A study of ROD compression schemes for the TRT

Zero suppression of the TRT data is foreseen already at the ROD level. Valid straws will be identified by applying a gate of tunable position and width to the low threshold data bits. Various schemes have been proposed for the encoding of data from valid straws. The schemes are answering the requirements posed by the different running modes of LHC/ATLAS: low luminosity, low luminosity b-physics programme, and high luminosity. This note presents a Monte Carlo study of the validity gate approach and of the proposed encoding schemes. Results are presented on the obtainable efficiency and background suppression as function of the validity gate position and width. The different encoding schemes are investigated and estimates of the output data volumes are presented for different luminosities.