[Yaesu] which is better? IF or AF dsp filters

[George, W5YR]

Hart, for a large number of reasons, IF DSP is far superior to AF
(only) DSP.

But, to explain  the reasons is more than I want to tackle in a list
posting. At the risk of sounding like I am telling you to RTFM, let me
recommend the DSP Processing chapter in the last couple of ARRL
Handbooks by Doug Smith for an outstanding summary of the entire DSP
universe as it is applied in amateur radio. There have also been some
more elementary articles in QST the past year or so.

Manufacturers who still produce conventional analog IF radios with AF
DSP tacked on the end will argue vehemently with my statements, but
the fact that virtually all military and commercial high-end receivers
sold in the last decade have been built around an IF-DSP "core" - as
are the Icom PRO rigs, for example - confirms the validity and
superiority of the architecture. Note also that such rigs use no
narrow crystal filters in their analog IF stages since the front-ends
perform sufficiently well that the 100+dB dynamic range of the DSP
section is adequate to deal with IMD issues without the use of analog
filters.

Finally, an IF DSP receiver does far more than just generate IF
filters in its DSP section. ALL signal operations - waveform
generation, frequency determination, modulation, demodulation, notch
filtering, bandpass filtering, keying, etc - are done by DSP alone.

73/72, George
Amateur Radio W5YR -  the Yellow Rose of Texas
In the 57th year and it just keeps getting better!
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
K2 #489  IC-765 #2349 IC-756 PRO  #2121 IC-756 PRO2 #3235

----- Original Message -----
From: "Hart Engel" <va3kis@hotmail.com>
To: <yaesu@mailman.qth.net>
Sent: Tuesday, January 21, 2003 8:51 AM
Subject: [Yaesu] which is better? IF or AF dsp filters


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> As you know some rigs come with the dsp filters in the IF stage and
some come in the AF stage.  Which is better?