Clifford Heath wrote: "No, the planet is not changing
the rate at which time passes, and it's not affecting our
ability to measure time. "

HOW can you make such a statement???
If the planet is gradually slowing down,
over millions of years as reported, the
period of time from noon to noon(or
midnight to midnight), is getting LONGER.
Our hyper-accurate master clocks have
to account for that somehow.


"Yes, but that has nothing to do with how we improve our ability to
measure time. Remember I was responding to N_Cook's comment:

"The new generation of atomic clocks, accurate to 1 second in 15 billion
years,supposedly - how do they know , without a more accurate clock than
that to check it against?" "

"The earth's slowing is also somewhat chaotic, inasmuch as equatorial
weather affects the sea-level heights, which introduces noise into the
earth's angular moment of inertia, and hence its rate of rotation. That
has nothing however to do with how we know we're measuring time accurately. "

OF COURSE IT DOES!! If our super-accurate
clocks don't account for an inconsistent Earth,
then sunrises, sunsets, and everything else
will start happening later & later by those clocks.
Sunrise in June in Connecticut will come at
5:23, 5:24(Daylight Time)instead of 5:20 as it
has for decades, and sunset - 8:32, 8:33,
instead of 8:30 as it has for years. It's
only adding those periodic seconds that
maintains that symmetry.

That's because of PLANET drift, not clock
drift. And overall, it is slowing down, not
speeding up.

On Friday, July 10, 2015 at 6:48:23 AM UTC-4, Clifford Heath wrote:
On 10/07/15 19:59com wrote:
Clifford Heath wrote: "No, the planet is not changing
the rate at which time passes, and it's not affecting our
ability to measure time. "

HOW can you make such a statement???
If the planet is gradually slowing down,
over millions of years as reported, the
period of time from noon to noon(or
midnight to midnight), is getting LONGER.

Whoosh! You completely missed the point.

The reason we know it's getting longer is because
we have clocks that *aren't* slowing down. I was
talking entirely about *how we know* they aren't
slowing down.

The Earth is a natural, living object. It's impossible
to match its movement with precision, repetitive
movements.



Our hyper-accurate master clocks have
to account for that somehow.

No,they don't. They just count the time passing,
and we decide what numbers to assign to the days,
hours, minutes, seconds. The *numbers* are not
the *time*.

"The earth's slowing is also somewhat chaotic, inasmuch as equatorial
weather affects the sea-level heights, which introduces noise into the
earth's angular moment of inertia, and hence its rate of rotation. That
has nothing however to do with how we know we're measuring time accurately. "

OF COURSE IT DOES!! If our super-accurate
clocks don't account for an inconsistent Earth,
then sunrises, sunsets, and everything else
will start happening later & later by those clocks.

And that is *exactly* what is happening.
That is why we need leap seconds etc, to
adjust the *numbering* to match the planet's
motion. But adjusting the numbering doesn't
make time pass slower or faster.

I never said it did. If we as a species never
had clocks at all, I'd guess we all just get used
to this light & dark cycle called days getting
longer and longer all the time and not even think
twice about it.

On 10/07/2015 12:06, wrote:
On Friday, July 10, 2015 at 6:48:23 AM UTC-4, Clifford Heath wrote:
On 10/07/15 19:59com wrote:
Clifford Heath wrote: "No, the planet is not changing
the rate at which time passes, and it's not affecting our
ability to measure time. "

HOW can you make such a statement???
If the planet is gradually slowing down,
over millions of years as reported, the
period of time from noon to noon(or
midnight to midnight), is getting LONGER.

Whoosh! You completely missed the point.

The reason we know it's getting longer is because
we have clocks that *aren't* slowing down. I was
talking entirely about *how we know* they aren't
slowing down.

The Earth is a natural, living object. It's impossible
to match its movement with precision, repetitive
movements.



Our hyper-accurate master clocks have
to account for that somehow.

No,they don't. They just count the time passing,
and we decide what numbers to assign to the days,
hours, minutes, seconds. The *numbers* are not
the *time*.

"The earth's slowing is also somewhat chaotic, inasmuch as equatorial
weather affects the sea-level heights, which introduces noise into the
earth's angular moment of inertia, and hence its rate of rotation. That
has nothing however to do with how we know we're measuring time accurately. "

OF COURSE IT DOES!! If our super-accurate
clocks don't account for an inconsistent Earth,
then sunrises, sunsets, and everything else
will start happening later & later by those clocks.

