Subject: [IGSMAIL-3398]: Yellowknife Maser Problem (fwd)
From: Jim Ray (USNO 202-762-1444) <[email-masked]>
To: [email-masked]
Date: Wed, 27 Jun 2001 8:37:48 EDT

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IGS Electronic Mail      27 Jun 05:37:50 PDT 2001      Message Number 3398
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Author: Irv Diegel (forwarded by Jim Ray)

Forwarded message:

From: "Diegel, Irvin F." <[email-masked]>
Subject: Yellowknife Maser Problem During CC102
Date: Wed, 27 Jun 2001 07:58:39 -0400

To All,

Due to a power outage and defective backup batteries in the NR13 maser at
Yellowknife, there will be some maser frequency instabilities during the
CC102 observation.

According to Bill Outhwaite at Yellowknife, the power went out at
approximately 171.20:06. At this time, the maser microprocessor glitched,
causing the cavity register to assume an arbitrary value which caused the
cavity to cool, thus lowering the frequency of the maser. From the time of
the power failure until approximately 172.16:30, the maser would have
exhibited a high negative drift as the frequency decreased. The drift will
not be constant over this 20 hour period since at some point, the
temperature servo would have regained control.

Then, at approximately 171.16:30, the site personnel reset the maser
microprocessor, re-entering the proper cavity register number. This will
have caused the frequency to start increasing at some high rate, probably
through the end of the observation.

It is also possible, but not certain, that there was a time position step of
the 1PPS maser pulse with reference to GPS. As the Yellowknife site does not
use the standard TAC GPS time interval measurement system, it is hard to
determine at this time. However, as I viewed the "setcl" plot for this
observation, there is definitely some activity which would indicate a time
step.

The Yellowknife and Algonquin masers are monitored continuously in Ottawa.
Plots of the Yellowknife performance for the above period can be viewed at:

http://www2.geod.nrcan.gc.ca/~lahaye/macsd/weekly/yell.html

As these plots are updated weekly, it may be prudent to download them now if
they would be of value. I have attached two of the plots to this message.

If I can be of further assistance, please do not hesitate to contact me.

Irv Diegel
Honeywell Technology Solutions, Inc.

[Note: The attached gif plots have been removed but can be viewed at the
 URL above.]