Empathy List Archives

RR

Russ Ramirez

Wed, Jan 23, 2013 4:48 PM

Greetings,

I have been reading what I can find on Rubidium and GPSDO approaches, but
there are some fine points that do not make it clear which is the best
'bang for the buck' solution. My requirement/desire is to have a 10 MHz
standard for my lab that I can trust to an accuracy of 7 decimal places (10
ppb?), so anything that is good to a few ppb is certainly adequate for what
I am looking for. I have a OCXO unit that is voltage adjustable - for
example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V.

So the simple (maybe) question is, should I go for a Rubidium disciplined
unit, or go with a home-brew GPSDO solution using the Vectron OCXO I
already have? My main cause of confusion is ignorance concerning all the
GPS solutions out there with 1pps outputs, to use in a GPSDO, and which
ones jitter too much to be useful (solutions under $50 exist).

Thanks in advance.

Russ
K0WFS

Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal places (10 ppb?), so anything that is good to a few ppb is certainly adequate for what I am looking for. I have a OCXO unit that is voltage adjustable - for example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V. So the simple (maybe) question is, should I go for a Rubidium disciplined unit, or go with a home-brew GPSDO solution using the Vectron OCXO I already have? My main cause of confusion is ignorance concerning all the GPS solutions out there with 1pps outputs, to use in a GPSDO, and which ones jitter too much to be useful (solutions under $50 exist). Thanks in advance. Russ K0WFS

MD

Magnus Danielson

Wed, Jan 23, 2013 7:17 PM

Russ,

Welcome!

On 01/23/2013 05:48 PM, Russ Ramirez wrote:

Greetings,

I have been reading what I can find on Rubidium and GPSDO approaches, but
there are some fine points that do not make it clear which is the best
'bang for the buck' solution. My requirement/desire is to have a 10 MHz
standard for my lab that I can trust to an accuracy of 7 decimal places (10
ppb?), so anything that is good to a few ppb is certainly adequate for what
I am looking for. I have a OCXO unit that is voltage adjustable - for
example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V.

So the simple (maybe) question is, should I go for a Rubidium disciplined
unit, or go with a home-brew GPSDO solution using the Vectron OCXO I
already have? My main cause of confusion is ignorance concerning all the
GPS solutions out there with 1pps outputs, to use in a GPSDO, and which
ones jitter too much to be useful (solutions under $50 exist).

Thanks in advance.

A rubidium or GPSDO such as Thunderbolt can be found fairly cheaply.
If you go for a Thunderbolt, get one with antenna as a kit, mostly
because it is a handy way to get started. For better stability you can
get a better antenna later, if the need would occur.

The rubidium should give you the precision you need straight out of the
box, unless it has "issues". In order to control if it has issues,
having the ability to at least compare to GPS becomes obvious, so you
end up wanting that GPSDO anyway. You can get both for reachable money
anyway, if you look around long enough.

Doing a home-cooked GPSDO is fun naturally, and there is an art in
low-budget designs giving fair amount of performance.

Cheers,
Magnus

Russ, Welcome! On 01/23/2013 05:48 PM, Russ Ramirez wrote: > Greetings, > > I have been reading what I can find on Rubidium and GPSDO approaches, but > there are some fine points that do not make it clear which is the best > 'bang for the buck' solution. My requirement/desire is to have a 10 MHz > standard for my lab that I can trust to an accuracy of 7 decimal places (10 > ppb?), so anything that is good to a few ppb is certainly adequate for what > I am looking for. I have a OCXO unit that is voltage adjustable - for > example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V. > > So the simple (maybe) question is, should I go for a Rubidium disciplined > unit, or go with a home-brew GPSDO solution using the Vectron OCXO I > already have? My main cause of confusion is ignorance concerning all the > GPS solutions out there with 1pps outputs, to use in a GPSDO, and which > ones jitter too much to be useful (solutions under $50 exist). > > Thanks in advance. A rubidium or GPSDO such as Thunderbolt can be found fairly cheaply. If you go for a Thunderbolt, get one with antenna as a kit, mostly because it is a handy way to get started. For better stability you can get a better antenna later, if the need would occur. The rubidium should give you the precision you need straight out of the box, unless it has "issues". In order to control if it has issues, having the ability to at least compare to GPS becomes obvious, so you end up wanting that GPSDO anyway. You can get both for reachable money anyway, if you look around long enough. Doing a home-cooked GPSDO is fun naturally, and there is an art in low-budget designs giving fair amount of performance. Cheers, Magnus

