Re: [ntp:questions] Time syncing with something other than ntpd

[Jakob Bohm]

On 01/02/2017 12:56, David Taylor wrote:

On 01/02/2017 10:59, Jakob Bohm wrote:
[]

As I am looking at the BBB myself, here are some extra questions:

1. Do you know if anyone has tried using the real-time coprocessors on
  the BBB to more accurately track the PPS signal?

2. I presume the BBB could be put in a shielded case (I see some
  offered online).  Any experience with that?

Enjoy
Jakob


Jakob,

(1) No.  Do you mean using the counters to record the timing of the PPS
more precisely?



No, I was thinking about the two "PRU" 200MHz low latency I/O
controllers on the chip, one of those could be made to run its own
little timing PLL loop directly watching the PPS GPIO pin, then
allowing the ARM CPU (running NTPD) to check the high resolution delta
between its own (NTP/Linux) time and the PPS synced loop.



(2) No, but without the BBB radiates more interference than the RPi.




Enjoy

Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded

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Re: [ntp:questions] Time syncing with something other than ntpd

[David Taylor]

On 03/02/2017 07:42, sean wrote:
[]

Just curious, any experience with those?

[]

I'm running a couple of Sure boards here one feeding one PC and the 
other feeding two PCs in parallel (only one PC has TX connected).  No 
problems.  I'm on the top storey of a two storey building, and both 
devices are using indoor puck antennas.

--
Cheers,
David
Web: http://www.satsignal.eu

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Re: [ntp:questions] Time syncing with something other than ntpd

[William Unruh]

On 2017-02-03, sean  wrote:
> On 2017-02-02, William Unruh  wrote:

 Another low-cost device is the Sure evaluation board:

http://www.satsignal.eu/ntp/Sure-GPS.htm

  
 http://www.ebay.com/itm/SKG16A-Bluetooth-RS232-USB-UART-GPS-Module-Demo-Board-/230844194302

>>>
>>> Thanks for the link! That's about half the price of the garmin and would
>>> likely get me better precision than just syncing to the NTP pool.
>>
>> Yes.
>>>
>
> Just curious, any experience with those?

Sure:-) Loads of it. I have used a couple for the past 4 years. Work
well. Needs a little bit of work to get out the PPS signal (soldering a
wire between a couple of points on the board). The GPS18 (both samples I
had) I found would
die after a few years. No idea why. Have not had that problem with the
Sure boards, except one antenna was flakey and then died after a few
months. No support from Sure-Electronics for that, so it seems it is a
WYSIWYG. (Mind you a new antenna was just a copule of bucks, and a
month wait. The free shipping is paid for in shipping time).


>
 Windows uses NTP but not with the reference implementation, so of 
 unknown quality, and not manageable in the same way.  It used to be 
 lousy, and I've not tested since then.

>>>
>>> I think I'll install the ntp client on my windows machine and see what
>>> kind of time I can get.
>>
>> You would probably be better off syncing a linux machine to the gps
>> board and then syncing the windows machine to that over the local Lan.
>>
>>
>
> Yes, but if the windows machine isn't at home, it won't sync. Allowing
> remote access will come later. :)

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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-02-02, William Unruh  wrote:
>>>
>>> Another low-cost device is the Sure evaluation board:
>>>
>>>http://www.satsignal.eu/ntp/Sure-GPS.htm
>>>
>>>  
>>> http://www.ebay.com/itm/SKG16A-Bluetooth-RS232-USB-UART-GPS-Module-Demo-Board-/230844194302
>>>
>>
>> Thanks for the link! That's about half the price of the garmin and would
>> likely get me better precision than just syncing to the NTP pool.
>
> Yes.
>>

Just curious, any experience with those?

>>> Windows uses NTP but not with the reference implementation, so of 
>>> unknown quality, and not manageable in the same way.  It used to be 
>>> lousy, and I've not tested since then.
>>>
>>
>> I think I'll install the ntp client on my windows machine and see what
>> kind of time I can get.
>
> You would probably be better off syncing a linux machine to the gps
> board and then syncing the windows machine to that over the local Lan.
>
>

Yes, but if the windows machine isn't at home, it won't sync. Allowing
remote access will come later. :)

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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-02-02, David Taylor  wrote:
> On 02/02/2017 04:34, sean wrote:
> []
>> Incidentally I do have a BBB and a few raspberry pis. The BBB goes back
>> and forth to/from work so I won't be able to use that as the NTP host.
>>
>> As an aside, have you done anything with SDR? You may be interested in
>> this:
>> https://github.com/flightaware/piaware
>
> Do lets us know how you get on with NTP.
>

Absolutely. You and others have been very helpful with all the links and
advice.

> Yes, I've done some ADS-B stuff, although using others' code as I don't 
> do "C" myself.  For multilateration we need times to better than a 
> microsecond (and ideally to within 100 ns) and this is achieved within 
> the software by comparing several aircraft which are mutually visible 
> between multiple stations, and for some of which GPS locations are known.
>
>http://www.satsignal.eu/raspberry-pi/dump1090.html
>

Your site has a little bit of everything, doesn't it?!

You're probably aware but flightaware is selling these little devices:

https://www.amazon.com/FlightAware-Stick-Receiver-Built-Filter/dp/B01M7REJJW/ref=sr_1_5?ie=UTF8=1486076686=8-5=flight+aware

I would still need to get an antenna for it. But of course you have a
link on how to make one:
http://www.lll.lu/~edward/edward/adsb/antenna/ADSBantenna.html

Is that the same one you're still using?

