On 09/08/09 15:18, dave perry wrote: > [The] note below caused me to ask if the LOC needle deflection is scaled > differently than the VOR needle deflection in navradio.cxx. It is and > the comment that it is 4x more sensitive is correct according to notes > from Instrument Ground School.
1) This was discussed in detail back in January 2009. 2) Yes, I know many ground-school instructors teach the "half degree per dot" rule ... but it is only a rough rule of thumb. Real world localizers adhere to the ICAO (and FAA) standard, which specifies that the localizer course shall be 210 meters (700 feet) wide at the threshold. That is the full side-to-side width. Some numerical examples are given below. Note that there are additional quirks that apply to exceptionally short runways. 3) The existing FGFS convention is perfectly reasonable, i.e. scaling the outputs of the nav receiver so that both the VOR and LOC deflections are represented the same way on the "wire" from the receiver to the CDI. 4) Back in January I wrote the code to implement correct ICAO localizer behavior. This includes the important service volume issues that Atadjanov Daniyar reminded us about recently, i.e. 09/08/09 09:30. This also includes false localizer courses, which are quite significant for real-world instrument flying. This also includes correct GS behavior, including false glideslopes. This also includes comments with references to the relevant standards, and why the output levels are as they are. Every rated pilot who tried out this code agreed that it behaved significantly better than the "half degree per dot" approximation. The code was never committed to CVS. No believable reason for rejecting it was ever given. > I don't think it is a good idea to go to a normalized value in a blanket > edit of other's instruments as the needle deflection in the animation I strongly agree! There is nothing wrong with the existing FGFS convention for CDI deflections. Indeed this is a rather realistic model of how real-world receivers interact with analog CDIs. On 01/01/09 04:32, I wrote in part: >> some rather extreme examples include: >> >> At Kennedy: >> IMOH localizer axis: 4771.2 m ==> +- 1.28109 full scale or 0.256217 degrees >> per dot >> >> At Robert J. Miller: >> IMJX localizer axis: 1964.73 m ==> +- 3.11101 full scale or 0.622203 degrees >> per dot ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Flightgear-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/flightgear-devel
