Filter transcript above background noise

Question

[anm17]

Hello community,

In the paper of the experiment I'm investigating is stated that they filtered all transcript, to only retrun transcript that are above the background noise, which is 75 RFU. (Below you find the original text of the paper) .How do I realize this kind of filtering method if I want to recalculate their results (in R)?

"For each of the pairwise comparisons, the 54,681 transcripts were first filtered to retain transcripts that had signal values above the background (> 150 RFU in one of two samples, either treated or control). The background/noise level is ∼75 RFU for these arrays"

Thank you very much