> and, of course, I monitor the performance where I can, comparing 
> different systems:
>
>http://www.satsignal.eu/mrtg/performance_ads-b.php
>
> I've also just started with earthquake detection, something which 
> requires good time keeping (perhaps to within a second!) and may be of 
> interest to west coast USA members:
>
>https://www.raspberrypi.org/blog/raspberry-shake-personal-seismograph/
>
Very neat. Even though I'm a proud owner of several pis, I don't check
their blog out very much. I should because they have great content.

Sorry for taking this so far off subject from NTP.

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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-02-02, Miroslav Lichvar  wrote:
> On 2017-02-02, sean  wrote:
>> I don't know if I'll be able to join the pool because I don't
>> have a static IP. Although, if I register with a DNS name, couldn't I
>> just update the A record if/when it changes?
>> something like time.example.com.
>
> That won't work. The pool works with IP addresses and they are not
> supposed to change. I'm in a similar situation. I have at home a nice
> low-power stratum-1 server using a u-blox neo-6m GPS with good network
> connection, but I can't add it to the pool, because its address may
> change without notice (although it rarely does).
>

Okay, that's too bad for me. I'll use it for my devices at home, which
will get good time.

> So I have a VPS that is synchronised to it and its time is served
> indirectly.
>

Ah, nice and something I'll also consider.

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Re: [ntp:questions] Time syncing with something other than ntpd

[Charles Elliott]

There is a Garmin GPS 18x High-Sensitivity LVC Sensor 010-00321-36 for sale
on eBay here:
http://www.ebay.com/itm/Garmin-GPS-18x-High-Sensitivity-LVC-Sensor-010-00321
-36-/77215324?hash=item33c0c1245c:g:L-gAAOSwOyJX-6Dn=mtr for only
$45.86 USD, $59.99 C in Canada.  I bought one from eBay for $39 not too long
ago, so all you really have to do is look.

The Sure device works, but for me it was too difficult to make the PPS work.
I bought two and was unable to make either one output a detectable PPS.  The
PPS was there, my scope told me so, but I could not make the computer detect
it.  On the other hand, I am very clumsy, and have little experience with
electronics.

Charles Elliott

-Original Message-
From: questions
[mailto:questions-bounces+elliott.ch=comcast@lists.ntp.org] On Behalf Of
William Unruh
Sent: Thursday, February 2, 2017 1:06 AM
To: questions@lists.ntp.org
Subject: Re: [ntp:questions] Time syncing with something other than ntpd

On 2017-02-02, sean <s...@sean.eternal-september.org> wrote:
> On 2017-02-01, David Taylor <david-tay...@blueyonder.co.uk.invalid> wrote:
>>
>> Sean,
>>
>> Thanks for your comments - much of the Web site is comprised of my 
>> own notes to remind me what to do next time!  Still waiting for one 
>> minor operation, and then to see if (or should it be when?) the Crohn's
returns.
>>
>
> Well your self made notes for yourself have proven to have a rich 
> amount of helpful information. :) Keep the faith with your healing.
>
>> Unfortunately I can't be part of the pool as my ISP doesn't offer 
>> static addresses.
>>
>
> I posted a followup whether a hostname could be used in lieu leui of 
> an IP address. I understand it can't change every few hours/days. Does 
> your changed that frequently?
>
>> I don't know whether FreeBSD is better than Linux any more, others 
>> will need to answer that.  My FreeBSD box refused to update from 
>> FreeBSD 7 to FreeBSD 8, so I stuck Linux on it in desperation!
>
> Wow, those versions are well before my time with FreeBSD. I'm not sure 
> if I'll be that concerned about the OS, and rather focus on the GPS 
> equipment you linked to below.
>
>>
>> Another low-cost device is the Sure evaluation board:
>>
>>http://www.satsignal.eu/ntp/Sure-GPS.htm
>>
>>  
>> http://www.ebay.com/itm/SKG16A-Bluetooth-RS232-USB-UART-GPS-Module-De
>> mo-Board-/230844194302
>>
>
> Thanks for the link! That's about half the price of the garmin and 
> would likely get me better precision than just syncing to the NTP pool.

Yes.
>
>> Windows uses NTP but not with the reference implementation, so of 
>> unknown quality, and not manageable in the same way.  It used to be 
>> lousy, and I've not tested since then.
>>
>
> I think I'll install the ntp client on my windows machine and see what 
> kind of time I can get.

You would probably be better off syncing a linux machine to the gps board
and then syncing the windows machine to that over the local Lan.


>
>> What will be good enough depends on your needs.  The lowest cost 
>> might be the Sure board attached to an existing FreeBSD box, running 
>> 24 x 7 and in as stable a thermal environment as necessary.  Both the 
>> Raspberry Pi and BeagleBone Black are low-power devices and therefore 
>> low-cost to run 24 x 7, with the BBB having a slightly better 
>> Ethernet implementation if you need to get down to the tens of 
>> microseconds level, but with the Raspberry Pi have a much wider 
>> support even though it might offer (approx) fifties of microseconds.
Judge for yourself here:
>>
>>http://www.satsignal.eu/ntp/BBB-vs-RPi.html
>>
>> If you already have an RPi doing something, adding a NTP server to 
>> its tasks will make little extra load for an environment with a 
>> thousand or more clients
>>
>
> Incidentally I do have a BBB and a few raspberry pis. The BBB goes 
> back and forth to/from work so I won't be able to use that as the NTP
host.
>
> As an aside, have you done anything with SDR? You may be interested in
> this:
> https://github.com/flightaware/piaware
>

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Re: [ntp:questions] Time syncing with something other than ntpd

[David Taylor]

On 02/02/2017 04:34, sean wrote:
[]

Incidentally I do have a BBB and a few raspberry pis. The BBB goes back
and forth to/from work so I won't be able to use that as the NTP host.

