Helping To Understand LINK 16
-
Esteemed BMS Community,
I have been delighted to work with the Dev team (particular thanks to Micro & Tiago) to try and dig a little deeper into how LINK 16 currently works within BMS. As a result of this engagement pilots will find some additional clarification within the updated BMS documentation.This post builds upon what was put into the BMS documentation to (hopefully) help pilots understand what LINK 16 is, how it is implemented in BMS and what LINK 16 is or is not showing the pilot (and why).
Of course, LINK 16 is new to BMS as of 4.37u4 and there is still a lot of development going on to add even more capability to this fantastic addition to our sim. So I will keep this post updated as any substantive changes are made.
The first part of this post is a set of notes regarding LINK 16 and how it is implemented in BMS, as well as clarifying some key terminology. After this, I have created three pictorial ‘scenarios’ which are designed to articulate what a pilot should expect to see from LINK 16 under certain ‘situations’.
Scenario 1: Shows what to expect when both PPLI and SURV air track data is available.
Scenario 2: Shows what to expect when there is no SURV air track data available, but PPLI air track information is available.
Scenario 3: Shows the impact of the unlikely situation where the pilot has access to SURV air track data but no PPLI air track information.Each scenario is deliberately identical, portraying 14 different situations (labelled A-N), with a description explaining what the pilot (‘ownship’) would expect to see (or not see) in that situation, and why.
I hope this post will help clarify how LINK 16 works in BMS 4.37u4. In the future, I hope to produce a video that talks through these scenarios and situations as I appreciate some people may prefer that type of content instead of ‘RTFM’ (Read the Flight Manual / Read The Forum Material).
Feedback is very much welcome, if you have any questions, please post below and I will attempt to answer (or if I don’t know, I am sure the Dev team can comment).
1) What Is LINK 16?
• At is most basic level, LINK 16 is a means for various LINK 16 enabled NATO platforms to share or view positional and contact data to enhance situational awareness under the right conditions.2) A brief, incomplete and oversimplified history of LINK 16.
• TADIL-J (Tactical Digital Information Link J), refers to the system of standardized J-series messages known by NATO as LINK 16.
• LINK 16 is the NATO standardization of the JTIDS system.
• JTIDS (Joint Tactical Information Distribution System) is an L band Distributed Time Division Multiple Access (DTDMA) network radio system used by the United States Department of Defence and their allies to support data communications needs, principally in the air and missile defence community.
• MIDS (Multifunctional Information Distribution System) is the successor to JTIDS.
• MIDS ‘communicates’ with other nodes using ‘J format’ ‘messages’ (originating from TADIL J).
• TADIL is no longer an official US Department of Defence term. Instead, it has been replaced by the generic term Tactical Data LINK (TDL). Despite this, “TADIL” is a legacy holdover and still used in the vernacular.3) Key Terminology:
• Improved Data Modem (IDM): IDM was designed in the late 70’s before JTIDS or LINK 16 was available. The F-16’s IDM enhances communication capabilities for both Command and Control purposes and data transfer between up to eight aircraft. The IDM facilitates transmission of various types of data, including sensor data, positional updates between aircraft and sharing certain tactical data such as mark points or air to air contacts. Even if limited in features compared to JTIDS/MIDS systems, it still has a valuable role to play in BMS 4.37u4, especially while LINK 16 is not fully implemented.
• Joint Data Net (JDN): An interconnected network of JTIDS/MIDS based systems which links air and missile defence Command and Control and weapons systems across L16 capable forces.
• Net Participation Group (NPG): FC and MC channels are part of dedicated NPG’s. Each channel and its number define what data can be exchanged on that channel. If you create a package for example, all LINK 16 capable aircraft of this package will have the same FC and MC (because one AWACS controller will be responsible for this package).
• Channel: A channel can have different NPGs. For example a channel number (e.g. 56) could have a Mission and Fighter-to-Fighter NPGs. So, in the MIDS/JTIDS, we can set the MC as ‘56’ and the FC also as ‘56’.
• Mission Channel (MC): Mission Channel (MC): (Automatically set by BMS), can be manually set between 0 and 127. Responsible for exchanging information with AWACS or other Command and Control platform.
• Fighter Channel (FC): (Automatically set by BMS), can be manually set between 0 and 126. Responsible for exchanging information between fighter aircraft (tracking and lock information not implemented yet)…
• Special Channel (SC) : Establishes the subnet for the SEAD NPG and identification information. [Not Currently Implemented]
• Flight STNS: Source Track Number. Contains all members of your own flight by default, can be manually changed between 00000 and 77776 (excluding 00077, 00167, 00177 and 07777).
