping-ieee1588-support/30107 
>


The BB-X15 obviously has no hardware-timestamping.

Gerhard
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[time-nuts] Re: NTP servers

[folkert]

RPI does allow GPIO PPS input
Also the RPI4 does PTP.

On Tue, Nov 23, 2021 at 12:53:02PM +0200, Avamander wrote:
> Speaking of Raspberry Pi's as time servers, does anyone here know of a nice
> single board computer that supports both Ethernet hardware timestamping and
> GPIO PPS input?
> 
> On Tue, Nov 23, 2021 at 12:49 PM McFail Troll 
> wrote:
> 
> > > If you have a good local NTP setup, you can measure how good other
> > servers are, or more likely how good the network connection is.  NTP
> > assumes the network delays are symmetric.  Often, that's not true.  So "how
> > good" turns into measuring network (a)symmetries.
> >
> > Yes this is what I'd like to do eventually. Trying to get a Raspberry pi +
> > gps setup going first though.
> >
> > On Mon, Nov 22, 2021 at 5:42 AM Hal Murray  wrote:
> >
> > > time.isan...@gmail.com said:
> > > > but I am curious to see if I could sync up with some of you guys who
> > > seem to
> > > > have some pretty cool set-ups.
> > >
> > > GPS has taken over the time-distribution business.
> > >
> > > If you want to use GPS, there are 2 ways to go.
> > >
> > > You can get a simple GPS receiver and plug that into your PC.  For decent
> > > time, you need a PPS signal and a real serial port, not USB.
> > >
> > > The other approach is to get a GPSDO -- GPS Disciplined Oscillator.
> > > That's a
> > > box with a GPS receiver and a good crystal and some software.  It
> > smoothes
> > > out
> > > the rough edges in the timing from the GPS signal and/or keeps going
> > > (holdover) when the GPS signal fades or dies.
> > >
> > > GPS is very very good in the long term but noisy in the short term.
> > Short
> > > means seconds to minutes.  Long means days/months.  A GPSDO will get rid
> > > of
> > > most of the short term noise.
> > >
> > > There are/were several models available at relatively low cost after they
> > > were recycled from cell phone towers.  HP Z3801A and Trimble Thunderbolt
> > > are popular.  "GPSDO" will get lots of hits on eBay.  I don't know how
> > good
> > > the recent ones are.
> > >
> > > Just reading the info available can be fun if you like that stuff.
> > >   http://www.realhamradio.com/GPS_Frequency_Standard.htm
> > > The Z3801A manual is a good read.
> > >   http://www.leapsecond.com/museum/z3801a/097-z3801-01-iss-1.pdf
> > > Time sink warning!
> > >
> > > GPS works much better if you have a good antenna location.  Modern GPS
> > > receivers are sensitive enough that they sometimes/often work indoors,
> > > maybe better on a window sill, maybe even better if the window faces
> > > south.  Just because it's working now doesn't mean it won't glitch often
> > > enough to cause problems.  Mumble.  Try it and see what happens.
> > >
> > > -
> > >
> > > There is actually a 3rd way: buy a box that does it all.  But that's not
> > > much
> > > fun, at least for most of the people on this list.
> > >
> > > --
> > >
> > > > there are plenty of good stratum 1 NTP servers open to the public (e.g.
> > > > NIST's servers),
> > >
> > > If you have a good local NTP setup, you can measure how good other
> > servers
> > > are, or more likely how good the network connection is.  NTP assumes the
> > > network delays are symmetric.  Often, that's not true.  So "how good"
> > turns
> > > into measuring network (a)symmetries.
> > >
> > >
> > > --
> > > These are my opinions.  I hate spam.
> > >
> > >
> > > ___
> > > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> > send
> > > an email to time-nuts-le...@lists.febo.com
> > > To unsubscribe, go to and follow the instructions there.
> > >
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> > To unsubscribe, go to and follow the instructions there.
> >
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Folkert van Heusden

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[time-nuts] Re: NTP servers

[Avamander]

Speaking of Raspberry Pi's as time servers, does anyone here know of a nice
single board computer that supports both Ethernet hardware timestamping and
GPIO PPS input?

