- 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 7:58 PM
Subject: Re: [time-nuts] Switching oscillators
Hi
Retrace assumes that the oscillator has some normal frequency that only
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 measurement
Subject: [time-nuts] Switching oscillators
I have
-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 you would want
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
Razr 4G LTE wireless tracker.
-Original Message-
From: Joseph Gray jg...@zianet.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sun, 09 Dec 2012 3:13 PM
Subject: [time-nuts] Switching oscillators
I have a device that has an internal TCXO. I want
...@febo.com
Date: Sun, 9 Dec 2012 14:12:51
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Switching oscillators
I have a device that has an internal TCXO. I want
-nuts@febo.com
Sent: Sun, 09 Dec 2012 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
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 /
@febo.com
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. I don't think this is cheap though
of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
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
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.
-Original Message-
From
switch as above.
Bob LaJeunesse
From: li...@lazygranch.com li...@lazygranch.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sun, December 9, 2012 5:05:09 PM
Subject: Re: [time-nuts] Switching oscillators
You would
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
From: li...@lazygranch.com li...@lazygranch.com
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Sun, December 9, 2012 5:05:09 PM
Subject: Re: [time-nuts] Switching oscillators
You would probably want to see when the external oscillator frequency
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
and that
should default to the internal source.
Tom
- Original Message -
From: Joseph Gray jg...@zianet.com
To: li...@lazygranch.com; Discussion of precise time and frequency
measurement time-nuts@febo.com
Sent: Sunday, December 09, 2012 5:21 PM
Subject: Re: [time-nuts] Switching oscillators
: Re: [time-nuts] Switching oscillators
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
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
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
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
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
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
time-nuts@febo.com
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 will always be better with a modern OCXO
than with a TCXO.
Bob
: Bob Camp li...@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
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 rate
and frequency measurement
time-nuts@febo.com
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 will always be better with a modern OCXO
than
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
Message - From: Bob Camp li...@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Sunday, December 09, 2012 7:58 PM
Subject: Re: [time-nuts] Switching oscillators
Hi
Retrace assumes that the oscillator has some normal frequency that only
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