CA

Chris Albertson

Wed, Jan 23, 2013 7:31 PM

No question, You want a GPSDO.

Yes you can buy a Rb or a high-end OCXO but neither of these is
connected to any kind of standard and will need to be calibrated to be
of use. The GPS serves as a "standard" and you need that before the
other options.

The next question is "which GPSDO?" For most people that would be a
Thunderbolt but the prices are going up on those. Then you will need
a good antenna installation.

On Wed, Jan 23, 2013 at 8:48 AM, Russ Ramirez russ.ramirez@gmail.com wrote:

Greetings,

I have been reading what I can find on Rubidium and GPSDO approaches, but
there are some fine points that do not make it clear which is the best
'bang for the buck' solution. My requirement/desire is to have a 10 MHz
standard for my lab that I can trust to an accuracy of 7 decimal places (10
ppb?), so anything that is good to a few ppb is certainly adequate for what
I am looking for. I have a OCXO unit that is voltage adjustable - for
example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V.

So the simple (maybe) question is, should I go for a Rubidium disciplined
unit, or go with a home-brew GPSDO solution using the Vectron OCXO I
already have? My main cause of confusion is ignorance concerning all the
GPS solutions out there with 1pps outputs, to use in a GPSDO, and which
ones jitter too much to be useful (solutions under $50 exist).

Thanks in advance.

Russ
K0WFS

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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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--

Chris Albertson
Redondo Beach, California

No question, You want a GPSDO. Yes you can buy a Rb or a high-end OCXO but neither of these is connected to any kind of standard and will need to be calibrated to be of use. The GPS serves as a "standard" and you need that before the other options. The next question is "which GPSDO?" For most people that would be a Thunderbolt but the prices are going up on those. Then you will need a good antenna installation. On Wed, Jan 23, 2013 at 8:48 AM, Russ Ramirez <russ.ramirez@gmail.com> wrote: > Greetings, > > I have been reading what I can find on Rubidium and GPSDO approaches, but > there are some fine points that do not make it clear which is the best > 'bang for the buck' solution. My requirement/desire is to have a 10 MHz > standard for my lab that I can trust to an accuracy of 7 decimal places (10 > ppb?), so anything that is good to a few ppb is certainly adequate for what > I am looking for. I have a OCXO unit that is voltage adjustable - for > example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V. > > So the simple (maybe) question is, should I go for a Rubidium disciplined > unit, or go with a home-brew GPSDO solution using the Vectron OCXO I > already have? My main cause of confusion is ignorance concerning all the > GPS solutions out there with 1pps outputs, to use in a GPSDO, and which > ones jitter too much to be useful (solutions under $50 exist). > > Thanks in advance. > > Russ > K0WFS > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California

CA

Chris Albertson

Wed, Jan 23, 2013 7:48 PM

.... My requirement/desire is to have a 10 MHz
standard for my lab that I can trust to an accuracy of 7 decimal places

At 10,000,000 Hz your required accuracy is 1Hz. You can get to that
level by "zero beating" to WWV. This is very inexpensive, free if you
already have a radio. What you do is adjust the frequency of any
local oscillator until the beat frequency with WWV is greater then one
Hz. You can either listen or use a scope

Most people here are wanting 10 to 13 digits and that requires more
work but 7 digitas is "way easy". That said you might just as well
get the GPS which gives about 13 digits over a longish measurement
period. But if you are looking for the lowest cost way to get to 1Hz
the old methods will do that.
In fact you can zero-beat any radio station that has a known
frequency. All comercial braodcast stations are good enough but WWV
just happens to use a "round number" carrier freq.

