Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of J. L. Trantham
Sent: Monday, December 10, 2012 8:18 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Switching oscillators
Not sure why
easier to build a battery back-up for your
'house standard'.
Hope this helps.
Joe
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Joseph Gray
Sent: Sunday, December 09, 2012 3:13 PM
To: Discussion of precise time and frequency measu
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?
>>>
>>> Than
etrace spec would give an indication of how close the
> > frequency will be?
> >
> > Thanks,
> > Tom
> >
> > - Original Message - From: "Bob Camp"
> > To: "Discussion of precise time and frequency measurement"
> >
> > Se
Ok, thanks for the explanation.
Tom
- Original Message -
From: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: Sunday, December 09, 2012 8:51 PM
Subject: Re: [time-nuts] Switching oscillators
Hi
That's one interpretation and
trace spec would give an indication of how close the
> frequency will be?
>
> Thanks,
> Tom
>
> - Original Message - From: "Bob Camp"
> To: "Discussion of precise time and frequency measurement"
>
> Sent: Sunday, December 09, 2012 7:58 PM
&
: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: Sunday, December 09, 2012 7:58 PM
Subject: Re: [time-nuts] Switching oscillators
Hi
Retrace assumes that the oscillator has some "normal" frequency that only
moves according to the aging
ion of precise time and frequency measurement"
>
> Sent: Sunday, December 09, 2012 7:24 PM
> Subject: Re: [time-nuts] Switching oscillators
>
>
> Hi
>
> Your TCXO will have the same sort of retrace issues as your OCXO. Past some
> number of minutes (5,10,15…) you
Hi Bob,
Can you give a good definition of retrace as it applies here?
Thanks,
Tom
- Original Message -
From: "Bob Camp"
To: "Discussion of precise time and frequency measurement"
Sent: Sunday, December 09, 2012 7:24 PM
Subject: Re: [time-nuts] Switching os
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 case,
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 wrote:
> Thanks for all the good suggestions. After further consideration, I
> think I'll just keep the equipment in standby until a s
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 wrote:
> Hi Joe,
>
> I think you all are not looking at this correctly.
>
>
On Sun, 09 Dec 2012 15:49:04 -0800, Hal Murray
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 "cheap / easy"
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
neighborhood
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 wil
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
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 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, the equipment will be
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 su
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 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
> p
Hi
Not real straightforward to do in the "cheap / easy" realm.
Bob
On Dec 9, 2012, at 6:08 PM, Magnus Danielson 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 OCXO when it's su
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 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 swit
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 de
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 u
you could mute the 10 MHz where it is fed to the instrument and that
> should default to the internal source.
>
> Tom
>
> - Original Message - From: "Joseph Gray"
> To: ; "Discussion of precise time and frequency
> measurement"
> Sent: Sund
t and that
should default to the internal source.
Tom
- Original Message -
From: "Joseph Gray"
To: ; "Discussion of precise time and frequency
measurement"
Sent: Sunday, December 09, 2012 5:21 PM
Subject: Re: [time-nuts] Switching oscillators
My first thought
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
nts
> and
> conditioning and SPDT analog switch as above.
>
>
> Bob LaJeunesse
>
>
>
>
> From: "li...@lazygranch.com"
> To: Discussion of precise time and frequency measurement
> Sent: Sun, December 9, 2012 5:05:09 PM
> Subject: Re: [time-n
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 woul
oning and SPDT analog switch as above.
Bob LaJeunesse
From: "li...@lazygranch.com"
To: Discussion of precise time and frequency measurement
Sent: Sun, December 9, 2012 5:05:09 PM
Subject: Re: [time-nuts] Switching oscillators
You would probably want
ncy measurement
> Sent: Sun, 09 Dec 2012 4:04 PM
> Subject: Re: [time-nuts] Switching oscillators
>
> 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.
ssion of precise time and frequency measurement
> Reply-To: Discussion of precise time and frequency measurement
>
> Subject: [time-nuts] Switching oscillators
>
> I have a device that has an internal TCXO. I want to feed it with an
> external OCXO, but I don't want to
n, 09 Dec 2012 4:04 PM
Subject: Re: [time-nuts] Switching oscillators
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.
-Origin
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 / e
3:53 PM
Subject: Re: [time-nuts] Switching oscillators
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
O
Date: Sun, 9 Dec 2012 14:12:51
To: Discussion of precise time and frequency measurement
Reply-To: Discussion of precise time and frequency measurement
Subject: [time-nuts] Switching oscillators
I have a device that has an internal TCXO. I want to feed it with an
external OCXO, but I don&#
;
>
> Sent from my Droid Razr 4G LTE wireless tracker.
>
>
>
> -Original Message-
> From: Joseph Gray
> To: Discussion of precise time and frequency measurement
> Sent: Sun, 09 Dec 2012 3:13 PM
> Subject: [time-nuts] Switching oscillators
>
> I have a de
4G LTE wireless tracker.
-Original Message-
From: Joseph Gray
To: Discussion of precise time and frequency measurement
Sent: Sun, 09 Dec 2012 3:13 PM
Subject: [time-nuts] Switching oscillators
I have a device that has an internal TCXO. I want to feed it with an
external OCXO, but I
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 be
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