DGF instruments accept inputs directly from
detector preamplifiers. The signals are conditioned, digitized,
and then subjected to first level digital processing in real time
at the ADC sampling rate (40 MHz to 80 MHz).
Events are identified by real time processing
units (RTPU's) implemented in field-programmable gate arrays (FPGA's)
and then passed to an on-board digital signal processor (DSP),
together with digitized signal traces captured in First-In-First-Out
(FIFO) memories. The DSP can wait for external acquisition control
logic to successfully complete global event validation before
executing second level of digital signal processing (2LDSP) on
the event data.
Accepted events are time stamped, which is
useful for event identification and measuring times between events.
Being performed only for accepted events, 2LDSP can be much more
comprehensive than the RTPU processing . For example, sophisticated
pulse shape analyses can be performed and only extracted values
sent to the central data collection system.
The DGF's distributed parallel digital processing
architecture thereby facilitates much higher event rates, at significantly
lower costs, than could previously be achieved using strictly