Seems the problem is possible asymmetry in the speed of network
connections. You really can not detect this with simple pings.
But what if you send 100MB messages?Even using NTP at the tens of
millisecond level you can measure the one way speed accurately if the
message is long enough.
On Tue, 21 Feb 2012 23:23:23 -0800
Chris Albertson albertson.ch...@gmail.com wrote:
Seems the problem is possible asymmetry in the speed of network
connections. You really can not detect this with simple pings.
But what if you send 100MB messages?Even using NTP at the tens of
I would not fully trust NTP, and as already explained taking your GPS
outside as a reference for just a while is not really going to help.
But..why not using GPS inside the building? Some receivers are quite
sensitive, so probably you will not need an external antenna to pick up a
signal. Probably
Moreover most of actual GPS receivers are indoor capable (once got a lock
with the antenna outside). I have briefly tested the uBlox and the NavSync
for this feature and it works as expected.
On Wed, Feb 22, 2012 at 11:52 AM, pablo alvarez
pabloalvarezsanc...@gmail.com wrote:
I would not fully
Of Chris Albertson
Sent: Monday, February 20, 2012 9:57 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Low-long-term-drift clock for board
levelintegration?
Even with a very minimal local Ethernet where the path is the same for
every packet you still have variable
On Tue, Feb 21, 2012 at 9:16 AM, Bob Camp li...@rtty.us wrote:
Hi
The only saving feature on a local LAN is that you get to run a *lot* of
data if you wish to.
Also, by definition a local LAN does not have a router.
BTW, Is the O.P. still here? I wonder if he is re-thinking his
...@kinali.ch wrote:
From: Attila Kinali att...@kinali.ch
Subject: Re: [time-nuts] Low-long-term-drift clock for board levelintegration?
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Received: Tuesday, February 21, 2012, 1:47 PM
On Tue, 21 Feb 2012 10:05:04 -0800
Chris
On Tue, Feb 21, 2012 at 10:47 AM, Attila Kinali att...@kinali.ch wrote:
If you read carefully what the OP wrote, you'll see that he
wants to measure one way trips.
Yes, just like the swim coach who wants to measure the swimmer doing
one length of the pool. He uses a stop watch, Not two
albertson.ch...@gmail.com said:
Now we can move the discussion to measuring the speed of the backwards
channel with some method better than just taking 1/2 the round trip.
The way to do that is to get a good clock on both systems. That puts us back
in the chicken-egg business.
--
These
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On Feb 21, 2012, at 11:12 AM, Mark Spencer wrote:
Perhaps another way to approach this problem would be to see if there are
entities and or individuals who already have precision time keeping equipment
(or at least access to GPS antennas) who
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What if one sends a message one way that triggers say, 10 response messages 1
second apart. Then you get distribution statistics on the return path. You
still don't know what the absolute forward or reverse path time was, of
course.
Yes,
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On Feb 21, 2012, at 10:05 AM, Chris Albertson wrote:
BTW, Is the O.P. still here? I wonder if he is re-thinking his
requirements.
The requirement is to do one-way delay measurements. The requirement isn't
changing. I'm just here to educate
I think a box that can't get some external source of time in three years is one that we can pretty well write off as lost.
Thank you (several of you, actually) for the clear explanation of the math.
http://www.msc-ge.com/en/news/pressroom/manu/1241-www/3567-www.html
Yes, the relation frequency_drift- time_error seems difficult to figure
out. I see this misunderstanding daily here at work and haven't yet found a
way to explain to my colleagues. I have already used: integral, area, count
accumulation but none worked.
On Mon, Feb 20, 2012 at 10:37 AM, Tom Van
Hello Bill Woodcock,
Many, many questions come to mind. Is this a fixed network that never changes
its character ? Or by network do you mean via the internet where you have no
control over path variations ? I guess the latter based upon your comments
thus far.
What is driving the
In a message dated 2/19/2012 21:21:35 Pacific Standard Time, wb6...@cox.net
writes:
Doing a few fixes for 30 minutes will, under best conditions, get you
somewhere on a circumference around your location with a radius of 15 meters
(50 feet). For GPS to get a useful coordinate result with
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