And that is *exactly* what is happening.
That is why we need leap seconds etc, to
adjust the *numbering* to match the planet's
motion. But adjusting the numbering doesn't
make time pass slower or faster.

I never said it did. If we as a species never
had clocks at all, I'd guess we all just get used
to this light & dark cycle called days getting
longer and longer all the time and not even think
twice about it.



The innate human biological clock is nearer 25 hour-day than 24 hours,
from the sensory deprivation experiments conducted in caves. Everyone
else, in normally life, gets sync'd to this artificial 24 hour system.

On Friday, July 10, 2015 at 9:21:18 AM UTC-4, N_Cook wrote:
On 10/07/2015 12:06,lifford Heath wrote:
On 10/07/15 19:59com wrote:
Clifford Heath wrote: "No, the planet is not changing
the rate at which time passes, and it's not affecting our
ability to measure time. "

HOW can you make such a statement???
If the planet is gradually slowing down,
over millions of years as reported, the
period of time from noon to noon(or
midnight to midnight), is getting LONGER.

Whoosh! You completely missed the point.

The reason we know it's getting longer is because
we have clocks that *aren't* slowing down. I was
talking entirely about *how we know* they aren't
slowing down.

The Earth is a natural, living object. It's impossible
to match its movement with precision, repetitive
movements.



Our hyper-accurate master clocks have
to account for that somehow.

No,they don't. They just count the time passing,
and we decide what numbers to assign to the days,
hours, minutes, seconds. The *numbers* are not
the *time*.

"The earth's slowing is also somewhat chaotic, inasmuch as equatorial
weather affects the sea-level heights, which introduces noise into the
earth's angular moment of inertia, and hence its rate of rotation. That
has nothing however to do with how we know we're measuring time accurately. "

OF COURSE IT DOES!! If our super-accurate
clocks don't account for an inconsistent Earth,
then sunrises, sunsets, and everything else
will start happening later & later by those clocks.

And that is *exactly* what is happening.
That is why we need leap seconds etc, to
adjust the *numbering* to match the planet's
motion. But adjusting the numbering doesn't
make time pass slower or faster.

I never said it did. If we as a species never
had clocks at all, I'd guess we all just get used
to this light & dark cycle called days getting
longer and longer all the time and not even think
twice about it.



The innate human biological clock is nearer 25 hour-day than 24 hours,
from the sensory deprivation experiments conducted in caves. Everyone
else, in normally life, gets sync'd to this artificial 24 hour system.


I suppose 24 developed out of need for dividing the day evenly. Of course, that doesn't explain the 7-day week. LOL

On Friday, July 10, 2015 at 6:25:19 AM UTC-7, wrote:
I suppose 24 developed out of need for dividing the day
evenly. Of course, that doesn't explain the 7-day week. LOL
The French Revolution also metricated the clock (10 hours in a day, 100 minutes in an hour, 100 seconds in a minture) and the calendar (3 decades in a month, 10 days in a decade, plus complementary days. This appears to be one part of the metric system that was not widely adopted.

On 07/09/2015 01:44 PM, Clifford Heath wrote:
On 10/07/15 12:07, Phil Hobbs wrote:
On 7/9/2015 9:14 PM, Jeff Liebermann wrote:
It would be a major disaster if a leap second were
thrown into the timing if you're tracking a spacecraft such as Voyager
1 moving at 17 km/sec (38,000 mph).
You'd be off by 17 km. Is Voyager 1's position known to that accuracy?
Didn't think so.

And yet if you were aiming at Pluto via a slingshot around Venus, you
don't want to be 17km off on approach to Venus. I can't do the math, but
I suspect it's rather closer to 17cm.


Well, you probably aren't using your computer's clock to do that
measurement anyway. Astronomers and orbital mechanics bods are used to
having to worry about different types of time scale--ephemeris time,
UT1, UT2, UTC, and so on.

The movement to abolish leap seconds is just another special interest
group.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On 10/07/2015 15:25, wrote:
On Friday, July 10, 2015 at 6:25:19 AM UTC-7, wrote:
I suppose 24 developed out of need for dividing the day
evenly. Of course, that doesn't explain the 7-day week. LOL
The French Revolution also metricated the clock (10 hours in a day, 100 minutes in an hour, 100 seconds in a minture) and the calendar (3 decades in a month, 10 days in a decade, plus complementary days. This appears to be one part of the metric system that was not widely adopted.


