Hi Jack, I'll hit the RFNoC side...
> I have tried using the RFNOC USRP block, however, this block does not have the "command" PMT message input for retuning while a flowgraph is running. And a related question is that the RFNOC block only has a master clock rate and a Bandwidth and no sample rate. Would it be safe to say the when using this block with the E310, that the sample rate and the clock rate are set to the same value always? This is correct. The "RFNoC Radio" GRC block attaches to the radio block in the FPGA, and the output rate is equal to the master_clock_rate. If you set up the following RFNoC connections, you'll get comparable functionality to the "USRP Source": RFNoC Radio -> RFNoC DDC -> Processor Using the RFNoC DDC, you can downsample from a master_clock_rate to your desired sample rate (also, if you want an "LO offset", you'll need to manually off-tune the RFNoC Radio center frequency, and then frequency shift in the opposite direction in the RFNoC DDC). > What I'm trying to do is rapidly retune between 24 Msps and 12 Msps, and possibly other arbitrary rates too shortly How rapidly? Like, 10s of microseconds? Or several Hz? A fundamental limitation for both the B200 and the E310 when changing the master_clock_rate or center frequency is going to be the characteristics of the AD9361 chip itself... I'd refer to the datasheet/manual/source code here, but there are definite switching penalties for changing center frequency, and there are likely limitations on changing master_clock_rate, too (you probably cant hit 10 microseconds when changing center frequency or master_clock_rate). However, since the FPGA includes digital downsampling performed in the DDC, you *should* be able to change the sample rate between 24 and 12 Msps very easily... I'd imagine a "rapid" sample rate change in the B200 relies on changing some digital downsampling parameters. I'd also be a little concerned trying to hit 12 Msps between the FPGA and Processor on the E310. Usually my tests max out around 1 to 2 Msps continuous streaming before I get Overflows. Have you had success with these higher sample rates on the E310?? EJ On Thu, Jan 4, 2018 at 3:48 PM, Jack Ziegler via USRP-users < usrp-users@lists.ettus.com> wrote: > Hello, > > I'm using gnuradio with the usrp_source block. What I'm trying to do is > rapidly retune between 24 Msps and 12 Msps, and possibly other arbitrary > rates too shortly. > > This is easy to do with a B200 series radio using the usrp_source block > and the command message port by sending a PMT message of the "rate" type. > > However, I'm now using an E310 and it will not easily retune. I can do 24 > and 12 Msps by starting out with a 24 and 12 as the clock rate, however, > the current API only allows setting the sample rate and not the clock rate > during run time. Would it make sense for the E310 only to hack the > usrp_source block code to set the clock rate and the sample rate at the > same time? > > Also, I have a related question. I have tried using the RFNOC USRP block, > however, this block does not have the "command" PMT message input for > retuning while a flowgraph is running. And a related question is that the > RFNOC block only has a master clock rate and a Bandwidth and no sample > rate. Would it be safe to say the when using this block with the E310, > that the sample rate and the clock rate are set to the same value always? > > Thanks > > Jack > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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