[time-nuts] FE-5680A Mechanical Question
EWKehren at aol.com
EWKehren at aol.com
Fri Jan 13 17:59:12 UTC 2012
we would be talking +- one step and using different rate but reading the
frequency over 1000 seconds would be my answer. Start at 1 1 Hz rate and
observe the lock indicator. At the same time measure frequency.
Bert Kehren
In a message dated 1/13/2012 12:52:16 P.M. Eastern Standard Time,
lists at rtty.us writes:
Hi
Another thing that would need to be investigated - How fast (and how
uniformly) does it respond to a frequency set command. If you dither, you
care about how long it's at this or that frequency. Measuring 7x10^-13
frequency shifts on the unit probably isn't the best way to check that out
....
Bob
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of EWKehren at aol.com
Sent: Friday, January 13, 2012 6:20 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] FE-5680A Mechanical Question
What we know is that you can set the Rb in 7 E-13. Dithering would allow
even closer setting, the question is what rate will the Rb accept with out
loosing lock or deterioration of the performance. Some one should explore
that. I am still waiting to se some aging. Taking the 10 MHz output and
than
use an analog loop and something like a Morion OCXO and you have the best
of
all.
Digitally controlling the Rb will cut the cost of the control loop in
half.
For $10 in parts and a PC board for less than $10 using Shera like
controller can be realized. What is needed is some one able to do the PIC.
If some one is interested and able, please contact me off list. A low cost
GPS or a 1 pps output of a Tbolt be perfect source.
Bert Kehren
In a message dated 1/12/2012 12:20:15 P.M. Eastern Standard Time,
lists at rtty.us writes:
Hi
I think it would be worth the effort to try dithering the DDS commands
into
the Rb while measuring ADEV. You *might* find that you can do it with
little
or no impact on the unit's stability. If so it takes out some modification
effort and should make the controller cheaper.
Bob
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of EWKehren at aol.com
Sent: Thursday, January 12, 2012 10:43 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] FE-5680A Mechanical Question
Bringing out the C field in my estimation does not effect long or short
term. External magnetic field I think is a joke. An other option is a
loop
that generates a tuning word for the DDS but that means your steps are 7
E-13.
Bert Kehren
In a message dated 1/12/2012 10:34:10 A.M. Eastern Standard Time,
davidwhess at gmail.com writes:
I was more interested in the technical details of how to adjust the
output of a RbO without sacrificing the short and long term stability.
I have seen a few designs that used a DDS to generate the 10 MHz
output which lends itself to this but they all suffer from DDS and
tuning noise. I see now that the RbO can be adjusted with an external
magnetic field.
On Thu, 12 Jan 2012 07:34:44 -0600, "J. L. Trantham" <jltran at att.net>
wrote:
>David,
>
>I have been following discussions on the list about a GPSDRbO for a
year
or
>so. Some interesting challenges and probably best implemented in a
'stable'
>environment rather than portable operation but as best I can tell, it
would
>require a very stable and good antenna location, stable and clean
power,
and
>I was thinking of using something like an LPRO-101 with an Ext C Field
>input, a Shera type controller, and a GPS timing receiver, though, I
suspect
>there are likely to be some 'multi-tasking' receivers out there that
will
>look at several sources including GPS, GLOSNASS, etc.
>
>While the project might be fun, for portable work, it is likely far
easier
>and probably just as good (almost), to use a Tbolt.
>
>In any event, something to think about for the future.
>
>Joe
>
>-----Original Message-----
>From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>Behalf Of David
>Sent: Wednesday, January 11, 2012 11:12 PM
>To: Discussion of precise time and frequency measurement
>Subject: Re: [time-nuts] FE-5680A Mechanical Question
>
>
>How would a GPSDRbO work? Phase lock the DDS output to the GPS? Phase
lock
>a VCXO to the GPS and then phase lock to the RbO on loss of GPS lock?
>
>On Wed, 11 Jan 2012 22:55:58 -0600, "J. L. Trantham" <jltran at att.net>
>wrote:
>
>>Bill, Brian, Bill, and Peter,
>>
>>Thanks for the info. All I need now is a 'project' to incorporate the
>>unit into.
>>
>>In the back of my mind, I have the thought of a 'box' that will be
>>battery powered or 110 VAC powered (perhaps with an internal SLA
>>battery) and include a GPSDO and Rb unit (possibly a GPSDRbO) for the
>>purpose of a 'reference' for portable operation in the microwave
>>regions.
>
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