Re: [time-nuts] RPi/ beagle bone-like computer without video

[Chris Albertson]

Yes, that was exactly my point, There are two kinds of ARM, the A and the
M.   "A" is the kind used in you smart phone and the Raspberry Pi and BBB
and these suck up a few watts of power.  The M type is made for low power
and could run off a few AA batteries and the battery shelf life would
expire before the battery was used up.   A simple data logger could keep
the CPU in sleep mode most of the time and then it uses literally a few
micro amps.

On Wed, Nov 30, 2016 at 5:07 PM, Attila Kinali  wrote:

> On Wed, 30 Nov 2016 16:57:10 -0800
> jimlux  wrote:
>
> > Power consumption - it's going to be battery powered
> > I've been looking through the literature, and you can power down some of
> > the chips on most of these things.
>
> If power consumption is an issue for you, then I would advise against
> going for a Linux board, unless you either find a board that is
> specifically
> designed for that purpose (and has the software support) or you have
> a few months time to iron out the problems in the Linux kernel to
> get the system to go into sleep.
>
> It's far easier to use something line Nuttx or FreeRTOS on an
> Cortex-M3 or arm9 and get that to use little power than it is
> to get an full fledged Linux system to behave.
> (Stay away from Zephyr, it's a trap)
>
> Attila Kinali
>
> --
> Malek's Law:
> Any simple idea will be worded in the most complicated way.
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Chris Albertson]

On Wed, Nov 30, 2016 at 12:42 PM, jimlux  wrote:

> I'm looking for a small linux single board - similar to RPi or Beaglebone
> Black, but don't need the HDMI, or video stuff.
> Preferably without weird connectors, and available for wide temperature
> ranges (it's for a data logger/collector in the field)
>

Does it really need to run Linux?   If you can give up Linux then there are
MANY ARM Cortex M SBCs that are tiny and run on literally micro amps and
sell for under $5.   You can run a very small-footprint RTOS on the Cortex
M that can do "hard" real-time as well is some multitasking and even
network.

If you really need Linux and it needs to be small and low cost and low
power, then look at the "Pi Zero".  It is a very small Pi that sells for
only $5.   It has video but just don't plug in the cable.

-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Best Chance GPS module

[Chris Albertson]

First question:   How accurate does your local NTP server need to be?   If
the answer is "a few tens of milliseconds" then you don't need GPS.  All yu
need is a decent Internet connection.

Second.  NTP is a VERY light load and certainly does not need to run on a
dedicated computer.   Any mail server, web server or any computer that runs
24x7 can run NTP and you will not notice the extra load on the system.
And even in the case where you need GPS, one need just ONE computer.
 Almost any computer is powerful enough and you only need 100 Bit Ethernet,
gigabit is not better for timing.

About the GPS receiver.   Even the (within reason) worst GPS receiver with
a partial view of the sky and some multiparty will by ODERS of MAGNITUDE
more accurate then needed for running NTP.  The reason is that the BESTR
one can hope for with a near perfect NTP setup is a few micro seconds error
and even a quite poor GPS will do better than 100 nanoseconds. I'd say
if yu can get the GPS to run at all it will be good enough for NTP.

One other thing:  Your GPS ABSOLUTELY MUST produce a one pulse per second
output.

If on the other hand your were trying to build a frequency standard or a
GPS controlled oscillator then you'd be worried about tons and tons of
details like you listed.   You literally just can't be good enough for
running a GPSDO.  But for NTP it is easy because even a run of the mill GPS
receiver is dramatically better than needed for NTP.

But take a serious look at your requirements.   I got into running NTP long
before therefore affordable GPS receivers.  In fact long before we all have
"always on" Internet connections and we all had dial-up phone modem.   So I
ran NTP over a phone modem and used that time standard to run an
astronomical telescope and was able to aim it at stars.   Many times your
requirements are not so hard and something simple works well.

Don't struggle getting the last nanosecond of accuracy out of a GPS when
NTP is only about to transfer millisecond level time over Ethernet.

On the other hand, if yu time stamping needs to be at the microsecond level
then the GPS must be physically connected to the computer doing the
stamping, yu can't transfer microseconds over an Ethernet and if you need
nanosecond level time stamps you can't get that in software




On Wed, Nov 30, 2016 at 1:11 PM, MLewis  wrote:

> (resending as I tried posting in html...)
>
> Hello,
>
> I'm a novice at time issues. I've been gathering info and I think I'm
> ready to start asking questions.
>
> I'm after a time solution for my personal computer. It looks like I need:
>
> *a standalone box to be my own local personal NTP server (so the
> variable processing load on my main box can no longer affect host polling
> software timestamps...)
> *run standard NTP Client & Host software on that box
> *discipline it with PPS from GPS, using an active antenna
> *use NTP to obtain the NTP time from this local personal NTP server as
> required
> *I don't know if I need two additional boxes: one for the NTP host and
> another for receiving the GPS PPS signal, like a Pi in kernal mode.
>
> GPS issues.
>
> *I'm in a semi-basement apartment.
> *Building faces due South.
> *Building is 1960's brick & concrete, steel trusses & sheets in place
> from the concrete floor pours.
> *Windows from 14" to 38" from the ground. My antenna has to be between
> those.
> *Window frame is plastic retrofit over wood Pearson-sliders.
> *There is a bank of buildings due south of me that leaves me with
> clearance elevations between 6 and 12 degrees. I'm at 45.42 North.
> *Due South within what open sky I have, are two heights of electrical
> wires, around 35 feet out from the building at the edge of the parking lot.
>
> I'm expecting multipath from: those buildings, my building and I assume
> the wires and possibly the cars?
>
> Between the multipath and a less than full view of the sky, I believe I'm
> needing a GPS module:
>
> *that is sensitive,
> *good multipath handling,
> *GPS & GLONASS, to get as many sats possible out of the sky-view I
> have.
>
> Due to my location difficulties, considering newer more sensitive GPS
> modules seems to make sense, even if they're not timing modules. I was
> tempted by a Qualtec L86 with -148|-165 dBm or a SkyTraq Venus838LPx-T.
> Then a ublox Max-M8Q with -165|-167 dBm & its stationary mode. But then I
> discovered I can get a ublox NEO-M8T with -165|-167 dBm sensitivity, its
> multipath handling and concurrent reception of GPS/QZSS, GLONASS, BeiDou &
> Galileo.
>
> A ublox NEO-M8T with an active timing antenna (GPS | GLONASS ?) seems to
> be my best chance of being successful at my location.
>
> Questions:
>
> *Is there a more suitable GPS module than the ublox NEO-M8T for my
> location issues?
> *Can anyone recommend an affordable suitable antenna for GPS & GLONASS?
> *One box or two, for running a local NTP host and 

Re: [time-nuts] Net4501 case

[Bob Darlington]

Joe, I'll be glad to give you my whole system.  Send me your contact info
on a direct message and it's yours.

