Unpacking PRDF Data
The purpose of the unpacking chain is to accept DCM packets from a PRDF raw-data stream, interpret the data that they contain, and present the raw data in a form that is useful to the reconstruction software. This is nearly the reverse process from the response chain between the raw-DCM stages, except that the FEM stage is skipped for convenience.
Figure 4. Objects involved in unpacking raw data.
The PRDF data stream is handled by software from the ONCS group. Specifically, an event iterator is attached to a PRDF file or pool; the iterator fills an ONCS Event object for each event's worth of data that is read from the stream. The Event object contains the raw DCM packets for each of the subsystems.
The mMuiDCMUnpack module extracts MuID packets from the Event object and interprets the bit patterns in each packet, which results in a list of "hardware" addresses (indexed by FEM, ROC, cable, and channel) of channels that produced signals in the event. The module then consults the map stored in the TMuiAddressTable object to convert these "hardware" addresses to "software" addresses (indexed by arm, gap, panel, orientation, and two-pack), and places each address as an entry in the dMuiRaw table. This table is then the starting point for the reconstruction chain.