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Re: [time-nuts] Holdover: Z3801A vs KS-24361

HM
Hal Murray
Sun, Apr 15, 2018 10:59 AM

A  KS-24361 says:
Predict  394.1 us/initial 24 hrs

That would suggest the unit is unlocked. It should be below 10 us. Just as
with the 3801, the estimate is a bit fuzzy. You should be able to see issues
in the data on the Z3809/Z3810.

It says it is locked and has been locked for days.

Locked to GPS      TFOM    3      FFOM    0

I used this as a learning exercise for my new TICC.  Something is clearly
fishy.

The reference for the TICC is the crystal in a HP 5334B with the good-crystal
option.  It's not calibrated, but there isn't any GPS logic to jerk it
around.  I assume the swing is due to temperature.  I corrected the slope of
the graph by hand.

Here is a day+ of data:
http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS.png

Here is a zoomed in chunk:
http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS-2.png

--
These are my opinions.  I hate spam.

kb8tq@n1k.org said: >> A KS-24361 says: >> Predict 394.1 us/initial 24 hrs > That would suggest the unit is unlocked. It should be below 10 us. Just as > with the 3801, the estimate is a bit fuzzy. You should be able to see issues > in the data on the Z3809/Z3810. It says it is locked and has been locked for days. >> Locked to GPS TFOM 3 FFOM 0 I used this as a learning exercise for my new TICC. Something is clearly fishy. The reference for the TICC is the crystal in a HP 5334B with the good-crystal option. It's not calibrated, but there isn't any GPS logic to jerk it around. I assume the swing is due to temperature. I corrected the slope of the graph by hand. Here is a day+ of data: http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS.png Here is a zoomed in chunk: http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS-2.png -- These are my opinions. I hate spam.
BK
Bob kb8tq
Sun, Apr 15, 2018 2:01 PM

Hi

There isn’t much you can really see on a GPSDO comparing it to a normal OCXO.
The OCXO simply is not accurate enough. You need something like a Cs standard,
a different GPSDO, or a good Rb for the reference. (Yes, if you have a hydrogen
maser, you can use that ….).

First thing to check is the DAC readings on the unit ….

Bob

On Apr 15, 2018, at 6:59 AM, Hal Murray hmurray@megapathdsl.net wrote:

kb8tq@n1k.org said:

A  KS-24361 says:
Predict  394.1 us/initial 24 hrs

That would suggest the unit is unlocked. It should be below 10 us. Just as
with the 3801, the estimate is a bit fuzzy. You should be able to see issues
in the data on the Z3809/Z3810.

It says it is locked and has been locked for days.

Locked to GPS      TFOM    3      FFOM    0

I used this as a learning exercise for my new TICC.  Something is clearly
fishy.

The reference for the TICC is the crystal in a HP 5334B with the good-crystal
option.  It's not calibrated, but there isn't any GPS logic to jerk it
around.  I assume the swing is due to temperature.  I corrected the slope of
the graph by hand.

Here is a day+ of data:
http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS.png

Here is a zoomed in chunk:
http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS-2.png

--
These are my opinions.  I hate spam.

Hi There isn’t much you can really see on a GPSDO comparing it to a normal OCXO. The OCXO simply is not accurate enough. You need something like a Cs standard, a different GPSDO, or a good Rb for the reference. (Yes, if you have a hydrogen maser, you *can* use that ….). First thing to check is the DAC readings on the unit …. Bob > On Apr 15, 2018, at 6:59 AM, Hal Murray <hmurray@megapathdsl.net> wrote: > > > kb8tq@n1k.org said: >>> A KS-24361 says: >>> Predict 394.1 us/initial 24 hrs >> That would suggest the unit is unlocked. It should be below 10 us. Just as >> with the 3801, the estimate is a bit fuzzy. You should be able to see issues >> in the data on the Z3809/Z3810. > > It says it is locked and has been locked for days. >>> Locked to GPS TFOM 3 FFOM 0 > > I used this as a learning exercise for my new TICC. Something is clearly > fishy. > > The reference for the TICC is the crystal in a HP 5334B with the good-crystal > option. It's not calibrated, but there isn't any GPS logic to jerk it > around. I assume the swing is due to temperature. I corrected the slope of > the graph by hand. > > Here is a day+ of data: > http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS.png > > Here is a zoomed in chunk: > http://users.megapathdsl.net/~hmurray/time-nuts/TICC/TICC-KS-2.png > > > -- > These are my opinions. I hate spam. > > >