Exceptional output of var 'freq' in 'mtm_svd_lfv'

Dear author, when I calculate LFV through function 'mtm_svd_lfv',  the output var 'freq' seems to go wrong because the value of 'freq' expanded from 0 to nearly 30. One possible reason is that I pretreated the data in the wrong way because the variable 'o2' in 'mtm-svd-python.py' may be undefined. So, would it be convenient for you to share with me the data that the file 'images' is describing? 