strom...@nexgo.de said:
> I have not yet managed to blind the GPS antenna completely, though, so I
> can't know what happens when it loses all signal.
Have you tried putting it under a metal pie tin?
Or inside a metal box? (being careful not to mangle the cord)
--
These are my opinions. I ha
g...@rellim.com said:
>> Most CPU chips include a temperature sensor.
> Which I have found does not correlate with any of my NTP data.
I have a Raspberry Pi sitting on a window sill. It gets a couple of hours of
late afternoon sun. There is a big temperature spike. Drift roughly follows
it.
Gary E. Miller writes:
> Most cheaper GPS always output PPS, even when they have no idea
> where they are or what time it is. Garmin documents this, as do others.
Well, the NavSpark mini does not output a PPS until it aquires a 3D
lock, as documented. The configuration program has options to eit
Yo Eric!
On Tue, 30 Aug 2016 00:08:17 -0400
"Eric S. Raymond" wrote:
> Gary E. Miller :
> > > 1. GPS outage length and frequencies are decreasing
> >
> > Don't care. If you need your NTP to work, you need to know it is
> > working. Otherwise failure are not noticed.
>
> OK, the test for "
Gary E. Miller :
> > 1. GPS outage length and frequencies are decreasing
>
> Don't care. If you need your NTP to work, you need to know it is working.
> Otherwise failure are not noticed.
OK, the test for "know it is working" is: you have lock, or you had lock
less than x seconds ago where x is
Yo Hal!
On Thu, 25 Aug 2016 15:30:25 -0700
Hal Murray wrote:
> e...@thyrsus.com said:
> > I have a USB thermometer on order, they're cheap. Might I suggest
> > you get one and repeat this experiment, actually plotting your
> > temperature variation?
>
> Most CPU chips include a temperature
Yo Achim!
On Thu, 25 Aug 2016 20:33:36 +0200
Achim Gratz wrote:
> Dan Drown writes:
> > The GPS module I'm using still outputs PPS even when it loses lock.
> > That won't be true for every GPS module.
>
> I also have a NavSpark mini attached at the moment and I was surprised
> it kept outputt
Yo Dan!
On Thu, 25 Aug 2016 10:23:50 -0500
Dan Drown wrote:
> I had setup a test along these lines a week ago:
> https://blog.dan.drown.org/gps-pps-drift-when-it-has-no-signal/
Yeah, and I've been watching it.
> My results were a long term average of 250us-500us lost per day
> (~3-6ppb). This
Yo Eric!
On Thu, 25 Aug 2016 00:19:46 -0400
"Eric S. Raymond" wrote:
> This was going to be a note to just Hal originally, but it will do the
> rest of the team no harm to know more about the scenarios and
> assumptions driving some of my design choices.
>
> Hal objected (off list) to me drawin
Achim Gratz writes:
> That'd give you the actual crystal
> temperature, which might enable forward temp compensation (there's a
> blog post somewhere from someone who's done that with x86 hardware, I
> can't find that link quickly enough).
This was the article I was referring to, plus the one it l
Hal Murray writes:
> e...@thyrsus.com said:
>> I have a USB thermometer on order, they're cheap. Might I suggest you get
>> one and repeat this experiment, actually plotting your temperature
>> variation?
>
> Most CPU chips include a temperature sensor.
>
> For Linux PCs, you need the coretemp mo
Hal Murray :
>
> e...@thyrsus.com said:
> > One of my agenda items for a while has been to develop a protocol for places
> > that want to firewall out NTP for security reasons - that is, a set of
> > practices and error estimates based on documented assumptions.
>
> Background data is good. I t
Hal Murray writes:
> Most CPU chips include a temperature sensor.
The temperature sensor for the CPU is close to useless unless you have
an SoC with the XO integrated. It tells you a lot about the average
load of the CPU, but not much else.
> For Linux PCs, you need the coretemp module loaded.
Dan Drown :
> Quoting "Eric S. Raymond" :
> >Is the CPU temp going to be a good approximation of what the clock sees,
> >though? I can think of several reasons to doubt it.