On Tue, Nov 23, 2021 at 12:49 PM McFail Troll 
wrote:

> > If you have a good local NTP setup, you can measure how good other
> servers are, or more likely how good the network connection is.  NTP
> assumes the network delays are symmetric.  Often, that's not true.  So "how
> good" turns into measuring network (a)symmetries.
>
> Yes this is what I'd like to do eventually. Trying to get a Raspberry pi +
> gps setup going first though.
>
> On Mon, Nov 22, 2021 at 5:42 AM Hal Murray  wrote:
>
> > time.isan...@gmail.com said:
> > > but I am curious to see if I could sync up with some of you guys who
> > seem to
> > > have some pretty cool set-ups.
> >
> > GPS has taken over the time-distribution business.
> >
> > If you want to use GPS, there are 2 ways to go.
> >
> > You can get a simple GPS receiver and plug that into your PC.  For decent
> > time, you need a PPS signal and a real serial port, not USB.
> >
> > The other approach is to get a GPSDO -- GPS Disciplined Oscillator.
> > That's a
> > box with a GPS receiver and a good crystal and some software.  It
> smoothes
> > out
> > the rough edges in the timing from the GPS signal and/or keeps going
> > (holdover) when the GPS signal fades or dies.
> >
> > GPS is very very good in the long term but noisy in the short term.
> Short
> > means seconds to minutes.  Long means days/months.  A GPSDO will get rid
> > of
> > most of the short term noise.
> >
> > There are/were several models available at relatively low cost after they
> > were recycled from cell phone towers.  HP Z3801A and Trimble Thunderbolt
> > are popular.  "GPSDO" will get lots of hits on eBay.  I don't know how
> good
> > the recent ones are.
> >
> > Just reading the info available can be fun if you like that stuff.
> >   http://www.realhamradio.com/GPS_Frequency_Standard.htm
> > The Z3801A manual is a good read.
> >   http://www.leapsecond.com/museum/z3801a/097-z3801-01-iss-1.pdf
> > Time sink warning!
> >
> > GPS works much better if you have a good antenna location.  Modern GPS
> > receivers are sensitive enough that they sometimes/often work indoors,
> > maybe better on a window sill, maybe even better if the window faces
> > south.  Just because it's working now doesn't mean it won't glitch often
> > enough to cause problems.  Mumble.  Try it and see what happens.
> >
> > -
> >
> > There is actually a 3rd way: buy a box that does it all.  But that's not
> > much
> > fun, at least for most of the people on this list.
> >
> > --
> >
> > > there are plenty of good stratum 1 NTP servers open to the public (e.g.
> > > NIST's servers),
> >
> > If you have a good local NTP setup, you can measure how good other
> servers
> > are, or more likely how good the network connection is.  NTP assumes the
> > network delays are symmetric.  Often, that's not true.  So "how good"
> turns
> > into measuring network (a)symmetries.
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send
> > an email to time-nuts-le...@lists.febo.com
> > To unsubscribe, go to and follow the instructions there.
> >
> ___
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> an email to time-nuts-le...@lists.febo.com
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>
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[time-nuts] Re: NTP servers

[McFail Troll]

> If you have a good local NTP setup, you can measure how good other
servers are, or more likely how good the network connection is.  NTP
assumes the network delays are symmetric.  Often, that's not true.  So "how
good" turns into measuring network (a)symmetries.

Yes this is what I'd like to do eventually. Trying to get a Raspberry pi +
gps setup going first though.

