Think of your roof blocking the rain so the ceiling doesn't have to work so hard.
It's not used for band-pass, it's to let the DSP work less. Sent from my iPhone ...nr4c. bill > On May 12, 2014, at 3:01 PM, Bill Turner <[email protected]> wrote: > > ORIGINAL MESSAGE: (may be snipped) > >> On 5/12/2014 9:33 AM, Jerome Sodus wrote: >> Hello Bill, >> The term "roofing-filter" made sense back in the 1980's when I designed >> roofing-filters at 70 MHz. >> Bandwidths would be in tens of KHz. >> The purpose then was to protect downstream circuitry by rejecting very >> strong out-of-band signals that could cause overload; selectivity was not >> the purpose. >> Selectivity was done further downstream. >> So the term has become corrupted over the years. >> 73 Jerry KM3K > > REPLY: > > I still don't get it. What does the word "roof" have to do with bandpass? > That's where the confusion comes from. > > 73, Bill W6WRT > [email protected] > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
