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]
