Greetings Time Nuts.
Time related, but unusually so:
I am examining the DCF77 (see http://en.wikipedia.org/wiki/DCF77 for a
refresher) data output from a master clock intended to drive a series of
slave clocks operated from 24V DC, interrupted by 100ms or 200ms pulses to
signal '0' '1' on the
We have a choice of two dual mixers, my copy of the original NBS with minor
changes and Bill Riley's unit. Comparison tests are ongoing to pick the
best. If Bill's shows better results I plan on laying one out using leaded
components. 2 channel and 4 channel counters are completed and are
Did do some more reading and I think what I suggest is the right approach.
Band 2 and 3 use the same VCO. So if band 2 is generally working
then its possibly the rf multiplier yig filter mixer diodes etc. But
if the RF detectors show RF then its going to be a much more interesting
issue.
Good practice with a spectrum analyzer is to put a 20 dB pad at the input all
the time unless you are sure you don't need it for a particular measurement.
It has saved my bacon many times.
It also protects the input connector from excessive wear.
Didier KO4BB
Sent from my Droid Razr 4G LTE
Le 09/12/2012 11:28, Tom Harris a écrit :
Greetings Time Nuts.
Time related, but unusually so:
I am examining the DCF77 (see http://en.wikipedia.org/wiki/DCF77 for a
refresher) data output from a master clock intended to drive a series of
slave clocks operated from 24V DC, interrupted by 100ms
Is the parity bit P3 consistent? It protects the day of the month and that
of the week.
On Sun, Dec 9, 2012 at 1:24 PM, mike cook mc235...@gmail.com wrote:
Le 09/12/2012 11:28, Tom Harris a écrit :
Greetings Time Nuts.
Time related, but unusually so:
I am examining the DCF77 (see
Hi
The flip flop would have a metastable region. It would be quite narrow, but it
would be there. As soon as you try to take the square wave into the processor,
you are right back to the same problems we've discussed before. The flip flop,
run this way does not improve that part of the
On Sat, 08 Dec 2012 11:24:15 -0500, Mike Garvey wrote:
Is there a way to search the Archive?
I can find the archive, but there seems to be no way to search the
content.
Thanks, Mike
I sometimes use this site , has excellent search
Didier is 100% correct though I use a 10 db pad for exactly the same
purpose. You have to be careful. In your case there is a +28 db power amp
that feeds the yig mixer in the 545. That would destroy the spectrum
analyzer frontend. In fact if measuring that component you would want 30 db
of loss
Chris
TP4 is not all that helpful its a control signal.
So let me back up for a minute. What are we troubleshooting?
I was thinking band 2 was semi working and you still had a totally dead
band 3.
My comments have been around trying to see what was going on with 3.
Other comment.
I think we should
On 09/19/2012 08:15 PM, Tom Knox wrote:
Hi Bob;
Actually a pair of each so you can cross-correlate against your DUT. I think
for us Time-Nuts this is the system that differentiates it from a hobby and a
disease.
Oh, that is what I do with mine when I get a chance to... :)
Cheers,
Magnus -
On Sun, 09 Dec 2012 15:11:34 +, cfo wrote:
On Sat, 08 Dec 2012 11:24:15 -0500, Mike Garvey wrote:
Is there a way to search the Archive?
I can find the archive, but there seems to be no way to search the
content.
Thanks, Mike
I sometimes use this site , has excellent search
On Sat, Dec 8, 2012 at 11:14 PM, Hal Murray hmur...@megapathdsl.net wrote:
albertson.ch...@gmail.com said:
What if I use a flip flop. The PPS from the GPS connects to the set
input
of the FF and also to the Arduino interrupt. The output of the OCXO
goes
to the reset pin of the same
Joe--
Thanks for that! A great deal of what makes the Arduino popular, as you've
identified, is the ease of use through the IDE.
