purpose of time of day display units
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g.,
http://www.xyht.com/wp-content/uploads/2015/05/Powers_Master_Clock.jpg.
All that these units do is merely display the time of day and sometimes
the date, typically by means of seven segment LED displays, of the time
code inputted to them (typically IRIG-B, I'm guessing). Any ideas why
such a unit is necessary when one can simply look at the time displayed
by timing receivers and time code generators (and even some standards),
and the interface of some fusor, defined in this context as a system
which performs timing data fusion (by implementing a paper clock or a
more primitive algorithm) and timekeeping, either by means of a direct
shell, or via something like NTP?
Thanks in advance,
Ruslan
Two reasons that come to mind are:
Displaying distributed time to distant sites from some master.
Readability at a distance.
Le 22 janv. 2017 à 07:31, Ruslan Nabioullin rnabioullin@gmail.com a écrit :
Hi, looking at pictures of various time metrology equipment setups for best practices and inspiration, I have commonly seen time of day display unit(s) installed in racks containing processing or time transfer equipment, e.g., http://www.xyht.com/wp-content/uploads/2015/05/Powers_Master_Clock.jpg. All that these units do is merely display the time of day and sometimes the date, typically by means of seven segment LED displays, of the time code inputted to them (typically IRIG-B, I'm guessing). Any ideas why such a unit is necessary when one can simply look at the time displayed by timing receivers and time code generators (and even some standards), and the interface of some fusor, defined in this context as a system which performs timing data fusion (by implementing a paper clock or a more primitive algorithm) and timekeeping, either by means of a direct shell, or via something like NTP?
Thanks in advance,
Ruslan
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In message 537E808D-731C-42DE-90F3-BEC55363B7AC@sfr.fr, Mike Cook writes:
All that these units do is merely display the time of day and
sometimes the date, typically by means of seven segment LED displays,
of the time code inputted to them (typically IRIG-B, I'm guessing).
I can imagine two reasons:
A) Trying to explain a $1M set of racks keeping track of time, without
them actually showing the time is a lot harder.
B) Visual indication that your IRIG-B is fine.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk@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.
On 1/21/17 10:31 PM, Ruslan Nabioullin wrote:
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g.,
http://www.xyht.com/wp-content/uploads/2015/05/Powers_Master_Clock.jpg.
All that these units do is merely display the time of day and sometimes
the date, typically by means of seven segment LED displays, of the time
code inputted to them (typically IRIG-B, I'm guessing).
There's a few reasons I can think of:
-
the display is also a distribution amplifier of some sort - one time
source going into rack, distributed to things in the rack (or the next rack) -
as phk commented, it lets you know that your time code isn't broken
(i.e. someone got in behind the rack and disconnected the wrong cable) -
It's a crude visual check - your eye/brain is pretty good at catching
a change in the pattern of blinky lights. IN this situation, you'd
expect all the displays to change simultaneously. -
the equipment configuration "just growed" from a collection of
smaller ones, each with its own display.
We put displays like this in all of our ground support equipment (GSE)
racks when doing spacecraft or subsystem tests, mostly for reason #2 and #4.
You might have a GSE rack or two in the lab when you're building up the
subsystem. Someone else's subsystem has their rack, also with a
timecode display. When you bring the two subsystems together for
integration, you bring the racks with them, and it's not worth it to
reconfigure.
The big clocks on the walls of the control center were largely eye-candy
for visitors, but the individual clocks at each console were continuously
used by the operators for everything (there was no computer display of
time). All important technical timing was run from dedicated sequencers but
it might be "kicked off" from IRIG-derived pulses on some occasions (in my
experience it might be spec'ed to be kicked off from IRIG but in real life
it was initiated by pushbutton).
Some control centers used a second audio channel to distribute elapsed
mission time via IRIG. That wasn't exactly my kind of control center but I
got to visit them.
In decades past I worked extensively with analog multitrack telemetry and
voice recorders that would record the IRIG analog code at same time as data
and voice. On playback we would both watch pulses and carrier from IRIG on
pen charts and scopes to derive timestamps, and we would also hook up a
standard IRIG-driven clock to the recorded IRIG audio show where we were in
the playback. We had at least one special playback station that could show
IRIG time correctly through variable speed forward and reverse driven by
the IRIG audio carrier. Much later we used minicomputers with ADC's to
digitize the data, timestamp derived from IRIG audio.
