FSS Review 18th August 2009

Opto-isolator:Opto-isolator: Top 4 frequency bits set by DIP switchTop 4 frequency bits set by DIP switch FPGA controls bits 8-26FPGA controls bits 8-26

Changes whilst testing Tested without RF amplifier Tested without RF amplifier Signals fed into Spectrum Analyser Signals fed into Spectrum Analyser No RF amp Spectrum Analyser

DIP Switches Found on Opto-Isolator board with max. output 500 MHz Found on Opto-Isolator board with max. output 500 MHz Control 4 most significant bits of output frequency; expect most significant is 250 MHz Control 4 most significant bits of output frequency; expect most significant is 250 MHz Ended up getting frequency changes corresponding to TWICE expected frequency jumps! Ended up getting frequency changes corresponding to TWICE expected frequency jumps!

Gradient of with standard error <1% Gradient of with standard error <1% In control of 1 GHz opto-isolator In control of 1 GHz opto-isolator

Opto-isolator schematic Signal controlling frequency bit 24 is fed into first pin of opto-isolator and outputted via pin 14 Signal controlling frequency bit 24 is fed into first pin of opto-isolator and outputted via pin 14 Fed to a particular output pin on 44- way connector Fed to a particular output pin on 44- way connector