NOTE: THIS IS AN 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, 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 of raw data recorded at the full time resolution (5 ns for the 200MHz clock). This temporal window can be extended by factors of 2-16 by storing data from fewer antennas.
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.
International stations have smaller TBBs (1 GB per antenna /1.3 seconds), but it is currently not possible to obtain TBB data from them.
The TBB subband mode, where subbands are stored instead of raw data, is currently not operational.
The TBB mode is an expert mode. If you haven't used it before, please contact science support before proposing an observation in this mode to verify that it can be accomodated.