I guess I would need a block to count samples if I am going to a null sink? Otherwise I am not sure how to guage how many samples have passed.
Well, this is probably ignorant of me, but I assumed a higher master clock rate would allow me some sort of speed benefit somewhere. I guess I can't say what since it has nothing to do with the Linux CPU speed.... What is the benefit to running at a slower rate? ________________________________ From: USRP-users <usrp-users-boun...@lists.ettus.com> on behalf of Marcus D. Leech via USRP-users <usrp-users@lists.ettus.com> Sent: Monday, April 29, 2019 8:33 PM To: usrp-users@lists.ettus.com Subject: Re: [USRP-users] E312 wrong sample rate On 04/29/2019 03:28 PM, Jason Matusiak via USRP-users wrote: I was debugging a problem with a flowgraph when I realized that I wasn't getting the amount of samples I expected passing out of the USRP source block. If I set a sample rate too low, it tells me it has to set the sample rate to 0.125MSps. Currently I have a single stream from my source block, 30MHz clock rate, 500kHz sample rate. If I run for 20 seconds streaming the data to a file (unbuffered set to off) as a complex, I would expect to see 20s * 8B * 500KHz = 80MB of data in the file. Instead, running it empirically (so the numbers will have to be ballpark and not exact), I see file size of 116153944. If I make the assumption that the sample rate was really 500kHz, that means it ran for 29.03s. This is obviously off by 50%. If I assume that 10s of data was really collected, that means I had an actual sample rate of 1.451924MSps. If I run these tests with the minimal 125kHz sample rate, I see things off by about double what I would expect. Moving my sample rate around the 1MSps range seems to work closer to what I expect, but of course I can't write files that fast without getting 'O' on the screen. Ultimately I need to use two receivers, so I don't believe that I can push the clock rate above 30.72MHz. I am running UHD-3_14 with RFNoC enabled (though I am not using RFNoC in this particular flowgraph). What am I missing here? Have it write to /dev/null, and time how long it takes to gather some large number of samples, and go from there. If your delivered sample rate is 500ksps, I don't see why you need a master clock rate as high as 30Msps, but perhaps you have your reasons.
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