[dsg-hdice] fsNMR program broken when using background files

[thomaso at jlab.org]

Hi Tyler,

Xiangdong and I confirmed the new 50 Ohm / 1 MOhm switch you added worked
fine.

However, we ran into a new issue with the fsNMR program.  We took a set of
sweeps for our background without issue.  The problem arises when we
select a previous background scan to use for subtraction during the signal
scan.

Normally the program looks for the peak value of the background curve as a
step in the background normalization/subtraction process.

In our case, we are looking for the signal in part of the curve.  There is
no peak in the region we are scanning.  As a result, the program is unable
to calculate values for R, X, and Y.  The frequency column is fine since
those values are not manipulated.  The phase column is fine due to that
being a straight subtraction between the two phase values (no
normalization used).

Could you please investigate this issue as soon as you can?  We can give
you access to the PC anytime you need, just let us know.

Thanks,
Tom