DSLstats for broadcom modems has a very interesting plot for diagnosing potential problem, in which it displays the count of Bitloading changes per carrier. I am not sure how this is implemented, but in theory it should be enough to take the absolute difference between consecutive bitloading data and just plot the count of these bitswap events per carrier. That will not be 100% correct (e.g. two bitswaps between samples might cancel each other out) but should show problematic carriers relative well.
DSLstats for broadcom modems has a very interesting plot for diagnosing potential problem, in which it displays the count of Bitloading changes per carrier. I am not sure how this is implemented, but in theory it should be enough to take the absolute difference between consecutive bitloading data and just plot the count of these bitswap events per carrier. That will not be 100% correct (e.g. two bitswaps between samples might cancel each other out) but should show problematic carriers relative well.