Group delay correction in jMRUI

Data Processing
1

Hi,

We acquired some MRS data from a Bruker scanner. When I load rawdata.job0 into jMRUI, a window pops up saying “group delay correction”

image
image501×233 22.2 KB

I’m just wondering how the number 67.9842834473 was obtained. Because I want to process the data in matlab, it will be helpful if I know how to decide the value for group dealy correction.

If I copy and paste rawdata.job0 to another folder, it can still be opened in jMRUI but the prefilled value for group delay correction will become zero. I guess the value 67.9842834473 must be calculated from some acqusition parameters.

I’ve searched the jMRUI manual, but didn’t find an answer. So I raised my question here.

Thank you for your great help!

2

Hello,
The group delay in Bruker data is a long story. In short: The GRPDLY parameter is given in the acqus file of Bruker TopSpin data. It’s related to digital filtering, dead time, and consequently the first-order phase correction. If you want to correct the group delay yourself in Matlab, I would recommend checking the Python source code of nmrglue as a starting point nmrglue.fileio.bruker.rm_dig_filter — nmrglue 0.9-dev documentation

1 Like
3

Hi my old friend!

Thank you so much! You have provided a very important piece of information.

I’m going to read acqus and get the parameter value GRPDLY! That’s exactly what I need!

Great thanks for your help!

Actually, I tried to search acqus file for 67.9842834473 However, I didn’t know that the value has been rounded. The accurate value in acqus file turned out to be 67.9842834472656

1 Like