GBM Block Diagram
The GBM baseline triggering scheme is similar to BATSE. Two detectors
are required to be above a threshold specified in standard deviations
above background in the 50-300 keV energy range on a 1.024 second
time-scale (although other time-scales and energy ranges are used).
Rather than process the signals at each detector, the centrally located
Data Processing Unit (DPU) collects, processes, and packages data from
all the individual detectors. The main functions of the DPU are
to digitize the analog pulse height signals, accumulate time-resolved
pulse height spectra with variable time resolution, tag the spectra
with time and detector information, package the data for telemetry,
and use the data to realize a burst trigger and compute burst locations.
The DPU also controls the operation of the instrument, including
power supply settings, and accumulates housekeeping and instrument
status data for inclusion in the telemetry.
It acts as the sole electrical interface between the GBM and the
GLAST spacecraft computer. Burst alerts and onboard
burst locations provide the
possibility of relocating the GLAST spacecraft to position the
burst in the field-of-view of the LAT.
Please return to
the GBM Description or
the GLAST Burst Monitor or
the Gamma Ray Astrophysics Home Page.
21 Apr, 2009