The P3 already does this if you have MENU:SpanScale set to anything other than "OFF".
Alan N1AL On Tue, 2012-01-03 at 19:52 -0500, Mike Markowski wrote: > I'll follow up on my own note because there's nothing as helpful as an > example: > > 1) I move to 17m band with P3 set for +/-100 kHz span > 2) P3 REF LVL knob used to set -122 dBm to match noise level at my QTH > > 3) -122 dBm = 6.30957 x 10^-13 mW > 4) Since noise power N = kTB, (k is Boltzman's constant), > T = N / (kB) = 6.30957 x 10^-13 / (k x 200 kHz) > k = 228500 K <--- recalc when REF LVL knob is twiddled again! > > Now I want to change P3 span to +/-5 kHz, or B = 10 kHz: > > 5) N = kTB = (1.380648813 x 10^-23) x 228500 x 10x10^3 > = 3.15479 x 10^-14 mW > = -135 dBm <--- new REF LVL setting, send to P3 > > Easy to add to firmware? If not, it is easy to add to external > software. The only thing not automatic is that the initial manual REF > LVL setting is required to take into account antenna system noise > presented to the P3. > > I hope other REF LVL twiddlers find this useful. 73, > > Mike ab3ap > > On 01/01/2012 03:26 PM, Mike Markowski wrote: > > Since the PA temp is available as well as the filter bandwidth in use, I > > wonder if the P3 could have an auto-adjust of REF LVL? It would only > > work within a given band and only after the op has adjusted the REF LVL > > to begin with. But after that it seems that the good ol' N = kTB would > > be a simple enough calc that P3 REF LVL could be auto-adjusted as SPAN > > or filter bw is changed. > > > > I know, talk about being lazy... :-) Happy 2012! > > > > Mike ab3ap > > ______________________________________________________________ > 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
