[Difx-users] Question : What library/code is DiFX using to read VDIF files

[Stuart Weston]

>> legacy (16 byte) headers?

I think our chain (DBBC/Fila10G/Jive5ab) is producing 16byte headers.

Well when I do a dumb read (python script) to check the data I have to use 16bytes

Stuart Weston

Mobile: 021 713062

Skype: stuart.d.weston
Email:  stuart.weston at aut.ac.nz

http://www.atnf.csiro.au/people/Stuart.Weston/index.html

Software Engineer
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School of Engineering, Computer and Mathematical Sciences
Faculty of Design and Creative Technologies
Auckland University of Technology, New Zealand.

http://www.irasr.aut.ac.nz/

From: Adam Deller <adeller at astro.swin.edu.au>
Sent: Friday, 20 March 2020 2:11 PM
To: Stuart Weston <stuart.weston at aut.ac.nz>
Cc: Phillips, Chris (CASS, Marsfield) <Chris.Phillips at csiro.au>; difx-users at listmgr.nrao.edu
Subject: Re: [Difx-users] Question : What library/code is DiFX using to read VDIF files

Hi Stuart,

Is your VDIF data regular (32 byte) or legacy (16 byte) headers?  I'm pretty sure that the latter is known to be not supported by VDIFIO (a relatively simple fix, that should certainly be made at some stage...)

Cheers,
Adam

On Fri, 20 Mar 2020 at 11:54, Stuart Weston <stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>> wrote:
Thanks Adam,

I am working with some code that Willem hacked together for DSPSR using Mark5Access.

Trying to get it to use our single dish data recorded in vdif format from the DBBC/Fila10G/Jive5ab.

Paul’s code doesn’t read our vdif ☹ data

Stuart Weston

Mobile: 021 713062

Skype: stuart.d.weston
Email:  stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>

http://www.atnf.csiro.au/people/Stuart.Weston/index.html

Software Engineer
Institute for Radio Astronomy & Space Research (IRASR)
School of Engineering, Computer and Mathematical Sciences
Faculty of Design and Creative Technologies
Auckland University of Technology, New Zealand.

http://www.irasr.aut.ac.nz/

From: Adam Deller <adeller at astro.swin.edu.au<mailto:adeller at astro.swin.edu.au>>
Sent: Friday, 20 March 2020 1:50 PM
To: Stuart Weston <stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>>
Cc: Phillips, Chris (CASS, Marsfield) <Chris.Phillips at csiro.au<mailto:Chris.Phillips at csiro.au>>; difx-users at listmgr.nrao.edu<mailto:difx-users at listmgr.nrao.edu>
Subject: Re: [Difx-users] Question : What library/code is DiFX using to read VDIF files

Hi Stuart,

mpifxcorr uses mark5access to unpack VDIF samples.  The vdifio library that is also included with DiFX is quite limited - apart from what Chris already noted, I believe it doesn't support legacy VDIF.  Without any disrespect to anyone who worked on it (including me :) ) it was really a fairly quick hack to support some simple utilities.

Now, dspsr I think based some of its VDIF support code on vdifio.  Paul Demorest first made a copy of vdifio onto git - whether it ultimately became an external mirror of the vdifio hosted on SVN in DiFX or if it has branched off (and had functionality added) I'm actually not sure.

I know dspsr is capable of processing the VDIF-formatted data produced by the VLA tied array system, so I'm pretty sure that unpacking is already available in dspsr somewhere!  I'd suggest checking with Paul Demorest, since he is definitely the key person for VDIF in dspsr.

Cheers,
Adam

On Fri, 20 Mar 2020 at 10:32, Stuart Weston via Difx-users <difx-users at listmgr.nrao.edu<mailto:difx-users at listmgr.nrao.edu>> wrote:
>> If your question is a licensing one

Nope its not that.

So I take it DiFX uses Mark5access, yes ?

Stuart Weston

Mobile: 021 713062

Skype: stuart.d.weston
Email:  stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>

http://www.atnf.csiro.au/people/Stuart.Weston/index.html

Software Engineer
Institute for Radio Astronomy & Space Research (IRASR)
School of Engineering, Computer and Mathematical Sciences
Faculty of Design and Creative Technologies
Auckland University of Technology, New Zealand.

http://www.irasr.aut.ac.nz/

From: Phillips, Chris (CASS, Marsfield) <Chris.Phillips at csiro.au<mailto:Chris.Phillips at csiro.au>>
Sent: Friday, 20 March 2020 11:43 AM
To: Stuart Weston <stuart.weston at aut.ac.nz<mailto:stuart.weston at aut.ac.nz>>
Cc: difx-users at listmgr.nrao.edu<mailto:difx-users at listmgr.nrao.edu>
Subject: Re: [Difx-users] Question : What library/code is DiFX using to read VDIF files

Hi Stuart



Just wondering if we can use the DiFX VDIF library/code instead ?


It is not clear what your question actually is.

The initial VDIFIO library I wrote had *no* sampling unpacking routines. Others may had added some, I am not sure. Without that the answer would be essentially be no. VDIFIO is in no way a plug in replacement for mark5access.

If your question is a licensing one, then yes as all of DFIX is GPLv3 now.

Cheers
Chris
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--
!=============================================================!
A/Prof. Adam Deller
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Centre for Astrophysics & Supercomputing
Swinburne University of Technology
John St, Hawthorn VIC 3122 Australia
phone: +61 3 9214 5307
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office days (usually): Mon-Thu
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--
!=============================================================!
A/Prof. Adam Deller
ARC Future Fellow
Centre for Astrophysics & Supercomputing
Swinburne University of Technology
John St, Hawthorn VIC 3122 Australia
phone: +61 3 9214 5307
fax: +61 3 9214 8797

office days (usually): Mon-Thu
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