On Mon, Nov 22, 2021 at 5:42 AM Hal Murray  wrote:

> time.isan...@gmail.com said:
> > but I am curious to see if I could sync up with some of you guys who
> seem to
> > have some pretty cool set-ups.
>
> GPS has taken over the time-distribution business.
>
> If you want to use GPS, there are 2 ways to go.
>
> You can get a simple GPS receiver and plug that into your PC.  For decent
> time, you need a PPS signal and a real serial port, not USB.
>
> The other approach is to get a GPSDO -- GPS Disciplined Oscillator.
> That's a
> box with a GPS receiver and a good crystal and some software.  It smoothes
> out
> the rough edges in the timing from the GPS signal and/or keeps going
> (holdover) when the GPS signal fades or dies.
>
> GPS is very very good in the long term but noisy in the short term.  Short
> means seconds to minutes.  Long means days/months.  A GPSDO will get rid
> of
> most of the short term noise.
>
> There are/were several models available at relatively low cost after they
> were recycled from cell phone towers.  HP Z3801A and Trimble Thunderbolt
> are popular.  "GPSDO" will get lots of hits on eBay.  I don't know how good
> the recent ones are.
>
> Just reading the info available can be fun if you like that stuff.
>   http://www.realhamradio.com/GPS_Frequency_Standard.htm
> The Z3801A manual is a good read.
>   http://www.leapsecond.com/museum/z3801a/097-z3801-01-iss-1.pdf
> Time sink warning!
>
> GPS works much better if you have a good antenna location.  Modern GPS
> receivers are sensitive enough that they sometimes/often work indoors,
> maybe better on a window sill, maybe even better if the window faces
> south.  Just because it's working now doesn't mean it won't glitch often
> enough to cause problems.  Mumble.  Try it and see what happens.
>
> -
>
> There is actually a 3rd way: buy a box that does it all.  But that's not
> much
> fun, at least for most of the people on this list.
>
> --
>
> > there are plenty of good stratum 1 NTP servers open to the public (e.g.
> > NIST's servers),
>
> If you have a good local NTP setup, you can measure how good other servers
> are, or more likely how good the network connection is.  NTP assumes the
> network delays are symmetric.  Often, that's not true.  So "how good" turns
> into measuring network (a)symmetries.
>
>
> --
> These are my opinions.  I hate spam.
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
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[time-nuts] Re: NTP servers

[McFail Troll]

Thanks I will definitely take a look.

On Mon, Nov 22, 2021 at 4:47 AM David Taylor via time-nuts <
time-nuts@lists.febo.com> wrote:

> On 22/11/2021 02:29, McFail Troll wrote:
> > Hi all, I am new to the mailing list, and pretty new to timing stuff in
> > general. I wanted to ask if any of you folks who have a more advanced
> > set-up (synchronization via gps/radio, or just a well working rubidium
> > clock or something) maintain a solid stratum 1 NTP server. Of course, I
> am
> > aware that there are plenty of good stratum 1 NTP servers open to the
> > public (e.g. NIST's servers), but I am curious to see if I could sync up
> > with some of you guys who seem to have some pretty cool set-ups.
> >
> > Btw, sorry if this has been asked before on this list. Thanks
>
> You may find some helpful information on my Web page:
>
>https://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html
>
> about using a GPS/PPS device with a Raspberry Pi.  This gets you down into
> the
> microsecond region at a low cost and a low power consumption - helpful as
> leaving the device on 24x7 is best.
>
> Be aware that many of the public stratum-1 servers are overloaded and
> perhaps
> not as good as you might want.
>
> Cheers,
> David
> --
> SatSignal Software - Quality software for you
> Web: https://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv
> ___
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[time-nuts] Re: NTP servers

[McFail Troll]

Thanks! The TimeHat looks like a good option considering the price. I am
trying to do a Raspberry pi + gps project myself, but will possibly end up
getting one of those in the future.

