I think that some of the convenience mechanisms that you might see in the examples (such as passing a tune request through the streamer) are likely only helpful in a "typical" graph. In your graph with 4 DUC ports connected to 1 Radio port with AddSub blocks to add the 4 DUC ports together, it is not a 1-to-1 relationship between DUC and Radio.
It seems to me that your step 3 below is not needed or helpful. It seems you could set the LO frequency via the Radio block. But, this will be quantized and not necessarily at the exact frequency you request. Thus, if it is important to get the right frequency, you will need to use the return value from the radio->set_tx_frequency function to determine your quantization error. Then, you can call duc->set_freq for your DUC ports with a frequency argument that includes both your desired values of -10, -5, 5, 10 MHz as well as the quantization error you determined setting the LO. Rob On Wed, May 21, 2025 at 10:45 AM <carmix...@gmail.com> wrote: > Yes Martin, for example I’m working on a X310+UBX160 with a multichannel > DUC that has 4 inputs each one with a different frequency offset and then i > sum the outputs with the addsub rfnoc block(I generated the FPGA firmware > accordingly). > > Actually I managed to have it work correctly but I had to discover by > myself some oddities, the correct steps in my configuration are in order: > > 1-configure the graph according to my needs (radio_control, duc, streamer) > > 2-set the RF output frequency on the radio control > > 3-make the tune request through the streamer > > 4-set the desired frequency offset on the DUC (for example: -10e6, -5e6, > 5e6, 10e6) > > The last step is the more critical, in order to get the exact offset I had > first to get the starting frequency offset of the DUC (which is not zero > after the tune request, but just on the first channel of the DUC!!!) and > then to sum up that residual frequency offset (which actually counts few > kHz) to the desired frequency offset. > > If I miss this step it won’t have the exact offset needed. > > It seems to me a bit clumsy, is there a cleaner way to do it? > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >
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