>
> It's better than nothing, but it does have two limitations:
>
> 1. the CPU heats itself at a different rate than the su
Quoting "Eric S. Raymond" :
Is the CPU temp going to be a good approximation of what the clock sees,
though? I can think of several reasons to doubt it.
It's better than nothing, but it does have two limitations:
1. the CPU heats itself at a different rate than the surrounding
board, so it
Hal Murray :
>
> e...@thyrsus.com said:
> > I have a USB thermometer on order, they're cheap. Might I suggest you get
> > one and repeat this experiment, actually plotting your temperature
> > variation?
>
> Most CPU chips include a temperature sensor.
>
> For Linux PCs, you need the coretemp
e...@thyrsus.com said:
> One of my agenda items for a while has been to develop a protocol for places
> that want to firewall out NTP for security reasons - that is, a set of
> practices and error estimates based on documented assumptions.
Background data is good. I think you will get into trou
e...@thyrsus.com said:
> I have a USB thermometer on order, they're cheap. Might I suggest you get
> one and repeat this experiment, actually plotting your temperature
> variation?
Most CPU chips include a temperature sensor.
For Linux PCs, you need the coretemp module loaded. The lm-sensors
Eric S. Raymond writes:
> Achim Gratz :
>> Forget about GPS outages. If you want to connect these time servers to
>> the net, they should have some form of sanity checking that's
>> independent from their primary time source and take them off the net as
>> soon as something looks fishy.
>
> What k
Achim Gratz :
> Forget about GPS outages. If you want to connect these time servers to
> the net, they should have some form of sanity checking that's
> independent from their primary time source and take them off the net as
> soon as something looks fishy.
What kind of sanity checking do you rec
Eric S. Raymond writes:
> I shall now discuss three interlocking reasons this possibility does
> not loom as large in my mind as it does in Hal's.
[…]
> When I think about this, I consider 10ms total deviation from UTC as
> the target for WAN service. Let's say your local clock drifts by 3ms
> per
Dan Drown writes:
> The GPS module I'm using still outputs PPS even when it loses lock.
> That won't be true for every GPS module.
I also have a NavSpark mini attached at the moment and I was surprised
it kept outputting the PPS when losing 3D lock (it stops blinking the
LED). It seems semi-docum
Dan Drown :
> >We may already be at a technological place where GPS outages don't bust the
> >tolerable-error budget, even with cheap hardware. If we aren't, we'll
> >probably be there soon. One of my medium-term agenda items is to measure
> >and see.
>
> I had setup a test along these lines a we
Daniel Franke :
> On 8/25/16, Eric S. Raymond wrote:
> > (Remember that the user story assumes a big hardware budget.)
>
> A big hardware budget should have room for a rubidium GPSDO,
> in which case you can get away with freerunning for a lot longer.
Yes, that did occur to me. Or, a TCxO like
Quoting "Eric S. Raymond" :
:
Hal objected (off list) to me drawing a conclusion from today's
offset multiplot that check servers aren't necessary when you have
a local GPS - a Stratum 1 really can run autonomously. He said,
correctly of course, that the check servers aren't there to improve
time
On 8/25/16, Eric S. Raymond wrote:
> (Remember that the user story assumes a big hardware budget.)
A big hardware budget should have room for a rubidium GPSDO,
in which case you can get away with freerunning for a lot longer.
___
devel mailing list
deve
Hal Murray :
> It sounds like you are trying to rationalize running without any network
> servers.
One of my agenda items for a while has been to develop a protocol for
places that want to firewall out NTP for security reasons - that is, a
set of practices and error estimates based on documented
There is lots of good stuff there.
But...
It sounds like you are trying to rationalize running without any network
servers.
Even if you do collect lots of data, you can't extrapolate very far from a
sample of one.
There are many ways to screw up. Even if you get a lot of data, there will
b
This was going to be a note to just Hal originally, but it will do the
rest of the team no harm to know more about the scenarios and
assumptions driving some of my design choices.
Hal objected (off list) to me drawing a conclusion from today's
offset multiplot that check servers aren't necessary w
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