key_stroked Posted June 7, 2018 Posted June 7, 2018 I set a tanker to a TACAN channel (22Y), and was testing tracking it on the HSI. If I have only T/R selected and 22 in the UFC window, and X as the channel, I still get a bearing but no distance to the tanker. If I select Y as the channel and also select A/A, then I get the bearing and the distance. Shouldn't I get nothing if I'm not on Y and not in A/A both simultaneously? The tanker was setup in the advanced waypoint options with 22Y specifically.
key_stroked Posted June 9, 2018 Author Posted June 9, 2018 Including screenshots to show the behavior of tanker TACAN. As a reference, the carrier TACAN, which is set to 55X, works correctly. T/R and X are both selected and the HSI/HUD gives bearing and range info. But tanker TACAN will work even if one of the two conditions (A/A and Y) is not met. The tanker was set to 22Y in the mission for these screenshots. In this screenshot, I set the Y but I did not select A/A, and I still got a bearing to the tanker (but no range). Here I correctly set A/A but I left it on X, and I still got a bearing (but no range). When selecting both A/A and Y, I get both range and bearing. Afaik, I should not get any bearing info if I don't have both A/A and Y selected at the same time.
Frederf Posted June 9, 2018 Posted June 9, 2018 22Y A/A means that your plane is interrogating on 1046MHz 24us pulse spacing and listening for single pulse reply on 1109MHz. The tanker is replying on 85Y A/A, 1109MHz single pulse. If you change to 22X A/A then you are still receiving 1109MHz and interrogating 1046MHz but pulse spacing is 12us. On the surface it seems the potential for function is there. Only the pulse spacing is screwy. It makes sense that this might break ranging. Also note that there is a system delay in A/A mode of 64us X 75us Y corresponding to 0 miles range which is different than air-to-ground behavior and may result in invalid range. On the other hand 22Y T/R (not A/A) is again interrogating 1046MHz and awaiting ground reply 1109MHz. The frequencies are correct but the expected pulse spacing is different, 30us pairs expected from ground but tanker would be giving single pulse reply. That might also break ranging but allow bearing which is separate from the interrogation pulses. And 22X T/R when 22Y A/A is called for simply misses frequencies. It's listening on 983MHz which the tanker simply isn't producing. Long story short, this might be correct behavior for your given "half match" configurations.
key_stroked Posted June 10, 2018 Author Posted June 10, 2018 22Y A/A means that your plane is interrogating on 1046MHz 24us pulse spacing and listening for single pulse reply on 1109MHz. The tanker is replying on 85Y A/A, 1109MHz single pulse. If you change to 22X A/A then you are still receiving 1109MHz and interrogating 1046MHz but pulse spacing is 12us. On the surface it seems the potential for function is there. Only the pulse spacing is screwy. It makes sense that this might break ranging. Also note that there is a system delay in A/A mode of 64us X 75us Y corresponding to 0 miles range which is different than air-to-ground behavior and may result in invalid range. On the other hand 22Y T/R (not A/A) is again interrogating 1046MHz and awaiting ground reply 1109MHz. The frequencies are correct but the expected pulse spacing is different, 30us pairs expected from ground but tanker would be giving single pulse reply. That might also break ranging but allow bearing which is separate from the interrogation pulses. And 22X T/R when 22Y A/A is called for simply misses frequencies. It's listening on 983MHz which the tanker simply isn't producing. Long story short, this might be correct behavior for your given "half match" configurations. Where does all that info come from?
Frederf Posted June 10, 2018 Posted June 10, 2018 Google for "TACAN frequencies" or similar. It's hard to find the more esoteric details like how A/A mode varies from the usual air-to-ground.
key_stroked Posted June 12, 2018 Author Posted June 12, 2018 I'd still be interested in hearing from the ED team on this.
Emmy Posted June 12, 2018 Posted June 12, 2018 There's something currently bugged in TACAN land. We have three KC-135s on our Squadron server and all are xxY but they show up on xxX. [sIGPIC][/sIGPIC] http://www.476vfightergroup.com/content.php High Quality Aviation Photography For Personal Enjoyment And Editorial Use. www.crosswindimages.com
key_stroked Posted June 14, 2018 Author Posted June 14, 2018 (edited) Has ED seen this thread? I see lots of threads being tagged with "Reported" or "No Bug". Edited June 14, 2018 by Halcyon
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