Spectrum efficiency must be measured in time necessary to get the info across, length of info transferred, and bandwidth. ((characters/second)/ bandwidth) or characters/(seconds * bandwidth). The bandwidth includes a certain guard band(minimum distance between 2 different signals), which for JT65 is quite small ... but the time is a large factor...
To give a small example: Pskmail using PSK500 ARQ has a spectrum efficiency of 23/500 = 0.046 CPS/Hz ... measured on 14094.0 kHz running 100 mW connected to SM0RWO (>1000Miles) ... The longest message in JT65 is 13 characters... and a message takes 48 seconds.. the bandwidth (according to the mode description) is 65 * 2.7 = 175 Hz ...which calculates to (13/48) / 175 = 0.001547619 CPS/Hz I would say this is a pretty bad value... :) Rein PA0R >Bill N9DSJ decoded two stations within 24 Hz of each other, how is >that for spectrum efficiency? I was transmitting 5 watts, > >I know many are already aware of this, but take a look > >N9DSJ-1 (EN52ti) Heard N6TE(DM12) on 3576.23 KHz -8dB at 03:32:00Z using JT65A >N9DSJ-1 (EN52ti) Heard K3UK(FN02) on 3575.99 KHz -5dB at 03:32:00Z using JT65A > >Bill N9DSJ decoded two stations within 24 Hz of each other, how is >that for spectrum efficiency? I was transmitting 5 watts, > >Andy K3UK > > >------------------------------------ > >http://www.obriensweb.com/digispotter.html >Chat, Skeds, and "spots" all in one (resize to suit)Yahoo! Groups Links > > >