On Fri, 2006-06-02 at 14:17 +0100, Vivian Meazza wrote: Hi Vivian
> I'm more than willing to be corrected on this one, but my understanding is > as follows: > > A VORTAC station has 3 frequencies in RL - TACAN, VOR, and DME. This is my understanding, too. Further A TACAN "channel" includes 3 frequencies, Two for TACAN/DME and one for VOR/ILS. [1] > In FG nav.dat only the VOR and DME are held. Actually, nav.dat only holds the VOR freq. The DME uses the associated VOR frequency. > Thus it is a fix in the case of VORTAC to misalign the TACAN > channel/frequency > pairing to the VOR frequency in stead of the TACAN frequency. There is not a mis-alignment. The TACAN spec includes the VOR freq pairing, as well as the DME freq pairing. It is possible in real life to tune a VOR/DME reciever to (most?) TACAN stations and receive DME information. > Unfortunately, there are other stations in > the world which are TACAN only, which seem to have the correct TACAN > frequency assigned: Flesland TACAN is one such example. Flesland TACAN (FLE) uses channel 092X [2] Flesland VOR/DME (FLS) uses channel 102Y (115.55 MHz) [3] zgrep Flesland nav.dat.gz: 12 60.300036 005.213589 185 11450 130 0.000 FLE Flesland TACAN 12 60.311261 005.212194 213 11555 130 0.000 FLS Flesland VOR-DME Under the current version of TACAN.dat FLE is tuned using 058Y and FLS is not tuneable. FLS should give DME only to the onboard TACAN system, currently the TACAN system in FG would ignore it, if it were tuneable, I think. > Thus we fix the VORTAC at the expense of the TACAN. I don't see this. With a corrected TACAN.dat and the current nav.dat both VORTAC and TACAN work fairly well. I use HIF TACAN all the time: 12 41.120503 -111.963681 4806 11120 40 0.000 HIF Hill TACAN > The correct fix is to modify nav.dat to show all 3 frequencies for the > VORTAC stations. If I understand correctly, you are concerned because the current TACAN uses the name of the DME station to determine whether or not to provide TACAN service. Adding a section for TACAN Azimuth that mirrors the DME entries for VORTAC and TACAN stations makes sense, the TACAN DME would respond to all DME entries (12/13) in nav.dat and TACAN azimuth would respond only to the new (number??) TACAN entries in nav.dat. Overall, I don't see a way to proceed without first replacing TACAN.dat. [1] http://www.vectorsite.net/ttradar5.html#m3 [2] http://worldaerodata.com/wad.cgi?nav=FLESLAND&nav_id=FLE&nav_type=3 [3] http://worldaerodata.com/wad.cgi?nav=FLESLAND&nav_id=FLS&nav_type=4 _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