• Team STNS: Source Track Number. Contains next four aircraft in your package by default, can be manually changed between 00000 and 77776 (excluding 00077, 00167, 00177 and 07777).
• Donor: [Partially Implemented]. For situational awareness during a mission, pilots may want to monitor aircraft or targets reported by aircraft that aren’t part of their flight or team. These aircraft, known as donors, can be designated during mission planning (via the Data Cartridge), or selection or deselection can be managed in the cockpit through the LINK 16 DNR page on the DED. Note: The ability to assign Donor’s from 2d and 3d has been implemented in BMS. But the effect is currently limited to seeing that Donor’s positional data.
• PPLI: Air Precise Participant Location Identification is a message transmission from LINK 16 air participants, furnishing network participation status, identification details, positional data and navigation information. It encompasses the voice call sign, position coordinates (latitude/longitude), altitude, course, IFF codes, air platform type (e.g. fighter, bomber, attack) and air platform activity (such as engaging, investigating etc.). PPLI air tracks are shared between aircraft sharing the same NPG.
• SURV: This message serves to share air track data, predominantly disseminated by a Command and Control agency. It comprises details regarding exercise/non-exercise tracks including; track number, strength, position, speed, course, identity (such as pending, unknown, assumed friend, friend, neutral, suspect, hostile), air platform type (generic categories like fighter, bomber, attack etc.) and specific air platform type (e.g. F15, F16 Mig29 etc.).4) Crucial Range Information
• Currently in BMS the AWACS radar has a maximum detection range of ~135nm. This does not mean everything within 135nm will always be detected, many things impact probability of detection.
• Currently the AWACS has a maximum transmission range of SURV air track L16 data of ~400nm (currently a fairly academic point as the AWACS can only detect contacts out to ~135nm).
• PPLI air tracks are shown in the HSD/FCR/HUD/HMCS to a range of ~150nm from the pilots aircraft.
• SURV air tracks are shown in the HSD/FCR/HUD/HMCS to a range of ~100nm from the pilots aircraft.5) Detection & Classification Sequence & Limitations of L16
• Currently in BMS only Command and Control aircraft (E3 Sentry and E2 Hawkeye) can provide SURV air track information.
• Flight lock lines, secondary fighter air target tracks and AMRAAM shot lines are not currently implemented.
• The detection of aircraft is conditional on the AWACS being able to sense the contact. This is not only a function of the AWACS notational detection range (up to ~135nm). An AWACS ability to sense a contact can also be impacted by the radar cross section of the contact, whether it is jamming, if it is terrain masking, lost in radar ground clutter (not currently modelled in BMS) or even certain atmospheric conditions (not currently modelled in BMS). The LINK 16 picture should never be considered to be showing all air contacts at all times.
• The classification of contacts is solely managed by Command and Control agencies.
• New contacts will typically follow this sequence when being classified:
• Classified as ‘Detected, Unknown/Assumed Friend/Pending’.
• Classified as ‘Suspect/Assumed Hostile /Pending’.
• Classified as either ‘Friendly’, ‘Neutral’ or ‘Hostile’.SCENARIO 1
A) Flight members, set as ‘Flight STNS’ in DTC and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
B) Flight member, set as ‘Flight STNS’ in DTC and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
C) Package Member, set as ‘Team STNS’ in DTC and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
D) Friendly, and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
E) Friendly, detected by AWACS, not sharing ownship’s Net Participation Group or not L16 capable and not within 100nm SURV display range: Not shown on HSD/FCR.
F) Hostile, detected by AWACS and classified ‘Hostile’, not within 100nm SURV display range: Not shown on HSD/FCR.
G) Hostile, not detected by AWACS (out of AWACS 135nm detection range): No SURV air track generated.
H) Hostile, within AWACS detection range and within 100nm SURV air track display range, but not detected by AWACS (bandit could be jamming, stealth or terrain masking): No SURV air track generated.
I) Hostile, detected by AWACS and classified ‘Hostile’, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
J) Friendly, not detected by AWACS (out of AWACS 135nm detection range) and not sharing ownship’s Net Participation Group or not L16 capable: No SURV air track generated.
K) Friendly, detected by AWACS, either not sharing ownship’s Net Participation Group or not L16 capable, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
L) Hostile, not detected by AWACS (out of AWACS 135nm detection range): No SURV air track generated.
