FSS ReviewFSS Review

18th August 200918th August 2009

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

Changes whilst testingChanges whilst testing

Tested without RF amplifierTested without RF amplifier Signals fed into Spectrum AnalyserSignals fed into Spectrum Analyser

No RF amp

Spectrum Analyser

DIP SwitchesDIP Switches

Found on Opto-Isolator board with Found on Opto-Isolator board with max. output 500 MHzmax. output 500 MHz

Control 4 most significant bits of Control 4 most significant bits of output frequency; expect most output frequency; expect most significant is 250 MHzsignificant is 250 MHz

Ended up getting frequency Ended up getting frequency changes corresponding to TWICE changes corresponding to TWICE expected frequency jumps!expected frequency jumps!

Gradient of 2.02735 with Gradient of 2.02735 with standard error <1%standard error <1%

In control of 1 GHz opto-isolatorIn control of 1 GHz opto-isolator

Opto-isolator Opto-isolator schematicschematic

Signal controlling Signal controlling frequency bit 24 frequency bit 24 is fed into first pin is fed into first pin of opto-isolator of opto-isolator and outputted via and outputted via pin 14pin 14

Fed to a particular Fed to a particular output pin on 44-output pin on 44-way connector way connector