On Sun, Nov 21, 2021 at 9:52 PM W7SLS  wrote:

> Welcome, and here are a few thoughts:
>
> One of the members developed a ’TimeHat’ that sits on top of a Raspberry
> Pi.
> GPS and more.   I purchased tow of them, and am quite happy with them.
> https://millerjs.org/timehat 
>
>
> Another option is the Leo Bodnar NTP device, though it appears to be out
> of stock at the moment
>
> http://www.leobodnar.com/shop/index.php?main_page=product_info=120_id=272
> <
> http://www.leobodnar.com/shop/index.php?main_page=product_info=120_id=272
> >
>
> Good luck on your new adventure!
>
> Scott
>
> > On Nov 21, 2021, at 6:29 PM, McFail Troll 
> wrote:
> >
> > Hi all, I am new to the mailing list, and pretty new to timing stuff in
> > general. I wanted to ask if any of you folks who have a more advanced
> > set-up (synchronization via gps/radio, or just a well working rubidium
> > clock or something) maintain a solid stratum 1 NTP server. Of course, I
> am
> > aware that there are plenty of good stratum 1 NTP servers open to the
> > public (e.g. NIST's servers), but I am curious to see if I could sync up
> > with some of you guys who seem to have some pretty cool set-ups.
> >
> > Btw, sorry if this has been asked before on this list. Thanks
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send an email to time-nuts-le...@lists.febo.com
> > To unsubscribe, go to and follow the instructions there.
>
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[time-nuts] Re: NTP servers

[Denny Page via time-nuts]

Strange. I have three of these that I have tracked pretty closely for several 
years. To my knowledge, I’ve never experienced any circumstance in which they 
were off by one or more seconds. 

Regarding the holdover behavior, I have not tested that.  But if you believe 
that the current behavior is incorrect, why don’t you reach out directly to Leo 
to discuss?  In my experience he is pretty responsive and thoughtful regarding 
issues with the device. 

Denny

> On Nov 22, 2021, at 20:16, Steven Sommars  wrote:
> 
> LeoNTP note:I've seen these units infrequently return NTP responses
> that are off by N-seconds (N is a small integer.)
> I could not determine the root cause.
> 
> One other oddity.  The returned NTP root dispersion is always 0, even when
> the unit runs in holdover mode.
> The support people say that this is intentional; the NTP "precision" field
> is varied instead.
> This is the wrong approach.
> 
> Despite this I use my LeoNTP constantly.  It is small, convenient, simple
> and can handle almost 100Mbps of NTP requests.
> 
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[time-nuts] Re: NTP servers

[Steven Sommars]

LeoNTP note:I've seen these units infrequently return NTP responses
that are off by N-seconds (N is a small integer.)
I could not determine the root cause.

One other oddity.  The returned NTP root dispersion is always 0, even when
the unit runs in holdover mode.
The support people say that this is intentional; the NTP "precision" field
is varied instead.
This is the wrong approach.

Despite this I use my LeoNTP constantly.  It is small, convenient, simple
and can handle almost 100Mbps of NTP requests.



On Mon, Nov 22, 2021 at 12:11 PM Lester Veenstra via time-nuts <
time-nuts@lists.febo.com> wrote:

> Yupp
>
> Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y (Reformed USNSG CTM1)
> les...@veenstras.com
>
> 452 Stable Ln
> Keyser WV 26726 USA
>
> GPS: 39.336826 N  78.982287 W (Google)
> GPS: 39.33682 N  78.9823741 W (GPSDO)
>
>
> Telephones:
> Home:+1-304-289-6057
> US cell  +1-304-790-9192
> Jamaica cell:+1-876-456-8898
>
>
> -Original Message-
> From: Denny Page via time-nuts [mailto:time-nuts@lists.febo.com]
> Sent: Monday, November 22, 2021 12:16 PM
> To: Discussion of precise time and frequency measurement
> Cc: Denny Page
> Subject: [time-nuts] Re: NTP servers
>
> Well, someone snatched that up quick.
>
>
> > On Nov 21, 2021, at 19:11, Denny Page via time-nuts
>  wrote:
> >
> > Highly recommend the LeoNTP. If you are in the US, there is still one in
> stock here:
> >
> > https://v3.airspy.us/product/upu-leontp/
> >
> > Denny
> >
> >> On Nov 21, 2021, at 18:52, W7SLS  wrote:
> >>
> >> Another option is the Leo Bodnar NTP device, though it appears to be out
> of stock at the moment
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe
> send
> an email to time-nuts-le...@lists.febo.com
> > To unsubscribe, go to and follow the instructions there.
> ___
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> an
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[time-nuts] Re: NTP servers

