DGF Introduction

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 or 75 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 analog instrumentation.