As an aside, have you done anything with SDR? You may be interested in
this:
https://github.com/flightaware/piaware


Do lets us know how you get on with NTP.

Yes, I've done some ADS-B stuff, although using others' code as I don't 
do "C" myself.  For multilateration we need times to better than a 
microsecond (and ideally to within 100 ns) and this is achieved within 
the software by comparing several aircraft which are mutually visible 
between multiple stations, and for some of which GPS locations are known.


  http://www.satsignal.eu/raspberry-pi/dump1090.html

and, of course, I monitor the performance where I can, comparing 
different systems:


  http://www.satsignal.eu/mrtg/performance_ads-b.php

I've also just started with earthquake detection, something which 
requires good time keeping (perhaps to within a second!) and may be of 
interest to west coast USA members:


  https://www.raspberrypi.org/blog/raspberry-shake-personal-seismograph/

--
Cheers,
David
Web: http://www.satsignal.eu

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Re: [ntp:questions] Time syncing with something other than ntpd

[Miroslav Lichvar]

On 2017-02-02, sean  wrote:
> I don't know if I'll be able to join the pool because I don't
> have a static IP. Although, if I register with a DNS name, couldn't I
> just update the A record if/when it changes?
> something like time.example.com.

That won't work. The pool works with IP addresses and they are not
supposed to change. I'm in a similar situation. I have at home a nice
low-power stratum-1 server using a u-blox neo-6m GPS with good network
connection, but I can't add it to the pool, because its address may
change without notice (although it rarely does).

So I have a VPS that is synchronised to it and its time is served
indirectly.

-- 
Miroslav Lichvar

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Re: [ntp:questions] Time syncing with something other than ntpd

[William Unruh]

On 2017-02-02, sean  wrote:
> On 2017-02-01, David Taylor  wrote:
>>
>> Sean,
>>
>> Thanks for your comments - much of the Web site is comprised of my own 
>> notes to remind me what to do next time!  Still waiting for one minor 
>> operation, and then to see if (or should it be when?) the Crohn's returns.
>>
>
> Well your self made notes for yourself have proven to have a rich amount
> of helpful information. :) Keep the faith with your healing.
>
>> Unfortunately I can't be part of the pool as my ISP doesn't offer static 
>> addresses.
>>
>
> I posted a followup whether a hostname could be used in lieu leui of an
> IP address. I understand it can't change every few hours/days. Does your
> changed that frequently?
>
>> I don't know whether FreeBSD is better than Linux any more, others will 
>> need to answer that.  My FreeBSD box refused to update from FreeBSD 7 to 
>> FreeBSD 8, so I stuck Linux on it in desperation!
>
> Wow, those versions are well before my time with FreeBSD. I'm not sure
> if I'll be that concerned about the OS, and rather focus on the GPS
> equipment you linked to below.
>
>>
>> Another low-cost device is the Sure evaluation board:
>>
>>http://www.satsignal.eu/ntp/Sure-GPS.htm
>>
>>  
>> http://www.ebay.com/itm/SKG16A-Bluetooth-RS232-USB-UART-GPS-Module-Demo-Board-/230844194302
>>
>
> Thanks for the link! That's about half the price of the garmin and would
> likely get me better precision than just syncing to the NTP pool.

Yes.
>
>> Windows uses NTP but not with the reference implementation, so of 
>> unknown quality, and not manageable in the same way.  It used to be 
>> lousy, and I've not tested since then.
>>
>
> I think I'll install the ntp client on my windows machine and see what
> kind of time I can get.

You would probably be better off syncing a linux machine to the gps
board and then syncing the windows machine to that over the local Lan.


>
>> What will be good enough depends on your needs.  The lowest cost might 
>> be the Sure board attached to an existing FreeBSD box, running 24 x 7 
>> and in as stable a thermal environment as necessary.  Both the Raspberry 
>> Pi and BeagleBone Black are low-power devices and therefore low-cost to 
>> run 24 x 7, with the BBB having a slightly better Ethernet 
>> implementation if you need to get down to the tens of microseconds 
>> level, but with the Raspberry Pi have a much wider support even though 
>> it might offer (approx) fifties of microseconds.  Judge for yourself here:
>>
>>http://www.satsignal.eu/ntp/BBB-vs-RPi.html
>>
>> If you already have an RPi doing something, adding a NTP server to its 
>> tasks will make little extra load for an environment with a thousand or 
>> more clients
>>
>
> Incidentally I do have a BBB and a few raspberry pis. The BBB goes back
> and forth to/from work so I won't be able to use that as the NTP host.
>
> As an aside, have you done anything with SDR? You may be interested in
> this:
> https://github.com/flightaware/piaware
>

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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-02-01, David Taylor  wrote:
>
> Sean,
>
> Thanks for your comments - much of the Web site is comprised of my own 
> notes to remind me what to do next time!  Still waiting for one minor 
> operation, and then to see if (or should it be when?) the Crohn's returns.
>

Well your self made notes for yourself have proven to have a rich amount
of helpful information. :) Keep the faith with your healing.

> Unfortunately I can't be part of the pool as my ISP doesn't offer static 
> addresses.
>

I posted a followup whether a hostname could be used in lieu leui of an
IP address. I understand it can't change every few hours/days. Does your
changed that frequently?

> I don't know whether FreeBSD is better than Linux any more, others will 
> need to answer that.  My FreeBSD box refused to update from FreeBSD 7 to 
> FreeBSD 8, so I stuck Linux on it in desperation!

Wow, those versions are well before my time with FreeBSD. I'm not sure
if I'll be that concerned about the OS, and rather focus on the GPS
equipment you linked to below.

