I don't know how elegant this solution from Google is
Christopher,
It's a clever, internal solution to the difficult problem leap seconds create
in any large automated system. That blog entry is 2 years old. The issue has
been discussed at length on the leap second mailing list; you can read
David,
The satellite has probably got a Rb as its clock (hopefully more than one).
All I can imagine is that there has been a major clock failure of some sort,
and everything is in free run and unable to sync up with ground.
Thoughts?
Rob
-Original Message-
From:
If I was to make an educated guess about this one I'd say that it is more
likely to be an overflow problem. The spacecraft was operating for
significantly longer than it's builders or programmers ever considered
likely.
-Geoff.
On Sat, 21 Sep 2013 07:30:54 pm Rob Kimberley wrote:
David,
Tom,
On 09/20/2013 06:37 PM, Tom Knox wrote:
We all have our idea of what a low or Ultra Low phase noise oscillator
is. For 5 and 10MHz references I usually look first at 1Hz offset then
the noise floor. At 5MHz I consider 125dB @ 1Hz state of the art. But
now with work by Archita Hati and
On 9/21/13 2:30 AM, Rob Kimberley wrote:
David,
The satellite has probably got a Rb as its clock (hopefully more than one).
Very, very few deep space probes carry a Rb ( I can't think of any off
hand). Regular old quartz, usually some sort of tcxo. If they are
doing radio science, then it
On 9/20/13 5:12 PM, Bob Camp wrote:
Hi
Low bid wrist watch used as time base?
-
I'd bet there is some form of master time tick in their RTOS that
keeps everything pumping. Loose the time tick (or the time tick
count) and it all goes away…
yes and no.
Most
from JPL
http://www.jpl.nasa.gov/news/news.php?release=2013-275
Mission controllers postulate that there was an anomaly generated by
the spacecraft's software which left the vehicle's computers in a
condition where they are continuously rebooting themselves. If this is
the case, the computers
Hi
I'd be a bit surprised if they were running anything as power hungry as an Rb
all the time when a quartz based device would be smaller / lower power / lower
volume. Of course they may have had mission requirements that drive them to a
hydrogen maser ...
Bob
On Sep 21, 2013, at 5:30 AM,
Hi
So it's a pretty good AT cut crystal without any compensation of heating. Not
quite a cheap wrist watch, but not a BVA in a dewar flask either.
Bob
On Sep 21, 2013, at 8:11 AM, Jim Lux jim...@earthlink.net wrote:
from JPL
http://www.jpl.nasa.gov/news/news.php?release=2013-275
Mission
Jim,
On 09/21/2013 01:32 PM, Jim Lux wrote:
On 9/21/13 2:30 AM, Rob Kimberley wrote:
David,
The satellite has probably got a Rb as its clock (hopefully more than
one).
Very, very few deep space probes carry a Rb ( I can't think of any off
hand). Regular old quartz, usually some sort of
I got a 5061A with high performance tube that I'm trying to get running.
The Cs oven works and the -3500 and -2500V are there.
The beam current has its maximum at the correct frequency.
90MHz from the multiplier are there and they are phase modulated with
137Hz at about 0.01 rad.
Measured on a
On 09/21/2013 02:52 PM, Bob Camp wrote:
Hi
So it's a pretty good AT cut crystal without any compensation of heating. Not
quite a cheap wrist watch, but not a BVA in a dewar flask either.
The environmental perturbations should go quite slow most of the time,
as it glides in the void slowly
On 9/21/13 5:41 AM, Bob Camp wrote:
Hi
I'd be a bit surprised if they were running anything as power hungry as an Rb
all the time when a quartz based device would be smaller / lower power / lower
volume. Of course they may have had mission requirements that drive them to a
hydrogen maser ...
On 9/21/13 5:52 AM, Bob Camp wrote:
Hi
So it's a pretty good AT cut crystal without any compensation of heating. Not
quite a cheap wrist watch, but not a BVA in a dewar flask either.
Yep. The AuxOsc is what is used if you don't want to have the downlink
locked to the uplink.
On 9/21/13 6:03 AM, Magnus Danielson wrote:
On 09/21/2013 02:52 PM, Bob Camp wrote:
Hi
So it's a pretty good AT cut crystal without any compensation of heating. Not
quite a cheap wrist watch, but not a BVA in a dewar flask either.
The environmental perturbations should go quite slow most of
On 09/21/2013 03:26 PM, Jim Lux wrote:
On 9/21/13 6:03 AM, Magnus Danielson wrote:
On 09/21/2013 02:52 PM, Bob Camp wrote:
Hi
So it's a pretty good AT cut crystal without any compensation of
heating. Not quite a cheap wrist watch, but not a BVA in a dewar
flask either.
