correct as is Datalink problems

[b0bl00i]

My friends and I was flying over the new Marianas map yesterday, all started from cold start.

We had issues with datalink contact not being shown on the HSD. All did ofc proper startup and alignment.

We restarted the server, did the same and all of a sudden, it worked.

 

We could also not that LIST -> ENT -> (DL) showed no GPS Time. When checking back in the DL menu, GPS time was there from time to time. Not sure if this is related. Don't have any track file.

 

 

[stalhuth]

Playing in MP I have some problems with DL, in cold start everything is fine, but then I land then rearm - refuel, takeoff again and the datalink don't show any contact (friend or foe) after a couple of minutes the contacts are there again and after some more seconds disappear again. 

Is this a know bug? or is not  a bug?

[Florence201]

1 hour ago, stalhuth said:

Playing in MP I have some problems with DL, in cold start everything is fine, but then I land then rearm - refuel, takeoff again and the datalink don't show any contact (friend or foe) after a couple of minutes the contacts are there again and after some more seconds disappear again. 

Is this a know bug? or is not  a bug?

Read some of the other DL posts on the forum to see if they help. Others have posted about this 

[BIGNEWY]

Please see this post 

 

 

check you are not using a degraded channel 

 

to investigate we will need short track replays

 

thanks

[SCPanda]

On 7/8/2021 at 7:35 PM, BIGNEWY said:

Please see this post 

 

 

check you are not using a degraded channel 

 

to investigate we will need short track replays

 

thanks

Well, finally we found the cause, but no solution so far except not using these TACAN channels? But I guess I cannot stop others from using them in MP? (i.e. not really a solution)

Edited July 14, 2021 by SCPanda

[SCPanda]

Check this topic

 

[BIGNEWY]

all we can do is make people aware of the degraded TACAN channels.

[SCPanda]

22 hours ago, BIGNEWY said:

all we can do is make people aware of the degraded TACAN channels.

Is this something realistic or something you guys are still investigating? 

[BIGNEWY]

39 minutes ago, SCPanda said:

Is this something realistic or something you guys are still investigating? 

Its realistic as far as I am aware. 

[SCPanda]

15 minutes ago, BIGNEWY said:

Its realistic as far as I am aware. 

OK thx

[Frederf]

My understanding of TACAN, IFF, L16 share frequency space and the MIDS equipment and configuration is designed to work around potential conflicts. For example Batumi's 16X frequencies would be eliminated from the MIDS TDMA traffic as part of the plan uploaded to the airplane so that MIDS would skip that frequency in it's 77,000 hops per second pattern. This is mostly to avoid unwanted interference with TACAN at short ranges (worst case often about 1nm).

 

Link 16 doesn't have a particular frequency of operation but can use up to 960-1215 MHz. "Link 16 operates normally in a frequency hopping mode. The successive Link1 6 pulses shall be hopped pseudo-randomly among 51 carrier frequencies or with up to 14 of the 51 carrier frequencies remapped."

 

The notion that if one of those 51 frequencies had some TACAN traffic on it that the entire network would grind to a halt seems wrong. Far from being jam-resistant, it would be exceptionally easy to jam.

 

The F-18 and other airplanes have specific antenna filter notches. From memory the F-18 has a smart switching filter on top (or bottom) and a dumb permanent filter on bottom (or top).  The filtered frequencies correspond to IFF operation and so MIDS TACAN traffic can be hampered by these filters which overlap with IFF. As far as I can tell MIDS TDMA Link 16 traffic is unaffected in any case. Other airplanes like F-16 could have different filter and antenna arrangements and it should not be assume the limitations which apply to one airplane apply to another.

 

I'm not at all an expert in Link 16 but I think one should be consulted as it seems highly suspicious that a premiere datalink network would be so delicate that a lone airplane using yardstick on a problematic channel would break the whole thing. I've read nothing which suggests L16 is so delicate but instead that it is TACAN which has the potential to suffer interference and loss of navigation service.

[Florence201]

40 minutes ago, Frederf said:

My understanding of TACAN, IFF, L16 share frequency space and the MIDS equipment and configuration is designed to work around potential conflicts. For example Batumi's 16X frequencies would be eliminated from the MIDS TDMA traffic as part of the plan uploaded to the airplane so that MIDS would skip that frequency in it's 77,000 hops per second pattern. This is mostly to avoid unwanted interference with TACAN at short ranges (worst case often about 1nm).

 

Link 16 doesn't have a particular frequency of operation but can use up to 960-1215 MHz. "Link 16 operates normally in a frequency hopping mode. The successive Link1 6 pulses shall be hopped pseudo-randomly among 51 carrier frequencies or with up to 14 of the 51 carrier frequencies remapped."

