C-101EB losing TACAN signal

[Sparrow_1976]

Greetings,

I'm having fun in navigating the Nevada map using the TACAN or VORTAC stations. I'm in single player. Unfortunately it occurs a bit often that I lose the signal from the selected station. If that station transmits in VHF too, I still can get the VHF signal. Sometimes I can solve the problem by shutting off the TNC receiver and then put the knob on T/R again. I don't think that it's a problem of terrain masking, since it can also happen at 12k feet. If I switch to another station, the signal of that station is usually available.

[kontiuka]

12k feet is not that high in Nevada. That's only 6 or 7,000 ft AGL. Mountain masking can still take place.

[Ramsay]

I'm having fun in navigating the Nevada map using the TACAN or VORTAC stations. I'm in single player. Unfortunately it occurs a bit often that I lose the signal from the selected station. If that station transmits in VHF too, I still can get the VHF signal. Sometimes I can solve the problem by shutting off the TNC receiver and then put the knob on T/R again.

It sounds like a known TACAN bug introduced with 2.5.x, where TACAN stops working/updating after approx. 40 minutes of operation**, it effects most (all ?) of ED's modules i.e. A-10C, F-5E and Hornet.

 

I haven't seen the bug in the C-101 myself but that doesn't mean it's not there - I rarely use the C-101's TACAN to navigate but might turn it on as I near a suitably equipped destination.

 

If it's the same bug as the one effecting ED's own modules, it's not a line-of-sight issue as I've seen it ~3 miles abeam from a carrier in the Hornet and ~ 0.5 miles from an airport threshold in the F-5E and on both Caucasus and Nevada maps (I assume it's common to all maps).

 

Only workaround I know of is turning TACAN on and off, after noticing the TACAN distance has stopped updating on the HSI.

 

For info. Razbam's Harrier and Mirage seem uneffected by the bug.

 

EDIT 28th Nov 2020

 

** Note: I couldn't reproduce the "old" TACAN bug using the C-101EB or FA-18C in my standardised "test" mission - hot ramp start at Batumi, Stennis on 71X sailing NW, x3 game speed.

 

Tested Open Beta 2.5.6.58125

[Sparrow_1976]

I've done a test flight and I think it's definitely a bug. As Ramsay said, the signal is there for a while (TCN 33X), then it stops emitting. The TCN and VHF signals are both gone, since in the magnetic compass the big arrow is rotating and the slim one is struck in a fixed position. Setting the TCN knob on OFF and then on T/R again doesn't solve the problem. And it's not depending on the altitude, since the signal disappeared when I was at 12,000ft. and still wasn't there at 28,000. The only "solution" to somehow resume navigation is to switch to another emitter, then I can have (at least for a while) a working signal. Note that if a go for a different TCN emitter, I receive the right direction in the magnetic compass, but the slim arrow is struck since the VHF frequency is still the one of the "broken" emitter.

[Vibora]

Apart that this seems to be a DCS bug, not necessarily related to our module, I can't reproduce in C-101EB. Bishop TACAN, 33X, the one you talk about in your post, is sorrounded by mountains, it's possible that you are losing radio horizon.

It's hard to post images in this new forum, please that a look at this pic:

http://www.alasrojas.com/Upload/Bishop_TACAN_33X.jpg

 

If you actually think there is a bug I would need a trk (and detail the version you use).

[Sparrow_1976]

Ok ok, it's all my fault.

As Vibora said, the problem with TCN 33X is that it's surrounded by mountains. At a certain distance and angle, the signal is there. If I fly toward the TCN, the signal eventually disappears but it's there again as I am near enough (it seems a bit strange to me that if a mountain blocks the signal I can't receive it unless I am near OR FAR ENOUGH, I'd say that to be very far is never good for the receiver). Anyway I confirm that it works like that, and I also verified selecting others TCN stations.

 

[Vibora]

It is most likely due to beam refraction. Probably not 100% accurate in DCS, but that should be the reason. The electromagnetic radiation propagation follows a curved path because of the variation in density of the different layers of the atmosphere, which causes refraction.

[Nodak]

For VOR's design limits stations to different ranges according to altitude in above the station, TACAN probably suffer the same hardware limits. 

 

The close in to the station 'bug' where it no longer give you accurate distance is due to slant range, in reality it is giving you an accurate distance, your just that far up and over, the closer to the station with higher altitude the more impact on slat range, the greater the inaccuracy.  If your flying two miles directly above station, you have a two mile reading when your distance is actually zero.

 

"https://www.youtube.com/watch?v=l4zJoKO-Zb8"

 

It's old but lots of good information on the stations themselves and principles of how they operate.

 

VOR's ranging

Ground to 14,500' 40 Nautical Miles range

14.5K - 18K 100 NM's

18K - 45K 130 NM's

45K - 60K 100 NM's

Under 5K gets reduced the lower you go they are line of sight stations.

Edited April 21, 2021 by Nodak