The best inventions are the ones that nobody ever thought to ask for. If
Edison had done marketing studies, he would have spent his life designing
incremental improvements to gas lights. Nobody asked him to invent the
electric light.
First let me say that what I'm about to write is
Did you ever run any tests on those UCT double oven OCXOs?
Only to the extent of running a short (10-minute) HDEV test after a ~2 hour
warmup, to see if it was capable of anything interesting near t=10s to
t=30s. It showed about 2E-12, and the PN was nothing special, so I didn't
do anything
It's the international science and engineering fair, so both kinds show
up.
The line between applied science and engineering is pretty fuzzy.
There is another category. I'm not sure what the right term is. How about
just having fun?
I think it's neat to see an experiment or demo that
Thanks Hal,
Will have to visit next time I am in San Fran sounds interesting
Chris
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Hal Murray
Sent: Friday, 10 February 2012 8:38 PM
To: Discussion of precise time and frequency
On 2/10/12 1:37 AM, Hal Murray wrote:
It's the international science and engineering fair, so both kinds show
up.
The line between applied science and engineering is pretty fuzzy.
There is another category. I'm not sure what the right term is. How about
just having fun?
Most
On 2/10/12 2:05 AM, Chris Dawes wrote:
Thanks Hal,
Will have to visit next time I am in San Fran sounds interesting
Makes a nice, but busy, day to do the Exploratorium and the California
Academy of Sciences/Steinhart Aquarium. They're pretty close to each
other, so it's not like you have
Hi
Have I seen system bandwidth in published data? - pretty much never. Kudos
to Symmetricom for putting it up on the display on the 5125. The system
bandwidth debate goes back well into the 1960's. Pretty much every paper
Dave Allan ever presented up through the 1980's, he got a question about
Hi
I think we have enough data on current batch of FE-5680A rubidiums to guess
that the ADEV plots on it's data sheet could only have been done in a
constant temperature / environmental chamber...
That said, I see no reason it will not meet the actual spec limits over the
temperature range.
Hi
I suspect that if you went into the GPS jamming business that the mob of
lawyers would be even more scary than the stuff being dropped on your
antennas...
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Magnus Danielson
Sent:
I see page 18 subframe 4 is now broadcasting a pending leap second being
transmitted by the GPS sats. I had checked it earlier this week and they
were still transmitting the old data. But sometime between Monday and today
they changed it. For those with receivers or software programs
In message e809eaf9-1182-43fc-82ab-6415c5f83d68@blur, k4...@aol.com writes:
I see page 18 subframe 4 is now broadcasting a pending leap second being
transmitted by the GPS sats. I had checked it earlier this week and they
were still transmitting the old data. But sometime between Monday and
I've tried both the MV89a and the Oscilloquartz 8663 (I think UCT is the same
or very close) with the Thunderbolt. The Oscilloquartz does not fit any of the
OCXO thru-hole combinations but the MV89a does fit one of the OCXO variations
that TB accommodates. That makes for a very clean/compact
Paul, I am looking at the data from the satellites and it shows dtls=16,
WNt=139, WNlsf=158, DN=7.
Connected by DROID on Verizon Wireless
-Original message-
From: Poul-Henning Kamp p...@phk.freebsd.dk
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Just for fun have built up a simple multi-chip project to try my hand at
locking the FE5680 using the external efc connection mod. mentioned in
time-nuts. Typical counter micro rs 232 port stuff.
Essentially the system is 2 X 24 bit counters that toggle back and fourth
every interval selectable
Hi
Without seeing the schematic it's a little hard to be sure this is all
correct...
If it is all based on 10 MHz, then yes you are doing it all modulo 100 ns. To
get 1 part in 1x10^13 you would need 100,000 seconds. If that drives the LSB of
a 16 bit counter for the DAC you would take a very
On Fri, Feb 10, 2012 at 2:53 PM, paul swed paulsw...@gmail.com wrote:
Just for fun have built up a simple multi-chip project to try my hand at
locking the FE5680 using the external efc connection mod. mentioned in
time-nuts. Typical counter micro rs 232 port stuff.
Essentially the system is 2
I saw it yesterday on my TBolt. Last time I looked was a couple of weeks
ago.
Joe
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of k4...@aol.com
Sent: Friday, February 10, 2012 2:16 PM
To: 'Discussion of precise time and
Hi
I think you will need some sort of analog detector to get what you are looking
for.
Bob
On Feb 10, 2012, at 6:34 PM, Chris Albertson albertson.ch...@gmail.com wrote:
On Fri, Feb 10, 2012 at 2:53 PM, paul swed paulsw...@gmail.com wrote:
Just for fun have built up a simple multi-chip
Good comments so I am on target in thinking.
Why 24 bits because it was pretty easy using 74hc596 8 bit counters with
latch and tristate outputs.
Unfortunately the schematics are on paper at the moment scribbles.
