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pulsarinstruments:psrix2:gain_atten_ctrl [2018/12/20 14:12] ramesh |
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| - | ====== ROACH2 Signal Levelling ====== | ||
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| - | 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. | ||
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| - | - connect to the VNC session asterix:4 | ||
| - | - load a firmware that has some ADC interfaces. eg. ''python /home/pulsar/roach2/r3xcontrol.py'' | ||
| - | - start the ADC displays now: ''python /home/pulsar/roach2/r3xadchist.py'' | ||
| - | - 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. | ||
| - | - Consult the setting on the histogram above - aim to get the signal between -25 to +25. | ||
| - | - For Galactic Centre magnetar observations, current settings are: 18.5/15.5/12.5/6.5 dB | ||
| - | - For normal pulsar observations: 9.5/7.5/6.5/2.5 | ||
| - | - Refer to the image below for an example display. | ||
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| - | {{ :pulsarinstruments:gain_ctrl.png?300|}} | ||
