Thank you for the detailed response. In the end, I want to take all 491.52e6 band (from 1 Rx) and split it into smaller bands. Is it possible in the rfnoc framework? Can I change the ce clock of my OOT block to a higher clock than 266e6 ? or I must upload the samples to the host ? + can i change the DDC clock to something lower than 266.66MHz (for sample rate smaller than 100M) thanks in advance
בתאריך יום ד׳, 14 בינו׳ 2026 ב-18:35 מאת niels.steffen.garibaldi--- via USRP-users <[email protected]>: > Hi Daniel, > > The short answer is that the current DDC/DUC implementations will not work > for Sampling rates above 250MHz. > > The long Answer: > The current implementation of the DDC/DUC RFNoC blocks only supports a > single sample per clock cycle processing of data. > > Internally the DDC/DUC blocks use the faster CE(Compute Engine) clocks to > do the Down-/Upconverting, which on your X440 device is running at > 266.66MHz <https://kb.ettus.com/RFNoC_Frequently_Asked_Questions#X440>. > > Therefore the highest sampling rates supported by the DDC/DUC blocks is > 250MHz, which corresponds to the 200MHz BW variants of the provided > bitfiles. > > If the radio provides samples at a higher rate, they will still reach the > DDC block but the internal serialization buffers will fill up quickly as > the block can not process incoming samples fast enough. This will lead to > an overflow, which might be related to why your rfnoc session times out. > > This is the also the main reason why only the “*_200_rfnoc_image_core.yml” > variants have the DDC/DUC blocks included. > > You can still capture samples at a faster sampling rate, but you will have > to stream them to your host first and then do the downconversion there. > Be aware that this requires a fast connection between USRP and Host, which > can be challenging in some setups. > > Another thing you could try is to reduce the MCR closer to your target > sampling rate. The x440 supports a wider variety of flexible sampling rates > than the other USRPs, so if you only care about the downsampled waveform, > you could just try to get close to your desired sampling rate that way. See > the > appendix of this document for a list of supported sampling rates of the x440 > <https://kb.ettus.com/About_Sampling_Rates_and_Master_Clock_Rates_for_the_USRP_X440#Appendix> > . > > If you still require this feature, you will either have to update the > implementation yourself and make the DDC/DUC multisample capable, or you > could try and contact Ettus/NI/Emerson support and put in a feature > request. Depending on your business case the implementation might be > prioritized and updated in a future release. > > Regards, > Niels > _______________________________________________ > USRP-users mailing list -- [email protected] > To unsubscribe send an email to [email protected] >
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