-Bob
N3XKB

On Nov 30, 2016 8:58 PM, "Joseph Gray"  wrote:

> Does anyone have a spare case for a Soekris Net4501? It looks like
> Soekris no longer sells them.
>
> Joe Gray
> W5JG
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Re: [time-nuts] Google public NTP service

[Chris Albertson]

On Wed, Nov 30, 2016 at 12:14 PM, Gary E. Miller  wrote:

> Yo Michael!
>
> On Wed, 30 Nov 2016 14:21:39 +
> Michael Rothwell  wrote:
>
> > ... was just announced.
> > https://cloudplatform.googleblog.com/2016/11/making-
> every-leap-second-count-with-our-new-public-NTP-servers.html?m=1
>
> I sort of see where they are coming from, but this will cause problems.
>
> The NTP packets google sends out have no way to be marked as 'not UTC'.
> Given how promiscuous people are sharing NTP chimers these 'not UTC'
> chimers will get into the mix.  When they diverge from the real UTC servers
> it will sorely confuse NTP clients.
>

No, not confused at all NTP is designed to detect this problem.   The
Google servers will be detected as "False Tickers" and ignored.   Of course
some clients might be configured to look ONLY at Google servers but those
people like did that on purpose because they wanted to wrong time.   Anyone
with a normal NTP client that uses several different servers will be fine.

The for people who don't know how Ntp works, it is simple:  If you (a
human) ask a bunch of people "what time is it?" you would expect them all
to give you the same answer (within the precision of their wrist watches)
and if one person tells you something that is very different from everyone
else.  You do NOT become confused you just say to yourself "His watch must
be wrong,"  then you ignore his answer."   NTP clients do about this same
thing.   This is why we configure our NTP clients to query a wide and
diverse group of servers, so as to detect problems.   So,.. Google will not
poison the pool e of NTP servers, Google's incorrect time will not
propagate very far.


>
> I would support an RFC to mark the type a time an chimer is servings.
> Not only smeared and UTC, but also TAI, UT, UT0, UT1, UT2, ET, TDT, TDB,
> TT, TCG, TCB, GPS, etc...
>

No,  that is the wrong way to do it.  Then no one flavor of time has enough
servers to make the system work.  A better way is to agree that all NTP
servers use UTC and then distribute the corrections from UTC to the other
flavors and those who need to to the conversions can do so.



> RGDS
> GARY
> 
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
> g...@rellim.com  Tel:+1 541 382 8588
>
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Scott Stobbe]

Having a full blown os is nice when all the processor is responsible for is
house keeping and storage. You also get plenty of RAM for buffering prior
to writing to persistent storage, like an SD card. That said I have found
SD cards to be fusy, at least the microchip FAT libraries. And write cycle
times are random sometimes being 0.5 seconds, which means you need to be
able to allocate memory the equivalent of a few seconds worth of data for
buffering (not an issue on linux systems).

On Wed, Nov 30, 2016 at 10:05 PM, Graham / KE9H 
wrote:

> If you are going to go battery powered, I would also recommend staying away
> from Linux, go with something like a 32 bit PIC32MX or PIC32MZ.  Full
> Ethernet stack, RTOS if you need it, can do deep sleep down into the
> microamp range when not active.
>
> --- Graham.
>
> On Wed, Nov 30, 2016 at 8:35 PM, Gary Chatters <
> gcarlis...@garychatters.com>
> wrote:
>
> > There do seem to be a lot of small SBCs out there.  I have used boards
> from
> > Technologic Systems, http://www.embeddedarm.com
> > and EMAC, Inc, http://www.emacinc.com
> >
> > They have numerous models for you to look though.  Some various features:
> > - SBC or SoM/CoM on baseboard
> > - Various form factors including PC/104
> > - Usually with RS-232, USB, GPIO, Ethernet.
> > - Many without video.
> > - ARM processor
> > - Many with industrial temperature range
> > - Linux and development environment provided (may not be latest)
> > - Lower power then BBB.  One model runs at 0.5 watts.  Many around 1.
> >
> > Prices generally 2 or 3 x BBB prices.
> >
> > Gary
> >
> > On 11/30/2016 03:42 PM, jimlux wrote:
> >
> >> I'm looking for a small linux single board - similar to RPi or
> >> Beaglebone Black, but don't need the HDMI, or video stuff.
> >> Preferably without weird connectors, and available for wide temperature
> >> ranges (it's for a data logger/collector in the field)
> >>
> >> What's out there?
> >>
> >> There's BBB in industrial flavor (-40 to +85C ) for $60-70
> >>
> >
> > ___
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> > ailman/listinfo/time-nuts
> > and follow the instructions there.
> >
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[time-nuts] Net4501 case

[Joseph Gray]

Does anyone have a spare case for a Soekris Net4501? It looks like
Soekris no longer sells them.

Joe Gray
W5JG
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Graham / KE9H]

If you are going to go battery powered, I would also recommend staying away
from Linux, go with something like a 32 bit PIC32MX or PIC32MZ.  Full
Ethernet stack, RTOS if you need it, can do deep sleep down into the
microamp range when not active.

--- Graham.

On Wed, Nov 30, 2016 at 8:35 PM, Gary Chatters 
wrote:

> There do seem to be a lot of small SBCs out there.  I have used boards from
> Technologic Systems, http://www.embeddedarm.com
> and EMAC, Inc, http://www.emacinc.com
>
> They have numerous models for you to look though.  Some various features:
> - SBC or SoM/CoM on baseboard
> - Various form factors including PC/104
> - Usually with RS-232, USB, GPIO, Ethernet.
> - Many without video.
> - ARM processor
> - Many with industrial temperature range
> - Linux and development environment provided (may not be latest)
> - Lower power then BBB.  One model runs at 0.5 watts.  Many around 1.
>
> Prices generally 2 or 3 x BBB prices.
>
> Gary
>
> On 11/30/2016 03:42 PM, jimlux wrote:
>
>> I'm looking for a small linux single board - similar to RPi or
>> Beaglebone Black, but don't need the HDMI, or video stuff.
>> Preferably without weird connectors, and available for wide temperature
>> ranges (it's for a data logger/collector in the field)
>>
>> What's out there?
>>
>> There's BBB in industrial flavor (-40 to +85C ) for $60-70
>>
>
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Gary Chatters]

There do seem to be a lot of small SBCs out there.  I have used boards from
Technologic Systems, http://www.embeddedarm.com
and EMAC, Inc, http://www.emacinc.com

They have numerous models for you to look though.  Some various features:
- SBC or SoM/CoM on baseboard
- Various form factors including PC/104
- Usually with RS-232, USB, GPIO, Ethernet.
- Many without video.
- ARM processor
- Many with industrial temperature range
- Linux and development environment provided (may not be latest)
- Lower power then BBB.  One model runs at 0.5 watts.  Many around 1.

Prices generally 2 or 3 x BBB prices.

Gary
On 11/30/2016 03:42 PM, jimlux wrote:

I'm looking for a small linux single board - similar to RPi or
Beaglebone Black, but don't need the HDMI, or video stuff.
Preferably without weird connectors, and available for wide temperature
ranges (it's for a data logger/collector in the field)

What's out there?

There's BBB in industrial flavor (-40 to +85C ) for $60-70


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Re: [time-nuts] Best Chance GPS module

[Rick Commo]

Before joining time-nuts I had purchased a QLG1 GPS receiver kit from 
www.qrp-labs.com.  It was $23 plus a few bucks for shipping.  I installed the 
patch antenna as it suited my purposes, but there is the means to omit the 
patch antenna and use an SMA to go to the antenna of your choice.  QRP-Labs 
claims that the ground plane on the side the patch antenna is mounted provides 
another 4+ DB of gain.  The actual GPS chip is the YIC51612.

