It reproduced ok on my download copy. 73, Doug VE3MV
----- Original Message ----- From: "Philippe Trottet" <[email protected]> To: "Kok Chen" <[email protected]>; "Elecraft Reflector" <[email protected]>; "turnbull" <[email protected]> Sent: Tuesday, February 16, 2010 6:10 AM Subject: Re: [Elecraft] P3 >P 130 is blank on the pdf document ! > 73's > Philippe A65BI > >>>> Kok Chen <[email protected]> 16-02-2010 14:16 >>> > > On Feb 16, 2010, at 12:39 AM, turnbull wrote: > >> When you write the manual for the P3 would you please include a good >> explanation of the use of waterfall displays. I have one on my OII but >> do not fully understand its benefits. > > Spectrograms, such as "waterfalls," make use of your eye-brain system to > help find signals that are below the noise level, especially when signals > are drifting and don't allow temporal averaging methods. > > You can see an example of its use (1971) here: > > http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730010095_1973010095.pdf > > Fig 11-7 on page 130 (although poorly reproduced in the PDF scan) and the > text on that page explains its use for discovering very, very weak and > very, very DX signals. > > In the amateur world, the first use of waterfalls was by Skip KH6TY in his > Digipan program, I believe. Without Digipan and the ease of "waterfall > tuning," PSK31 probably would not have become as popular as it is today. > > With the addition of some special filtering, you can make a waterfall see > even deeper into the noise when the signal is not drifting. The two > figures here > > http://homepage.mac.com/chen/w7ay/cocoaModem/UsersManual/mfskManual/mfskManual/dominoex.html#weak > > show the same weak DominoEX signal with 18 FSK carriers. The top figure > is what the weak signal looks like in a simple waterfall, and the figure > at the bottom, with the same input SNR, takes advantage of a signal that > is not drifting, as explained in the accompanying text. > > In the digital world, you can't work them unless you can *see* them :-). > > A good waterfall display will also show a CW signal that you can't hear, > and can make "zero beating" a virtually instantaneous effort. Or zero > beating to a synchronous AM carrier, etc etc. > > 73 > Chen, W7AY > > ______________________________________________________________ > 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 > ______________________________________________________________ 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
