[Difx-users] Lack of mixed-mode fringes with 2.6.3, then segfault with 2.8.1? {External} {External}

[Adam Deller]

Hey Eskil,

Have you tried vex2difx -v -v and/or valgrind vex2difx to see where the
segfault is occurring?  Obviously, it shouldn't be segfaulting, so
presumably finding that and fixing it should go a fair way towards solving
the problem.

Cheers,
Adam

On Sat, 12 Aug 2023 at 04:22, Eskil Varenius via Difx-users <
difx-users at listmgr.nrao.edu> wrote:

> Dear Difx-users,
>
>
>
> Background: I have mixed-mode continuum data from 3 stations: Ns(16 MHz
> VDIF), Ny(16 MHz M5B), Nn 32 MHz VDIF). Ns and Ny observe standard S/X with
> R-pol only, and Nn (VGOS) observe dual linear X/Y (strictly speaking H/V
> but I'm using X/Y here since that's the VEX labels). Correlating Ns-Ny
> baseline with DiFX 2.6.3, is all good. I use zoom windows (to get 16 MHz
> from all stations) and FreqId selection (to only correlate X-band and skip
> S-band channels). But when trying to correlate all three stations I run
> into problems.
>
>
>
> Problem 1: With DiFX 2.6.3 I can correlate all three stations, and then
> run difx2mark4. Fourfit then gives me nice fringes on the Ns-Ny baseline
> (R-R pol), and the Ns-Nn baseline (RX and RY pol). But while I do get nice
> XR fringes on the Nn-Ny baseline, I do not get any YR fringes on this
> baseline. I know the data are good, since I get fringes to these
> polarisations on another baseline. So I suspect I have fallen into the
> "Warning: Limited support for mixed-mode..." here, or do you have other
> suggestions?
>
>
>
> I saw there are improvements for mixed-mode in DiFX 2.8.1, so I decided to
> try it, but:
>
>
>
> Problem 2: With DiFX 2.8.1, I get "segfault" when I run ”vex2difx” (this
> worked with 2.6.3). Any ideas?
>
>
>
> I guess hunting the "segfault in 2.8.1" is the most profitable route for
> the future? If so, please let me know what info you may need to speculate
> further. I am happy to share output, v2d, vex, and even raw data for one
> scan for someone to reproduce this if you would be so kind to help.
>
>
>
> I am very puzzled by this!
>
>
>
> Kind regards
>
> Eskil
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> Difx-users at listmgr.nrao.edu
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>


-- 
!=============================================================!
Prof. Adam Deller
Centre for Astrophysics & Supercomputing
Swinburne University of Technology
John St, Hawthorn VIC 3122 Australia
phone: +61 3 9214 5307
fax: +61 3 9214 8797
!=============================================================!
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