CUBIC supplies the 8 most significant bits of our most critical analog housekeeping signals plus two digital status words (BL1, BL2) to the Telemetry Processor for inclusion in the SAC-B housekeeping major frames. We refer to these housekeeping data as Real-Time Housekeeping. One digital status word (BL1) will be transmitted to the Telemetry Processor via a bilevel channel as 8 parallel bilevel data lines. It is assigned to a single telemetry channel ( SAC-B Bilevel Channel 00, which appears at word 48 in the Real-Time Housekeeping Telemetry Format) and is sampled at the housekeeping minor frame rate, once every 16 seconds. The remaining Real-Time housekeeping words (23 analog signals plus one bilevel status word) are multiplexed by our ICP and transmitted to the Telemetry Processor via a single serial housekeeping channel ( SAC-B Housekeeping Serial Channel 00). These 24 data words are assigned to three telemetry words (words 49--51), and are sampled at the major frame rate, once per 128 seconds. (One of these data channels, word 51 of minor frame 1, is submultiplexed by CUBIC and presents five voltage calibration values, each of which is sampled once per 640 seconds.) The CUBIC housekeeping (HK) therefore occupies 32 words in the HK telemetry major frame, as shown in Table 16.
Table 16: CUBIC Real-Time Housekeeping Major Frame format
In addition, we provide four temperature sensors to the SAC-B \ thermal control system on conditioned analog housekeeping channels. These occupy SAC-B Housekeeping Temperature channels 00--03 and are assigned positions in the SAC-B spacecraft analog housekeeping telemetry.