On-Board Trigger Dead Time

Once the on-board logic has been triggered, the HTR Mode starts, producing the HTR counters (tab. ). As there is only one buffer devoted to containing these counters, a potential new burst, detected during the data acquisition and readout of the previous one, does not trigger the generation of another set of HTR counters, but it only sets a proper flag to positive.

The duration of this on-board trigger dead time is not fixed, but depends on the overall data transmission rate: actually, the On-Board Data Handling (OBDH) Subsystem, in charge of acquiring and storing the science data from the whole payload, guarantees a maximum throughput of 100 Kbps; therefore, the payload data rate must be apportioned between the instruments in a coordinated way. To this aim, there is a proper algorithm determining the best way to operate this overall data packets transfer, which depends on the acquisition mode (there are direct and indirect modes, see [PDS S/W User Manual, 1995]) of each instrument.

The consequence of this is that the time needed to complete the HTR counters transmission can vary; a lower limit on this dead time can be set to $\sim$ 7 minutes.