[Lester Veenstra via time-nuts]

Yupp

Lester B Veenstra  K1YCM  MØYCM  W8YCM   6Y6Y (Reformed USNSG CTM1)
les...@veenstras.com

452 Stable Ln
Keyser WV 26726 USA

GPS: 39.336826 N  78.982287 W (Google)
GPS: 39.33682 N  78.9823741 W (GPSDO)


Telephones:
Home:+1-304-289-6057 
US cell  +1-304-790-9192 
Jamaica cell:    +1-876-456-8898 


-Original Message-
From: Denny Page via time-nuts [mailto:time-nuts@lists.febo.com] 
Sent: Monday, November 22, 2021 12:16 PM
To: Discussion of precise time and frequency measurement
Cc: Denny Page
Subject: [time-nuts] Re: NTP servers

Well, someone snatched that up quick.


> On Nov 21, 2021, at 19:11, Denny Page via time-nuts
 wrote:
> 
> Highly recommend the LeoNTP. If you are in the US, there is still one in
stock here:
> 
> https://v3.airspy.us/product/upu-leontp/
> 
> Denny
> 
>> On Nov 21, 2021, at 18:52, W7SLS  wrote:
>> 
>> Another option is the Leo Bodnar NTP device, though it appears to be out
of stock at the moment
> ___
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an email to time-nuts-le...@lists.febo.com
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[time-nuts] Re: NTP servers

[Denny Page via time-nuts]

Well, someone snatched that up quick.


> On Nov 21, 2021, at 19:11, Denny Page via time-nuts 
>  wrote:
> 
> Highly recommend the LeoNTP. If you are in the US, there is still one in 
> stock here:
> 
> https://v3.airspy.us/product/upu-leontp/
> 
> Denny
> 
>> On Nov 21, 2021, at 18:52, W7SLS  wrote:
>> 
>> Another option is the Leo Bodnar NTP device, though it appears to be out of 
>> stock at the moment
> ___
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[time-nuts] Re: NTP servers

[Gregory Beat via time-nuts]

A couple of years ago, I acquired a related “time-nuts” NTP appliance.  As 
usual, it was not working properly and waited for service time on my 
electronics workbench.

The ESE ES-188 is an NTP referenced Master Clock and Time Code Generator (circa 
2007).
It displays nine digits (Day of Year, Hour, Minute & Second) of time, as 
received via a user selected NTP server.  It has option to be an NTP Server.  
The newer ES-188E Master Clock is the current ESE production model.
https://www.ese-web.com/188e.htm

ES-188 Master Clocks are often found used (>10 years old) for $1,000 to $1,500 
by a handful of Florida based eBay resellers.  I purchased mine for 10% of 
asking prices, from an eBay reseller in Oklahoma, who had no idea how it worked 
(“but the lights come on”).  Closer inspection demonstrated that it was not 
working properly, and likely why it was discarded by original owner.

Visiting the Electronics workbench, the two backup batteries (Coin Cell for 
backing up the User settings, and a SLA/Gel-Cell for a 4-hour operational 
backup) were DEAD.
In addition, a majority of the electrolytic capacitors in the DC voltage 
section were faulty (bulging or beginning to leak).
Two integrated circuits (7400 series) near data I/O ports were damaged (likely 
due to DC voltage issue, or an external induced surge event), but thankfully 
the CPU and Ethernet module were functional. 
Replacement parts were acquired from Digi-Key.  I used high quality Panasonic 
electrolytic capacitors for the DC power section.  The failed (bulging) 
capacitors were from a southern California “shell company” for a Chinese mfg. 
(telltale green capacitors, seen during earlier “Capacitor Plaque”).

The ES-188E generates several types of time code, including SMPTE LTC, 
ESE-TC89, ESE-TC90, ASCII (RS-232C & USB), EBU, IRIG-B and a 1PPS signal. These 
outputs allow the ES-188E to drive external clock displays as well as interface 
with computers, automation and clock systems.

The Ethernet port (RJ-45) serves a dual purpose (client/server), when the 
Optional NTP Server is installed or configured.
 
The ES-188E became popular for users in urban areas.
1.) Trouble getting a reliable GPS Signal into a facility, such as a basement 
or a building with metallic coating on the windows.
2.) Trouble getting an antenna to the outside of a facility, because the cable 
run will be too expensive or the facility cannot be modified, which is the case 
with many historical buildings.
3.) The specific facility needs to be time synchronized to a remote location 
through NTP, for example, universities with multiple campuses or NPR affiliate 
broadcast stations. ESE has a specific option for NPR broadcast station usage.

Powering up the ES-188, I configured the Master Clock settings.  
One step is selecting the primary and secondary NTP reference servers, as well 
as delay / latency factors.  I selected my ISP’s NTP servers (Xfinity/Comcast), 
instead of Google, NIST, or other known NTP references (higher latency 
potential).
This ESE Master Clock drives (IRIG-B) an old Masterclock TCD-26 series I 
(2-1/4” high digits) in the workshop (cannot internally DST adjust - since 
2007).

The differences between my GPSDO references and the ES-188 are very small, 
BUT a hard-core “time-nut” would likely need restraints after a year. :-)

greg
==
Date: Sun, 21 Nov 2021 21:29:52 -0500
From: McFail Troll 
Subject: [time-nuts] NTP servers
To: time-nuts@lists.febo.com

Hi all, I am new to the mailing list, and pretty new to timing stuff in 
general. I wanted to ask if any of you folks who have a more advanced set-up 
(synchronization via gps/radio, or just a well working rubidium clock or 
something) maintain a solid stratum 1 NTP server. Of course, I am aware that 
there are plenty of good stratum 1 NTP servers open to the public (e.g. NIST's 
servers), but I am curious to see if I could sync up
with some of you guys who seem to have some pretty cool set-ups.

Btw, sorry if this has been asked before on this list. 
Thanks.

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[time-nuts] Re: NTP servers

[Andy Talbot]

GPS with any serial port can be used (along with PPS) for accurate time.
You write a routine for a microcontroller that maintains time  keeping and
clock it from the 1 PPS signal.  That gives you correct display of accurate
time.   You read the NMEA from the GPS and use it to set your registers on
a regular basis.  I usually do every minute, at second number 58.  The NMEA
read can be done in time so the next PPS increments to the correct
setting.   NMEA string is always less than one second long

The only time this falls over is for leap seconds when they don't show on
the display for up to one minute after they happened.

Andy
www.g4jnt.com



On Mon, 22 Nov 2021 at 10:42, Hal Murray  wrote:

