Sounds like I should put a couple boxes on the Config page for linear fit parameters. Then an explanation to users on how to compute them.
I think I'll give that a go. Also, could put the observed watts into the log box too. I was also thinking it might be nice to have the ability to put in "10W" as your output power goal and WSJT-X could adjust the input level automagically to give you that all the time. 73 Mike W9MDB -----Original Message----- From: John Nelson [mailto:j...@rmnjmn.demon.co.uk] Sent: Wednesday, August 05, 2015 3:31 PM To: WSJT software development Subject: Re: [wsjt-devel] Power/S-Level Mike, STRENGTH vs External power meter (Daiwa) (output to 50ohm load) Smeter readings are not accurate since these are discrete dots not continuous: For S1 through S9 the linear (r=0.999) relationship is: Strength = 5.4 n - 48.2 where n is S meter. From this, difference between S1 and S2, for instance, is 5.4 not 6 as one might expect for Smeter reading power. Strength between S9 and S9+20 = 18 S9+20 and S9+40 = 18 and not 20. In both cases delta-Sreading is low. It appears that S meter is calibrated to 6dB per unit as you thought, which is what I expect for Smeter power. Since Strength is evidently on a log scale (dB), plot Strength vs log power: linear (r=0.96) relationship: Strength = 52.7 log (power) - 76.5 Now, if I change HamlibTransceiver.cpp as: // strength.i = pow(10,(strength.i-30-107)/10.0); strength.i = pow(10,(strength.i + 76.5)/52.7); then I get a sensible answer. There are obvious inaccuracies here, not least the measurement of power from the Daiwa meter - all I have at the moment. But basically this works. Power on your meter also changes when I alter RFPOWER with L RFPOWER 0.25, for instance. How this fits in with the service manual on the Smeter and the meaning of "Strength" returned from hamlib is something you will no doubt have a look at. --- John G4KLA ---------------------------------------------------------------------------- -- _______________________________________________ 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