The environmental
Adrian
It looks like you are gathering a lot of good detail. I have a couple of
thoughts. But will say there are many on this list that are far far more
knowledgeable then me. My experience was in building a hp 5060/61 combo. A
mixed marriage that worked.
That said. You don't mention the current
The instructions I got with this Rb said that you could hook an LED through a
5-10K resistor to the +15 supply and get a lock indication. I'm using a 10K
resistor and the LED lights as soon as it's powered up from cold. Is the loop
lock indicator circuit broken or is it just another strange
Adrian,
Most used High stability tubes are DOA but you might get lucky!
You say the low frequency test worked.
What was the amplitude of the peak in nanoamps and was the peak well
above the noise or baseline level?
Once you were on the peak did you adjust the 41.6Khz amplitude to max the
On 09/20/2013 04:34 AM, quartz55 wrote:
But when working with clocks (time, frequency, stability measurements) this
assumption often not true and it's helpful to think of averaging more as a
disease than a cure.
/tvb
I can understand that.
Dave
Are you applying +5V to pin as well? See:
http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq
Within 5 minutes after powering up (apply +15V on DB9 pin 1 and
+5V on pin 4) the unit should indicate lock (pin 3 voltage drops low).
John WA4WDL
Hi John,
Thanks for the response. I don't think my unit is the same as that one. The
instructions I got did not mention any +5V. Also, this is not a 10MHz unit, it
is only a timing unit. The internal frequency is 8.38860798/9 (last digit
jitter) MHz.
Bob
from JPL
http://www.jpl.nasa.gov/news/news.php?release=2013-275
Mission controllers postulate that there was an anomaly generated by
the spacecraft's software which left the vehicle's computers in a
condition where they are continuously rebooting themselves. If this is
the case, the computers
If the lock output comes from the micro or a logic port with a maximum
output of 3.3 or 5V, a LED connected to it from +15 will be always ON.
On Sat, Sep 21, 2013 at 4:55 PM, Bob Stewart b...@evoria.net wrote:
The instructions I got with this Rb said that you could hook an LED through a
5-10K
There is a problem introduced if you sink too much current off the lock pin.
An LED draws enough current to cause the issue, I think to do with not going
into lock or PPS output.
If I could just remember what the issue is...
Anyway, this guy has it nailed:
R is to read files.
I tried all 3 reset (!) commands, warm, cold and hard. (and said 'OH no what
have I done) Warm locked in about 3 minutes and cleared the holdover, cold
locked in 10 minutes, hard locked in 10 minutes but cleared the lat lon, reset
the EL to 10, AMU to 4. I put the lat lon
If this at first appears to be off topic read on.
Having this year survived fire evacuations and most recently what has been
called anything from a five to 1000 year flood here in Boulder, I have has a
little time to reflect on just how lucky I was. Over the last few years I have
made a few
If you have another reference like a GPS or Rubidium it makes set up much
easier since you simply tune to 5MHz and then adjust current.
The High Perf Tubes often needed to be degaussed, I have the 10638A but no
cable if that is any help contact me off list.
Also placing an external power supply
Tom:
I would like to see that paper.
Thanks,
jim
wb4...@amsat.org
On 9/21/2013 1:50 PM, Tom Knox wrote:
If this at first appears to be off topic read on.
Having this year survived fire evacuations and most recently what has been
called anything from a five to 1000 year flood here in Boulder, I
Corby,
many thanks for the comprehensive instructions.
After the harmonic generator alignment I measured 90mV into the 10Meg
DMM input, so the beam current should be 9nA.
The floor with the harmonic generator pot fully ccw was 6nA.
I didn't change the generator output during the LF test. To
Hi
As far as I know the lock output is a CMOS output that will drive a couple of
ma. There are so many variations that yours may indeed be an open collector and
good to +15 volts.
Bob
On Sep 21, 2013, at 10:55 AM, Bob Stewart b...@evoria.net wrote:
The instructions I got with this Rb said
I did a bit of sleuthing today about my dBc numbers. Looks like my best
numbers happened (47.2 and 44.7) when the antenna was on the shortest piece of
feed line, maybe 30', right above my room but well under the canopy of trees.
Highest dBc I get now is in the low 40's with 150' of feed and
Hi,
On 09/21/2013 07:50 PM, Tom Knox wrote:
If this at first appears to be off topic read on.
Having this year survived fire evacuations and most recently what has been
called anything from a five to 1000 year flood here in Boulder, I have has a
little time to reflect on just how lucky I
Hi Bob,
It's rather curious. Using my handheld DVM in the diode scale, I get a reading
of 448 in one direction and 458 in the other with it off and cold. In the 2K
ohms scale, I get 561 and 562 ohms. Later on, I'll pop the top off again and
take a pic so I can expand it and look at it. For
Hi
Those readings sound a lot more like a CMOS gate output than some sort of open
drain / open collector discrete driver.
Bob
On Sep 21, 2013, at 4:43 PM, Bob Stewart b...@evoria.net wrote:
Hi Bob,
It's rather curious. Using my handheld DVM in the diode scale, I get a
reading of 448
Hi Bob,
I hooked the big voltmeter up to it, and it shows +4.2V out for about a minute,
and then goes to 0. Looking on the web, it seems like I can use that to drive
a 2N and put the LED and dropping resistor in the collector path with the
emitter to ground? Does that sound right?
Bob
Tom,
Don't forget the 'stand-by' generator to keep that pump running.
If you have natural gas and can 'plant' a propane tank in the ground, you
can get an automatic transfer, dual fuel, generator with an automatic
transfer switch to power the entire house and automatically put the
generator and
Adrian,
You can use either Zeeman frequency as long as you use the corresponding
A1 frequency synthesizer setting.
See: http://www.febo.com/pipermail/time-nuts/2005-April/018171.html
This does not matter for troubleshooting but once you want to get on
frequency they need to match.
Corby
Yes, but put an isolation resistor between the output and the base of the
transistor, something between 3K and 5K should work. The LED will light upon
power on and extinguish when lock is achieved.
John WA4WDL
--
From: Bob Stewart
For those that have not been in Boulder, you should realize that it is just
downhill from the mountains. Multiple small creeks run through Boulder as
the rain poors off the Rocky Mountains, like the Flatirons that dominate the
view of Boulder. Boulder really stops at the Rocky Mountains.
Looks like Colorado's version of a hurricane.
I'm pretty much convinced that, no matter what you have or where you live,
Mother Nature can pretty much take it all away from you without much warning
using wind, fire, water, and/or earth quake.
Life is about the journey, not the destination. All
jim...@earthlink.net said:
If it gets cold enough (without power from solar cells, it won't generate
enough internal heat to keep warm), it will die. That's probably what
happened to Spirit on Mars. It got cold enough during the Martian winter,
and with not enough solar power, enough
Hi John,
Thanks for the response. I managed to cobble something up with LTSpiceIV, and
get it to work. And for me, that's saying something! Here's what I wound up
with: http://www.evoria.net/AE6RV/GPSstd_PLL/LED-driver.png;, where V2 is the
Loop Lock Indicator. The PN shorts out the
Bob,
I would bump that base resistor up a lot higher, to load the FE-5680 less. The
PN has enough gain it only needs about 0.3 mA base drive to work as
intended. You'd get that with a 10K base resistor.
Bob LaJeunesse
From: Bob Stewart
Thanks for the heads-up, Bob. I'll do it the next time the iron is hot.
Fortunately, it's only on for about a minute or so, then there's no drive from
the FE-5680A. Is 3ma really that big a deal? I know squat about CMOS gates.
I guess it is pulling the voltage down by 25%, though.
Bob
jim...@earthlink.net said:
Then on the ground, we time tag (with an atomic clock) when the telemetry
frame is received. (giving you Earth Received Time or ERT) Someone on the
ground does a process of time correlation figuring out what spacecraft time
corresponds to what TAI time, allowing
On 9/21/13 6:40 PM, Hal Murray wrote:
jim...@earthlink.net said:
If it gets cold enough (without power from solar cells, it won't generate
enough internal heat to keep warm), it will die. That's probably what
happened to Spirit on Mars. It got cold enough during the Martian winter,
and
b...@evoria.net said:
Is 3ma really that big a deal? I know squat about CMOS gates. I guess it
is pulling the voltage down by 25%, though.
There should be something in the data sheet. 1/2 :)
If you trace the signal back the next time you have it open, you might be
able to figure out
On Sat, Sep 21, 2013 at 6:40 PM, Hal Murray hmur...@megapathdsl.net wrote:
What stops working when things get cold?
On Mars, the solar cells are pointed in the right direction. Why doesn't it
recover when the sun comes back in the Spring?
They run out of power for running the battery
I have heard it called about everything up to a 1000 year flood. But I also
heard a University of Colorado professor who monitors Boulder creek called it a
twenty five year flood. In any case I was lucky.
Thanks;
Thomas Knox
To: time-nuts@febo.com
From: hmur...@megapathdsl.net
Date: Sat, 21
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