Please note: Expert Mode only.
The LOFAR digital processing offers the unique option of a RAM buffer at station level. These RAM buffers, the Transient Buffer Boards (TBBs) can provide access to a snapshot of the running data-streams from the antennas and operates in parallel with the normal streaming data processing.
Each TBB can store up to 4 GB of data (upgraded from 1 GB w.r.t. previous cycles), enough for 8 dual polarized antennas (individual dipoles for LBA or tiles for HBA) either before or after the conversion to subbands (the polyphase filter and FFT). This amount is sufficient to store 5 seconds (1.3 seconds previously) of raw data recorded at the full time resolution (5 ns for the 200MHz clock). This temporal window can be extended by factors of ~10-500 by storing data from fewer antennas and/or subbands.
Data dumps will be initiated by internal (either at station or central system level) as well as external triggers. Upon a dump command the data are read out of the RAM over the WAN network to the storage part of the CEP post-processing cluster.
At the present time, triggers from the LORA particle detector, external to the TBBs, have been successfully conducted.