Thanks for the explanation Joe. I had not seen that before. Signals do not affect the noise estimate which was one of the answers I was looking for.
Joe > On Dec 10, 2023, at 11:21, Joe Taylor via wsjt-devel > <wsjt-devel@lists.sourceforge.net> wrote: > > Hi Joe, > >> On 12/9/2023 9:56 PM, w0fy--- via wsjt-devel wrote: >> Been wondering how WSJT-X generates the noise power estimate it uses to >> calculate SNR for each FT8 signal. Does it simply collect all the signals >> and noise over the bandwidth selected on the waterfall and call that the >> noise power level or does it take a quick snapshot of the background noise >> level during the brief quiet period at the end of each 15 second FT8 >> sequence? Or is it more complicated than that? > > This question has been asked and answered many times on this and similar > forums. WSJT-X measures noise power by computing the spectrum of the > receiver's output, averaged over the reception interval, and fitting a > baseline to the regions that have no discernible signal present. The > resulting value -- effectively a noise power density, or power per unit > bandwidth -- is then scaled to yield noise power in 2500 Hz bandwidth. > >> I am plagued with a S2 -S3 noise level on 6 meters nearly all the time that >> if not AWGN is pretty close to it. 10 meters is even worse. The DSP noise >> blanker in my TS590 will reduce it slightly. I estimate this is degrading my >> ability to decode FT8 signals on 6 by nearly 20 dB compared to the noise >> level generated by a 50 ohm resistor. I don’t use an LNA ahead of the radio >> – would be pointless. I don’t use the noise reduction feature in the radio >> either as it tends to lose very weak signals completely. > > It's OK to use your receiver's noise blanker to remove impulsive noise. > > Do NOT use "noise reduction" features, and do NOT use a receiver bandwidth > narrower than about 2.5 kHz. Wider bandwidths are even better, up to 4 or 5 > kHz. WSJT-X does all necessary narrow-band filtering in software. > > -- 73, Joe, K1JT > > > _______________________________________________ > wsjt-devel mailing list > wsjt-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/wsjt-devel _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
