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IIO 9371 TX Attenuation

Question asked by epiq-meaghan on Feb 24, 2017
Latest reply on Mar 3, 2017 by gverma



We've been trying to use the IIO Oscilloscope tool with our AD9371 evaluation board to perform some basic analysis of the TX attenuation settings and are having difficulty.  With the oscilloscope tool, under "AD9371->BIST", we can enable the TX NCO test tone and are able to view the test tone on the spectrum analyzer.  However, when we then navigate to the "AD9371->AD9371 Transmit Chain" settings and attempt to modify the TX1 attenuation setting, it appears as though the setting is accepted, however, the tone's level does not change on the spectrum analyzer.  Additionally, if we observe the value "out_voltage0_hardwaregain" of the ad9371-phy IIO device, we do not see that value change when modifying the setting in oscilloscope.  Also, if we try to change it by directly writing a value to that attribute on the command line, we are unable to make it change.  We've also attempted to modify the attenuation setting while having the FPGA generating the tone instead of using the BIST (via the Transmit / DDS test configuration) and are unable to have the attenuation setting impact the tone transmitted.


Is there a specific way that the attenuation setting needs to be configured in order to take affect?  Is modifying the attenuation setting while running in the BIST tone mode supported?  Are there any known issues with the TX attenuation settings being modified when using the IIO oscilloscope tool?


Any suggestions on this are appreciated.