Unfortunately, this really points towards some hardware issue. How do we get to this error: The ADC Selfcal is shared code between X410 and X440. We play a tone with our DACs through the loopback towards the ADC to be calibrated. On the ADC side we configure a threshold value that we need to hit with the calibration tone. Therefore, in X410 we increase the gain until that's the case. In X440 we don't have any gain stages. Therefore we can only check if we are above the configured threshold. If that's not the case we throw this error because then we know that the cal tone is not loud enough to create a good calibration. We have a utility to check which threshold values your ADCs achieve: https://github.com/EttusResearch/uhd/blob/master/host/utils/x4xx_query_adc_threshold.py
This may give you an idea about how bad the erroneous ADC really is compared to the others. From our experience this isn't an intermittent kind of issue, so RMA seems to be the way forward. I cannot say how often this occurs in the field - we have mainly seen it during development when daughterboard connections were bad. Using the cal_ch_list argument helps to open a UHD session by skipping the calibration for that one channel. But even without this argument the second session after startup/clocking change will work anyway because it will have tried the ADC Selfcal already in the session before. The erroneous channel will never have been calibrated completely, though. I hope that helps understanding what is going on. /Martin ________________________________ From: Eugene Grayver <[email protected]> Sent: Tuesday, March 3, 2026 6:33 PM To: usrp-users <[email protected]> Subject: [EXTERNAL] [USRP-users] X440: Could not find appropriate gain for performing ADC self cal Hi, I get the following error about every fourth time I start the software. ------- Error during initialization of block 0/Radio#0! [ERROR] [RFNOC::GRAPH] Caught exception while initializing graph: RuntimeError: Could not find appropriate gain for performing ADC self cal Error: RuntimeError: Failure to create rfnoc_graph. ------- UHD 4.9.0.1 I see it with either uhd_usrp_probe OR rx_samples_to_file. NOTE: there may be an actual hardware problem with one of the channels (TBD). Anyone seen this? Thanks. Eugene Grayver, Ph.D. Principal Engineer 310-336-1274
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