[Difx-users] integration time

[Hagatiana Andrianomena]

Hi Adam,

Many thanks for your explanations.

Cheers,
Sam

On Sat, May 13, 2017 at 1:37 PM, Adam Deller <adeller at astro.swin.edu.au>
wrote:

> Hi Sam,
>
> Integration time will affect the maximum fringe rate you are sensitive
> to.  Shorter integrations = higher fringe rate before you lose signal due
> to decorrelation.  But normally this is not a limitation.  I would be
> fairly surprised if a 1 second integration time was a problem (unless there
> is an issue with the observing setup).
>
> Spectral resolution will affect the maximum residual delay you are
> sensitive too.  Finer spectral resolution = larger delay before you lose
> signal due to decorrelation.
>
> These are not DiFX-specific things, but general to radio interferometers /
> correlators.  To know what values are reasonable, you need to know your
> instrument and what the expected residual fringe rate and delay are.
>
> Cheers,
> Adam
>
> On 12 May 2017 at 23:59, Hagatiana Andrianomena <handrianomena at ska.ac.za>
> wrote:
>
>> Hi DiFX users,
>>
>> I got a question regarding the integration time in the setup:
>> SETUP default
>> {
>>   tInt = 1.000000
>>   fftSpecRes = 0.12500000
>>   specRes = 0.12500000
>>   doPolar = True
>>   maxNSBetweenACAvg = 2000000
>> }
>>
>> I got this default setup by running oms2v2d using the .oms file from the
>> experiment. When running the difx I got no fringe but from changing the
>> tInt to
>> 0.08 and both fftSpecRes and specRes the result seems to suggest I got
>> fringe (see plot attached).
>>
>> I am not quite sure whether it is a naive question but I wonder if there
>> is a simple rule of thumb to get the right values of those parameters in
>> order to get fringe. I do not have much experience with DiFX I must say
>> though.
>>
>> Regards,
>> Sam
>>
>> _______________________________________________
>> Difx-users mailing list
>> Difx-users at listmgr.nrao.edu
>> https://listmgr.nrao.edu/mailman/listinfo/difx-users
>>
>>
>
>
> --
> !=============================================================!
> Dr. Adam Deller
> ARC Future Fellow, Senior Lecturer
> Centre for Astrophysics & Supercomputing
> Swinburne University of Technology
> John St, Hawthorn VIC 3122 Australia
> phone: +61 3 9214 5307 <+61%203%209214%205307>
> fax: +61 3 9214 8797 <+61%203%209214%208797>
>
> office days (usually): Mon-Thu
> !=============================================================!
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listmgr.nrao.edu/pipermail/difx-users/attachments/20170513/5d189863/attachment.html>