4 S2-TCI software control system

  The heart of the S2-TCI system is the control system software, known as 2tci. It provides for simple and automated data transfer from S2 tape to computer RAM, and subsequently (nominally) to disk or output tape device. An overview of the 2tci control system architecture is shown in Fig. 4. The user specifies transfer parameters such as transfer mode (S2 playback mode), tape start-time and scan length (length of data transfer, e.g. 10 minutes), maximum output file size and output file name(s). 2tci parameters may be entered on the command line or read in from an input configuration file. Upon program initiation, 2tci checks the user input parameters, available disk space, and other miscellaneous transfer-related issues. It then starts the tapes and checks for valid tape times specified by the user. When a valid transfer configuration is confirmed, 2tci begins the data transfer and monitors overall performance. During S2 tape-to-computer data transfer, 2tci warns of data transfer difficulties and writes a log file summarizing transfer results. "Bad" portions of tape are flagged and automatically picked up in subsequent "retry passes". A DMA transfer burst from tape is deemed "bad" and warrants a "retry" if the number of tape (Decoder) sync errors or the estimated percentage of data deemed invalid (both reported by the S2 each second) exceeds thresholds established in the input configuration file.

If data are written to disk or other device, the file format consists of a header containing parameters such as radio source, observing frequency, etc., and data transfer parameters such as S2 tape ID, transfer mode, start time and scan length, followed by the tape (reproduced acquisition system) data bits. A typical individual output file may be 960 MBytes in size, representing one minute of data at a rate of 16 MBytes/s. Various software on- and off-line utilities are provided within 2tci for diagnostics and to examine the contents of transferred data files. Data from disk may be written to output tape devices by using standard tape archive programs such as "tar". They can also be transferred to a more capable computer via fast links such as "fast ethernet" or FDDI if such support exists within the local computer. 2tci may be executed from the computer command line, within shell scripts, or within other programs for full flexibility to the user.

  

Figure 4: S2-BPS - Processing Center S2-TCI Control System Overview. In the upper portion of the figure, 2tci accepts a user-input transfer configuration file, controls and monitors the S2 recorder and DMA Card (DMAC) systems, manages the DMA data bursts from S2 tape to final destination ("local" or "remote" processing RAM/disk), and writes a log file summarizing the data transfer results. The lower portion of the figure demonstrates the three data management/processing schemes described in Sect. 3. All aspects of S2-TCI operation may be performed as part of an automated unattended supervisory system (even under remote operation), as logically represented in the "Data (Burst) Management" functional block