[TenTec] Roofing Filters

[w8au at sssnet.com]

At 06:05 PM 5/29/06, Ken Brown wrote:
>Every filter in my receiver from the
>frontend bandpass filters to the first IF and second IF filters limit
>bandwidth before the final audio filtering. So there is virtually no
>filter, by that definition, that is not a roofing filter. I suspect 
>that without a clear definition, the term is being used slightly 
>differently by every one who uses it.

(snip)

For those of us in commercial telecommunications vocations, "roofing 
filter" meant something that had an upper frequency cut-off...ie: a 
"ROOF" over a lower band of used frequencies.  (Also called a "Low 
pass filter.")  This roofing term was used for years in microwave 
baseband applications.

Initially, I was confused with the "new" amateur radio use of the 
term, since it NOW means a bandpass filter at or near the input 
stages of a receiver.   Hmmmm...  is this now to mean the "roof" over 
the radio? :-)

OK.. fine with me.  I'll not be stubborn about it.  It would be nice 
to know when an electronics entity changes the meaning of a term.... 
After all, we did have some advance notice about the "cycles" to 
"Hertz" changeover some years ago...  :-)

Happy Memorial Day...

Perry   w8au