Interesting I get ghost images when I create an artifical filter via dsp that I see in DM780. My IF is a 2.1k and I am cranking down to 500hz or less for some of the modes.
Maybe I need an additional IF at 500 to 700 hz? Don KD8NNU On Mon, Feb 28, 2011 at 3:23 PM, kk7uq wrote: > Hello Guy > > I agree that the 3x signal is caused by clipping. I had to really > raise the > signal up to get it to show up. If I set the noise baseline at -80 to > -60 > dB, the harmonic does not show up. It looks like if the signal peak > goes > higher than -20 dB on the MixW waterfall, the 3x starts to show up on > DX > Skimmer, but still is not seen on the MixW waterfall. I have to > increase > the signal even more to the point where the signal is just below 0 dB > to see > the 3x signal on the MixW waterfall. > I have tried with the AGC on and off, with about the same results re: > where > DX Skimmer shows it. > > The bottom line is keep your sound system adjusted so that the noise > baseline is under -60 db, with AGC on, and you will not see these > extra > signals. The easiest way to adjust this is to use another program > such as > MixW in the spectrum display mode to see where the noise baseline is, > and > how strong the signal can get when AGC is on. I am seeing AGC kicking > in > when the strongest signal is about 30 dB above noise. > > 73, Clint > KK7UQ > > Snip > --------------------- > 3 X the sound frequency sounds like sound card over-drive, or simply > exceeding the actual linear range of the sound card. On-board sound > chips > and cheep Chinese sound cards are particularly vulnerable to showing > odd-order effects if you look way down. Those can sometimes be > significantly improved by managing the range of input sound and > line-in > levels. > If you want to see a clean 100 dB range in audio devices, you will > have to > get a high-end audio card. The cheep stuff just doesn't go there. > > 73, Guy. > ---------------------- > > > -- > View this message in context: > http://elecraft.365791.n2.nabble.com/Multiple-Ghost-Image-CW-Decodes-While-Using-CW-Skimmer-a-K3-tp6070469p6074752.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > 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 ______________________________________________________________ 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
