From: DL4YHF@aol.com
Message-ID: <fc.10928b0c.2948fc6e@aol.com>
Date: Wed, 12 Dec 2001 13:31:10 EST
Subject: Re: LF: spectrum analysis
To: rsgb_lf_group@blacksheep.org
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<HTML><FONT FACE=arial,helvetica><FONT  SIZE=2>Using a spectrum analysis program to observe weak normal CW signals ?
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<BR>As I see it, using a spectrum analysis program with waterfall display does not really help to copy weak CW signals at conventional speeds around 20wpm. 
<BR>One of "these programs" &nbsp;has a fast running waterfall which draws a new line of pixels every 10 milliseconds, but the frequency resolution *must be* much lower than for QRSS so there is not much gain from this. So it is quite useless for detecting weak CW signals, but gives an impressive colorful display when monitoring shortwave during a CQWW contest.
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<BR>The best one can do is using an appropriate narrow-band filter for aural copy, no matter if it's an analogue one, a DSP box, or a PC running Spectran etc. &nbsp;An alternative may be the use of Coherent CW, I guess there are some programs on the market making CCW a bit easier now than it was many years ago. 
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<BR>Don't expect the ultimate wonder from DSP-based audio filters, if the IF bandwidth of your receiver, selective pegel meter or whatever is already below 100 Hz ! 
<BR>The benefit when going from 100Hz BW to 50Hz BW is not 3dB, because the human ear already does a good job to detect the presence of a single tone in the noise...
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<BR>Regards, 
<BR> &nbsp;Wolf DL4YHF.
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