I just finished re-doing code for a portable RF power meter (AD8307, LTC1288),
and the Arduino implementation was quick, easy, and provides a lot more
capability.
Hi
In order to get a useful average, you need to have the pps arrive just a bit
ahead and a bit behind the 10 MHz out of the OCXO. If the GPS PPS moves more
than 100 ns between samples you get data from different cycles on the OCXO.
That does not give you useful information to average. If the
Hi
The interesting thing about cross correlation sources is that they don't need
to be tuned. A fixed frequency device works just as well as one that's at
exactly this or that frequency. There are a number of issues that creep into an
OCXO based on the need to tune it. Simply put - the more
Chris
TP4 is not all that helpful its a control signal.
So let me back up for a minute. What are we troubleshooting?
I was thinking band 2 was semi working and you still had a totally dead
band 3.
My comments have been around trying to see what was going on with 3.
Other comment.
I think
I realize this is pretty mundane for such an elite group, but would anyone have
some information(specifically the pinout) for an EGG Cinox 10Mhz source. It
has the following numbers printed on it: 10085-0611 and 20296-1891 and has
three feedthrus labelled E1(orange wire), E2(black wire), and
I have a device that has an internal TCXO. I want to feed it with an
external OCXO, but I don't want to completely replace the TCXO.
Here is the scenario. On initial power on, or after a power loss, I
want the internal TCXO to be used. Once the OCXO is up, I want to
switch to it. How could this
The finished project will be placed where I won't have regular access
to it, so I think I have justification for wanting this complication.
Also, I want to monitor which oscillator is in use, so my application
will know.
Joe Gray
W5JG
On Sun, Dec 9, 2012 at 2:18 PM, shali...@gmail.com wrote:
li...@rtty.us said:
The flip flop would have a metastable region. It would be quite narrow, but
it would be there. As soon as you try to take the square wave into the
processor, you are right back to the same problems we've discussed before.
The flip flop, run this way does not improve that
You would probably want to see when the external oscillator frequency is close
to the internal oscillator. I suppose than could be done with a mixer and glue
circuitry. I don't think this is cheap though.
-Original Message-
From: Joseph Gray jg...@zianet.com
Sender:
I'm doing some work with a couple of geophones (long story...) and
stumbled across TI's ADS1282 geophone ADC.
It has some pretty amazing specs for low frequencies, and having played
with the EVAL board for an evening here in my lab, I'm pretty impressed.
People working with close-in phase-noise
Hi
A picture of the label might help people track it down.
Bob
On Dec 9, 2012, at 3:14 PM, johnk0...@juno.com wrote:
I realize this is pretty mundane for such an elite group, but would anyone
have some information(specifically the pinout) for an EGG Cinox 10Mhz
source. It has the
Then the next best thing is a time-delay relay set for a delay sufficient to
ensure the OCXO has warmed up.
Didier
Sent from my Droid Razr 4G LTE wireless tracker.
-Original Message-
From: Joseph Gray jg...@zianet.com
To: Discussion of precise time and frequency measurement
Hi
Two basic choices:
1) Convert them both to logic levels and use a gate.
2) Use a relay.
Both would need some sort of timer to drive them. Both would disrupt the
instrument when the switch took place. I know of no cheap / easy ways to take
care of the switching glitch. There are fancy /
Hi
It's the big brother of the ADS127x parts that I mentioned a little while
back. I'm sure it works quite well. The 127x's are fine parts. The internal
filtering combined with the chopper is a very nice combination.
Bob
On Dec 9, 2012, at 5:13 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
If they don't get close, which is right?
If you only have 2 references, you cannot tell which is right.
Didier KO4BB
Sent from my Droid Razr 4G LTE wireless tracker.
-Original Message-
From: li...@lazygranch.com
To: Discussion of precise time and frequency measurement
My first thought is to simply wait a fixed time until the OCXO has
warmed up and then switch over. I thought that others here might
suggest a better method.
