From: <Brett.Reid_at_email.protected>
Date: Wed, 09 May 2012 22:10:37 +1000

Hi All,
Sorry if you already have this.
I thought I would circulate it widely amongst our Australian VLBI groups
such as AuScope stations/observers and the LBA. Jamie or Jim would
probably update, as necessary, the AuScope VLBI observers wiki for the
exact procedure we should follow when encountering Mark5B recording
problems. Maybe we had this problem during LBA astronomy week at
Katherine and Yarragadee recently requiring the premature module changes.
Regards,
Brett.

-------- Original Message --------
Subject: [IVS-stations] Mark 5B/B+ ",E" scan_check problem, version 2
Date: Tue, 08 May 2012 15:43:25 -0400
From: Ed Himwich <Ed.Himwich_at_nasa.<!--nospam-->gov>
To: pcfs_at_ivscc.<!--nospam-->gsfc.nasa.gov <pcfs_at_ivscc.<!--nospam-->gsfc.nasa.gov>
CC: ivs-stations_at_ivscc.<!--nospam-->gsfc.nasa.gov <ivs-stations_at_ivscc.<!--nospam-->gsfc.nasa.gov>,
EVNTech <EVNTech_at_jb.<!--nospam-->man.ac.uk>

To: Stations with Mark 5B/5B+ Recorders

From: Ed Himwich, Dan Smythe, and Rich Strand

Date: 8 May 2012

Re: Mark 5B/B+ recorder ",E" errors from "scan_check"

INTRODUCTION

It has been recently noticed with Mark 5B/5B+ recorders that sometimes a
",E" occurs at the end of the "scan_check" response. This indicates a
problem with the data format on the disk. It is not entirely understood
what causes this problem, but when it occurs, the scan with the error is
unusable. If it occurs all the time, corrective action is needed. We
list below steps to take to deal with this problem if it occurs at your
station.

Please be aware that once this error occurs persistently on a module, it
is not safe to record any more data on that module. Set the module
aside, appropriately labeled, and in its place use an empty module that
has been erased/condition in your recorder.

After changing modules, you should test with the new module using the
following "recscan" procedure, which you can place in your station
procedure library.

   "recscan
   disk_record=on
   !+9s
   disk_record=off
   !+1s
   scan_check

The next section gives a complete procedure for recovery.

RECOVERY PROCEDURE

If the ",E" error is occurring persistently, please take the following
actions:

(1) Halt the schedule:

       disk_record=off
       halt

     When there is a problem with any Mark 5 Recorder, it is rarely
     helpful to terminate the FS. It's not good to halt the schedule
     or terminate the FS while recording, you will fill the disk. The FS
     will try to prevent you from terminating while recording, but it
     won't try to stop you from halting the schedule while recording,
     so please try to avoid that.

(2) Remove the module that is having the error and label it
     appropriately.

(3) Insert an empty module in this recorder, preferably already
     erased/conditioned.

(4) Please make sure the new module is the one selected for recording.
     If not, use "mk5=bank_set=inc;" to change which is selected.

(5) Once you have verified that the new module has been selected, erase
     it with:

       mk5=protect=off
       mk5=reset=erase

     (standard procedure for any fresh Mark 5 module)

(6) Test the new module with (see INTRODUCTION section above):

       recscan

(7) If the scan_check from (6) does not show the ",E" error, the problem
     is probably resolved.

(8) After verifying, again, that the new module that you used in step
     (6) is selected, erase this new module:

       mk5=protect=off
       mk5=reset=erase

(9) If the problem was resolved in step (7), you can rejoin the
     schedule at the next opportunity using the "schedule=..." command.
     Do not use the "CONT" command since this will attempt to observe
     the scans you missed since you entered "halt". You can (should) use
     the new module that you used for step (6) and erased in step (8) to
     continue the schedule.

     If the problem was not resolved, please contact us. You can try a
     complete restart of the Mark 5 with a power cycle to see if that
     helps. You can also try another new module.

(10) Unless the module that was in use when the problem was originally
      discovered is bound for correlation at JIVE, it can be erased and
      reused if all the scans on it had the error. Any module going to
      JIVE should be not be erased and should be sent there regardless
      of whether all scans have the ",E' error or not. If there are some
      scans on the module without the error, it should be sent for
      correlation regardless of where it is going.

ADDITIONAL NOTES

If you have this problem, please send us an e-mail to let us know that
it happened and how it was resolved. This will help us to develop a
better understanding of the problem.

One action that may cause this error is to sync or set the time in the
Mark 5B while it is recording. Please try avoid to doing that. When you
e-mail a report about your recovery, please let us know if there was any
activity before the error occurred, such as setting the time while
recording, that we might be able to relate to the occurrence of this
problem.

The next version of the FS will generate an error message when ",E"
occurs in "scan_check".
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Received on 2012-05-09 22:11:28