>
> Another low-cost device is the Sure evaluation board:
>
>http://www.satsignal.eu/ntp/Sure-GPS.htm
>
>  
> http://www.ebay.com/itm/SKG16A-Bluetooth-RS232-USB-UART-GPS-Module-Demo-Board-/230844194302
>

Thanks for the link! That's about half the price of the garmin and would
likely get me better precision than just syncing to the NTP pool.

> Windows uses NTP but not with the reference implementation, so of 
> unknown quality, and not manageable in the same way.  It used to be 
> lousy, and I've not tested since then.
>

I think I'll install the ntp client on my windows machine and see what
kind of time I can get.

> What will be good enough depends on your needs.  The lowest cost might 
> be the Sure board attached to an existing FreeBSD box, running 24 x 7 
> and in as stable a thermal environment as necessary.  Both the Raspberry 
> Pi and BeagleBone Black are low-power devices and therefore low-cost to 
> run 24 x 7, with the BBB having a slightly better Ethernet 
> implementation if you need to get down to the tens of microseconds 
> level, but with the Raspberry Pi have a much wider support even though 
> it might offer (approx) fifties of microseconds.  Judge for yourself here:
>
>http://www.satsignal.eu/ntp/BBB-vs-RPi.html
>
> If you already have an RPi doing something, adding a NTP server to its 
> tasks will make little extra load for an environment with a thousand or 
> more clients
>

Incidentally I do have a BBB and a few raspberry pis. The BBB goes back
and forth to/from work so I won't be able to use that as the NTP host.

As an aside, have you done anything with SDR? You may be interested in
this:
https://github.com/flightaware/piaware

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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-02-01, Miroslav Lichvar  wrote:
> On 2017-02-01, sean  wrote:
>> On 2017-01-30, William Unruh  wrote:
>>> You do not say which OS you use. Windows (which version?), Mac, linux,
>>> BSD?
>>
>> Primarily FreeBSD and OpenBSD, but also Linux. Knowning that, what's
>> that mean in terms of a ntp client?
>
> IIRC openntpd runs on all these systems, but reference clocks are
> supported only on OpenBSD. chrony supports FreeBSD and Linux (both with
> refclocks), but not OpenBSD. ntpd supports everything.
>

Cool. I'll probably install ntpd on my one windows laptop system to get
more accurate time to the NTP pool.

>>> chrony does not work on windows. ntpd is what what tends to ship with
>>> linux distros. chrony gives better time discipline but has a smaller
>>> user group. 
>>
>> Well if I use Chrony with a GPS unit on something like a raspberry pi,
>> would I be able to be apart of the NTP pool or is it limited to NTPD
>> users only?
>
> Yes, you can do that. The pool project page recommends ntpd, but it's
> not a requirement. There are quite a few openntpd and chrony servers in
> the pool, including a couple of my own.
>

ah, cool. I didn't know I could see the ntp source. I'll have to check
that out. I don't know if I'll be able to join the pool because I don't
have a static IP. Although, if I register with a DNS name, couldn't I
just update the A record if/when it changes?
something like time.example.com.

Thanks!

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Re: [ntp:questions] Time syncing with something other than ntpd

[Dan Drown]

Quoting Jakob Bohm :

1. Do you know if anyone has tried using the real-time coprocessors on
  the BBB to more accurately track the PPS signal?


I have a driver for the BBB's input capture timer hardware here:  
https://github.com/ddrown/pps-gmtimer


There's a bug in the recent BBB kernels (4.4.17-ti) that I haven't  
been able to track down.  When you enable timer2, the ethernet  
hardware loses link.  So this driver only works on the older  
3.8.x-bone kernels.


The results were 30%-50% better offsets with pps-gmtimer vs pps-gpio.   
Both numbers are dwarfed by the network interface jitter for NTP  
clients (which is in the 15us-20us range for my environment).


There's some more info here (including a histogram comparing pps-gpio  
vs pps-gmtimer):  
https://blog.dan.drown.org/beaglebone-black-timer-capture-driver/



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Re: [ntp:questions] Time syncing with something other than ntpd

[Brian Inglis]

On 2017-01-31 22:55, sean wrote:
> On 2017-01-30, David Taylor  wrote:
>> On 30/01/2017 04:13, sean wrote:
>>> I'm real interested in NTP and accurate time, hence why I'm on this
>>> newsgroup. I would like to look into getting a time sensor and I hear
>>> the Garmin GPS 18X is what some folks run unless they need much more
>>> precision. Is this still a pretty well regarding GPS unit for pretty
>>> accurate (I know that's highly subjective) time keeping? This would be
>>> a hobbyist thing and I'm not running an important business, if you were
>>> going to ask.
>>> Next question...Do most folks here use the NTPD client, or it is a
>>> mixture of Chrony and openNTPD? Maybe some folks just go with what ships
>>> with their OS?
>>> The comparison chart is pretty nice and lays each option out nicely:
>>> https://chrony.tuxfamily.org/comparison.html
>>> I think that's all for now. Feel free to provide any URLs to any
>>> resources I should check out about time sycing, NTP, etc.
>> I have been running NTP on multiple systems since 2002, including Linux 
>> and Windows (2000 and later), both with hardware sync (GPS18, GPS18x and 
>> multiple GPS devices for the Raspberry Pi), and with LAN and Wi-Fi 
>> network sources.  I find NTP easy to manage and monitor over multiple 
>> systems, and the fact that it runs on Windows, and can accept GPS 
>> devices on Windows very valuable.  You can easily get within 10 
>> microseconds in Linux (but be careful of the temperature and GPS antenna 
>> location), and within 200 microseconds on Windows when using an attached 
>> GPS/PPS device.
> Thank you for the reply. I found your website about 3 weeks ago and got
> the urge to checkout GPS devices, like the GPS18, Raspberry pi options,
> etc. Thank you for it and all of the graphs. You certainly have many Pis
> keep track of the time! I don't recall, are you apart of the NTP Pool?
> I found your website to have a wealth of great information that's quite
> well compiled and thoughout. I hope your health is much better this
> year and that you're on the road to recovery.
> Primarily I run FreeBSD and was surprised to learn that it can have
> better precision than Linux, although the articles I read were FreeBSD
> 8.0 era. Do you find FreeBSD generic kernel comparable with Linux? From
> what it sounds like, a Raspberry Pi with the device below will give me
> "pretty accurate" (my words) time, which I can use to sync my devices in
> my home.
>>http://www.satsignal.eu/mrtg/performance_ntp.php
>> For the Raspberry Pi:
>> https://store.uputronics.com/index.php?route=product/product_id=81
> That's pretty well priced, cheaper than the Garmin