Joe Gray
W5JG
On Sun, Dec 9, 2012 at 3:04 PM, li...@lazygranch.com wrote:
You would probably want to see when the external oscillator
Hi
You pretty much have to assume that after 15 minutes or so the OCXO is right
and the TCXO is wrong. You could play with this or that, but it's still going
to be a leap of faith switch.
Bob
On Dec 9, 2012, at 5:19 PM, shali...@gmail.com wrote:
If they don't get close, which is right?
It could be done cheaply with a small micro that is clocked by the device's
TCXO
and uses an internal timer to measure the external clock frequency (or external
frequency divided by 10 or 16 if that better suits the timer capabilities). The
micro, when satisfied the frequency is close enough
Hi
There are other devices where a simultaneous set and reset will toggle the
device.
Since the useful operating point is simultaneous inputs, what you are
building is a metastability tester.
Bob
On Dec 9, 2012, at 5:00 PM, Hal Murray hmur...@megapathdsl.net wrote:
li...@rtty.us said:
Hi Joseph,
On 12/09/2012 10:53 PM, Joseph Gray wrote:
The finished project will be placed where I won't have regular access
to it, so I think I have justification for wanting this complication.
Also, I want to monitor which oscillator is in use, so my application
will know.
First reaction
Hi
The gotcha with a comparison is that the TCXO likely is further off than the
OCXO's settling characteristics. Put another way, the OCXO goes from 10 ppm to
1 ppm in no time at all. Going from 1 ppm to 0.1 takes longer. It's the 0.1 to
0.01 range that really tells you about settling and
Hi
I think the idea is to run the TCXO while the OCXO is 1 ppm off frequency and
then switch to the OCXO when it's sure to be OK. Most inexpensive approaches to
locking the TCXO will give you a pretty major frequency transient. Depending on
what you are doing, that may muck things up as much
Some of the HP OCXOs (the one in the HP856x SA) have a oven ready signal.
That could be used to force the switch. Some Rubidium standards (FEI
FE-5680A for sure) have a locked indicator that could do this function.
I think you could mute the 10 MHz where it is fed to the instrument and that
On 9 Dec, 2012, at 02:14 , Hal Murray hmur...@megapathdsl.net wrote:
Which brings up another worm for the can. How are you going to get a PPS
from the OCXO? That's going to be hard without some soldering. My straw man
would be to use the OCXO to clock whatever uP you end up using and
Hi
Often the oven ready signals are actually a oven not broke signal. They may
be of little use if the idea is to only switch once the OCXO is significantly
more accurate than the TCXO. The lock signal on an Rb is indeed quite adequate
for this task.
Bob
On Dec 9, 2012, at 5:36 PM, Tom
I don't know if this makes things easier or not, but the act of sampling itself
is like a mixer. If you sample one clock with the other, it would produce a
beat frequency. Sampling here just means a strobing a D flip flop. The output
will be low frequency, so the error could be measured with a
Hi
Without a specific goal, there's no real way to pick a set of hardware. The
Freescale board I mentioned earlier is a reasonably cheap (sub $15) ARM board.
The only way to decide which / what to use is to have an objective. Without
agreement on that we'll each just go on and on tossing up
Hi
You still have the which one's right issue. With most settling situations,
the closest approach of the oscillators isn't what you are after. You are
actually trying to make sure the OCXO is both on frequency and stable. A TCXO
likely drifts a bit as the instrument warms up. That makes a
For my use, I don't think the switching glitch will be a concern. Most
of the time, the equipment will be in a standby mode. There is a high
probability that the OCXO will be in use most of the time.
I guess my original idea of simply waiting a sufficient time for the
OXCO to warm up and then
On 12/09/2012 11:31 PM, Bob Camp wrote:
Hi
I think the idea is to run the TCXO while the OCXO is 1 ppm off frequency and
then switch to the OCXO when it's sure to be OK. Most inexpensive approaches to
locking the TCXO will give you a pretty major frequency transient. Depending on
what you
I just want to say thanks to all who participate on this list.