I am running it sub-grade in a “split entry” where the first floor is mostly 
below ground on a slopes property.  It connects to an Arduino programmed to 
sent the time from the $GPRMC sentence to an LCD.  I will ultimately use the 
1PPS output from the receiver as well.  I use the presence of the 1PPS signal 
as an indication that the receiver is happy with life at that moment.  It has 
been chugging away for a few months now.

Cheers,
-rick, K7LOG


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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Attila Kinali]

On Wed, 30 Nov 2016 16:57:10 -0800
jimlux  wrote:

> Power consumption - it's going to be battery powered
> I've been looking through the literature, and you can power down some of 
> the chips on most of these things.

If power consumption is an issue for you, then I would advise against
going for a Linux board, unless you either find a board that is specifically
designed for that purpose (and has the software support) or you have
a few months time to iron out the problems in the Linux kernel to 
get the system to go into sleep.

It's far easier to use something line Nuttx or FreeRTOS on an
Cortex-M3 or arm9 and get that to use little power than it is
to get an full fledged Linux system to behave.
(Stay away from Zephyr, it's a trap)

Attila Kinali

-- 
Malek's Law:
Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[jimlux]

On 11/30/16 3:26 PM, Hal Murray wrote:


jim...@earthlink.net said:

I'm looking for a small linux single board - similar to RPi or  Beaglebone
Black, but don't need the HDMI, or video stuff.


Don't limit your search to things that doen't have what you don't need.  It
may be cheaper to get a high volume part and ignore the sections you don't
need.


Power consumption - it's going to be battery powered
I've been looking through the literature, and you can power down some of 
the chips on most of these things.



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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Bob Camp]

Hi

There are a nearly infinite number of ARM based modules and boards. They all 
are very much 
a “same / same” sort of thing. They are far more alike than they are different. 
That’s not to say 
that they are interchangeable, far from it. The issue for low volume is often 
more the toolchain 
(and it’s cost(s)) rather than the hardware.

Bob


> On Nov 30, 2016, at 7:40 PM, Attila Kinali  wrote:
> 
> On Wed, 30 Nov 2016 12:42:51 -0800
> jimlux  wrote:
> 
>> I'm looking for a small linux single board - similar to RPi or 
>> Beaglebone Black, but don't need the HDMI, or video stuff.
>> Preferably without weird connectors, and available for wide temperature 
>> ranges (it's for a data logger/collector in the field)
>> 
>> What's out there?
> 
> If you can acommodate SO-DIMM connectors, then I probably would go for
> modules by Toradex[1] or aries[2]. I know that both companies do a good
> job of getting complete support for their SoCs and the modules upstream
> (very important if you want it to just work) and I also know people I can
> kick if something doesn't. A friend also pointed me at [3], but I don't
> know how good they are.
> 
> Generally speaking, if you google for "ARM SOM" you will get lots of
> results, some of them specially made for industrial environments.
> The connectors vary a lot and are too often high density connectors.
> Though usually not going below 1mm pitch. SO-DIMM has kind of become
> a standard formfactor for a lot of those modules (but all with
> different pin-outs!). Outside the ARM sphere, there is very little else.
> MIPS processors are mostly networking and video coding SoC's, so probably
> overpowered for your application. There are the Intel based Minnowboards,
> but they are bascially full fledged PCs with low power consumption.
> (I have a Minnow Turbot here, I really like it, tiny as it is, but it's
> a heavy handed beast compared to the ARM boards)
> 
> HTH
> 
>   Attila Kinali
> 
> [1] https://www.toradex.com/
> [2] http://www.aries-embedded.de/
> [3] 
> http://www.variscite.com/products/system-on-module-som/cortex-a8/var-som-am33-cpu-ti-am335x-am3354-am3352
> 
> -- 
> Malek's Law:
>Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Attila Kinali]

On Wed, 30 Nov 2016 12:42:51 -0800
jimlux  wrote:

> I'm looking for a small linux single board - similar to RPi or 
> Beaglebone Black, but don't need the HDMI, or video stuff.
> Preferably without weird connectors, and available for wide temperature 
> ranges (it's for a data logger/collector in the field)
> 
> What's out there?

If you can acommodate SO-DIMM connectors, then I probably would go for
modules by Toradex[1] or aries[2]. I know that both companies do a good
job of getting complete support for their SoCs and the modules upstream
(very important if you want it to just work) and I also know people I can
kick if something doesn't. A friend also pointed me at [3], but I don't
know how good they are.

Generally speaking, if you google for "ARM SOM" you will get lots of
results, some of them specially made for industrial environments.
The connectors vary a lot and are too often high density connectors.
Though usually not going below 1mm pitch. SO-DIMM has kind of become
a standard formfactor for a lot of those modules (but all with
different pin-outs!). Outside the ARM sphere, there is very little else.
MIPS processors are mostly networking and video coding SoC's, so probably
overpowered for your application. There are the Intel based Minnowboards,
but they are bascially full fledged PCs with low power consumption.
(I have a Minnow Turbot here, I really like it, tiny as it is, but it's
a heavy handed beast compared to the ARM boards)

HTH

Attila Kinali

[1] https://www.toradex.com/
[2] http://www.aries-embedded.de/
[3] 
http://www.variscite.com/products/system-on-module-som/cortex-a8/var-som-am33-cpu-ti-am335x-am3354-am3352

-- 
Malek's Law:
Any simple idea will be worded in the most complicated way.
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Re: [time-nuts] Best Chance GPS module

[Bob Camp]

Hi

Most of this is “I have an idea, I can (loosely)  connect the idea to big 
volume, give me *big* piles of money”. 
Trying to work it out on a technical basis is not going to work very well ….

Bob

> On Nov 30, 2016, at 6:49 PM, Jay Grizzard  
> wrote:
> 
> On 2016-11-30 13:45 , André Esteves wrote:
>> Millimeter accurate GPS in smartphones and self driving cars would
>> result from tiny atomic clocks
> I saw a different form of this article a month or so back, and for the life 
> of me I can't figure out how having a tiny atomic clock helps GPS accuracy at 
> all (nor how it would help w/ inertial reckoning, which was a claim I saw in 
> a different article on the same folks). Especially since (AFAIK) the error 
> budget of the GPS system in general far exceeds "millimeter" accuracy, 
> without post-processing all your data...
> 
> I'm also pretty sure numerous people here would object to the 
> characterization of atomic clocks as "room sized", in general. ;)
> 
> -j
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Re: [time-nuts] Best Chance GPS module

[Jay Grizzard]

On 2016-11-30 13:45 , André Esteves wrote:

Millimeter accurate GPS in smartphones and self driving cars would
result from tiny atomic clocks
I saw a different form of this article a month or so back, and for the 
life of me I can't figure out how having a tiny atomic clock helps GPS 
accuracy at all (nor how it would help w/ inertial reckoning, which was 
a claim I saw in a different article on the same folks). Especially 
since (AFAIK) the error budget of the GPS system in general far exceeds 
"millimeter" accuracy, without post-processing all your data...


I'm also pretty sure numerous people here would object to the 
characterization of atomic clocks as "room sized", in general. ;)


-j
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Re: [time-nuts] Google public NTP service

[Hal Murray]

tn1...@nic.fi said:
> I wonder what this stupid "leap smear" will do to NTP driftfiles. ...

There was a report on that area mentioned here a while ago.

As long as the smearing is slow enough, the client servers easily track the 
drift.  There is a bump in their drift, but it's not a problem for ntp.  It's 
on the same scale as a big change in temperature.

