- From: Frank Mori Hess <fmhess_at_users.sourceforge.net>
- Date: Tue, 8 Apr 2003 14:10:18 -0500
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Monday 07 April 2003 05:43 pm, Herman Bruyninckx wrote: > I am working on the Comedi documentation (you can peek at what I am > doing at > <http://people.mech.kuleuven.ac.be/~bruyninc/comedi/>, > with the HTML version at > <http://people.mech.kuleuven.ac.be/~bruyninc/comedi/comedi.html>, > and there are quite some things I do not understand very well. Here is > a first list. You seem to be working from a slightly older version of the documentation. I recommend using cvs, it makes it easier to keep your work in sync and to generate patches. > > What exactly does the following phrase mean: "The > argument is reserved and should be set to 0." (It occurs in the > explanation of the TRIG_OTHER argument for a Comedi command.) It means if the *_src is TRIG_OTHER, then you should set the *_arg to zero because we reserve the right to make arbitrarily bad things happen in the future if you don't. > > In the section on "Slowly-varying inputs" it reads: "The more noise > you have, the greater your SFDR, but it takes many more samples to > compensate for the increased noise." > I thought that more noise gave a _smaller_ SFDR, such that it requires > more samples. I'm not sure what the exact definition of spurious free dynamic range is, but he's talking about using noise to overcome distortion caused by digitization. If you have an 'ideal' a/d converter that always returns the digital value closest to the actual voltage, you can not increase the resolution by averaging many samples. But if you add at least 1 bit of random noise to the analog signal, you can average many readings and get better than 1 bit resolution. > > THe first option for the flags in the comedi_cmd is TRIG_BOGUS; the > comment that comes with it is "do the motions?". What does this mean? > What are the exact meanings of "dithering" adn "deglitching"? dithering and deglitching are referring to adding a bit of random noise. > > What is the status of the sections that document "Status: design" > features, such as counters, "Bitfield Pattern Matching Extended > Trigger", etc. > (I'm in the first place interested in the counter/encoder design.) > > Herman - -- Frank -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iD8DBQE+kx6b5vihyNWuA4URAt0rAKCj+KWDQBpc5G378TAnKDtfFX35ywCdGgvX 6UC31gEnlLlr2ZP2u454tlU= =/n0b -----END PGP SIGNATURE-----
Received on 2003-04-08Z18:10:18