For that and the below you also need power supply, antenna, and interface.

http://www.ebay.com/itm/Trimble-Resolution-T-Timing-GPS-module-12ns-1pps/252474351979

http://www.ebay.com/itm/UBLOX-LEA-5T-high-precision-timing-GPS-module-dev-board-1PPS-USB-RS232-ntp-ser/251785217093

For easy as Pi there's the GPS HAT:

https://www.adafruit.com/product/2324

which works fine on the Pi3 if you disable BT or switch BT to 
the mini-uart with a DT overlay despite AdaFruit statement 
(do web search for Adafruit Ultimate GPS HAT Pi3 NTP).

Cheapest Garmin 18x LVC I have found anywhere is US$60 (shipping 
extra) from my local dealer who also ships world wide from LV, NV:

http://www.gpscity.com/garmin-gps-18x-high-sensitivity-lvc.html
http://www.gpscity.ca/garmin-gps-18x-high-sensitivity-lvc.html

I run both of the above and average offset is low us with offset 
spiking up to about +/-50us, probably temperature swings. 

-- 
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Re: [ntp:questions] Time syncing with something other than ntpd

[David Taylor]

On 01/02/2017 10:59, Jakob Bohm wrote:
[]

As I am looking at the BBB myself, here are some extra questions:

1. Do you know if anyone has tried using the real-time coprocessors on
  the BBB to more accurately track the PPS signal?

2. I presume the BBB could be put in a shielded case (I see some
  offered online).  Any experience with that?

Enjoy
Jakob


Jakob,

(1) No.  Do you mean using the counters to record the timing of the PPS 
more precisely?


(2) No, but without the BBB radiates more interference than the RPi.

--
Cheers,
David
Web: http://www.satsignal.eu

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Re: [ntp:questions] Time syncing with something other than ntpd

[David Taylor]

On 01/02/2017 05:55, sean wrote:
[]

Hi Dave,

Thank you for the reply. I found your website about 3 weeks ago and got
the urge to checkout GPS devices, like the GPS18, Raspberry pi options,
etc. Thank you for it and all of the graphs. You certainly have many Pis
keep track of the time! I don't recall, are you apart of the NTP Pool?

I found your website to have a wealth of great information that's quite
well compiled and thoughout. I hope your health is much better this
year and that you're on the road to recovery.

Primarily I run FreeBSD and was surprised to learn that it can have
better precision than Linux, although the articles I read were FreeBSD
8.0 era. Do you find FreeBSD generic kernel comparable with Linux? From
what it sounds like, a Raspberry Pi with the device below will give me
"pretty accurate" (my words) time, which I can use to sync my devices in
my home.



   http://www.satsignal.eu/mrtg/performance_ntp.php

For the Raspberry Pi:


https://store.uputronics.com/index.php?route=product/product_id=81



That's pretty well priced, cheaper than the Garmin


In terms of installations, I think that NTP will have by far the
greatest number, and of the three you listed, only NTP runs on Windows.


Well I don't really have any Windows installations, but I will keep NTP
in mind when I want to run time syncing on Windows. As an aside, what
does Windows natively use to keep time and sync?

Thanks,
Sean


Sean,

Thanks for your comments - much of the Web site is comprised of my own 
notes to remind me what to do next time!  Still waiting for one minor 
operation, and then to see if (or should it be when?) the Crohn's returns.


Unfortunately I can't be part of the pool as my ISP doesn't offer static 
addresses.


I don't know whether FreeBSD is better than Linux any more, others will 
need to answer that.  My FreeBSD box refused to update from FreeBSD 7 to 
FreeBSD 8, so I stuck Linux on it in desperation!


Another low-cost device is the Sure evaluation board:

  http://www.satsignal.eu/ntp/Sure-GPS.htm


http://www.ebay.com/itm/SKG16A-Bluetooth-RS232-USB-UART-GPS-Module-Demo-Board-/230844194302

Windows uses NTP but not with the reference implementation, so of 
unknown quality, and not manageable in the same way.  It used to be 
lousy, and I've not tested since then.


What will be good enough depends on your needs.  The lowest cost might 
be the Sure board attached to an existing FreeBSD box, running 24 x 7 
and in as stable a thermal environment as necessary.  Both the Raspberry 
Pi and BeagleBone Black are low-power devices and therefore low-cost to 
run 24 x 7, with the BBB having a slightly better Ethernet 
implementation if you need to get down to the tens of microseconds 
level, but with the Raspberry Pi have a much wider support even though 
it might offer (approx) fifties of microseconds.  Judge for yourself here:


  http://www.satsignal.eu/ntp/BBB-vs-RPi.html

If you already have an RPi doing something, adding a NTP server to its 
tasks will make little extra load for an environment with a thousand or 
more clients


--
Cheers,
David
Web: http://www.satsignal.eu

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Re: [ntp:questions] Time syncing with something other than ntpd

[Jakob Bohm]

On 01/02/2017 06:55, sean wrote:

On 2017-01-30, David Taylor  wrote:

On 30/01/2017 04:13, sean wrote:

Hi All,

I'm real interested in NTP and accurate time, hence why I'm on this
newsgroup. I would like to look into getting a time sensor and I hear
the Garmin GPS 18X is what some folks run unless they need much more
precision. Is this still a pretty well regarding GPS unit for pretty
accurate (I know that's highly subjective) time keeping? This would be
a hobbyist thing and I'm not running an important business, if you were
going to ask.