 

The notion that if one of those 51 frequencies had some TACAN traffic on it that the entire network would grind to a halt seems wrong. Far from being jam-resistant, it would be exceptionally easy to jam.

 

The F-18 and other airplanes have specific antenna filter notches. From memory the F-18 has a smart switching filter on top (or bottom) and a dumb permanent filter on bottom (or top).  The filtered frequencies correspond to IFF operation and so MIDS TACAN traffic can be hampered by these filters which overlap with IFF. As far as I can tell MIDS TDMA Link 16 traffic is unaffected in any case. Other airplanes like F-16 could have different filter and antenna arrangements and it should not be assume the limitations which apply to one airplane apply to another.

 

I'm not at all an expert in Link 16 but I think one should be consulted as it seems highly suspicious that a premiere datalink network would be so delicate that a lone airplane using yardstick on a problematic channel would break the whole thing. I've read nothing which suggests L16 is so delicate but instead that it is TACAN which has the potential to suffer interference and loss of navigation service.

Not 100% accurate. In no way, shape or form is L16 allowed to be used/transmit on civilian frequencies. Ie, TACAN, IFF

 

Thia is from a rl L16 operator (me). L16 isn’t cleared to operate on any civ freqs and is therefore offset from the KNOWN civilian freqs in the 960-1215 range. There even transmit restrictions to doubly ensure it does not interfere with ground based civ freqs too

Edited July 16, 2021 by Florence201

[SCPanda]

1 hour ago, Florence201 said:

Not 100% accurate. In no way, shape or form is L16 allowed to be used/transmit on civilian frequencies. Ie, TACAN, IFF

 

Thia is from a rl L16 operator (me). L16 isn’t cleared to operate on any civ freqs and is therefore offset from the KNOWN civilian freqs in the 960-1215 range. There even transmit restrictions to doubly ensure it does not interfere with ground based civ freqs too

 

So Florence, in your opinion, is the current behavior in DCS that TACAN can disrupt Link 16 on the F-16 realistic? Because according to @BIGNEWY, it is. Tho, I certainly hope it shouldn't. 

[Florence201]

5 hours ago, SCPanda said:

So Florence, in your opinion, is the current behavior in DCS that TACAN can disrupt Link 16 on the F-16 realistic? Because according to @BIGNEWY, it is. Tho, I certainly hope it shouldn't. 

IMO no. But I have yet to experience this MP issue 

Edited July 16, 2021 by Florence201

[Frederf]

12 hours ago, Florence201 said:

Not 100% accurate. In no way, shape or form is L16 allowed to be used/transmit on civilian frequencies. Ie, TACAN, IFF

 

Thia is from a rl L16 operator (me). L16 isn’t cleared to operate on any civ freqs and is therefore offset from the KNOWN civilian freqs in the 960-1215 range. There even transmit restrictions to doubly ensure it does not interfere with ground based civ freqs too

 

Are these restrictions "we tailor what parts of the spectrum we use in planning so as not to interfere with local navaids" or "the system by design can and will never interfere with TACAN even if every single channel is in use 1X, 1Y, 2X, 2Y...126X, 126Y even if we tried"?

 

I didn't say Link 16. I said MIDS LVT equipment which handles both.

[Florence201]

3 hours ago, Frederf said:

Are these restrictions "we tailor what parts of the spectrum we use in planning so as not to interfere with local navaids" or "the system by design can and will never interfere with TACAN even if every single channel is in use 1X, 1Y, 2X, 2Y...126X, 126Y even if we tried"?

 

I didn't say Link 16. I said MIDS LVT equipment which handles both.

The type of terminal is irrelevant. The network design is standard across all terminals. Some have more functionality but they use the same L16 network and load files. 

[WHOGX5]

It would be impressive if Iran could just send up a single F-14 tuned to a goofy TACAN channel and jam all NATO L16 ops in the entire Strait of Hormuz. If L16 can't even handle that, how in the world would it function in any kind of jamming environment? 

 

On 7/16/2021 at 12:37 PM, Florence201 said:

IMO no. But I have yet to experience this MP issue 

 

In my community this issue was specifically identified and ever since limiting ourselves to everything except channels 1-36 and 64-99 we haven't had any D/L issues. Before we did that we had D/L issues every single week.

[SCPanda]

On 7/17/2021 at 7:54 PM, WHOGX5 said:

It would be impressive if Iran could just send up a single F-14 tuned to a goofy TACAN channel and jam all NATO L16 ops in the entire Strait of Hormuz. If L16 can't even handle that, how in the world would it function in any kind of jamming environment? 

 

LOL. RIght?