If you are trying to use your drift as a thermometer, things will get screwed 
up.  If you know the parameters of the smearing server, you could probably 
correct for it.



-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] RPi/ beagle bone-like computer without video

[bownes]

Fits very nicely into a 5370 in fact. :)

> On Nov 30, 2016, at 17:12, Graham / KE9H  wrote:
> 
> The BeagleBone Green is a BeagleBone Black with the HDMI and video chip
> removed.
> 
> Mouser Part number *Mouser Part #: *713-102010027, $39, In stock.
> 
> 
> Makes a great little headless server.
> 
> --- Graham
> 
> ==
> 
>> On Wed, Nov 30, 2016 at 3:51 PM, Clint Jay  wrote:
>> 
>> Raspberry Pi compute module? Maybe even a Pi Zero?
>> 
>>> On 30 Nov 2016 21:47, "Adrian Godwin"  wrote:
>>> 
>>> The tiny g3 routers are worth looking at. They have WiFi, Ethernet and
>> USB,
>>> cost very little and will usually run wrt54g Linux. Can be rather short
>> on
>>> memory though.
>>> 
 On 30 Nov 2016 8:43 p.m., "jimlux"  wrote:
 
 I'm looking for a small linux single board - similar to RPi or
>> Beaglebone
 Black, but don't need the HDMI, or video stuff.
 Preferably without weird connectors, and available for wide temperature
 ranges (it's for a data logger/collector in the field)
 
 What's out there?
 
 There's BBB in industrial flavor (-40 to +85C ) for $60-70
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 To unsubscribe, go to https://www.febo.com/cgi-bin/m
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Hal Murray]

jim...@earthlink.net said:
> I'm looking for a small linux single board - similar to RPi or  Beaglebone
> Black, but don't need the HDMI, or video stuff. 

Don't limit your search to things that doen't have what you don't need.  It 
may be cheaper to get a high volume part and ignore the sections you don't 
need.

I learned that ages ago when a TI rep suggested a codec chip for an A/D.  We 
just ignored half the chip.  It did what we needed at a lower cost that any 
of the alternatives we could find.


-- 
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Re: [time-nuts] Google public NTP service

[Esa Heikkinen]

Michael Rothwell kirjoitti:


... was just announced.
https://cloudplatform.googleblog.com/2016/11/making-every-leap-second-count-with-our-new-public-NTP-servers.html?m=1


I wonder what this stupid "leap smear" will do to NTP driftfiles. Only 
Google may be stupid enough to grow one second lasting minor timing 
issue to ten hours lasting serious timing issue with even longer effects 
if driftfiles will be adjusted to neet their temporary and changing 
non-standard clock rate.


--
73s!
Esa
OH4KJU
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Graham / KE9H]

The BeagleBone Green is a BeagleBone Black with the HDMI and video chip
removed.

Mouser Part number *Mouser Part #: *713-102010027, $39, In stock.


Makes a great little headless server.

--- Graham

==

On Wed, Nov 30, 2016 at 3:51 PM, Clint Jay  wrote:

> Raspberry Pi compute module? Maybe even a Pi Zero?
>
> On 30 Nov 2016 21:47, "Adrian Godwin"  wrote:
>
> > The tiny g3 routers are worth looking at. They have WiFi, Ethernet and
> USB,
> > cost very little and will usually run wrt54g Linux. Can be rather short
> on
> > memory though.
> >
> > On 30 Nov 2016 8:43 p.m., "jimlux"  wrote:
> >
> > > I'm looking for a small linux single board - similar to RPi or
> Beaglebone
> > > Black, but don't need the HDMI, or video stuff.
> > > Preferably without weird connectors, and available for wide temperature
> > > ranges (it's for a data logger/collector in the field)
> > >
> > > What's out there?
> > >
> > > There's BBB in industrial flavor (-40 to +85C ) for $60-70
> > > ___
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> > > To unsubscribe, go to https://www.febo.com/cgi-bin/m
> > > ailman/listinfo/time-nuts
> > > and follow the instructions there.
> > >
> > ___
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> > mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Clint Jay]

Raspberry Pi compute module? Maybe even a Pi Zero?

On 30 Nov 2016 21:47, "Adrian Godwin"  wrote:

> The tiny g3 routers are worth looking at. They have WiFi, Ethernet and USB,
> cost very little and will usually run wrt54g Linux. Can be rather short on
> memory though.
>
> On 30 Nov 2016 8:43 p.m., "jimlux"  wrote:
>
> > I'm looking for a small linux single board - similar to RPi or Beaglebone
> > Black, but don't need the HDMI, or video stuff.
> > Preferably without weird connectors, and available for wide temperature
> > ranges (it's for a data logger/collector in the field)
> >
> > What's out there?
> >
> > There's BBB in industrial flavor (-40 to +85C ) for $60-70
> > ___
> > 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] Best Chance GPS module

[André Esteves]

Millimeter accurate GPS in smartphones and self driving cars would
result from tiny atomic clocks
--

http://www.nextbigfuture.com/2016/11/millimeter-accurate-gps-in-smartphones.html
https://arxiv.org/abs/0707.4624

including energy harvesting, bio-sensing and quantum nanoelectronics.

They are producing designer endohedral fullerene molecules with
tailored electronic properties. Designer Carbon Materials Ltd is a
spin-out company from the University of Oxford. It is based on
research led by Dr Kyriakos Porfyrakis and his academic group of 9
researchers.

They have developed technology for the scaled-up production of
endohedral fullerenes. Our patented arc-reactor system can bring
endohedral metallofullerene production to the gram-scale and beyond,
faster and more efficiently than conventional arc reactors. They have
access to state-of-the-art facilities for the purification of a range
of fullerene molecules, including endohedral metallofullerenes and
endohedral nitrogen fullerenes.

Endohedral fullerenes, also called endofullerenes, are fullerenes that
have additional atoms, ions, or clusters enclosed within their inner
spheres. The first lanthanum C60 complex was synthesized in 1985 and
called La@C60.[2] The @ (at sign) in the name reflects the notion of a
small molecule trapped inside a shell. Two types of endohedral
complexes exist: endohedral metallofullerenes and non-metal doped
fullerenes.

Nitrogen endohedral fullerenes is being used to create a small and
portable atomic clock – the most accurate time-keeping system in the
world – and could make the GPS navigation on driverless cars accurate
to 1 millimeter.

"At the moment, atomic clocks are room-sized," said Lucius Cary, a
director of the Oxford Technology SEIS fund, which now holds a
minority stake. "This endohedral fullerene would make it work on a
chip that could go into your mobile phone.

In 2007, there was an arxiv paper which described the design of a
Micron-Scale Atomic Clock

Nitrogen atom is introduced into a fullerene cage. This endohedral
fullerene is then coated with an insulating shell and a number of them
are deposited as a thin layer on a silicon chip. Next to this layer a
GMR sensor is fabricated which is close to the endohedral fullerenes.
This GMR sensor measures oscillating magnetic fields on the order of
micro-gauss from the nuclear spins varying at the frequency of the
hyperfine transition (413 MHz frequency). Given the micron scale and
simplicity of this system only a few transistors are needed to control
the waveforms and to perform digital clocking. This new form of atomic
clock exhibits extremely low power (nano watts), high vibration and
shock resistance, stability on the order of 10^-9, and is compatible
with MEMS fabrication and chip integration. As GMR sensors continue to
improve in sensitivity the stability of this form of atomic clock will
increase proportionately.

