[fitsbits] Bintable proposals

[Arnold Rots]

I think the alternative provided by Bill Cotton is far more
attractive: make bintables of fixed length.  Start a new table every
10,000/100,000/1,000,000 rows, keep them all as extensions in the same
file, and you have essentially your variable length table - just with
headers interspersed at regular intervals.

  - Arnold

Mike Nolan wrote:
> 
> > 
> > Assertions that the FITS data format is not suitable for real-time use
> > have been made repeatedly over the 22_year history of FITS. 
> > 
> > I do not agree with these assertions.
> >
> > ... 
> >
> > It is important to note that 'using a disk as intermediary' in a
> > real-time data acquisition system is a practical and effective solution
> > for the NAXIS2 problem in the majority of cases today.
> 
> We are using a system that buffers data to disk then writes to 2 DLTs,
> and sustains a data rate of 10 MB/s. I like it: The tapes can't quite
> keep up, but they always have data available to write, avoiding some
> weird behaviors, and the disk slowly fills (over hours).  The data
> aren't FITS, but the probably should be. The main users don't keep the
> data once they've done their processing, so they're not too concerned
> with an exportable format.
> 
> However, I don't think it's really reasonable to have your data format
> dictate hardware, particularly when the data rates get close to the
> edge: if we could sample faster, we would, and that will be true for
> another factor of 20 in speed. We're getting to the point where our
> desired data rates are comparable to the memory bus speed on a
> reasonable computer, and the second pass through the system (disk to
> tape) would be a problem.  I think that problem has been true in the
> past as well, but not for the past few years.
> 
> I am under the impression that Parkes has a similar system with more
> samplers (and thus a higher data rate).
> 
> Now if we could get somebody to put raw VLBA data into FITS format, that
> would help me immensely...
> 
> -Mike
> 
> 
> ---------------------------
> Mike Nolan <nolan at naic.edu>
> +1 787 878 2612x334  Fax: +1 787 878 1861
> Arecibo Observatory / Cornell University
> HC03 Box 53995, Arecibo, Puerto Rico 00612  USA
> _______________________________________________
> fitsbits mailing list
> fitsbits at nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/fitsbits
> 

--------------------------------------------------------------------------
Arnold H. Rots                                Chandra X-ray Science Center
Smithsonian Astrophysical Observatory                tel:  +1 617 496 7701
60 Garden Street, MS 81                              fax:  +1 617 495 7356
Cambridge, MA 02138                             arots at head-cfa.harvard.edu
USA                                     http://hea-www.harvard.edu/~arots/
--------------------------------------------------------------------------