I believe the new term was first used when the filter in front of the IF
string became selectable. The filters you are speaking of are IN the IF
string. To my knowledge, in the past most good receivers were designed with
a 20KHz roofing filter. Adding DSP in the IF stages likely led to the need
to narrow the front end filter.
73, Keith NM5G
-----Original Message-----
From: yaesu-bounces@contesting.com [mailto:yaesu-bounces@contesting.com] On
Behalf Of Paul Manuel
Sent: Friday, July 21, 2006 9:54 AM
To: yaesu@contesting.com
Subject: Re: [Yaesu] FW: roofing filters
I am a bit confused about the term "roofing filters" as it seems to be a new
term for an old idea.
Is "roofing filter" today's term for a hardware, high-IF filter, to be used
in conjunction with the DSP filtering used at low IFs (such as
32kHz?)
If so, I don't see the need for the new term, especially if the rig in
question offers these switchable filters in different IFs. How is this
different from what we used to see? For instance, my Kenwood TS-850SAT had
12kHz, 6kHz, 2.4kHz, and 500Hz hardware filters. How was this different from
today's use of roofing filters, except that they depend solely upon
hardware? And are we not taking a step back from the "DSP is the Latest and
Greatest" philosophy?
Not to be critical and certainly not for flaming purposes, just wanting to
know! Fifteen years ago I was able to keep up with ham technology, but now
its passing me by...
73,
Paul K4PDM
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