As I recall from my broadcasting classes years ago, human speech has a "typical" bandwidth of just 3KHz. "Normal" human hearing, IIRC, picks up frequencies from 20Hz to 20KHz.
If someone has a copy of Schrader's "Electronic Communications" ready to hand, the specifics should be in there somewhere. - - 73 de N5ILN Alan On Wed, Aug 7, 2013 at 10:33 AM, Jim Brown <j...@audiosystemsgroup.com>wrote: > On 8/7/2013 8:39 AM, Ron D'Eau Claire wrote: > >> So if you enjoy music on your A.M. radio, note that it's unlikely >> your radio is reproducing much of anything above 5 kHz. >> > > 99.99% of AM broadcast receivers have audio bandwidth of less than 5 kHz. > The only ones I know of with bandwidth greater than 9 kHz are the GE Super > Radio, the Carver TX-11, and a couple of models made by McKay Dymek, and > all of them are long discontinued. I have a Carver and several of the GE > Super Radios. In the early 80s I was selling the McKay Dymek radios to > broadcasters for use as monitors, and had one at home for a while. > > Beginning more than 30 years ago, consumer radios were built to use the > same detector and audio circuitry for AM that they used for FM, which > includes 6 dB/octave de-emphasis starting around 1 kHz. This equalizes for > the pre-emphasis applied at the transmitter, which was, and still is, the > standard for FM broadcasting. This made AM even muddier than it already > was, so AM broadcasters adopted the standard of applying pre-emphasis to > their signals. I don't remember when that was adopted, but I'd guess at > least 30 years ago. As I recall, that standard also required a low pass > around 10 kHz. > > 73, Jim K9YC > > ______________________________**______________________________**__ > Elecraft mailing list > Home: > http://mailman.qth.net/**mailman/listinfo/elecraft<http://mailman.qth.net/mailman/listinfo/elecraft> > Help: http://mailman.qth.net/mmfaq.**htm<http://mailman.qth.net/mmfaq.htm> > Post: mailto:elecr...@mailman.qth.**net <Elecraft@mailman.qth.net> > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
