On 2/12 Dave Perry wrote: > It occurred to me that we should use John's interpolation function in > several other places: > 1. We use a form of this function in kap140.nas without the efficiency > of the interpolation. > 2. The encoder uses a similar interpolation that a general form of > this > function could replace. > ... > What I am proposing is to create a C++ function (say height_ft) that > has two arguments, P0 and P1 that does the interpolation in John's new > patch using his constants. > To which John responded:
> >That is the same spirit as what I was suggesting in the opening > >paragraphs of: > > http://www.av8n.com/fly/fgfs/README.altimetry.html > > Then the kap140.nas could use that function, the encoder could use > that function to compute PA > ... > This would have the added advantage of standardizing the constants > used in all three applications. > I thought that would be one of the outcomes of your effort. On Sun, 2007-02-25 at 19:58 -0500, John Denker wrote: > How about > 2') Have the autopilot calculate the Kollsman shift on its own. > That is counter to the "same spirit" you reference above. That is why I wrote: > > > At the start of this discussion, I thought you wanted just one model of > > the atmosphere. So it is a bad idea to have each autopilot use it's own > > model. Users are going to want to ignore different returned values for > > different instantiations for "realism" reasons. > But a real autopilot *does* have its own model ... not a model > of the real atmosphere, but an ISA-model atmosphere (or, more > precisely, a Kollsman-model atmosphere). > The present cvs kap140 does approximate the baro shift with such a model as you well know. Since you already compute the kollsman shift for the value of "setting-inhg", why not save that value to the property tree? That would accomplish giving the kap140, the altimeter, and the encoder access to your "improved" interpolation model for the two terms in equation (15) in your paper. You compute both PA and the kollsman shift, but only allow others access to PA. That only requires two additional lines of c++ in altimeter.cxx plus a declare in altimeter.hxx. I can integrate a 2nd instantiation into the kap140 including the identified changes to altimeter.cxx and altimeter.hxx. Regards, -- Dave Perry ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