--

Chris Albertson
Redondo Beach, California

>>.... My requirement/desire is to have a 10 MHz >> standard for my lab that I can trust to an accuracy of 7 decimal places At 10,000,000 Hz your required accuracy is 1Hz. You can get to that level by "zero beating" to WWV. This is very inexpensive, free if you already have a radio. What you do is adjust the frequency of any local oscillator until the beat frequency with WWV is greater then one Hz. You can either listen or use a scope Most people here are wanting 10 to 13 digits and that requires more work but 7 digitas is "way easy". That said you might just as well get the GPS which gives about 13 digits over a longish measurement period. But if you are looking for the lowest cost way to get to 1Hz the old methods will do that. In fact you can zero-beat any radio station that has a known frequency. All comercial braodcast stations are good enough but WWV just happens to use a "round number" carrier freq. -- Chris Albertson Redondo Beach, California

BC

Bob Camp

Wed, Jan 23, 2013 7:48 PM

Hi

Not to pick nits, but 7 decimal places at what input frequency? Seven places
is 10 ppb at 10 MHz. If the input was 100 MHz, it would be 1 ppb.

The distinction is significant, since it crosses a boundary. At 10 ppb a
free running Rb is fine with no adjustments. At 1 ppb, some adjustment might
be needed.

You might also want a standard that's 5X better than the expected result.
That would get you into the 2 to 0.2 ppb range.

Lots of fiddly little details...

Bob

-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of Russ Ramirez
Sent: Wednesday, January 23, 2013 11:48 AM
To: time-nuts@febo.com
Subject: [time-nuts] Least costly 10 MHz reference solution

Greetings,

I have been reading what I can find on Rubidium and GPSDO approaches, but
there are some fine points that do not make it clear which is the best
'bang for the buck' solution. My requirement/desire is to have a 10 MHz
standard for my lab that I can trust to an accuracy of 7 decimal places (10
ppb?), so anything that is good to a few ppb is certainly adequate for what
I am looking for. I have a OCXO unit that is voltage adjustable - for
example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V.

So the simple (maybe) question is, should I go for a Rubidium disciplined
unit, or go with a home-brew GPSDO solution using the Vectron OCXO I
already have? My main cause of confusion is ignorance concerning all the
GPS solutions out there with 1pps outputs, to use in a GPSDO, and which
ones jitter too much to be useful (solutions under $50 exist).

Thanks in advance.

Russ
K0WFS

time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Hi Not to pick nits, but 7 decimal places at what input frequency? Seven places is 10 ppb at 10 MHz. If the input was 100 MHz, it would be 1 ppb. The distinction is significant, since it crosses a boundary. At 10 ppb a free running Rb is fine with no adjustments. At 1 ppb, some adjustment might be needed. You might also want a standard that's 5X better than the expected result. That would get you into the 2 to 0.2 ppb range. Lots of fiddly little details... Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of Russ Ramirez Sent: Wednesday, January 23, 2013 11:48 AM To: time-nuts@febo.com Subject: [time-nuts] Least costly 10 MHz reference solution Greetings, I have been reading what I can find on Rubidium and GPSDO approaches, but there are some fine points that do not make it clear which is the best 'bang for the buck' solution. My requirement/desire is to have a 10 MHz standard for my lab that I can trust to an accuracy of 7 decimal places (10 ppb?), so anything that is good to a few ppb is certainly adequate for what I am looking for. I have a OCXO unit that is voltage adjustable - for example, adjusting this to 10.0000000 MHz per my HP 5334A requires -12.71V. So the simple (maybe) question is, should I go for a Rubidium disciplined unit, or go with a home-brew GPSDO solution using the Vectron OCXO I already have? My main cause of confusion is ignorance concerning all the GPS solutions out there with 1pps outputs, to use in a GPSDO, and which ones jitter too much to be useful (solutions under $50 exist). Thanks in advance. Russ K0WFS _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.

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Least costly 10 MHz reference solution