It is possible to separate each endohedral fullerene from its
neighbors by coating it with a glass shell. Silica gel, an inorganic
polymer, has a three-dimensional network and can easily be synthesized
via the sol-gel route. Fullerenes cannot be incorporated into sol-gel
glasses homogeneously due to low solubility. This problem can be
overcome by functionalization of the fullerenes with such groups as
will form some kind of bond (hydrogen, van der Waals, or covalent)
with the growing silica network

The simple scheme discussed gives us a micron scale atomic clock with
10^−9 accuracy and a power dissipation of a nanowatt (10 nW capacitive
drive but we can use resonant circuits to store the energy). This will
likely be adequate for many mobile/sensor net applications but not
adequate for more demanding situations. What can be done?

First, as GMR sensors improve (BMR, etc.), we can use more diluted
fullerene stacks to gain a sharper line by a cubic factor in
separation as we lose an equal amount of magnetic signal. A
nanoscale-precise placing of fullerenes would give us a very well
determined perturbation situation that can be exploited for accuracy.
In the limit of true nanotechnology the ultimate clock is a single
fullerene with considerable shielding. This should be competitive with
very good atomic clocks of vastly more volume.

2016-11-30 21:36 GMT+00:00 Mark Sims :
> I have found that the cheap  V.KEL SIRF=III modules (I paid $15-$20 for 
> three)  have excellent indoor performance with their built-in patch antenna.  
> They don't do GLONASS.  I even get indoor tracking with the module sitting on 
> the ground floor of a 2 story hose with the patch antenna facing the floor!
>
> The NEO M8 is a decent device.  I've seen mine tracking over 24 sats.  The 
> module that I have has a U.FL antenna connector with pads for adding an 
> edge-launch SMA connector (I hate U.FL connectors).  I seem to remember that 
> they can't track GPS, GLONASS, and BEIDOU at the same time.
>
> I have gotten surprisingly good performance with a cheap 

Re: [time-nuts] Google public NTP service

[Mike S]

On 11/30/2016 3:35 PM, Gary E. Miller wrote:

> Not true.  NTP has provision for arbitrrary extensions to an ntp packet.
> 
> See RFC 5905. https://www.ietf.org/rfc/rfc5905.txt section 7.3:

HA! ntp (the implementation) doesn't follow the RFC, which says that ntp
(the protocol) is supposed to count seconds in an epoch. It doesn't, it
deliberately miscounts when there's a leap second. Instead of simply
counting seconds like TAI, it's broken just like POSIX.
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Re: [time-nuts] RPi/ beagle bone-like computer without video

[Adrian Godwin]

The tiny g3 routers are worth looking at. They have WiFi, Ethernet and USB,
cost very little and will usually run wrt54g Linux. Can be rather short on
memory though.

On 30 Nov 2016 8:43 p.m., "jimlux"  wrote:

> I'm looking for a small linux single board - similar to RPi or Beaglebone
> Black, but don't need the HDMI, or video stuff.
> Preferably without weird connectors, and available for wide temperature
> ranges (it's for a data logger/collector in the field)
>
> What's out there?
>
> There's BBB in industrial flavor (-40 to +85C ) for $60-70
> ___
> 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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[time-nuts] Best Chance GPS module

[Mark Sims]

I have found that the cheap  V.KEL SIRF=III modules (I paid $15-$20 for three)  
have excellent indoor performance with their built-in patch antenna.  They 
don't do GLONASS.  I even get indoor tracking with the module sitting on the 
ground floor of a 2 story hose with the patch antenna facing the floor!

The NEO M8 is a decent device.  I've seen mine tracking over 24 sats.  The 
module that I have has a U.FL antenna connector with pads for adding an 
edge-launch SMA connector (I hate U.FL connectors).  I seem to remember that 
they can't track GPS, GLONASS, and BEIDOU at the same time.  

I have gotten surprisingly good performance with a cheap GPS/GLONASS puck like:
http://www.ebay.com/itm/201698154683?_trksid=p2060353.m2749.l2649=STRK%3AMEBIDX%3AIT

For NTP applications,  multi-path errors will be swamped out by the "noise" in 
NTP.  I don't think that a timing receiver adds much value except possibly the 
ability to still work with one or two sats visible.   Many GPS/GLONAS/BEIDOU 
capable timing receivers don't do precision timing with more than one sat 
system type enabled...  I think the Venus devices are like that... they only to 
GPS timing.
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Re: [time-nuts] Google public NTP service

[Gary E. Miller]

Yo Tom!

On Wed, 30 Nov 2016 13:06:06 -0800
"Tom Van Baak"  wrote:

> From Gary Miller:
> > You gotta start sometime.  Now is a good time.  This is not the
> > first time Google has done this, and certainly will not be the
> > last.  It had bad consequences last time and they did not learn
> > from that.  
> 
> This is not the fault of google. The big players will continue to
> innovate and solve timing problems as long as the official scientific
> and political world do nothing.

This is not innovation, this is anarchy.  We have standards that hard
working people have build over decades.  Ignoring the lessons of the past
is a bad thing.  Arbitrarily changing standards is the path to madness.

> May I request that further discussion of this google / NTP / leap
> second issue take place in ntp forums or the LEAPSECS list, and not
> here on time-nuts.

I'll continue to suggest this move to de...@ntpsec.org.  There are many
people on the NTP IETF committes there.


RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Google public NTP service

[Gary E. Miller]

Yo Poul-Henning!

On Wed, 30 Nov 2016 21:01:44 +
"Poul-Henning Kamp"  wrote:

> 
> In message <20161130125857.7229b...@spidey.rellim.com>, "Gary E.
> Miller" writes :
> 
> >Not 'odd'.  Fully specified in the RFC.  Anyone that did not
> >implement the spec gets what they deserve.  
> 
> Actually, anybody who does implement the spec *precisely* gets a lot
> of things nobody should ever be at the receiving end of.

If you know of any such thing I suggest you bring it up on de...@ntpsec.org.
Several of the authors of the upcoming NTS spec hang out there.

If you can document anything specific the NTPsec team would like to get
it handled in their code and documentation.  Currently they are turning
around fixes in days for most issues.

They have already changed a bit of their implementation of the RFC for
security reasons and would do so for any new issues.  Things like
symetric mode are now automagically downgraded to a more secure client
server mode.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Best Chance GPS module

[Bob Camp]

Hi

A few basics:

1) GPS receivers really can’t / don’t do a lot about multipath. The newer 
devices with a lot 
of correlators help a bit, but that’s about it. Simply put - newer is better. 
2) Because of near the omnidirectional nature of GPS, antennas don’t do a lot 
for multipath. They
can help a bit on low angle stuff, but that’s not going to be your problem. 
3) Unless you can reasonably expect 4 sat’s in view at all time, don’t bother 
with setting up a GPS
timing system. It will just make you angry with all the issues. A USB GPS on 
your PC will give you a 
pretty good idea of what you can or can’t pick up. 
4) If the sole reason to do this is for NTP, consider simply setting up a local 
server and doing sync
over your internet connection. Much less fuss ….

