0000291: The problem on 6X,6Y,7X,7Y in Band7
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ID Category Severity Reproducibility Date Submitted Last Update
0000291 [DZB] 0.unknown/unspecified major sometimes 17-09-10 11:35 24-01-12 14:02
Reporter Yuan Tang View Status public  
Assigned To Sjouke Zwier
Priority normal Resolution fixed  
Status resolved  
Summary 0000291: The problem on 6X,6Y,7X,7Y in Band7
Description The problem appeared on 6X,6Y,7X,7Y in Band7:
  It happened at 6cm and 21cm.
  The Ampls of 6X6X,6Y6Y,7X7X,7Y7Y are unstable in band7.
(It seems to me it might come from the backend, a local RFI nearby 6X,6Y,7X,7Y?
or from a unit which is shared by 6X,6Y,7X,7Y?)

From Hans van der Marel:

Hi Yuan,

The autocorrelations of 6x, 6y, 7x, 7y band 7 are not stable and sometimes drop out (almost) completely. My guess is that it is due to an ADC board with some problem, but it can also be a link problem between ADC and correlator.

Did you try to reboot the correlator? If it is a link synchronization problem rebooting can resolve it. If this doesn't work, Hans Weggemans has something to look at next week.

Cheers,

Hans
Additional Information 20100922:
According the suggestion from Hans van der Marel the following things have been done:
  (1) rebooting the DZB and made a test observation, but the problem is still there,
       so the problem doesn't come from the link between ADC and correlator.
  (2) The ADC board of band7 has been swapped with band6, then made a test observation,
       but the problem is still in band7. So it also not comes from the ADC.
  (3) What is the next step?
nr subbands 1
nr polarisations
nr channels
bandwidth
multi-subarray no
recirculation no
Attached Files

- Relationships

- Notes
(0000307)
Hans Weggemans
09-11-10 14:34

 controlboard band6 en band7 onderling verwisseld.
slechte clock op adc ??
 
(0000317)
Yuan Tang
23-11-10 09:59

 20101123:
The problem on the 6X,6Y,7X,7Y at band7 is still there:
The Ampls of 6X*X,6Y*Y,7X*X,7Y*Y are unstable and drop out quite often, which
can be seen at all frequencies, eg. 6cm,13cm,21cm,92cm.
(The problem doesn't come from the link between the ADC and the Correlator, and
also not come from the ADC according the test done before.)
 
(0000322)
Yuan Tang
14-12-10 13:09

 20101214
To locate the problem the DDU Presel Board1 has been swapped with
the DDU Presel Board0.
 

- Issue History
Date Modified Username Field Change
17-09-10 11:35 Yuan Tang New Issue
17-09-10 11:35 Yuan Tang nr subbands  => 1
17-09-10 11:35 Yuan Tang multi-subarray  => no
17-09-10 11:35 Yuan Tang recirculation  => no
17-09-10 11:36 Yuan Tang Assigned To  => Hans Weggemans
17-09-10 11:36 Yuan Tang Status new => assigned
22-09-10 11:23 Yuan Tang Additional Information Updated
09-11-10 14:34 Hans Weggemans Note Added: 0000307
09-11-10 14:34 Hans Weggemans Status assigned => testing
23-11-10 09:59 Yuan Tang Note Added: 0000317
23-11-10 09:59 Yuan Tang Status testing => assigned
14-12-10 13:09 Yuan Tang Note Added: 0000322
08-02-11 10:52 Harm Munk Assigned To Hans Weggemans => Sjouke Zwier
24-01-12 14:02 Sjouke Zwier Status assigned => resolved
24-01-12 14:02 Sjouke Zwier Resolution open => fixed