The DCR takes an analog signal and converts it to a digital format. This digitized information is then integrated and processed by the hardware noted and as described in the next paragraph. The resulting output is broadband continuum data representing either total or switched power as determined by the observer.
A description of how signals (and then data) flow through the DCR's various components:
Signals flow to the DCR via fiber optic cables and enter through the Fiber Optic Receiver.
From the Fiber Optic Receiver, 32 input lines received are reduced to 16 data lines. At this point, the computer can select which bank (A or B) of the V/F converters to use.
From here, a switch is incorporated in the system to allow switching between the V/F clocks (normal ops) and a 5 MHz test clock. The 5 MHz clock is provided for test purposes. Switching is also incorporated to allow selection of the reference signal from either the DCR itself or the Spectrometer. This can be accomplished via computer control or manually by using the thumb wheel switches on the Switching Signal Selector/Distributor panel.
Now it's on to a multiplexor and the integrating counter cards. The multiplexor is included to allow the VME computer to select which channels to monitor. The integrating counters, located in a Field Programmable Gate Array (FPGA), are next.
The logic in the FPGA is designed so it can control which counters are integrating data and which are being read. To do this, VME computer interrupt logic allows a time code processor to latch on a time code. The interrupt logic, which can generate two kinds of interrupt's; one for errors and one to signal the start of a new phase, allows blanking to occur. During this blanking period, integrating counters are switched, data read, the counters are flip flopped, reset, and the whole process is readied to start again.
The Timing Generator fits into the whole picture as the device controlling the start of a scan, it's duration, and the state of the switching signals.
As an additional note, provisions are made in this system for the detection of bad data. Any bad data detected can be either accepted or rejected at the discretion of the VME computer.