Bob


> On Nov 30, 2016, at 4:11 PM, MLewis  wrote:
> 
> (resending as I tried posting in html...)
> 
> Hello,
> 
> I'm a novice at time issues. I've been gathering info and I think I'm ready 
> to start asking questions.
> 
> I'm after a time solution for my personal computer. It looks like I need:
> 
> *a standalone box to be my own local personal NTP server (so the variable 
> processing load on my main box can no longer affect host polling software 
> timestamps...)
> *run standard NTP Client & Host software on that box
> *discipline it with PPS from GPS, using an active antenna
> *use NTP to obtain the NTP time from this local personal NTP server as 
> required
> *I don't know if I need two additional boxes: one for the NTP host and 
> another for receiving the GPS PPS signal, like a Pi in kernal mode.
> 
> GPS issues.
> 
> *I'm in a semi-basement apartment.
> *Building faces due South.
> *Building is 1960's brick & concrete, steel trusses & sheets in place 
> from the concrete floor pours.
> *Windows from 14" to 38" from the ground. My antenna has to be between 
> those.
> *Window frame is plastic retrofit over wood Pearson-sliders.
> *There is a bank of buildings due south of me that leaves me with 
> clearance elevations between 6 and 12 degrees. I'm at 45.42 North.
> *Due South within what open sky I have, are two heights of electrical 
> wires, around 35 feet out from the building at the edge of the parking lot.
> 
> I'm expecting multipath from: those buildings, my building and I assume the 
> wires and possibly the cars?
> 
> Between the multipath and a less than full view of the sky, I believe I'm 
> needing a GPS module:
> 
> *that is sensitive,
> *good multipath handling,
> *GPS & GLONASS, to get as many sats possible out of the sky-view I have.
> 
> Due to my location difficulties, considering newer more sensitive GPS modules 
> seems to make sense, even if they're not timing modules. I was tempted by a 
> Qualtec L86 with -148|-165 dBm or a SkyTraq Venus838LPx-T. Then a ublox 
> Max-M8Q with -165|-167 dBm & its stationary mode. But then I discovered I can 
> get a ublox NEO-M8T with -165|-167 dBm sensitivity, its multipath handling 
> and concurrent reception of GPS/QZSS, GLONASS, BeiDou & Galileo.
> 
> A ublox NEO-M8T with an active timing antenna (GPS | GLONASS ?) seems to be 
> my best chance of being successful at my location.
> 
> Questions:
> 
> *Is there a more suitable GPS module than the ublox NEO-M8T for my 
> location issues?
> *Can anyone recommend an affordable suitable antenna for GPS & GLONASS?
> *One box or two, for running a local NTP host and receiving the PPS from 
> a GPS module?
> *Is there a better solution for a micro board than a Rasp Pi with its USB 
> controlled Ethernet, or the BBB with it's RF issues?
> *What am I not considering that could end up biting me?
> 
> Thanks,
> 
> Michael
> 
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Re: [time-nuts] Best Chance GPS module

[Gary E. Miller]

Yo MLewis!

On Wed, 30 Nov 2016 16:11:05 -0500
MLewis  wrote:

> I'm after a time solution for my personal computer. It looks like I
> need:

I suggest you take this over to NTPsec: de...@ntpsec.org, or
on gpsd: gpsd-us...@nongnu.org

They are working on a HOWTO that does exactly what you want.

You can download a git copy of it:

https://gitlab.com/NTPsec/stratum-1-microserver-howto

I have 4 RasPis with various GPS attached, and an Orange Pi to add
soon.  Works great.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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[time-nuts] Best Chance GPS module

[MLewis]

(resending as I tried posting in html...)

Hello,

I'm a novice at time issues. I've been gathering info and I think I'm 
ready to start asking questions.


I'm after a time solution for my personal computer. It looks like I need:

*a standalone box to be my own local personal NTP server (so the 
variable processing load on my main box can no longer affect host 
polling software timestamps...)

*run standard NTP Client & Host software on that box
*discipline it with PPS from GPS, using an active antenna
*use NTP to obtain the NTP time from this local personal NTP server 
as required
*I don't know if I need two additional boxes: one for the NTP host 
and another for receiving the GPS PPS signal, like a Pi in kernal mode.


GPS issues.

*I'm in a semi-basement apartment.
*Building faces due South.
*Building is 1960's brick & concrete, steel trusses & sheets in 
place from the concrete floor pours.
*Windows from 14" to 38" from the ground. My antenna has to be 
between those.

*Window frame is plastic retrofit over wood Pearson-sliders.
*There is a bank of buildings due south of me that leaves me with 
clearance elevations between 6 and 12 degrees. I'm at 45.42 North.
*Due South within what open sky I have, are two heights of 
electrical wires, around 35 feet out from the building at the edge of 
the parking lot.


I'm expecting multipath from: those buildings, my building and I assume 
the wires and possibly the cars?


Between the multipath and a less than full view of the sky, I believe 
I'm needing a GPS module:


*that is sensitive,
*good multipath handling,
*GPS & GLONASS, to get as many sats possible out of the sky-view I have.

Due to my location difficulties, considering newer more sensitive GPS 
modules seems to make sense, even if they're not timing modules. I was 
tempted by a Qualtec L86 with -148|-165 dBm or a SkyTraq Venus838LPx-T. 
Then a ublox Max-M8Q with -165|-167 dBm & its stationary mode. But then 
I discovered I can get a ublox NEO-M8T with -165|-167 dBm sensitivity, 
its multipath handling and concurrent reception of GPS/QZSS, GLONASS, 
BeiDou & Galileo.


A ublox NEO-M8T with an active timing antenna (GPS | GLONASS ?) seems to 
be my best chance of being successful at my location.


Questions:

*Is there a more suitable GPS module than the ublox NEO-M8T for my 
location issues?

*Can anyone recommend an affordable suitable antenna for GPS & GLONASS?
*One box or two, for running a local NTP host and receiving the PPS 
from a GPS module?
*Is there a better solution for a micro board than a Rasp Pi with 
its USB controlled Ethernet, or the BBB with it's RF issues?

*What am I not considering that could end up biting me?

Thanks,

Michael

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Re: [time-nuts] Google public NTP service

[Tom Van Baak]

>From Gary Miller:
> You gotta start sometime.  Now is a good time.  This is not the first
> time Google has done this, and certainly will not be the last.  It had
> bad consequences last time and they did not learn from that.

This is not the fault of google. The big players will continue to innovate and 
solve timing problems as long as the official scientific and political world do 
nothing.

May I request that further discussion of this google / NTP / leap second issue 
take place in ntp forums or the LEAPSECS list, and not here on time-nuts.

Thanks,
/tvb
Moderator, http://leapsecond.com/time-nuts.htm

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Re: [time-nuts] Google public NTP service

[Gary E. Miller]

Yo Bob!

On Wed, 30 Nov 2016 15:42:58 -0500
Bob Camp  wrote:

> I believe the point was: If you start tossing around packets that are
> odd sized, it is likely to break a lot of existing code.

Not 'odd'.  Fully specified in the RFC.  Anyone that did not implement
the spec gets what they deserve.

IMHO, better for a packet that can be misinterpreted be dropped, Like 
the new non-standard Google NTP.  Unmarked these new packets can cause
havoc.

But, to be fair, some assert the spec is a bit ambiguous. So any
extention should be a new RFC.  Like Autokey.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Google public NTP service

[Gregory Maxwell]

On Wed, Nov 30, 2016 at 2:21 PM, Michael Rothwell  wrote:
> ... was just announced.
> https://cloudplatform.googleblog.com/2016/11/making-every-leap-second-count-with-our-new-public-NTP-servers.html?m=1

Obvious outcome is obvious. Leap smear prevented faults between google
systems but then created the problem that other things don't agree
with google's timestamps-- and the leapseconds still cause problems
for many other parties.
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Re: [time-nuts] Google public NTP service

[Gary E. Miller]

Yo Poul-Henning!

