PSRIX2

For pulsar observations with the C+/K/Qu band receivers, the 4 or 8GHz outputs are processed using the wideband ADCs and the ROACH2 in 2GHz basebands. In addition the 7Beam signals can be processed by this system to generate a 512-channel full Stokes output down to 50μs. Refer to the figure below to get an overview of the system set up.

To handle a total of 8GHz bandwidth, the PSRIX2 system makes use of 4x ROACH2 boards, a gain control and an ADC calibration unit. All of these systems have their own RaspBerry Pi controls and can be accessed either as pulsar@asterix or as spobs@uptotrix machines. Details on controlling the ROACH2 clocks, and the ADC Cals are listed separately.

• Choose the ADC CAL signal (100MHz signal based on the H-maser), noise output or modulated noise on the output of the calunit.
• Choose between the CAL signal or the RF input using the ROACH2 Raspberry PI. Also use this interface to set the FPGA clocks in the ROACH2s.
• Set the attenuation of the RF signal using this interface.