CUBIC provides 25 of the most critical digital housekeeping signals (with 8 bit resolution) to the Telemetry Processor for incorporation into the SAC-B \ Real-Time Housekeeping telemetry stream as described above in §4.4.11. This allows quick-look analysis of the CUBIC status by the ground station. The Real-Time Housekeeping includes 2 bilevel digital status words, 22 digitized analog housekeeping voltages monitoring power supply voltages and currents plus several temperatures and pressures, and one submultiplexed word that cycles through reference voltages.
In addition to the Real-Time Housekeeping data supplied to the SAC-B \ central housekeeping with 8 bit resolution, these signals are also stored with full 12 bit resolution in the CUBIC science data, which store 50 of our analog housekeeping channels in every CCD frame (every seconds) and the remaining 50 analog housekeeping channels in every other CCD frame. The secondary HK data include direct monitoring of a pixel region on the CCD to allow us to continuously monitor the CCD performance, dark current, bias levels, etc. This region is taken from the last 4 rows of the CCD after the standard event processing has been completed but before the housekeeping checks are done. (These 4 rows are stored in the CCD line buffers at that time, so the pixels can be read out after the event recognition algorithm is complete.)
In order to retain some information on transient events and to provide a quick synopsis of housekeeping data, we also monitor the housekeeping data every word clock (every 250 ms) when we are not processing CCD frames. A summary of the housekeeping data obtained this way is stored in the Science Data Header. This includes a summed value (all measurements since the last data dump summed together, so that the mean value can be calculated in ground processing), the minimum value since the last data dump, and the maximum value since the last data dump. The Science Data Header also includes a 4096 bin histogram of cumulative events since the previous T/M dump to the ground station, a list of the serial commands executed since the previous data dump, and a complete dump of the on-board ICP code. The latter will be monitored to detect any SEUs that require a CUBIC RESET to re-load the code into RAM.