On Thu, May 04, 2006 at 02:01:31PM -0400, Michael Milner wrote: > Hello, > > I was just wondering if anyone has used GNURadio for any non-radio > applications, specifically phone line modulation/demodulation. > > It shouldn't be too difficult to design a daughter board for the USRP to > sample phone line voltage (with an appropriate line interface circuit of > course). After that it should be rather easy in GNURadio to generate DTMF > tones for dialing, and modem tones for data communication. > > Any thoughts? > Mike
A simple DAA (Data Access Arrangement) plus the LF daughterboard would probably work. There are two chip DAA's available. Been a while since I looked, but I think that Crystal Semiconductor used to make them. Google "solid state daa" There's also the classic Midcom transformer plus a couple of other discretes. These things are tricky to get right. You definitely want to find somebody's reference design and use that. Or use the pre-approved chipset. The USRP is pretty much thermonuclear overkill for this application. You could just use a sound card with a DAA. That's how all the "soft-modems" work. IIRC some of the the AC97 codecs support a second channel for telecom (modem) apps. Eric _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