On Wed, 30 Nov 2016 20:42:17 +
"Poul-Henning Kamp"  wrote:

> 
> In message <20161130123506.63853...@spidey.rellim.com>, "Gary E.
> Miller" writes :
> 
> >Not true.  NTP has provision for arbitrrary extensions to an ntp
> >packet.  
> 
> Good luck getting that through firewalls after the lastest rounds
> of NTP amplification attacks...

Good, then we get the firewalls eventually fixed as well.

Seems to me you gotta break things badly on the internet before they get
fixed.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Google public NTP service

[Bob Camp]

Hi

I believe the point was: If you start tossing around packets that are odd 
sized, it is 
likely to break a lot of existing code.

Bob

> On Nov 30, 2016, at 3:35 PM, Gary E. Miller  wrote:
> 
> Yo Poul-Henning!
> 
> On Wed, 30 Nov 2016 20:31:09 +
> "Poul-Henning Kamp"  wrote:
> 
>> 
>> In message , Bob Camp
>> writes:
>> 
 I would support an RFC to mark the type a time an chimer is
 servings. Not only smeared and UTC, but also TAI, UT, UT0, UT1,
 UT2, ET, TDT, TDB, TT, TCG, TCB, GPS, etc…  
>>> 
>>> That would probably be a good point to make on the NTP list :)
>>> 
>>> The gotcha is that there is essentially zero time to approve and
>>> implement something like that before the end of next month …  
>> 
>> And no space in the NTP packets for the bits.
> 
> Not true.  NTP has provision for arbitrrary extensions to an ntp packet.
> 
> See RFC 5905. https://www.ietf.org/rfc/rfc5905.txt section 7.3:
> 
>"The packet format consists of three components: the header itself,
>one or more optional extension fields, and an optional message
>authentication code (MAC). "
> 
> RGDS
> GARY
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>   g...@rellim.com  Tel:+1 541 382 8588
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[time-nuts] RPi/ beagle bone-like computer without video

[jimlux]

I'm looking for a small linux single board - similar to RPi or 
Beaglebone Black, but don't need the HDMI, or video stuff.
Preferably without weird connectors, and available for wide temperature 
ranges (it's for a data logger/collector in the field)


What's out there?

There's BBB in industrial flavor (-40 to +85C ) for $60-70
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Re: [time-nuts] Google public NTP service

[Poul-Henning Kamp]

In message <20161130123506.63853...@spidey.rellim.com>, "Gary E. Miller" writes
:

>Not true.  NTP has provision for arbitrrary extensions to an ntp packet.

Good luck getting that through firewalls after the lastest rounds
of NTP amplification attacks...


-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Google public NTP service

[Gary E. Miller]

Yo Poul-Henning!

On Wed, 30 Nov 2016 20:31:09 +
"Poul-Henning Kamp"  wrote:

> 
> In message , Bob Camp
> writes:
> 
> >> I would support an RFC to mark the type a time an chimer is
> >> servings. Not only smeared and UTC, but also TAI, UT, UT0, UT1,
> >> UT2, ET, TDT, TDB, TT, TCG, TCB, GPS, etc…  
> >
> >That would probably be a good point to make on the NTP list :)
> >
> >The gotcha is that there is essentially zero time to approve and
> >implement something like that before the end of next month …  
> 
> And no space in the NTP packets for the bits.

Not true.  NTP has provision for arbitrrary extensions to an ntp packet.

See RFC 5905. https://www.ietf.org/rfc/rfc5905.txt section 7.3:

"The packet format consists of three components: the header itself,
one or more optional extension fields, and an optional message
authentication code (MAC). "

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Google public NTP service

[Gary E. Miller]

Yo Bob!

On Wed, 30 Nov 2016 15:26:34 -0500
Bob Camp  wrote:

> > I would support an RFC to mark the type a time an chimer is
> > servings. Not only smeared and UTC, but also TAI, UT, UT0, UT1,
> > UT2, ET, TDT, TDB, TT, TCG, TCB, GPS, etc…  
> 
> 
> That would probably be a good point to make on the NTP list :)

Already done.  In private and on BTPsec.

> The gotcha is that there is essentially zero time to approve and
> implement something like that before the end of next month …

You gotta start sometime.  Now is a good time.  This is not the first
time Google has done this, and certainly will not be the last.  It had
bad consequences last time and they did not learn from that.

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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Re: [time-nuts] Google public NTP service

[Poul-Henning Kamp]

In message , Bob Camp writes:

>> I would support an RFC to mark the type a time an chimer is servings.
>> Not only smeared and UTC, but also TAI, UT, UT0, UT1, UT2, ET, TDT, TDB, 
>> TT, TCG, TCB, GPS, etc…
>
>That would probably be a good point to make on the NTP list :)
>
>The gotcha is that there is essentially zero time to approve and implement 
>something like that before the end of next month …

And no space in the NTP packets for the bits.

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Google public NTP service

[Bob Camp]

Hi

> On Nov 30, 2016, at 3:14 PM, Gary E. Miller  wrote:
> 
> Yo Michael!
> 
> On Wed, 30 Nov 2016 14:21:39 +
> Michael Rothwell  wrote:
> 
>> ... was just announced.
>> https://cloudplatform.googleblog.com/2016/11/making-every-leap-second-count-with-our-new-public-NTP-servers.html?m=1
> 
> I sort of see where they are coming from, but this will cause problems.
> 
> The NTP packets google sends out have no way to be marked as 'not UTC'.
> Given how promiscuous people are sharing NTP chimers these 'not UTC' 
> chimers will get into the mix.  When they diverge from the real UTC servers
> it will sorely confuse NTP clients.
> 
> I would support an RFC to mark the type a time an chimer is servings.
> Not only smeared and UTC, but also TAI, UT, UT0, UT1, UT2, ET, TDT, TDB, 
> TT, TCG, TCB, GPS, etc…


That would probably be a good point to make on the NTP list :)

The gotcha is that there is essentially zero time to approve and implement 
something like that before the end of next
month …

Bob

> 
> RGDS
> GARY
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>   g...@rellim.com  Tel:+1 541 382 8588
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Re: [time-nuts] Google public NTP service

[Gary E. Miller]

Yo Michael!

On Wed, 30 Nov 2016 14:21:39 +
Michael Rothwell  wrote:

> ... was just announced.
> https://cloudplatform.googleblog.com/2016/11/making-every-leap-second-count-with-our-new-public-NTP-servers.html?m=1

I sort of see where they are coming from, but this will cause problems.

The NTP packets google sends out have no way to be marked as 'not UTC'.
Given how promiscuous people are sharing NTP chimers these 'not UTC' 
chimers will get into the mix.  When they diverge from the real UTC servers
it will sorely confuse NTP clients.

I would support an RFC to mark the type a time an chimer is servings.
Not only smeared and UTC, but also TAI, UT, UT0, UT1, UT2, ET, TDT, TDB, 
TT, TCG, TCB, GPS, etc...

RGDS
GARY
---
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
g...@rellim.com  Tel:+1 541 382 8588


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[time-nuts] Best Chance GPS module

[MLewis]

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Re: [time-nuts] Google public NTP service

[Poul-Henning Kamp]

In message <706C789A8B5440B3911A8A02C93E3E54@Alta>, "David J Taylor" writes:

>Hope it doesn't mess up too many folk.  It's completely against the 
>recommendations, of course.

