The Phase generator Board is based around a Xilinx CPLD chip that is used in conjunction with a primary crystal oscillator to provide the synchronised TTL modulation frequencies used by the PSD board. Six TTL signals are available in total at three frequencies, f (~6kHz), 2f (12kHz) and 3f (18kHz). A set of these signals is available phase synchronised at the output. In addition, three banks of board mounted switches can be used to control the individual phase relationship of each of these signals relative to the synchronised outputs. Individual 9 bit phase control (0.7o) of each of these output signals is possible.

In addition an 8 bit ROM and digital to analogue converter (DAC) synchronised with the fundamental modulation frequency (~6kHz) can be used to provide any form of analogue output signal. Typically a sinusoidal waveform is written into the ROM and used to provide the fundamental modulation frequency for this measurement technique. This voltage is also made available through a stacked connector to the laser driver board where fitted.

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View a .pdf of the  Phase Controller Specification here.