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noise.lag0 and noise.vel in fitacf-format files #570
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@egthomas , from years ago my recollection is that there was some serious technical problem with removing the existing fields, but I never knew the exact details. I think then we were talking about removing fields related to XFC power fitting. |
@pasha-ponomarenko I removed all the unused XCF fields for |
Gee, I am getting senile! 🤔 |
On a somewhat related note, I just realized that grid (and map) files use the |
Yep, this is probably a better solution. I was always uneasy with using the search noise level in conjunction with FITACF data as its magnitude is established using a very different algorithm and much shorter integration time. I believe that originally there was some magic scaling coefficient applied to make the search noise compatible with that estimated from low-power ACFs. |
@pasha-ponomarenko thanks for the response - I've just opened a pull request to change the underlying library to use the sky noise value rather than the search noise. (I haven't yet had the time to examine removing the |
@egthomas, do you know how the noise level is utilised in gridding/mapping routines? I can only see that it is copied into the respective file formats. |
@pasha-ponomarenko as far as I can tell, the noise values recorded in the grid files are only for informative purposes and not used in any subsequent processing algorithms (eg Map Potential, or even plotting). |
Thanks, @egthomas , this was my impression too: just to maintain consistency between the formats. |
I have been trying to better educate myself on the different noise parameters in the
rawacf
andfitacf
format files, and was wondering about thenoise.lag0
andnoise.vel
fields infitacf
files. As far as I can tell, these fields were populated by older versions of FITACF via thenoise_acf
function, which was removed from FITACF following discussions at the 2006 SD workshop, eg:and
(and likely influenced by the work of Ponomarenko and Waters [2006])
The "modern" fitting algorithms in the RST (eg,
fitacf2
,fitacf3
,lmfit2
) all seem to setnoise.lag0
andnoise.vel
to zero (thenoise.sky
value, however, is of course still used).So, here is a philosophical question - we have added several new fields to
fitacf
,map
, etc files over the years, but would we ever remove a field that is no longer relevant? Is there value in reading/storing thenoise.lag0
andnoise.vel
values fromfitacf
-format files (or more likelyfit
-format files) processed with pre-2007 versions of the software?Note there are several fields from the old parameter block which were dropped with the conversion from
dat
/fit
torawacf
/fitacf
(e.g.,nbaud
and the varioususr_*
-defined parameters).The text was updated successfully, but these errors were encountered: