First off, I should say that I know very little about this hardware stuff, so I'm sure others will correct me. Having a receiver and transmitter on the same card would be challenging to engineer: when a transmitter is close to a receiver, there's leakage. Even if the TX/RX frequencies are far apart, it's still possible for interference, depending on harmonics and stuff that I don't understand well enough to explain. Of course, it may not be necessary to support simultaneous RX and TX, but it's worth considering.
And of course, there's a reason the available consumer FM transmitters are so weak - FCC rules. Even many of those weak FM transmitters used in cars are even running in at illegal power levels - NPR has been lobbying to get the FCC to enforce those rules more. Legally, these things are only supposed to have a max range of something like 12 feet. Not that it would really harm anyone to build a transmitter that is little more powerful, but it's worth noting. For receivers, there are a lot of PCI FM receivers out there. AudioScience even makes one with 4 HD receivers, or 8 standard FM tuners, and they have open source Linux drivers. But, they cost more than most computers these days - they're really aimed at radio stations monitoring multiple transmitters, not consumers. It's a great idea though. Right now, my little home server computer plays my music collection using MPD, using the built audio card, and Icecast. I've been trying to figure out how to get audio to other places in my apartment. I don't really want to invest in stream receiver radios/computers, and I don't want to run audio cable since I don't own the place . . . an FM transmitter might be a nice solution. Asa On Fri, Jun 19, 2009 at 10:38 AM, Rion D'Luz <[email protected]> wrote: > Hail Vaguers: > > An acquaintance forwarded me this email with the hope that this list > might provide a tip or pointer. > Me, I'm clueless. > > Rion > > ---------- Forwarded Message ---------- > > Subject: PCI FM Transmitter > Date: Thursday 18 June 2009 > From: Stephen Alrich Marshall <[email protected]> > To: [email protected] > > Rion, > I hope all is well with you. I have a project that V.A.G.U.E. might take > an interest in. I could use at minimum advice. > > I like to broadcast from my computer directly to radios around my house. > The unit I am using does not provide a reliable signal beyond one room. > So I have found several schematics for transmitters online. Thinking > about how to build this, I thought it would be cool to attach it > directly to a sound card, or build it onto a sound card, and put up a > broadcast antenna behind my computer. To have it powered directly by the > computer would be doubly cool. > > Another cool idea would be to build a receiver directly onto a sound > card, for direct reception and recording. > > Of course, why not put the receiver and transmitter on the same card, > with a sound card? So far I don't see any need to program anything, > although programmed tuning (on screen) would be cool. > > Hopefully this idea will peke your interest, and I will hear from you. > > Stephen Marshall > > ------------------------------------------------------- > > -- > 3010 Rte 109 > Waterville, VT 05492 > email: rion_at_dluz.com > web: http://dluz.com/Rion/ > AIM/Jabber/Google: riondluz > Phone: 802.644.2255 > http://www.linkedin.com/pub/6/126/769 > > "Documentation is like sex: when it is good, it is very, very good; > and when it is bad, it is better than nothing." -- Dick Brandon > >
