GE OPTIMA MR360 Service Training page 127

VRF board contains an optical interface to receive scan data from Remote Receiver (RRx)
board, filters the data and DMAs the data to the ICN for image reconstruction. The VRF
board is physically installed in PCIs slot on the ICN. The VRF will receive an 80MHz
reference clock from the exciter board.
VRF is used in Sun 4100, and VRF2 is used in Sun 4170. The VRF2 is a redesign of the VRF
to change the FPGA from an Altera StratixGX device to an Altera ArriaGX device.
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