James Turner writes: > - it looks like the scaling of ADF frequencies in the Robin Peel data > is wrong: they're in KHz? (eg 340.0), whereas the VORs are in MHz (eg > 109.8), but there's a uniform scaling of 100 applied .... this seems a > bit odd to me. I'd rather 'freq' was just the frequency in Hertz.
That's a legitimate approach, but it might confuse people. Most people think of a frequency as just '236' or '118.8' and then apply it to the appropriate radio, without considering the magnitude implied by KHz or MHz. > - All the navids in the DAFIFT have a supplied Magnetic Variance, so I > need some help dealing with the format. It's basically: > E/W (direction) > degrees variation (actually deg / min / tenths of minute, but I can > convert) > year / month stamp. > > Now, what I'm wondering is whether I can do anything with the year / > month stamp to update the variation? Oh, and what's the sign convention > for our magvar values? +ve = East, -ve = West? You probably should ignore the MAG_VAR field and concentrate on the SLAVED_VAR one -- that's the one that shows the VOR twist. > Anyway, the DAFIT stuff is going well, I'm able to pull in lots of > extra data which will be useful for ATC and the like, as well as > reception quality: there are things like guaranteed service ranges / > volumes, transmitter wattages and the like. Don't base too much on the service volumes -- they're just a learning and regulatory tool that the FAA uses, and have only a light relationship to physical reality (i.e. they can help us distinguish high-, medium-, and low-powered VOR transmitters). As we've discussed recently on this list, the best way to determine VHF range (over flat terrain with no interference) is something like this range_nm = 1.23 * sqrt(altitude_ft_agl) To that, we have to add limits based on the transmitter power. Some day, we might get very smart and start to account for interference from buildings and terrain as well. All the best, David -- David Megginson, [EMAIL PROTECTED], http://www.megginson.com/ _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