But in difference from these, it actually works.

Trust me, they'll get thousands of users...

-- 
Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer   | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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Re: [time-nuts] Google public NTP service

[David J Taylor]

Subject: [time-nuts] Google public NTP service

... was just announced.
https://cloudplatform.googleblog.com/2016/11/making-every-leap-second-count-with-our-new-public-NTP-servers.html?m=1
___

One "service" I will /not/ be using.

Hope it doesn't mess up too many folk.  It's completely against the 
recommendations, of course.


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] I am looking to measure phase jitter between two synchronized DDS signals

[Bob Camp]

Hi

The highest sensitivity approach to jitter measurement is to look at phase 
noise with a phase noise test set. You 
don’t mention jitter bandwidth or what sort of cleanup you have after the DDS. 
That will all impact the degree to which
phase noise is a useful indicator. 

Likely the quickest way to do that with your sources would be to run a 
regenerative divider to get the 3 GHz back down
to 750 MHz. Then compare the two signals at 750 with a double balanced mixer. 
Effectively you have built a vector
voltmeter to do what you need. If you have concerns about the regenerative 
dividers, build two and look at them 
against each other. If you can lock the 750 and 3 GHz, you can use the same 
setup for phase noise and get very
good resolution (-170 dbc / Hz) without a lot of trouble. 

Yes it is a bit of construction. You have an odd requirement and off the shelf 
test gear isn’t targeted at odd things …

Bob

> On Nov 30, 2016, at 4:47 AM, Jim Potter  wrote:
> 
> I just posted this on the HP Equipment forum. Someone reading it there 
> suggested I contact timenuts because what I want to do is effectively an 
> accurate time stability measurement.
> 
> I am attempting to look at the phase jitter between two synchronized DDS rf 
> sources, one at 3 Ghz and one at 750 GHz. My 10 Gs/s scope has way to much 
> jitter to be useful. A vector voltmeter might be just the thing. I have had 
> an HP 8508A VVM and would buy another one if it was useful, but it is rated 
> only to 2 GHz. I also have an old PRD 2020 with the 2021 head that is in 
> working condition. It is rated to 2.4 Ghz, but syncs on the 750 MHz signal 
> and apparently passes the 3 GHz signal somewhat. I get a reading of about -40 
> dBm for +10 dBm in at 3 Ghz. However, I do get a phase measurement that 
> varies with the phase of the 3 Ghz signal corresponding to the changes I make 
> in the output phase. The issue is the noise. I see about +/- 1 degree jitter 
> in the phase reading on the panel meter. I also see a drift of 2 to 3 
> degrees. I don't think the DDS units are the source of the drift, and I'd 
> like to show that the phase noise is lower than what I am observing.
> 
> I don't know of any VVM that works at 3 GHz, beyond the out of spec use of my 
> PRD unit. Using an oscilloscope is problematic because I have measured the 
> trigger jitter on a 100 Gs/s Tektronix unit when it was brand new. It's about 
> 3.5 ps RMS. A 3 GHz signal has a period of 333 ps so that corresponds to 10 
> degrees. I see that Tek has a new scope with 70 GHz bandwidth and 200 Gs/s, 
> but I don't think that is a big enough improvement over the 100 Gs/s unit. In 
> any case even renting one of these is probably too expensive.
> 
> I would appreciate any suggestions for how to accurately measure the phase 
> jitter. I have a Tektronix RSA 306A which has been handy, but I'm uncertain 
> about how to use it to measure phase jitter. In any case, what really matters 
> is not the jitter of the individual signals but the jitter in the phase 
> difference between the two signals which are all derived from the same time 
> base.
> 
> One obvious question is, if I can't measure it how can it matter? The answer 
> is that each rf unit is a signal source for a section of linear accelerator. 
> If the phase jitter is excessive, it will show up as loss of beam quality and 
> current. It's a bit hard to set up a proton accelerator to see if the jitter 
> is acceptable. I really need able to make a bench measurement to qualify the 
> performance.
> 
> Thanks in advance for any suggestions.
> 
> Jim
> 
> 
> James M. Potter PhD, Pres.
> JP Accelerator Works, Inc.
> 2245 47th Street
> Los Alamos, NM 87544
> 
> TEL:505-690-8701
> FAX: 888-301-2833
> 
> mailto:jpot...@jpaw.com
> http://www.jpaw.com
> 
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[time-nuts] Google public NTP service

[Michael Rothwell]

... was just announced.
https://cloudplatform.googleblog.com/2016/11/making-every-leap-second-count-with-our-new-public-NTP-servers.html?m=1
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[time-nuts] I am looking to measure phase jitter between two synchronized DDS signals

[Jim Potter]

I just posted this on the HP Equipment forum. Someone reading it 
there suggested I contact timenuts because what I want to do is 
effectively an accurate time stability measurement.


I am attempting to look at the phase jitter between two synchronized 
DDS rf sources, one at 3 Ghz and one at 750 GHz. My 10 Gs/s scope has 
way to much jitter to be useful. A vector voltmeter might be just the 
thing. I have had an HP 8508A VVM and would buy another one if it was 
useful, but it is rated only to 2 GHz. I also have an old PRD 2020 
with the 2021 head that is in working condition. It is rated to 2.4 
Ghz, but syncs on the 750 MHz signal and apparently passes the 3 GHz 
signal somewhat. I get a reading of about -40 dBm for +10 dBm in at 3 
Ghz. However, I do get a phase measurement that varies with the phase 
of the 3 Ghz signal corresponding to the changes I make in the output 
phase. The issue is the noise. I see about +/- 1 degree jitter in the 
phase reading on the panel meter. I also see a drift of 2 to 3 
degrees. I don't think the DDS units are the source of the drift, and 
I'd like to show that the phase noise is lower than what I am observing.


I don't know of any VVM that works at 3 GHz, beyond the out of spec 
use of my PRD unit. Using an oscilloscope is problematic because I 
have measured the trigger jitter on a 100 Gs/s Tektronix unit when it 
was brand new. It's about 3.5 ps RMS. A 3 GHz signal has a period of 
333 ps so that corresponds to 10 degrees. I see that Tek has a new 
scope with 70 GHz bandwidth and 200 Gs/s, but I don't think that is a 
big enough improvement over the 100 Gs/s unit. In any case even 
renting one of these is probably too expensive.


I would appreciate any suggestions for how to accurately measure the 
phase jitter. I have a Tektronix RSA 306A which has been handy, but 
I'm uncertain about how to use it to measure phase jitter. In any 
case, what really matters is not the jitter of the individual signals 
but the jitter in the phase difference between the two signals which 
are all derived from the same time base.


One obvious question is, if I can't measure it how can it matter? The 
answer is that each rf unit is a signal source for a section of 
linear accelerator. If the phase jitter is excessive, it will show up 
as loss of beam quality and current. It's a bit hard to set up a 
proton accelerator to see if the jitter is acceptable. I really need 
able to make a bench measurement to qualify the performance.


Thanks in advance for any suggestions.

Jim


James M. Potter PhD, Pres.
JP Accelerator Works, Inc.
2245 47th Street
Los Alamos, NM 87544

TEL:505-690-8701
FAX: 888-301-2833

mailto:jpot...@jpaw.com
http://www.jpaw.com

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