Tim N3QE
On Sun, Jan 22, 2017 at 1:31 AM, Ruslan Nabioullin rnabioullin@gmail.com
wrote:
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g., http://www.xyht.com/wp-content/uploads/2015/05/Powers_
Master_Clock.jpg. All that these units do is merely display the time of
day and sometimes the date, typically by means of seven segment LED
displays, of the time code inputted to them (typically IRIG-B, I'm
guessing). Any ideas why such a unit is necessary when one can simply look
at the time displayed by timing receivers and time code generators (and
even some standards), and the interface of some fusor, defined in this
context as a system which performs timing data fusion (by implementing a
paper clock or a more primitive algorithm) and timekeeping, either by means
of a direct shell, or via something like NTP?
Thanks in advance,
Ruslan
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.
#5) Everyone likes blinkenlights.
On Jan 22, 2017, at 08:55, jimlux jimlux@earthlink.net wrote:
On 1/21/17 10:31 PM, Ruslan Nabioullin wrote:
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g.,
http://www.xyht.com/wp-content/uploads/2015/05/Powers_Master_Clock.jpg.
All that these units do is merely display the time of day and sometimes
the date, typically by means of seven segment LED displays, of the time
code inputted to them (typically IRIG-B, I'm guessing).
There's a few reasons I can think of:
-
the display is also a distribution amplifier of some sort - one time source going into rack, distributed to things in the rack (or the next rack)
-
as phk commented, it lets you know that your time code isn't broken (i.e. someone got in behind the rack and disconnected the wrong cable)
-
It's a crude visual check - your eye/brain is pretty good at catching a change in the pattern of blinky lights. IN this situation, you'd expect all the displays to change simultaneously.
-
the equipment configuration "just growed" from a collection of smaller ones, each with its own display.
We put displays like this in all of our ground support equipment (GSE) racks when doing spacecraft or subsystem tests, mostly for reason #2 and #4.
You might have a GSE rack or two in the lab when you're building up the subsystem. Someone else's subsystem has their rack, also with a timecode display. When you bring the two subsystems together for integration, you bring the racks with them, and it's not worth it to reconfigure.
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and follow the instructions there.
I used to work at a place that used a lot of those LED time displays that
were hooked up to IRIG. Why were they there? Because everyone hates to
toss out nice working equipment. The displays were bought ages ago and
still work just fine. Many of those racks you see were assembled 15 or
more years ago.
Today my cell phone has a time display that is just as accurate as a GPS
controlled LED display because the bottle neck for displays is human
perception, We just can't see better than about 1/20th of a second.
Sometimes however we'd run the equipment with the time of day not set to
the actual time of day, say for re-playing historic data. THEN the display
is nice to have if for nothing else to verify the setup is working and you
are in fact sync's up to recored IRIG from some 20 year old database or
even tape. But even for real time, the display verifies the system is
running. If it matches your iPhone then all is good.
In short the best use of these displays is confidence that things are
working. Because you know they display is driven by IRIRG and not by a
realtime clock, so if you are getting IRIG data, you are up and running to
at least some degree.
On Sat, Jan 21, 2017 at 10:31 PM, Ruslan Nabioullin rnabioullin@gmail.com
wrote:
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g., http://www.xyht.com/wp-content/uploads/2015/05/Powers_
Master_Clock.jpg. All that these units do is merely display the time of
day and sometimes the date, typically by means of seven segment LED
displays, of the time code inputted to them (typically IRIG-B, I'm
guessing). Any ideas why such a unit is necessary when one can simply look
at the time displayed by timing receivers and time code generators (and
even some standards), and the interface of some fusor, defined in this
context as a system which performs timing data fusion (by implementing a
paper clock or a more primitive algorithm) and timekeeping, either by means
of a direct shell, or via something like NTP?
Thanks in advance,
Ruslan
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.