> time.isan...@gmail.com said:
> > but I am curious to see if I could sync up with some of you guys who
> seem to
> > have some pretty cool set-ups.
>
> GPS has taken over the time-distribution business.
>
> If you want to use GPS, there are 2 ways to go.
>
> You can get a simple GPS receiver and plug that into your PC.  For decent
> time, you need a PPS signal and a real serial port, not USB.
>
> The other approach is to get a GPSDO -- GPS Disciplined Oscillator.
> That's a
> box with a GPS receiver and a good crystal and some software.  It smoothes
> out
> the rough edges in the timing from the GPS signal and/or keeps going
> (holdover) when the GPS signal fades or dies.
>
> GPS is very very good in the long term but noisy in the short term.  Short
> means seconds to minutes.  Long means days/months.  A GPSDO will get rid
> of
> most of the short term noise.
>
> There are/were several models available at relatively low cost after they
> were recycled from cell phone towers.  HP Z3801A and Trimble Thunderbolt
> are popular.  "GPSDO" will get lots of hits on eBay.  I don't know how good
> the recent ones are.
>
> Just reading the info available can be fun if you like that stuff.
>   http://www.realhamradio.com/GPS_Frequency_Standard.htm
> The Z3801A manual is a good read.
>   http://www.leapsecond.com/museum/z3801a/097-z3801-01-iss-1.pdf
> Time sink warning!
>
> GPS works much better if you have a good antenna location.  Modern GPS
> receivers are sensitive enough that they sometimes/often work indoors,
> maybe better on a window sill, maybe even better if the window faces
> south.  Just because it's working now doesn't mean it won't glitch often
> enough to cause problems.  Mumble.  Try it and see what happens.
>
> -
>
> There is actually a 3rd way: buy a box that does it all.  But that's not
> much
> fun, at least for most of the people on this list.
>
> --
>
> > there are plenty of good stratum 1 NTP servers open to the public (e.g.
> > NIST's servers),
>
> If you have a good local NTP setup, you can measure how good other servers
> are, or more likely how good the network connection is.  NTP assumes the
> network delays are symmetric.  Often, that's not true.  So "how good" turns
> into measuring network (a)symmetries.
>
>
> --
> These are my opinions.  I hate spam.
>
>
> ___
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>
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[time-nuts] Re: NTP servers

[Hal Murray]

time.isan...@gmail.com said:
> but I am curious to see if I could sync up with some of you guys who seem to
> have some pretty cool set-ups. 

GPS has taken over the time-distribution business.

If you want to use GPS, there are 2 ways to go.

You can get a simple GPS receiver and plug that into your PC.  For decent 
time, you need a PPS signal and a real serial port, not USB.

The other approach is to get a GPSDO -- GPS Disciplined Oscillator.  That's a 
box with a GPS receiver and a good crystal and some software.  It smoothes out 
the rough edges in the timing from the GPS signal and/or keeps going 
(holdover) when the GPS signal fades or dies.

GPS is very very good in the long term but noisy in the short term.  Short 
means seconds to minutes.  Long means days/months.  A GPSDO will get rid of 
most of the short term noise.

There are/were several models available at relatively low cost after they were 
recycled from cell phone towers.  HP Z3801A and Trimble Thunderbolt are 
popular.  "GPSDO" will get lots of hits on eBay.  I don't know how good the 
recent ones are.

Just reading the info available can be fun if you like that stuff.
  http://www.realhamradio.com/GPS_Frequency_Standard.htm
The Z3801A manual is a good read.
  http://www.leapsecond.com/museum/z3801a/097-z3801-01-iss-1.pdf
Time sink warning!

GPS works much better if you have a good antenna location.  Modern GPS 
receivers are sensitive enough that they sometimes/often work indoors, maybe 
better on a window sill, maybe even better if the window faces south.  Just 
because it's working now doesn't mean it won't glitch often enough to cause 
problems.  Mumble.  Try it and see what happens.

-

There is actually a 3rd way: buy a box that does it all.  But that's not much 
fun, at least for most of the people on this list.

--

> there are plenty of good stratum 1 NTP servers open to the public (e.g.
> NIST's servers), 

If you have a good local NTP setup, you can measure how good other servers are, 
or more likely how good the network connection is.  NTP assumes the network 
delays are symmetric.  Often, that's not true.  So "how good" turns into 
measuring network (a)symmetries.


-- 
These are my opinions.  I hate spam.


