On Sun, Jun 08, 2003 at 04:34:54PM -0400, Russell Nelson wrote: > David Young writes: > > It's not quite as bad as that. 50 MHz is an adequate sampling rate > > for a 25 MHz-wide 802.11b channel, and virtually every 802.11b radio > > shifts from the carrier frequency to some lower frequency (374 MHz > > is typical) where the modulator/demodulator runs. An 802.11b SDR will > > be no different, but the shift will be longer. > > Thanks for pointing that out. That's good news -- means that we're > much closer to SDR being seriously useful. But ... doesn't that limit > the bands in which the radio can operate? Or are you already limited > in that you need multiple front-ends anyway?
Right, you will use different front-ends for different bands. I think that sometimes different front-ends can have pieces in common, for example, a synthesizer (generator of the RF/IF frequencies). There are probably examples of tight integration of front-ends, for the cost savings, in the new 802.11 a/b/g radios. Check out the block diagrams at the Atheros website. > Don't you need different > antenna lengths for such disparate frequencies? It probably depends how fancy an antenna you use, but I am pretty sure that my 8dBi 2.4 GHz omnis will not operate too well at 5 GHz. Dave -- David Young OJC Technologies [EMAIL PROTECTED] Urbana, IL * (217) 278-3933 -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
