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gsteinb88

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BladeRF 2.0 micro 8 years ago

Yeah, the BladeRF uses an AD9361[1] as the transceiver, which features a pair of ADCs per channel, of which there are two (so, a total of 4 ADCs and 4 DACs in the package). It's got a bunch of other convenient features like built-in PLLs both LO and baseband.

[1]

So long as all frequencies you're trying to represent are below the Nyquist frequency, there's still only one band-limited reconstruction of the samples. So yes, it's still possible to reproduce everything accurately so long as all of the individual frequencies (no matter their relationships) fall below 1/2 the sample rate.

FFTW is one of the seminal examples of the importance of cache awareness, if I remember my history correctly. As I understand it, the reason the fftw authors (Matteo Frigo and Steven G. Johnson) won the Wilkinson prize was essentially because fftw exemplified the importance of cache-aware algorithms, as opposed to blindly optimizing number of operations.

I don't know, but I would guess that intel's implementation post-dates fftw?

Same goes for me when doing CAD and having to constantly convert between standard & metric -- 254, 508, etc show up in numbers a lot and it gives you a nice hint that it's a "clean" value in the other system. Super useful for reading IC footprints off datasheets that only use one of the two systems

[1] turns out to be more subtle than people originally thought. Even assuming you can make loophole free bell tests (hey, it's been done!), the best anyone has been able to show this does -- even theoretically -- is randomness /amplification/ not true verifiable randomness. This boils down to the need for an initial random basis preparation of the qubits for which you have no true random seed.

I know some people have been working on solving that chicken and egg problem, but -- unless there's very new work I'm unaware of -- it's still unsolved.

Not universally true -- I know students on NDSEG fellowships (i.e. DoD) receive a 1099. I can't speak to the other fellowships though, and I don't get any deduction/withholding done for me, so I have to pay estimated quarterly.

And funds that come through my university do get a W-2 come tax time.

Wow, I've literally never heard of a PhD where you were only expected to work 20 hours/week. I'd say 50-60 is closer to the norm, especially once you're done with your coursework (usually a year or two into a 5-7 year long PhD).

If you don't mind, what field(s) are you two in?

That was a fantastic post, thank you for sharing. Ironically, while affirming the view I held above, it also makes me think I should -- maybe -- give them another chance now that I'm well along in graduate school as opposed to a struggling undergrad.

I'm not sure that Feynman is the best example here. In fact, in my experience, he's actually more of an example of the problem than the solution. While Feynman does a great job of explaining concepts if you never need to use them, I always found his lectures to be of the "captivating until you try to use them" variety.

This wasn't just my experience either -- after struggling with this as a physics undergrad for a while (after all, they're supposed to help!) I started asking around. My academic advisor, several other professors, and many students felt the same way. Feynman may get closer -- or may do more to bring common understanding to complex principles -- but his approach broke down for actually learning to /do physics/.

But I'll agree that he's a major step in the right direction; I just want to caution against the hero worship. There's no magic formula, no one person, who can make learning complex concepts easier. Some things are hard, and trying to make them seem easier can easily make them more confusing in practice.