--
Chris Albertson
Redondo Beach, California
There is a lot to be said about a tool that just works. In the advent of a
piece of gear failing whether that be a firmware bug or a cooling fan, or
more severe, having a known diagnostic tool during that time is priceless
(well maybe not priceless but extremely nice to have).
On Sun, Jan 22, 2017 at 1:31 AM, Ruslan Nabioullin rnabioullin@gmail.com
wrote:
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g., http://www.xyht.com/wp-content/uploads/2015/05/Powers_
Master_Clock.jpg. All that these units do is merely display the time of
day and sometimes the date, typically by means of seven segment LED
displays, of the time code inputted to them (typically IRIG-B, I'm
guessing). Any ideas why such a unit is necessary when one can simply look
at the time displayed by timing receivers and time code generators (and
even some standards), and the interface of some fusor, defined in this
context as a system which performs timing data fusion (by implementing a
paper clock or a more primitive algorithm) and timekeeping, either by means
of a direct shell, or via something like NTP?
Thanks in advance,
Ruslan
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.
One must remember the original use of these displays was displaying IRIG time either distributed from a master clock, locally generated or from a recording (tape) They long predate GPS. There are more sophisticated units that include controls for the tape recorder so you could auto search to a certain time. Multiple displays could be used for locally generated time, time received from a remote site by fixed line or radio and time from data or video recorders.I have a number of them and one sits above my GPStar as the LCD on the GPStar is hard to read from across the workshop and it lets me have time available while showing timing or satellite status on the GPS. Just picked up 3 more (RAPCO 104 anyone have a manual for these) at the weekend.
Robert G8RPI.
From: Bob Bownes <bownes@gmail.com>
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sunday, 22 January 2017, 18:33
Subject: Re: [time-nuts] purpose of time of day display units
#5) Everyone likes blinkenlights.
On Jan 22, 2017, at 08:55, jimlux jimlux@earthlink.net wrote:
On 1/21/17 10:31 PM, Ruslan Nabioullin wrote:
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g.,
http://www.xyht.com/wp-content/uploads/2015/05/Powers_Master_Clock.jpg.
All that these units do is merely display the time of day and sometimes
the date, typically by means of seven segment LED displays, of the time
code inputted to them (typically IRIG-B, I'm guessing).
There's a few reasons I can think of:
-
the display is also a distribution amplifier of some sort - one time source going into rack, distributed to things in the rack (or the next rack)
-
as phk commented, it lets you know that your time code isn't broken (i.e. someone got in behind the rack and disconnected the wrong cable)
-
It's a crude visual check - your eye/brain is pretty good at catching a change in the pattern of blinky lights. IN this situation, you'd expect all the displays to change simultaneously.
-
the equipment configuration "just growed" from a collection of smaller ones, each with its own display.
We put displays like this in all of our ground support equipment (GSE) racks when doing spacecraft or subsystem tests, mostly for reason #2 and #4.
You might have a GSE rack or two in the lab when you're building up the subsystem. Someone else's subsystem has their rack, also with a timecode display. When you bring the two subsystems together for integration, you bring the racks with them, and it's not worth it to reconfigure.
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.
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
"If the clocks are right — on churches and in classrooms, on stores and in
bars — they tell us that things are in order. They tell us that people
are paying attention. If a clock is wrong, maybe everything else is,
too."
On Sun, Jan 22, 2017 at 1:31 AM, Ruslan Nabioullin rnabioullin@gmail.com
wrote:
Hi, looking at pictures of various time metrology equipment setups for
best practices and inspiration, I have commonly seen time of day display
unit(s) installed in racks containing processing or time transfer
equipment, e.g., http://www.xyht.com/wp-content/uploads/2015/05/Powers_
Master_Clock.jpg. All that these units do is merely display the time of
day and sometimes the date, typically by means of seven segment LED
displays, of the time code inputted to them (typically IRIG-B, I'm
guessing). Any ideas why such a unit is necessary when one can simply look
at the time displayed by timing receivers and time code generators (and
even some standards), and the interface of some fusor, defined in this
context as a system which performs timing data fusion (by implementing a
paper clock or a more primitive algorithm) and timekeeping, either by means
of a direct shell, or via something like NTP?
Thanks in advance,
Ruslan
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.