Next question...Do most folks here use the NTPD client, or it is a
mixture of Chrony and openNTPD? Maybe some folks just go with what ships
with their OS?
The comparison chart is pretty nice and lays each option out nicely:
https://chrony.tuxfamily.org/comparison.html

I think that's all for now. Feel free to provide any URLs to any
resources I should check out about time sycing, NTP, etc.


Sean,

I have been running NTP on multiple systems since 2002, including Linux
and Windows (2000 and later), both with hardware sync (GPS18, GPS18x and
multiple GPS devices for the Raspberry Pi), and with LAN and Wi-Fi
network sources.  I find NTP easy to manage and monitor over multiple
systems, and the fact that it runs on Windows, and can accept GPS
devices on Windows very valuable.  You can easily get within 10
microseconds in Linux (but be careful of the temperature and GPS antenna
location), and within 200 microseconds on Windows when using an attached
GPS/PPS device.



Hi Dave,

Thank you for the reply. I found your website about 3 weeks ago and got
the urge to checkout GPS devices, like the GPS18, Raspberry pi options,
etc. Thank you for it and all of the graphs. You certainly have many Pis
keep track of the time! I don't recall, are you apart of the NTP Pool?

I found your website to have a wealth of great information that's quite
well compiled and thoughout. I hope your health is much better this
year and that you're on the road to recovery.

Primarily I run FreeBSD and was surprised to learn that it can have
better precision than Linux, although the articles I read were FreeBSD
8.0 era. Do you find FreeBSD generic kernel comparable with Linux? From
what it sounds like, a Raspberry Pi with the device below will give me
"pretty accurate" (my words) time, which I can use to sync my devices in
my home.



   http://www.satsignal.eu/mrtg/performance_ntp.php

For the Raspberry Pi:


https://store.uputronics.com/index.php?route=product/product_id=81



That's pretty well priced, cheaper than the Garmin


In terms of installations, I think that NTP will have by far the
greatest number, and of the three you listed, only NTP runs on Windows.


Well I don't really have any Windows installations, but I will keep NTP
in mind when I want to run time syncing on Windows. As an aside, what
does Windows natively use to keep time and sync?



Microsoft's own NTP/SNTP client, known as W32Time.  It has 3 major
operational modes:

- Triggered SNTP mode, where it is launched (briefly) from a weekly
 "cron" job, this is the default for machines not in a domain (because
 such machines also default to hitting the same overloaded public
 server, but the two settings are not tied directly).

- A regular NTP/SNTP mode with registry/command line options to set NTP
 modes etc., this is the default for machines in a domain (because such
 machines also default to using the W32Time on the nearest domain
 controller as its time source).  Instructions for switching to this
 mode are somewhat hard to find, to reduce the risk of dumb users
 enabling this mode while still using one of the overloaded public
 servers.

- A broken SNTP mode where various protocol details are wrong, this was
 a property of old versions of W32Time but is still mentioned in
 various NTPD related documents.


Enjoy

Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark.  Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded

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Re: [ntp:questions] Time syncing with something other than ntpd

[Miroslav Lichvar]

On 2017-02-01, sean  wrote:
> On 2017-01-30, William Unruh  wrote:
>> You do not say which OS you use. Windows (which version?), Mac, linux,
>> BSD?
>
> Primarily FreeBSD and OpenBSD, but also Linux. Knowning that, what's
> that mean in terms of a ntp client?

IIRC openntpd runs on all these systems, but reference clocks are
supported only on OpenBSD. chrony supports FreeBSD and Linux (both with
refclocks), but not OpenBSD. ntpd supports everything.

>> chrony does not work on windows. ntpd is what what tends to ship with
>> linux distros. chrony gives better time discipline but has a smaller
>> user group. 
>
> Well if I use Chrony with a GPS unit on something like a raspberry pi,
> would I be able to be apart of the NTP pool or is it limited to NTPD
> users only?

Yes, you can do that. The pool project page recommends ntpd, but it's
not a requirement. There are quite a few openntpd and chrony servers in
the pool, including a couple of my own.

-- 
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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-01-30, William Unruh  wrote:
> On 2017-01-30, sean  wrote:
>> Hi All,
>>
>> I'm real interested in NTP and accurate time, hence why I'm on this
>> newsgroup. I would like to look into getting a time sensor and I hear
>> the Garmin GPS 18X is what some folks run unless they need much more
>> precision. Is this still a pretty well regarding GPS unit for pretty
>> accurate (I know that's highly subjective) time keeping? This would be
>> a hobbyist thing and I'm not running an important business, if you were
>> going to ask.
>>
>> Next question...Do most folks here use the NTPD client, or it is a
>> mixture of Chrony and openNTPD? Maybe some folks just go with what ships
>> with their OS?
>
> You do not say which OS you use. Windows (which version?), Mac, linux,
> BSD?

Primarily FreeBSD and OpenBSD, but also Linux. Knowning that, what's
that mean in terms of a ntp client?

>
> chrony does not work on windows. ntpd is what what tends to ship with
> linux distros. chrony gives better time discipline but has a smaller
> user group. 