With one admirable exception - lobster thermidor

On Fri, 10 Jul 2015 12:08:45 +1000, Clifford Heath
wrote:

And that is *exactly* what is happening.
That is why we need leap seconds etc, to
adjust the *numbering* to match the planet's
motion. But adjusting the numbering doesn't
make time pass slower or faster.

Sure it does. If you watch the clock, time will seem to go slower.
Surely there's a standard for Universal Perceived Time.

I don't want to be late, I simply set my clocks to about 15 minutes
ahead. That would be a Leap Quarter Hour.

It also works in the other direction. If I'm expecting a package
delivery, it will always be late, the result of time dilation due to
the movement of the package. I've also noticed that the faster
someone appears to be working towards a deadline, the further behind
the project slips, again the result of time dilation and movement.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Fri, 10 Jul 2015 06:25:16 -0700 (PDT),
wrote:

The innate human biological clock is nearer 25 hour-day than 24 hours,
from the sensory deprivation experiments conducted in caves. Everyone
else, in normally life, gets sync'd to this artificial 24 hour system.

Mine used to be synchronized to the television show schedule.

I suppose 24 developed out of need for dividing the day evenly.
Of course, that doesn't explain the 7-day week. LOL

"Why are there 24 hours in a day?"
http://www.abc.net.au/science/articles/2011/11/15/3364432.htm
The ancient Egyptians apparently were on a decimal system but got
derailed by a special interest faction in their standards committee
that favored a 12 hr day. At least they tried. I would give the
blame/credit to the Babylonians.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Friday, July 10, 2015 at 9:39:02 AM UTC-7, Jeff Liebermann wrote:
"Why are there 24 hours in a day?"
http://www.abc.net.au/science/articles/2011/11/15/3364432.htm
The ancient Egyptians apparently were on a decimal system but
got derailed by a special interest faction in their standards
committee that favored a 12 hr day. At least they tried.
I would give the blame/credit to the Babylonians.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
The Babylonians got it from some alien astronauts who had six fingers on each hand and six toes on each foot. It must be true. I read it on the internet.

On Fri, 10 Jul 2015 10:18:50 -0700 (PDT), "
wrote:

On Friday, July 10, 2015 at 9:39:02 AM UTC-7, Jeff Liebermann wrote:
"Why are there 24 hours in a day?"
http://www.abc.net.au/science/articles/2011/11/15/3364432.htm
The ancient Egyptians apparently were on a decimal system but
got derailed by a special interest faction in their standards
committee that favored a 12 hr day. At least they tried.
I would give the blame/credit to the Babylonians.

The Babylonians got it from some alien astronauts who had
six fingers on each hand and six toes on each foot.

No visitors from otter space required. Six fingers and/or toes not so
ra
https://www.google.com/search?q=six+fingers+and+toes&tbm=isch
https://en.wikipedia.org/wiki/Polydactyly

Please note that we all have 11 fingers total. Start counting down on
one hand with 10 - 9 - 8 - 7 - 6 and 5 more on the other hand makes
11.

It must be true. I read it on the internet.

The surest signs of success is pollution. I guess the internet must
be successful.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:
The only time I've seen an incorrect
display was when I was building a WWVB emulator and spraying garbage
data everywhe
http://www.instructables.com/id/WWVB-radio-time-signal-generator-for-ATTINY45-or-A/?ALLSTEPS
However, I've never seen a random erroneous date or time.

Nice project. Now I think of someone trying to increase its range with a power stage and going way too far...

This reminds me of these projects:
http://www.erikyyy.de/tempest/
http://bellard.org/dvbt/

I guess something similar could be done to generate a DCF77/WWVB signal.

The algorithm could also check for a reasonable deviation against
the current setting.

I don't think so. Once it gets a valid time to display, it turns off
the receiver to save battery power. No need to decode more than one
or maybe two frames.

Oh, I think I didn't explain it right. I meant an additional check for valid data would be to verify that the received time falls within a reasonable window around the current time. If the clock knows that now is 1:00am +/- 2 minutes it makes no sense to receive 7:42am and take that as valid time.

So the algorithm would be: if there was never a sync before or the user set the time manually = belive whatever time is received, in this case decoding of several minutes can be done as an extra check).
Otherwise (there was a valid sync before and clock time was not changed manually) check the received time is within a few minutes of clock time.
That would help save battery since decoding a single minute would be enough for safe daily sync.