You guys are way above my batting average and I learn a lot
just by hanging around.
Thanks for being patient with newbies and dummies.
p.s. my GPSDO (the VE2ZAZ design and board) is running
great thanks to advice from you all.
Hi
Not real straightforward to do in the cheap / easy realm.
Bob
On Dec 9, 2012, at 6:08 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote:
On 12/09/2012 11:31 PM, Bob Camp wrote:
Hi
I think the idea is to run the TCXO while the OCXO is 1 ppm off frequency
and then switch to the
Hi
Having done this a lot of times - a simple timer is about as good as you are
going to get.
Bob
On Dec 9, 2012, at 6:06 PM, Joseph Gray jg...@zianet.com wrote:
For my use, I don't think the switching glitch will be a concern. Most
of the time, the equipment will be in a standby mode.
Joe,
On 12/10/2012 12:06 AM, Joseph Gray wrote:
For my use, I don't think the switching glitch will be a concern. Most
of the time, the equipment will be in a standby mode. There is a high
probability that the OCXO will be in use most of the time.
I guess my original idea of simply waiting a
albertson.ch...@gmail.com said:
I don't think that is going to do what you want. The problem is what
happens if set and reset are on at the same time?
This would be the best case. The result will be random and we'd read an
average value of 0.5 from the flip flop.
The problem is that FFs
Hi
A runt pulse during the switch over might well do some odd things.
Bob
On Dec 9, 2012, at 6:17 PM, Magnus Danielson mag...@rubidium.dyndns.org wrote:
Joe,
On 12/10/2012 12:06 AM, Joseph Gray wrote:
For my use, I don't think the switching glitch will be a concern. Most
of the time,
li...@rtty.us said:
1) Convert them both to logic levels and use a gate.
2) Use a relay.
Both would need some sort of timer to drive them. Both would disrupt the
instrument when the switch took place. I know of no cheap / easy ways to
take care of the switching glitch. There are fancy /
Thanks for all the good suggestions. After further consideration, I
think I'll just keep the equipment in standby until a sufficient time
has elapsed for the OXCO to stabilize. That way I don't have to switch
oscillators at all. The whole project will be controlled by a uC board
anyway, so this
Hi Joe,
I think you all are not looking at this correctly.
1.First, as has been pointed out, a TCXO will vary around till the
environment it is in has returned to its nominal operating temperature.
2.A typical TCXO is nominally spec'ed around +/- 0.5 x 10-7
On Sun, 09 Dec 2012 15:49:04 -0800, Hal Murray
hmur...@megapathdsl.net wrote:
li...@rtty.us said:
1) Convert them both to logic levels and use a gate.
2) Use a relay.
Both would need some sort of timer to drive them. Both would disrupt the
instrument when the switch took place. I know of no
Hi
Unless the OCXO and PPS both stay within +/-50 ns (100 ns p-p) over the entire
lock in period, the PLL will not lock up. If you slip outside that range the
error signal changes sign. It drives away from lock rather than towards lock.
The XOR and mixer phase detectors have this same
Hi
Your TCXO will have the same sort of retrace issues as your OCXO. Past some
number of minutes (5,10,15…) you will always be better with a modern OCXO than
with a TCXO.
Bob
On Dec 9, 2012, at 7:05 PM, WB6BNQ wb6...@cox.net wrote:
Hi Joe,
I think you all are not looking at this
Hi
What happens if the OCXO is to far off frequency? How far off is to far? You
may not have to wait very long….
Bob
On Dec 9, 2012, at 6:54 PM, Joseph Gray jg...@zianet.com wrote:
Thanks for all the good suggestions. After further consideration, I
think I'll just keep the equipment in
On 12/10/2012 12:45 AM, Bob Camp wrote:
Hi
A runt pulse during the switch over might well do some odd things.