Well if I use Chrony with a GPS unit on something like a raspberry pi,
would I be able to be apart of the NTP pool or is it limited to NTPD
users only?

Best,
Sean

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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-01-30, Terje Mathisen  wrote:
> sean wrote:
>> Hi All,
>>
>> I'm real interested in NTP and accurate time, hence why I'm on this
>> newsgroup. I would like to look into getting a time sensor and I hear
>> the Garmin GPS 18X is what some folks run unless they need much more
>> precision. Is this still a pretty well regarding GPS unit for pretty
>> accurate (I know that's highly subjective) time keeping? This would be
>> a hobbyist thing and I'm not running an important business, if you were
>> going to ask.
>
> I have had a Garmin 18 as well as 3-4 SURE kits, the latter is half the 
> price, requires about the same amount of soldering, and has been 
> measured at the 20-30 ns level, so quite accurate.
>>

Do you have a URL to the sure kits? What do you have it hooked up to
that's running your NTP daemon?

>> Next question...Do most folks here use the NTPD client, or it is a
>> mixture of Chrony and openNTPD? Maybe some folks just go with what ships
>> with their OS?
>
> Since I've been on the NTP Hackers team for a couple of decades I'm 
> partial to the original ntpd. :-)
>

Yeah, hard to imagine you wanting to change from something you know so
very well. Thank you for your contributions to NTP!

> Terje

Best,
Sean

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Re: [ntp:questions] Time syncing with something other than ntpd

[sean]

On 2017-01-30, David Taylor  wrote:
> On 30/01/2017 04:13, sean wrote:
>> Hi All,
>>
>> I'm real interested in NTP and accurate time, hence why I'm on this
>> newsgroup. I would like to look into getting a time sensor and I hear
>> the Garmin GPS 18X is what some folks run unless they need much more
>> precision. Is this still a pretty well regarding GPS unit for pretty
>> accurate (I know that's highly subjective) time keeping? This would be
>> a hobbyist thing and I'm not running an important business, if you were
>> going to ask.
>>
>> Next question...Do most folks here use the NTPD client, or it is a
>> mixture of Chrony and openNTPD? Maybe some folks just go with what ships
>> with their OS?
>> The comparison chart is pretty nice and lays each option out nicely:
>> https://chrony.tuxfamily.org/comparison.html
>>
>> I think that's all for now. Feel free to provide any URLs to any
>> resources I should check out about time sycing, NTP, etc.
>
> Sean,
>
> I have been running NTP on multiple systems since 2002, including Linux 
> and Windows (2000 and later), both with hardware sync (GPS18, GPS18x and 
> multiple GPS devices for the Raspberry Pi), and with LAN and Wi-Fi 
> network sources.  I find NTP easy to manage and monitor over multiple 
> systems, and the fact that it runs on Windows, and can accept GPS 
> devices on Windows very valuable.  You can easily get within 10 
> microseconds in Linux (but be careful of the temperature and GPS antenna 
> location), and within 200 microseconds on Windows when using an attached 
> GPS/PPS device.
>

Hi Dave,

Thank you for the reply. I found your website about 3 weeks ago and got
the urge to checkout GPS devices, like the GPS18, Raspberry pi options,
etc. Thank you for it and all of the graphs. You certainly have many Pis
keep track of the time! I don't recall, are you apart of the NTP Pool?

I found your website to have a wealth of great information that's quite
well compiled and thoughout. I hope your health is much better this
year and that you're on the road to recovery.

Primarily I run FreeBSD and was surprised to learn that it can have
better precision than Linux, although the articles I read were FreeBSD
8.0 era. Do you find FreeBSD generic kernel comparable with Linux? From
what it sounds like, a Raspberry Pi with the device below will give me
"pretty accurate" (my words) time, which I can use to sync my devices in
my home.


>http://www.satsignal.eu/mrtg/performance_ntp.php
>
> For the Raspberry Pi:
>
>  
> https://store.uputronics.com/index.php?route=product/product_id=81
>

That's pretty well priced, cheaper than the Garmin

> In terms of installations, I think that NTP will have by far the 
> greatest number, and of the three you listed, only NTP runs on Windows.

Well I don't really have any Windows installations, but I will keep NTP
in mind when I want to run time syncing on Windows. As an aside, what
does Windows natively use to keep time and sync?

Thanks,
Sean

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Re: [ntp:questions] Time syncing with something other than ntpd

[Miroslav Lichvar]

On 2017-01-30, David Taylor  wrote:
> I have been running NTP on multiple systems since 2002, including Linux 
> and Windows (2000 and later), both with hardware sync (GPS18, GPS18x and 
> multiple GPS devices for the Raspberry Pi), and with LAN and Wi-Fi 
> network sources.  I find NTP easy to manage and monitor over multiple 
> systems, and the fact that it runs on Windows, and can accept GPS 
> devices on Windows very valuable.  You can easily get within 10 
> microseconds in Linux (but be careful of the temperature and GPS antenna 
> location), and within 200 microseconds on Windows when using an attached 
> GPS/PPS device.

Speaking of Windows, does anyone know how well (if at all) work the
NTP implementations in the Windows Subsystem for Linux (WSL) that's now
available in Windows 10?

