Hi,

On 04/20/2017 07:17 AM, Jim Palfreyman wrote:

Wither it is timing residuals (time error (TE) or time interval error
(TIE) ) or time itself does not change the core of it being integrated time.

I have never heard of any definition for is, as we have for phase,
frequency and linear drift.

When considering similar problems with charge and current you end up
with As (or Ah) which is a measure of energy (assuming a voltage), often
referred to as capacity, but it doesn't really help.

In this case, integrated time error is what I would use. It is not as
catchy, but it is correct at least.

Cheers,
Magnus

I think that should be "absity" (s not c)

Dave

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces@febo.com] On Behalf Of Jim Palfreyman
Sent: 20 April 2017 06:18
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Name of integral of timing residual

Hi

Hi

I think your “quest” to find the terms as they relate to motion is a pretty good
example of just how unusual these terms are. Once you go past displacement,
they are hardly common vocabulary. My guess is that nobody has ever come
up with terms in the time domain that have made it into the common vocabulary
describing this stuff.

Bob

I looked at AN1279 and other HP Smartclock documents that were written for
the telco holdover specs, and they always put a zero axis on the frequency
offset, but I was surprised that for example fig A4 of AN1279 seems to be
suppressing the zero axis for the time error. So they seemed to be
unconcerned with the integral you speak of.

Tim N3QE

On Thu, Apr 20, 2017 at 1:17 AM, Jim Palfreyman jim77742@gmail.com wrote:

Hi

On a normal GPSDO holdover spec, you are concerned with the maximum
time error over a specified period. Generally it’s going to be a 24 hour holdover,
but it can be longer or shorter depending on the application. The good old CDMA
spec got out into the 10 to 11 us range at 24 hours. Various OEM’s padded the number
to give a bit of wiggle room. The spec typically referred to it as “maximum
allowed error”. While a straight(ish) line from zero to max is a typical example, they
really didn’t care if it was a second, third, or fourth order wiggle bouncing go either side
of zero over the period. Figure 8  in the application note is a pretty good example of this.
I think what is being asked for is the integral of figure 8 ….which is indeed not
something I’ve ever seen named.

Bob

Jim Palfreyman writes:

We usually don't use the word residual for this. When you compare a watch with a maser, or any DUT time against REF time, you get a quantity like: phase difference, or sometimes just "phase", or time difference, time error, time interval, time interval error, etc.

What residual usually refers to is if you post-process the raw time or frequency data in some way to better expose underlying structure. For example, if you remove a linear or quadratic fit from your phase data the resulting data set can be called phase residuals. This is done with free-running clocks because both frequency, and especially phase, diverge badly over time. So plotting residuals removes large systematic effects and exposes small effects of interest.

A traditional phase plot of residuals is itself "an overall view of how the clock is performing over time". That's why even before we make ADEV plots we want to see the phase (actually, phase difference) plot and maybe also the frequency (usually, normalized frequency) plot. Both give an overall view of how the clock is performing, not to mention the ADEV plot which even further summarizes clock performance.

A cumulative sum, an integral, of the timing residuals is a bit odd, but not wrong. This is the "area under the curve" of any residual phase plot. A traditional phase plot gives you a series of points on a line -- these tell you your clock error as a function of elapsed time. But plots are 2D, so your eye also senses the amount of area under the line -- this tells you not only how far off your clock is, but how long your clock has been how far off. The plot shows, and the eye recognizes both the line (how far) and the area (how far x how long).

Yes, exactly. And the reason this is explicit in PID (or PIID) is that there is no human eye and no 2D plot. Therefore the PID algorithm has to manually compute the "area under the curve"; it has to calculate the cumulative sum as a scaler value. And it sounds like this single scaler value, as opposed to a rendered plot image, is what you're after.

Ok, thanks for that word of the day! Full list here:

https://en.wikipedia.org/wiki/Absement#Higher_integrals

Nope. But let's make one up in honor of your time spent doing Pulsar work. Some sources suggest absement is a portmanteau of absent and displacement. Ok, could be, but just as likely ab- is a fine Latin prefix on its own, meaning away, depart. Think of abnormal, abhor, absent, abdicate, aberrant. Or the German abfahren, to depart from. (Ah, I finally got to put my Latin and German to use; or is that abuse).

https://en.wiktionary.org/wiki/ab-
http://membean.com/wrotds/ab-away
https://www.vocabulary.com/lists/135086

Anyway, in the world of space / distance:

-4 abserk
-3 abseleration
-2 absity
-1 absement
0 displacement
+1 velocity
+2 acceleration
+3 jerk

So how about for the world of time, we call integrated phase error: abtimer, or just abtime:

-1 abtime (integrated phase error, cumulative sum of time error, etc.) units: s^2
0 time (phase, time error, phase difference, etc.) units: s
+1 frequency (rate of phase change, etc.) units: /s, Hz
+2 drift (linear frequency change) units: /s^2, Hz/s

I can imagine cases where abtime would be useful, especially for closed loops. Units are seconds^2, or second*days, etc. For example, it may come in handy when I post plots of the new WWVB receiver, or characterizing a sloppy GPSDO timing receiver.

/tvb

+1 to abtime

On Thu, Apr 20, 2017 at 1:35 PM, Tom Van Baak tvb@leapsecond.com wrote: