[daip] amplitude in AIPS

[Z.-Q. Shen]

Dear Amy,

Thanks for the quick reply. Yes, please do tell me more about quantitative
corrections made to the correlator outputs in AIPS. Will these affect
the noise level? At the correlator end, noise (sigma) can be expressed as

	sigma = 1/[L * SQRT (2BT)],

where B is the recording bandwidth, T the integration, and L the loss factor.
I guess this will also be adjusted accordingly, right?

Cheers,

Zhiqiang

>Dear Zhi-Qiang,
>
> > What are those amplitudes immediately after the data is loaded into
> > AIPS using FITLD (probably plus ACCOR)? Are they exactly the same as
> > the outputs from the correlator, i.e. the correlation coefficients?
>
>The quick answer is "probably not".  If you are using data from
>the VLBA correlator, there is a correction that is applied automatically
>in FITLD (the second order delay corrections).  Also there is a
>correction you can turn on with FITLD (DIGICOR, applies digital
>correction) and then ACCOR will also add another layer of corrections,
>making what you get out not what you get out of the correlator.
>
>If you want to know if after all these corrections the correlation
>coefficients are basically preserved (with just small tweeks to fix
>up what the correlator does not do perfectly), I will investigate
>that further and get back to next week.
>
>Cheers,
>
>Amy