But the cntrs are stacked on top each other as a unit and soldered
together. Only a
On Fri, Feb 10, 2012 at 3:52 PM, Bob Camp li...@rtty.us wrote:
Hi
I think you will need some sort of analog detector to get what you are
looking for.
I don't think it needs to be analog. For example you can xor the two
10MHz signals and then sample the digital xor output then deduce its
On Fri, Feb 10, 2012 at 4:48 PM, paul swed paulsw...@gmail.com wrote:
Hang on here. If the signal was 10 MHz for ref and RB its easy as suggested
here XOR gates and such.
But the GPS is a 1 second interval and the RB is 10 Mhz. So the GPS 1
second is the reference. Thats much harder then
On Fri, 10 Feb 2012 16:35:26 -0800, Chris Albertson
albertson.ch...@gmail.com wrote:
On Fri, Feb 10, 2012 at 3:52 PM, Bob Camp li...@rtty.us wrote:
Hi
I think you will need some sort of analog detector to get what you are
looking for.
I don't think it needs to be analog. For example you
Sampling unsychronized signals with a DFF is problematic, since if setup and
hold times are not met the output could oscillate and maybe settle to some
noise
driven value. I can't help thinking that if you are sampling the 10MHz
signal at
1Hz the only way to get reasonable resolution is to
On Fri, Feb 10, 2012 at 5:10 PM, David davidwh...@gmail.com wrote:
All you need for this is the flip-flop. Clock the flip-flop with the
1 PPS signal and capture whether the oscillator is leading or lagging.
I can see how this can detect lock. If the FF is the same each second
you are good.
Flip-flops hardened against metastability are available.
I would try a track and hold before a sample and hold but I wonder how
accurate it would be having to rely on the oscillator waveform. Fast
sample gates are non-trivial. I believe better than either would be a
time to voltage converter
On Fri, 10 Feb 2012 17:28:53 -0800, Chris Albertson
albertson.ch...@gmail.com wrote:
On Fri, Feb 10, 2012 at 5:10 PM, David davidwh...@gmail.com wrote:
All you need for this is the flip-flop. Clock the flip-flop with the
1 PPS signal and capture whether the oscillator is leading or lagging.
Good question and the reason for the large counter.
If locked its a hard number and a number above or below that number is how
far its off and in what direction. Yup 24 bits was a bit crazy but it
wasn't anything to do.
That said a single 8 bit counter would have been fine given the stability
the
On Fri, 10 Feb 2012 19:54:11 -0600, David davidwh...@gmail.com
wrote:
Flip-flops hardened against metastability are available.
I would try a track and hold before a sample and hold but I wonder how
accurate it would be having to rely on the oscillator waveform. Fast
sample gates are
Hi
If your GPS puts out 1 pps, you get one sample per second out of your phase
detector. If it's digital you get a one or a zero. Dead time between edges is
50 ns. You throw away a lot of the accuracy of GPS by doing it this way. With
an analog detector you would know how early or late you
Hi
If you go to a sample and hold, just use it to capture the voltage of the 10
MHz sine wave. That is one way to do an analog phase detector...
Bob
On Feb 10, 2012, at 8:54 PM, David davidwh...@gmail.com wrote:
Flip-flops hardened against metastability are available.
I would try a
paulsw...@gmail.com said:
Why 24 bits because it was pretty easy using 74hc596 8 bit counters with
latch and tristate outputs. Unfortunately the schematics are on paper at the
moment scribbles. But the cntrs are stacked on top each other as a unit and
soldered together. Only a few pins are
paulsw...@gmail.com said:
Hang on here. If the signal was 10 MHz for ref and RB its easy as suggested
here XOR gates and such.
Assume I have 2 signals that are (very) close to 10 MHz and I get to read
their XOR. How do I know which one is faster?
--
These are my opinions, not necessarily
You don't. That's why the HC4046 has 3 phase comparators. Different strokes for
different folks...
From: Hal Murray hmur...@megapathdsl.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Fri, February 10, 2012 9:35:01 PM
It got here around 2785 seconds UTC after midnight on Feb 10th. (unless I
fatfingered something)
From a NTP log file while watching a HP Z3801A. The + says insert a leap
second.
55967 2401.038 127.127.26.1 T2201202100040023001028 64 0
55967 2465.034 127.127.26.1 T220120210004106300102D 64
On Fri, 10 Feb 2012 18:19:53 -0800, Hal Murray
hmur...@megapathdsl.net wrote:
Flip-flops hardened against metastability are available.
Do you have a part number in mind?
Some logic families are better than others. In general you want
faster ones with shorter setup and hold times.
On
All these different suggestions build down to one thing, the precision
with which you measure the phase when you sample it each second. The
single flip flop will tell you which half cycle. a simple two bit
counter made with two '74 FFs tells you which half cycle and with
direction.
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