New to the list
Just a note to let you know that George, K2CM, has joined the list.
George
K2CM, Vestal, NY
Hi, George
Is there anything that distinguishes you from the thousand others on this
list?
What is there about time that interests you? That makes you a nut?
Do you lean towards theory or the soldering iron? Is bit twiddling your
interest?
Assuming that you have followed human nature and collected stuff that might
be
interesting, what have you collected? Who will throw it in the dumpster when
you die?
If you are completely new to this, where would you like to start? Something
cheap
from an "auction" site or a new hydrogen maser?
Don't mind me, I've been around too long.
Bill Hawkins
-----Original Message-----
From: George Allen
Sent: Tuesday, March 13, 2012 9:26 PM
Just a note to let you know that George, K2CM, has joined the list.
George
K2CM, Vestal, NY
Hi George, welcome aboard. If you are a beginner about time and frequency
don't forget to get and read what was pointed out to be our introduction to
the subject http://gpstime.com/files/tow-time2011.pdf written by Tom Clark
and Rick Hambly.
On Wed, Mar 14, 2012 at 5:27 AM, Bill Hawkins bill@iaxs.net wrote:
Hi, George
Is there anything that distinguishes you from the thousand others on this
list?
What is there about time that interests you? That makes you a nut?
Do you lean towards theory or the soldering iron? Is bit twiddling your
interest?
Assuming that you have followed human nature and collected stuff that might
be
interesting, what have you collected? Who will throw it in the dumpster
when
you die?
If you are completely new to this, where would you like to start? Something
cheap
from an "auction" site or a new hydrogen maser?
Don't mind me, I've been around too long.
Bill Hawkins
-----Original Message-----
From: George Allen
Sent: Tuesday, March 13, 2012 9:26 PM
Just a note to let you know that George, K2CM, has joined the list.
George
K2CM, Vestal, NY
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
I joined the list at the suggestion of Bill, Wb6BNQ.
I am currently experimenting with several frequency standards, an Rb and an OCXO. While I feel that I am able to measure frequencies with reasonable accuracy, I have no way of accurately determining time, so have ordered a T-Bolt. I expect that to be here in about 2 weeks.
The big question is "why am I doing this"? Just because I can.
George
K2CM
From: Bill Hawkins bill@iaxs.net
To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com
Sent: Wednesday, March 14, 2012 12:27 AM
Subject: Re: [time-nuts] New to the list
Hi, George
Is there anything that distinguishes you from the thousand others on this
list?
What is there about time that interests you? That makes you a nut?
Do you lean towards theory or the soldering iron? Is bit twiddling your
interest?
Assuming that you have followed human nature and collected stuff that might
be
interesting, what have you collected? Who will throw it in the dumpster when
you die?
If you are completely new to this, where would you like to start? Something
cheap
from an "auction" site or a new hydrogen maser?
Don't mind me, I've been around too long.
Bill Hawkins
I understand the cartoon at the beginning; but, it will take me a very, very long time to understand the concepts of the paper!
George
K2CM
Vestal, NY
From: Azelio Boriani azelio.boriani@screen.it
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Wednesday, March 14, 2012 4:51 AM
Subject: Re: [time-nuts] New to the list
Hi George, welcome aboard. If you are a beginner about time and frequency
don't forget to get and read what was pointed out to be our introduction to
the subject http://gpstime.com/files/tow-time2011.pdf written by Tom Clark
and Rick Hambly.
On Wed, Mar 14, 2012 at 5:27 AM, Bill Hawkins bill@iaxs.net wrote:
Hi, George
Is there anything that distinguishes you from the thousand others on this
list?
What is there about time that interests you? That makes you a nut?
Do you lean towards theory or the soldering iron? Is bit twiddling your
interest?
Assuming that you have followed human nature and collected stuff that might
be
interesting, what have you collected? Who will throw it in the dumpster
when
you die?
If you are completely new to this, where would you like to start? Something
cheap
from an "auction" site or a new hydrogen maser?
Don't mind me, I've been around too long.
Bill Hawkins
-----Original Message-----
From: George Allen
Sent: Tuesday, March 13, 2012 9:26 PM
Just a note to let you know that George, K2CM, has joined the list.
George
K2CM, Vestal, NY
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On Wed, 14 Mar 2012 08:10:42 -0700 (PDT)
George Allen george_gloria99@yahoo.com wrote:
I understand the cartoon at the beginning; but, it will take me
a very, very long time to understand the concepts of the paper!
Don't worry. There isn't that much magic to it. With a little bit
of technical background you can understand most of the stuff in
a very short time.
The most important "Concept" is that of fractional deviation.
It's expressed in ppm (part per million, 10^-6), ppb (per billion, 10^-9)
or just as a fraction (eg 10^-12). It tells you that if you measure
some value x, you will be +/- x * 10^-9 (in the case of 1ppb) off of
the true x value.
What is important to note here is, that this deviation is dependent
on how large x is. I.e. if you measure 5 units your deviation could
be 1ppb, going up to 100 units, you will get 10ppb. Also note that
knowing some deviation values for some points does not tell you
much (or anything at all) about the deviation at other values.
In the above example you could guess that the large x is, the higher
the deviation is. But it could actually be that at 200 units, you
get a deviation of 5ppb. To get a better feeling of this, google
for ADEV plots, or go to febo.com or leapsecond.com and have a look
at some of the graphs.
If you get that concept, everything else is just technicalities
or getting better clocks ;-)
Oh.. by the way.. would you mind not to top post? I know it's common
on this mailinglist, but i think it makes the mails harder to read.
Attila Kinali
--
The trouble with you, Shev, is you don't say anything until you've saved
up a whole truckload of damned heavy brick arguments and then you dump
them all out and never look at the bleeding body mangled beneath the heap
-- Tirin, The Dispossessed, U. Le Guin
These pretty ADEV/Tau plots, do people have an automated
system to produce these things? How much work is involved?
How many samples are taken? Sample for a month, omputer crunching
for weeks?
I have no feel for what the process is like.
I have two oscillators and a Racal 1992 counter. If I were
to hook up the computer to the counter would I have the minimum
amount of "stuff" needed?
On 3/14/2012 1:35 PM, Chris Howard wrote:
These pretty ADEV/Tau plots, do people have an automated
system to produce these things? How much work is involved?
How many samples are taken? Sample for a month, omputer crunching
for weeks?
I have no feel for what the process is like.
I have two oscillators and a Racal 1992 counter. If I were
to hook up the computer to the counter would I have the minimum
amount of "stuff" needed?
The stuff on my pages at febo.com come primarily from two sources:
-
Screenshots from the TSC analyzer's display (actually, I trick the
TSC into thinking it's network printing to a Postscript device, then I
grab the incoming bitstream and convert it to .png -- not a pretty process. -
Phase or frequency data from the TSC or other counters manually
massaged using a *nix WYSIWIG graphing tool called Grace. In a few
cases, I've also munged a way to automatically generate Grace plots
every X minutes from live data. That, also, is not pretty.
However, lately I've been using John Miles' TimeLab software (even
though it's Windows...) because it is so damn easy to capture data from
lots of counter types, and display multiple runs and various plot types.
It just takes all the work out of it.
Length of capture depends on what you're trying to do. Generally, you
want a minimum data length of X times the longest tau, where X can range
from 3 (but huge error bars) on out to perhaps 8 - 10 for good
reliability. So if you want to plot stability out to 100K seconds,
you're going to be collecting data for at least a week or two.
I've had PPS measurement setups where I took data perhaps every 10
minutes for several months. That starts to be an exercise in "design
for reliability"!
John