The power input to the ROACH2s can be controlled by the Raspberry Pi integrated in to the gain box. A feedback on the power levels are only possible by consulting the output of the ROACH2 ADCs (either ADC histograms or the output of the PFB-FFT). This of course will only be possible if the ROACH2 FPGA is programmed appropriately, or configured with he right gateware.

1. connect to the VNC session asterix:4
2. load a firmware that has some ADC interfaces. eg. python /home/pulsar/roach2/r3xcontrol.py
3. start the ADC displays now: python /home/pulsar/roach2/r3xadchist.py
4. Now change the attenuator setting from another terminal: roach2attn <id> <atten>, where id is 1,2,3 or 4, and attenuation is in the range of 0.5-30.5 dB in steps of 0.5.
5. Consult the setting on the histogram above - aim to get the signal between -25 to +25.
6. For Galactic Centre magnetar observations, current settings are: 18.5/15.5/12.5/6.5 dB
7. For normal pulsar observations: 9.5/7.5/6.5/2.5
8. Refer to the image below for an example display.