On Sat, 11 Jul 2015 04:07:45 -0700 (PDT), Jeroni Paul
wrote:

Nice project. Now I think of someone trying to increase its
range with a power stage and going way too far...

It's amazingly easy to do, but at 60 KHz, the range would be rather
limited. It takes some serious power to produce a field strength
sufficiently strong to overcome atmospheric noise levels.

I guess something similar could be done to generate a DCF77/WWVB signal.

Yep. With a 1 baud data rate, it won't take much horsepower to
generate the code. You can also buy IRIG-H (used by WWVB etc) time
code generators that should work.
https://en.wikipedia.org/wiki/IRIG_timecode
For example:
http://www.gigatest.net/datum/tymmachine_7000.htm
Just add an AM modulated RF signal generator to produce the 60 KHz,
and you're well on your way to becoming the local time lord.

So the algorithm would be: if there was never a sync before or the
user set the time manually = belive whatever time is received,
in this case decoding of several minutes can be done as an extra check).
Otherwise (there was a valid sync before and clock time was not
changed manually) check the received time is within a few minutes of
clock time.
That would help save battery since decoding a single minute would
be enough for safe daily sync.

Well, that would work, but there's an easier way. Since one frame is
exactly 1 minute long, and there's no way to obtain identical data
twice in a row, simply truncating the data to eliminate the minutes
and seconds data, would give the clock an hour to obtain to
identically truncated receptions. No need for a complex sanity check
algorithm. Of course, the receiver would not be turned on for the
full hour, but a successful spot check a few minutes after the first
successful reception would be sufficient to conserve battery power. I
suspect that's the way it's done in the C-Max chips, but I'm not sure.


Diversion: I worked on a failed proposal for an accurate time
distribution system that used carrier current repeaters (i.e.
HomePlug) to distribute the data. The time source was the GOES
satellite system, which belched time sync data on 468.xxx MHz. The
satellite data was to be retransmitted at the home or office over
power line carrier current frequencies (now Home Plug) to any device
that needs accurate time (clocks, computahs, appliances, test
equipment, cell sites, SONET, etc). The difference with other radio
clock systems is that this one would be continuous, not updated
erratically. The GOES signal was strong (+45.5dBm EIRP) that a simple
RHCP patch antenna aimed towards the bird was sufficient. I had it
mostly working when NASA announced that it was going to pull the plug
in 2004. Oh well. Today, it's done with GPSDO driven clocks with
much better accuracy.

GOES time receivers.
http://www.leapsecond.com/pages/goes/
TrueTime 468-DC GOES Time Receiver
http://www.leapsecond.com/museum/468-dc/theory.htm
468-DC SATELLITE CLOCK
http://www.ebay.com/gds/468-DC-SATEL...6640775/g.html
Meteorological Satellite Frequencies
http://mdkenny.customer.netspace.net.au/metsat_frequencies.html#goes-n

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 7/9/2015 11:18 PM, Jeff Liebermann wrote:
On Thu, 09 Jul 2015 22:07:57 -0400, Phil Hobbs
wrote:

On 7/9/2015 9:14 PM, Jeff Liebermann wrote:
On Fri, 10 Jul 2015 01:37:30 +1000, Clifford Heath
wrote:

The earth's slowing is also somewhat chaotic, inasmuch as equatorial
weather affects the sea-level heights, which introduces noise into the
earth's angular moment of inertia, and hence its rate of rotation. That
has nothing however to do with how we know we're measuring time accurately.

It might help to mention that we have two types of time accuracy. One
is sidereal time, where 12AM on Jan 1 is astronomically correct and is
used to aim telescopes on earth.

Nope. Sidereal time is different from civil (solar) time. The Earth
rotates 365 and change times per year with respect to the Sun, but 366
and (the same) change with respect to the fixed stars. So the two get
out of phase pretty fast.

Sorry, my mistake.

The problem is that the two systems don't quite coincide. The current
difference between UTC and International Atomic Time (UTC-TAI) is now
36 sec and growing. The recent leap second just made things worse.

Well, worse if you don't think that the Gregorian reform was an advance.
Pretty soon the vernal equinox would have been in February.

