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.
The "best" may
On Fri, 10 Feb 2012 18:19:53 -0800, Hal Murray
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 Semiconductor has an interes
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 6
You don't. That's why the HC4046 has 3 phase comparators. Different strokes for
different folks...
From: Hal Murray
To: Discussion of precise time and frequency measurement
Sent: Fri, February 10, 2012 9:35:01 PM
Subject: Re: [time-nuts] GPS lock of the FE568
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 necessaril
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
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 wrote:
> Flip-flops hardened against metastability are available.
>
> I would try a track and hold before
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 are.
> Flip-flops hardened against metastability are available.
Do you have a part number in mind?
The only data sheet that I remember for a part that looked interesting was
actually 2 FFs inside one package. For something like that, you save the
prop time of the output driver and the input receive
On Fri, 10 Feb 2012 19:54:11 -0600, David
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 non-trivial. I believe bet
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 R
On Fri, 10 Feb 2012 17:28:53 -0800, Chris Albertson
wrote:
>On Fri, Feb 10, 2012 at 5:10 PM, David 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. I
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 whi
On Fri, Feb 10, 2012 at 5:10 PM, David 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. But if it changes h
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 sam
On Fri, 10 Feb 2012 16:35:26 -0800, Chris Albertson
wrote:
>On Fri, Feb 10, 2012 at 3:52 PM, Bob Camp 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 signal
On Fri, Feb 10, 2012 at 4:48 PM, paul swed 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 dealing with 100 Hz
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 dealing with 100 Hz or up.
So the answer I have seen which seems to fit is Bobs
On Fri, Feb 10, 2012 at 3:52 PM, Bob Camp 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
duty cycle b
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 fe
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 wrote:
> On Fri, Feb 10, 2012 at 2:53 PM, paul swed wrote:
>> Just for fun have built up a simple multi-chip project to try my hand at
>> locking the FE56
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 frequencymeasur
On Fri, Feb 10, 2012 at 2:53 PM, paul swed 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 X 24 bit count
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
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 fr
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
To: Discussion of precise time and frequency measurement
Sent: Fri, Feb 10, 2012 20:33:56 GMT+00:00
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 rep
In message , "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 today
>they changed it. For those
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 moni
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: Th
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.
Bob
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
ba
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
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 defi
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 measure
> 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
> 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
> 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 compl
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