And just for some empirical evidence here are some histograms on the last 1M decode in my ALL.TXT file since Sep 2014. I don't see the -10dB+ compression Joe refers to...-1dB compression most certainly. But you can see JT9 decoding more stuff peaking at -24dB where JT65 rolls off at around -17dB. Is that cuz' people are using less power on JT9 I wonder?? Or is JT9 better at the lower signal levels? I also did a plot of JT65 signals since 2015-11-01 and it's very close to the same shape. RRR Mike W9MDB [image: Inline image 1] [image: Inline image 2] But...if you compress -1dB and higher this is what is would look like [image: Inline image 3] [image: Inline image 4]
On Tue, Dec 22, 2015 at 11:18 AM, Edson W. R. Pereira <[email protected]> wrote: > > Hello Joe and Bill, > > Thanks for the reminding. I have read the manual and have completely > forgotten about the signal strength range differences. > > The recent improvements in the JT65 decoder is just remarkable. There are > times that two or more signals are interlaced with one another and the > decoder decodes all signals. Really impressive. > > 73, Edson PY2SDR > > --- > - We humans have the capability to do amazing things if we work together. > - Nós seres humanos temos a capacidade de fazer coisas incríveis se > trabalharmos juntos. > > On Tue, Dec 22, 2015 at 3:03 PM, Joe Taylor <[email protected]> wrote: > >> Hi Edson, >> >> Signal strengths reported by JT65 have always maxed out at -1 dB. >> (Indeed, they start compressing and are significantly nonlinear above >> -10 dB or so.) The reason is historical: JT65 was developed for EME, >> where the SNR in 2500 Hz BW is essentially never greater than 0. As >> originally defined, the JT65 protocol supports signal reports from -1 to >> -30 dB. >> >> JT9 uses (almost) the same source encoding to compress user messages >> into 72 bits. But it was developed for use st MF and HF, where signals >> can be much stronger. By co-opting some code ranges otherwise used for >> grid squares near the North or South poles, JT9 supports signal reports >> from -50 to +49 dB. >> >> You'll find some relevant information here in the User Guide: >> >> http://www.physics.princeton.edu/pulsar/K1JT/wsjtx-doc/wsjtx-main-1.7.0-devel.html#_standard_exchange >> : >> >> "JT65 reports are constrained to lie in the range –30 to –1 dB, and >> values are significantly compressed above about -10 dB. JT9 supports the >> extended range –50 to +49 dB and assigns more reliable numbers to >> relatively strong signals." >> >> -- Joe, K1JT >> >> On 12/22/2015 11:54 AM, Edson W. R. Pereira wrote: >> > Hello everyone, >> > >> > I have been monitoring using wsjt-x v1.7.0 r6286 and am noticing that >> the >> > JT65 decoder is not showing signal strengths stronger than -1 dB. Even >> with >> > very strong signals the decoder shows -1 dB. The JT9 decoder does show >> > signal strengths above 0 dB. >> > >> > Has anyone noticed this? >> > >> > 73 and season's greetings, >> > >> > Edson PY2SDR >> > >> > --- >> > - We humans have the capability to do amazing things if we work >> together. >> > - Nós seres humanos temos a capacidade de fazer coisas incríveis se >> > trabalharmos juntos. >> > >> > >> > >> > >> > >> ------------------------------------------------------------------------------ >> > >> > >> > >> > _______________________________________________ >> > wsjt-devel mailing list >> > [email protected] >> > https://lists.sourceforge.net/lists/listinfo/wsjt-devel >> >> >> ------------------------------------------------------------------------------ >> _______________________________________________ >> wsjt-devel mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/wsjt-devel >> > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > wsjt-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/wsjt-devel > >
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