The Julian calendar was working just fine for 1500 years as everyone
know how to tweak the date so that it matches the solar calendar. That
was fine for farmers and bankers, but didn't do much for the church,
which had the bad taste to celebrate their holidays by the calendar
month and date. Most everyone else used the signs of the zodiac to
set the beginning of the month. That worked well for the GUM (great
unwashed masses) except that the church equated the zodiac with pagan
religions, alchemy and witchcraft, so that wasn't going to work. A
pope previous to Gregory XIII tried to switch the holidays to the
zodiac months (can't find the name) but gave up before going public.
I suspect that Gregory XIII must have had second throughts when he
allowed the astronomers to fix the calendar. At least they named it
after him, so I guess he was happy.

Incidentally, if you want a really screwed up calendar, try the Hebrew
calendar, which adds an extra month every 2 or 3 years, every 7 of 11
years.
https://en.wikipedia.org/wiki/Hebrew_calendar
There's nothing like a duplicated month (adar) to create confusion.

Personally I think that civil time is more important than atomic time.
Folks who need to know the difference, do.

If we knuckle under to atomic time in civil life, our version of the
Julian problem is that midnight by the clock will soon start occurring
at sundown. The leap second inconvenience principally affects software
developers (and those who trust them).

I don't see a problem. If every political time standards organization
can have it's own time standard, I see no reason why they can't expand
theirs to a calendar standard. You just pick the calendar that is
appropriate for whatever you're doing. It's not much different than
the US before the railroads, where every town had it's own time and
DST standard.

Yeah, there were some hiccups in 2012.
http://www.wired.com/2012/07/leap-second-bug-wreaks-havoc-with-java-linux/
http://www.wired.com/2012/07/leap-second-glitch-explained/
I missed the fire drill, but still managed to get wakened by a
customer wanting to know why their backup failed. Stupid me had set
cron to start the backup exactly at midnight. That worked, but one
second later, it started a 2nd backup during the leap second. Why, I
don't know, but that's what the log files showed. I killed both
processes and started over.

The fun starts when tracking spacecraft in otter space. Not only does
one have to deal with relativistic effects, but one also has to use a
time system that is independent of how the earth spins, wobbles, and
thrashes around. It would be a major disaster if a leap second were
thrown into the timing if you're tracking a spacecraft such as Voyager
1 moving at 17 km/sec (38,000 mph).

You'd be off by 17 km. Is Voyager 1's position known to that accuracy?
Didn't think so.

I was thinking of it in terms of the change in angular error for the
rotation of the earth.
degrees = 17km/40,075km * 360 degrees = 0.15 degrees
Let's see if that works. Voyager 1 and 2 uses the DSN (deep space
network) with 34 or 70 meter dishes at about 8 GHz. That's about 67dB
gain and a -3db beamwidth of about 0.07 degrees for the 34 meter dish,
and 73 db gain and 0.04 degree beamwidth for the 70 meter dish. Since
the DSN tracks the rotation of the earth, a change of 0.15 degrees
would move the main lobe sufficiently to miss the spacecraft.
http://www.satsig.net/pointing/antenna-beamwidth-calculator.htm
http://www.uhf-satcom.com/misc/datasheet/dh2va.pdf

Maybe so, if they'd lost their minds and were using their computer
clocks to aim the DSN, but that's a fantasy. Orbital mechanics bods are
all over this timekeeping stuff. It's the stupid software developers
who don't know or don't care.

Cheers

Phil Hobbs



--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On 7/10/2015 3:34 AM, N_Cook wrote:
On 10/07/2015 03:07, Phil Hobbs wrote:
On 7/9/2015 9:14 PM, Jeff Liebermann wrote:
On Fri, 10 Jul 2015 01:37:30 +1000, Clifford Heath
wrote:

The earth's slowing is also somewhat chaotic, inasmuch as equatorial
weather affects the sea-level heights, which introduces noise into the
earth's angular moment of inertia, and hence its rate of rotation. That
has nothing however to do with how we know we're measuring time
accurately.

It might help to mention that we have two types of time accuracy. One
is sidereal time, where 12AM on Jan 1 is astronomically correct and is
used to aim telescopes on earth.

Nope. Sidereal time is different from civil (solar) time. The Earth
rotates 365 and change times per year with respect to the Sun, but 366
and (the same) change with respect to the fixed stars. So the two get
out of phase pretty fast.

This is where we says "at the tone,
the time will be... (beep). The other is the length of 1 second,
minute, hour, day... year which is a numerical count of how many
wavelengths of light or cycles of atomic gigahertz
vibrations pass during these intervals also known as atomic time.