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[time-nuts] Re: NTP servers

[David Taylor via time-nuts]

On 22/11/2021 02:29, McFail Troll wrote:

Hi all, I am new to the mailing list, and pretty new to timing stuff in
general. I wanted to ask if any of you folks who have a more advanced
set-up (synchronization via gps/radio, or just a well working rubidium
clock or something) maintain a solid stratum 1 NTP server. Of course, I am
aware that there are plenty of good stratum 1 NTP servers open to the
public (e.g. NIST's servers), but I am curious to see if I could sync up
with some of you guys who seem to have some pretty cool set-ups.

Btw, sorry if this has been asked before on this list. Thanks


You may find some helpful information on my Web page:

  https://www.satsignal.eu/ntp/Raspberry-Pi-quickstart.html

about using a GPS/PPS device with a Raspberry Pi.  This gets you down into the 
microsecond region at a low cost and a low power consumption - helpful as 
leaving the device on 24x7 is best.


Be aware that many of the public stratum-1 servers are overloaded and perhaps 
not as good as you might want.


Cheers,
David
--
SatSignal Software - Quality software for you
Web: https://www.satsignal.eu
Email: david-tay...@blueyonder.co.uk
Twitter: @gm8arv
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[time-nuts] Re: NTP servers

[Sanjeev Gupta]

Hi,

I am running a very interesting public server, for about 15 years.

i386, 32-bit, Linux, on very old hardware with a serial port.  Has a GPS
(single constellation) device plugged in, about $35.

I run gpsd (https://gpsd.io) , and it talks to the NTP servers over SHM,
with PPS.

When the NTPsec project started, I shifted over, and run git HEAD.

I also run debian/testing ; so bleeding edge all the way :-)

The server is very stable, I have been in the NTP pool since 2003 or so.

With a Linux machine, I would estimate your total time, from plugging in
your gpsd mouse to going live to be about 30 minutes, including testing the
device, installing and testing gpsd, and installing and configuring
ntpsec.  This is from upstream packages, if you are compiling from git, add
15 minutes.

My GPS graphs is at https://ntpmon.dcs1.biz/ , and NTPsec logs are
available at https://ntpmon.dcs1.biz/ntp/

-- 
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane


On Mon, Nov 22, 2021 at 10:47 AM McFail Troll 
wrote:

> Hi all, I am new to the mailing list, and pretty new to timing stuff in
> general. I wanted to ask if any of you folks who have a more advanced
> set-up (synchronization via gps/radio, or just a well working rubidium
> clock or something) maintain a solid stratum 1 NTP server. Of course, I am
> aware that there are plenty of good stratum 1 NTP servers open to the
> public (e.g. NIST's servers), but I am curious to see if I could sync up
> with some of you guys who seem to have some pretty cool set-ups.
>
> Btw, sorry if this has been asked before on this list. Thanks
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send
> an email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.
>
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[time-nuts] Re: NTP servers

[W7SLS]

Welcome, and here are a few thoughts:

One of the members developed a ’TimeHat’ that sits on top of a Raspberry Pi.
GPS and more.   I purchased tow of them, and am quite happy with them.
https://millerjs.org/timehat 


Another option is the Leo Bodnar NTP device, though it appears to be out of 
stock at the moment

http://www.leobodnar.com/shop/index.php?main_page=product_info=120_id=272
 


Good luck on your new adventure!

Scott

> On Nov 21, 2021, at 6:29 PM, McFail Troll  wrote:
> 
> Hi all, I am new to the mailing list, and pretty new to timing stuff in
> general. I wanted to ask if any of you folks who have a more advanced
> set-up (synchronization via gps/radio, or just a well working rubidium
> clock or something) maintain a solid stratum 1 NTP server. Of course, I am
> aware that there are plenty of good stratum 1 NTP servers open to the
> public (e.g. NIST's servers), but I am curious to see if I could sync up
> with some of you guys who seem to have some pretty cool set-ups.
> 
> Btw, sorry if this has been asked before on this list. Thanks
> ___
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> email to time-nuts-le...@lists.febo.com
> To unsubscribe, go to and follow the instructions there.

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