Exactly. For instance, two FFs holding the state may not both trigger,
so inconsistent state may occur. I've had one of those problems, turned
out to be evil cross-talk in that
Hi Bob,
Can you give a good definition of retrace as it applies here?
Thanks,
Tom
- Original Message -
From: Bob Camp li...@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Sunday, December 09, 2012 7:24 PM
Subject: Re: [time-nuts] Switching
Have you tried Princeton Applied Research who seem to own the EGG rights
now??
Alan G3NYK
- Original Message -
From: johnk0...@juno.com
To: time-nuts@febo.com
Sent: Sunday, December 09, 2012 8:14 PM
Subject: [time-nuts] Cinox source
I realize this is pretty mundane for such an
Hi
Retrace assumes that the oscillator has some normal frequency that only moves
according to the aging rate. Retrace occurs after the oscillator has been off
power for some period. The rate of change is greater than the aging rate.
Warmup and retrace are obviously inter-related. Warmup is
Hi
Cinox merged with Oscillatek in the 1990's. Oscillatek merged with Vectron a
bit later in the 1990's. Vectron now operates out of what was the Oak / McCoy
facility (merger about 6 years ago).
Bob
On Dec 9, 2012, at 7:57 PM, Alan Melia alan.me...@btinternet.com wrote:
Have you tried
HI
Princeton was part of EGG for quite a while. EGG bought out Perkin Elmer in
the 90's. The EGG name was not as warm and fuzzy as Perkin Elmer. The
switched over the name of the combined company to Perkin Elmer a bit after they
got together.
Bob
On Dec 9, 2012, at 7:57 PM, Alan Melia
So if I understand it, you allow the OCXO several days of warm-up to set the
frequency. Then when turned off for a while, then restarted. After some
warm-up period, the retrace spec would give an indication of how close the
frequency will be?
Thanks,
Tom
- Original Message -
From:
Hi
That's one interpretation and one method of measurement. The other method is to
measure frequency shift from say one hour after power on to 24 hours after
power on. A lot depends on the requirements of the system the OCXO was intended
to be used in.
If you use the measure / power off /
Ok, thanks for the explanation.
Tom
- Original Message -
From: Bob Camp li...@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Sunday, December 09, 2012 8:51 PM
Subject: Re: [time-nuts] Switching oscillators
Hi
That's one interpretation and
Bob,
I don't know where you got your multiple versions. RETRACE deals with the
object in a fully realized steady state operating condition, then removal of
power for a period of time (usually stated in real specs as 24 hours) and then
re application of power with a stated result. Really
On 12/9/12 5:38 PM, Bob Camp wrote:
HI
Princeton was part of EGG for quite a while. EGG bought out Perkin Elmer in the 90's. The
EGG name was not as warm and fuzzy as Perkin Elmer. The switched over the name of
the combined company to Perkin Elmer a bit after they got together.
P-E is also
http://www.scmagazine.com.au/News/325731,researchers-find-crippling-flaws-in
-global-gps.aspx
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and follow the instructions
For the record, my device did have an OSMT (not Hirose) connector on the
DDS board.
I'm having trouble getting the internal RS232 port on the DDS board to work
and I was wondering if there were any tricks to it? I'm not able to get it
to respond to the 'S' command and when I measure the voltage
ja...@peroulas.com said:
I'm not able to get it to respond to the 'S' command and when I measure the
voltage on the RS232 TX pin (#2 from the left) it's always 0v. Shouldn't it
be -12v when idle?
Newer RS-232 allows 6V rather than 12.
In practice, it's not all that uncommon for designers to
EIA-232 trip points are positive so that you can cheat and drive them
with logic, so it is not unusual to find 232 that doesn't go negative.
This is OK for short distances. This should not be called 232, but often
they state 232 compatible. You can take a logic gate and make it
handle +/-15V
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