The problem is that the two systems don't quite coincide. The current
difference between UTC and International Atomic Time (UTC-TAI) is now
36 sec and growing. The recent leap second just made things worse.

Well, worse if you don't think that the Gregorian reform was an advance.
Pretty soon the vernal equinox would have been in February. Personally
I think that civil time is more important than atomic time. Folks who
need to know the difference, do.

If we knuckle under to atomic time in civil life, our version of the
Julian problem is that midnight by the clock will soon start occurring
at sundown. The leap second inconvenience principally affects software
developers (and those who trust them).


The fun starts when tracking spacecraft in otter space. Not only does
one have to deal with relativistic effects, but one also has to use a
time system that is independent of how the earth spins, wobbles, and
thrashes around. It would be a major disaster if a leap second were
thrown into the timing if you're tracking a spacecraft such as Voyager
1 moving at 17 km/sec (38,000 mph).

You'd be off by 17 km. Is Voyager 1's position known to that accuracy?
Didn't think so.

Cheers

Phil Hobbs

IIRC the Etruscan day started at midday, the Jewish day at 6am, the
midnight start is just a hangover from the Romans, so sundown start is
no great problem

It is if it gets out of phase. There's no reason in the world to let it
move at all--leap seconds keep civil time in synchrony with mean solar
time to within a couple of PPM of a day.

Wanting to get rid of leap seconds is a classical example of a special
interest group trying to seize control.

Not that that's unusual, especially these days.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

On Sat, 11 Jul 2015 15:02:41 -0400, Phil Hobbs
wrote:

The fun starts when tracking spacecraft in otter space. Not only does
one have to deal with relativistic effects, but one also has to use a
time system that is independent of how the earth spins, wobbles, and
thrashes around. It would be a major disaster if a leap second were
thrown into the timing if you're tracking a spacecraft such as Voyager
1 moving at 17 km/sec (38,000 mph).

You'd be off by 17 km. Is Voyager 1's position known to that accuracy?
Didn't think so.

I was thinking of it in terms of the change in angular error for the
rotation of the earth.
degrees = 17km/40,075km * 360 degrees = 0.15 degrees
Let's see if that works. Voyager 1 and 2 uses the DSN (deep space
network) with 34 or 70 meter dishes at about 8 GHz. That's about 67dB
gain and a -3db beamwidth of about 0.07 degrees for the 34 meter dish,
and 73 db gain and 0.04 degree beamwidth for the 70 meter dish. Since
the DSN tracks the rotation of the earth, a change of 0.15 degrees
would move the main lobe sufficiently to miss the spacecraft.
http://www.satsig.net/pointing/antenna-beamwidth-calculator.htm
http://www.uhf-satcom.com/misc/datasheet/dh2va.pdf

Maybe so, if they'd lost their minds and were using their computer
clocks to aim the DSN, but that's a fantasy. Orbital mechanics bods are
all over this timekeeping stuff. It's the stupid software developers
who don't know or don't care.

Digging deeper. See:
http://descanso.jpl.nasa.gov/performmetrics/DSN_NavSysAccuracy.pdf
http://descanso.jpl.nasa.gov/performmetrics/perfmetric.html
It shows the current DSN aiming accuracy at 0.1 nanorads or 15 meters
at 1 AU distance. Voyager 1 is currently at 131 AU distance:
http://voyager.jpl.nasa.gov/where/
That grinds out to an accuracy of 2 km meters at a range of 19.6
billion km. Yes, NASA does know the position of Voyager 1 to less
than 17 km.

Incidentally, that an angular resolution of:
arctan(2/19.6*10^9) = 0.000000006 degrees (or 6*10^-9 deg)
A 0.15 degree error, caused by a leap second, would produce a rather
astronomical pointing error.

Wow, that's impressive (or I mangled the math again).

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Jeff Liebermann wrote:

Personally, I want a graph of signal strength and SNR over a few days
period. Whether anyone is willing to pay for such a feature is
debatable.


Fluke must have thought so. Their 207 receiver has a strip chart
recorder. Microdyne used one for decades as part of their time &
frequency standard, before replacing it with a GPS derived system for
the in house cal lab, and for their Electrical Engineering department. I
built a 64 output 10 MHz distribution amp to add the production areas to
the system, somewhere around 2000.