-- 
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Re: [ntp:questions] Time syncing with something other than ntpd

[Brian Inglis]

On 2017-01-30 00:53, David Taylor wrote:
> On 30/01/2017 04:13, sean wrote:
>> I'm real interested in NTP and accurate time, hence why I'm on
>> this newsgroup. I would like to look into getting a time sensor and
>> I hear the Garmin GPS 18X is what some folks run unless they need
>> much more precision. Is this still a pretty well regarding GPS unit
>> for pretty accurate (I know that's highly subjective) time keeping?
>> This would be a hobbyist thing and I'm not running an important
>> business, if you were going to ask.
>> Next question...Do most folks here use the NTPD client, or it is a 
>> mixture of Chrony and openNTPD? Maybe some folks just go with what
>> ships with their OS?
>> The comparison chart is pretty nice and lays each option out
>> nicely:
>> https://chrony.tuxfamily.org/comparison.html
>> I think that's all for now. Feel free to provide any URLs to any 
>> resources I should check out about time syncing, NTP, etc.
> I have been running NTP on multiple systems since 2002, including 
> Linux and Windows (2000 and later), both with hardware sync (GPS18, 
> GPS18x and multiple GPS devices for the Raspberry Pi), and with LAN 
> and Wi-Fi network sources. I find NTP easy to manage and monitor
> over multiple systems, and the fact that it runs on Windows, and can 
> accept GPS devices on Windows very valuable. You can easily get 
> within 10 microseconds in Linux (but be careful of the temperature 
> and GPS antenna location), and within 200 microseconds on Windows 
> when using an attached GPS/PPS device.
>   http://www.satsignal.eu/mrtg/performance_ntp.php
> For the Raspberry Pi:
> https://store.uputronics.com/index.php?route=product/product_id=81
> In terms of installations, I think that NTP will have by far the 
> greatest number, and of the three you listed, only NTP runs on 
> Windows.

Worth checking out David Taylor's site above for the practical 
operational details about configuring and running NTP servers 
on various platforms and interfaces, and about building the 
software.
For the definitive reference docs for each release see 

http://doc.ntp.org/ 

-- 
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Re: [ntp:questions] Time syncing with something other than ntpd

[David Taylor]

On 30/01/2017 04:13, sean wrote:

Hi All,

I'm real interested in NTP and accurate time, hence why I'm on this
newsgroup. I would like to look into getting a time sensor and I hear
the Garmin GPS 18X is what some folks run unless they need much more
precision. Is this still a pretty well regarding GPS unit for pretty
accurate (I know that's highly subjective) time keeping? This would be
a hobbyist thing and I'm not running an important business, if you were
going to ask.

Next question...Do most folks here use the NTPD client, or it is a
mixture of Chrony and openNTPD? Maybe some folks just go with what ships
with their OS?
The comparison chart is pretty nice and lays each option out nicely:
https://chrony.tuxfamily.org/comparison.html

I think that's all for now. Feel free to provide any URLs to any
resources I should check out about time sycing, NTP, etc.


Sean,

I have been running NTP on multiple systems since 2002, including Linux 
and Windows (2000 and later), both with hardware sync (GPS18, GPS18x and 
multiple GPS devices for the Raspberry Pi), and with LAN and Wi-Fi 
network sources.  I find NTP easy to manage and monitor over multiple 
systems, and the fact that it runs on Windows, and can accept GPS 
devices on Windows very valuable.  You can easily get within 10 
microseconds in Linux (but be careful of the temperature and GPS antenna 
location), and within 200 microseconds on Windows when using an attached 
GPS/PPS device.


  http://www.satsignal.eu/mrtg/performance_ntp.php

For the Raspberry Pi:


https://store.uputronics.com/index.php?route=product/product_id=81

In terms of installations, I think that NTP will have by far the 
greatest number, and of the three you listed, only NTP runs on Windows.

--
Cheers,
David
Web: http://www.satsignal.eu

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Re: [ntp:questions] Time syncing with something other than ntpd

[Terje Mathisen]

sean wrote:

Hi All,

I'm real interested in NTP and accurate time, hence why I'm on this
newsgroup. I would like to look into getting a time sensor and I hear
the Garmin GPS 18X is what some folks run unless they need much more
precision. Is this still a pretty well regarding GPS unit for pretty
accurate (I know that's highly subjective) time keeping? This would be
a hobbyist thing and I'm not running an important business, if you were
going to ask.


I have had a Garmin 18 as well as 3-4 SURE kits, the latter is half the 
price, requires about the same amount of soldering, and has been 
measured at the 20-30 ns level, so quite accurate.


Next question...Do most folks here use the NTPD client, or it is a
mixture of Chrony and openNTPD? Maybe some folks just go with what ships
with their OS?


Since I've been on the NTP Hackers team for a couple of decades I'm 
partial to the original ntpd. :-)


Terje


The comparison chart is pretty nice and lays each option out nicely:
https://chrony.tuxfamily.org/comparison.html

I think that's all for now. Feel free to provide any URLs to any
resources I should check out about time sycing, NTP, etc.




--
- 
"almost all programming can be viewed as an exercise in caching"

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Re: [ntp:questions] Time syncing with something other than ntpd

[William Unruh]

On 2017-01-30, sean  wrote:
> Hi All,
>
> I'm real interested in NTP and accurate time, hence why I'm on this
> newsgroup. I would like to look into getting a time sensor and I hear
> the Garmin GPS 18X is what some folks run unless they need much more
> precision. Is this still a pretty well regarding GPS unit for pretty
> accurate (I know that's highly subjective) time keeping? This would be
> a hobbyist thing and I'm not running an important business, if you were
> going to ask.
>
> Next question...Do most folks here use the NTPD client, or it is a
> mixture of Chrony and openNTPD? Maybe some folks just go with what ships
> with their OS?

You do not say which OS you use. Windows (which version?), Mac, linux,
BSD?

chrony does not work on windows. ntpd is what what tends to ship with
linux distros. chrony gives better time discipline but has a smaller
user group. 

> The comparison chart is pretty nice and lays each option out nicely:
> https://chrony.tuxfamily.org/comparison.html
>
> I think that's all for now. Feel free to provide any URLs to any
> resources I should check out about time sycing, NTP, etc. 

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