On Tue, May 2, 2023 at 2:04 PM <ri28...@mit.edu> wrote: > What is the sample rate of your transmitted samples? If it isn't 200 Msps > for the X310, then you are using the DUC. > > I use a couple different sample rates. The plots I showed earlier were > taken at 25 MSPs. >
Try interpolating on the host to 200 Msps and see how things go. Interpolating by 8x goes through the 3 halfband filters. Note the halfband filters have 0's in between each coefficient. > Not adding 0's to the end of a burst which you intend to be interpolated > is > problematic in general, since you won't be flushing the FIR filters of > their current state. Remember there is no automatic zero stuffing to push > the last of the data through. > > What’s the point of the start/end burst flags then? In theory UHD should > know the number of taps on the DUC/DDC for a given sample rate and be able > to push zeros for me. How do I know how many zeroes I need to pad? I’ve > apparently empirically determined it, but is there documentation somewhere? > The source code is your best bet: https://github.com/EttusResearch/uhd/tree/master/fpga/usrp3 The DUC can be seen here: https://github.com/EttusResearch/uhd/tree/master/fpga/usrp3/lib/rfnoc/blocks/rfnoc_block_duc Brian
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