M) Hostile aircraft, detected by AWACS, but currently classified as ‘Suspect/Assumed Hostile/Pending’, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
N) Hostile aircraft, detected by AWACS, but currently classified as ‘Unknown/Assumed Friend/Pending’, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
SCENARIO 2
A) Flight members, set as ‘Flight STNS’ in DTC and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
B) Flight member, set as ‘Flight STNS’ in DTC and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
C) Package Member, set as ‘Team STNS’ in DTC and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
D) Friendly, and sharing ownship’s Net Participation Group, within 150nm PPLI display range: Shown on HSD/FCR/HUD/HMCS (PPLI air track).
E) Friendly, no AWACS so not detected and either not on ownship’s Net Participation Group or not L16 capable: No PPLI or SURV air track generated.
F) Hostile, no AWACS so not detected: No SURV air track generated.
G) Hostile, no AWACS so not detected: No SURV air track generated.
H) Hostile, no AWACS so not detected: No SURV air track generated.
I) Hostile, no AWACS so not detected: No SURV air track generated.
J) Friendly, no AWACS so not detected and either not on ownship’s Net Participation Group or not L16 capable: No PPLI or SURV air track generated.
K) Friendly, no AWACS so not detected and either not on ownship’s Net Participation Group or not L16 capable: No PPLI or SURV air track generated.
L) Hostile, no AWACS so not detected: No SURV air track generated.
M) Hostile, no AWACS so not detected: No SURV air track generated.
N) Hostile, no AWACS so not detected: No SURV air track generated.
SCENARIO 3
A) Flight members, no PPLI available, detected by AWACS, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
B) Flight member, no PPLI available, not detected by AWACS (out of AWACS 135nm detection range): No SURV air track generated.
C) Package Member, no PPLI available, detected by AWACS, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
D) Friendly, no PPLI available, detected by AWACS, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
E) Friendly, detected by AWACS, not within 100nm SURV display range: Not shown on ownship HSD/FCR.
F) Hostile, detected by AWACS, not within 100nm SURV display range: Not shown on HSD/FCR.
G) Hostile, not detected by AWACS (out of AWACS 135nm detection range): No SURV air track generated.
H) Hostile, within AWACS detection range and within 100nm SURV air track display range, but not detected by AWACS (bandit could be jamming, stealth or terrain masking): No SURV air track generated.
I) Hostile, detected by AWACS and classified ‘Hostile’, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
J) Friendly, not detected by AWACS (out of AWACS 135nm detection range) and no PPLI available : No SURV air track generated.
K) Friendly, detected by AWACS, no PPLI available, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
L) Hostile, not detected by AWACS (out of AWACS 135nm detection range): No SURV air track generated.
M) Hostile aircraft, detected by AWACS, but currently classified as ‘Suspect/Assumed Hostile/Pending’, within 100nm SURV display range: Shown on HSD/FCR (SURV air track).
N) Hostile aircraft, detected by AWACS, but currently classified as ‘Unknown/Assumed Friend/Pending’, within 100nm SURV display range: Shown on HSD/FCR (SURV air track)
-
Good work mate!!!
-
M Micro_440th pinned this topic on
-
Hey, excellent work, what detail and depth.
-
Thanks a lot detailed and usefull information. Great work.
-
Sorry to add noise to the thread, feel free to delete this post, but WOW what an useful and great read! Thanks man!
-
Re: Helping To Understand LINK 16
Time Stamp: 09:00(UK), 06.07/24.
All,
For those that read the original post over the last 12 hours or so, I have made a couple of slight editorial changes.Change log:
Nothing substantive, a few additions for clarity, addressing some typos and re-ordering the examples, but if you read the original before the time of this post you might want to quickly look through the material before the examples (examples remain unchanged, except the ordering).I hope this will be the last time I mess around with the original post, except in the event of needing to clarify something, address any errors spotted or update the pack to address changes within BMS.
I will continue to post messages such as these in this thread with any relevant change log to help pilots understand when things change, what has changed and why.
-
Fantastic reference post, thanks! It also highlights once again what an amazing platform BMS has become.
-
Thanks, great work!
-
Is there a reason or rationale why the range is only 135 nm? The public information is 250+ miles, and public information is always lower than operational capabilities. It would be good to be able to configure this as a setting because current ranges expose AWACS to SAM and air threats.
-
@Krause it will be set correctly soon.
PS: Old value in DB was not changed to check if BW in MP etc would be ok, and many other codewise reasons, which are not relevant here. A new more correct value will be set based on Janes/CMO open source data in the next version. -
Awesome and perfectly condensed presentation!
-
@tiag cool glad to hear it. Thanks!
-
Hey @Sharpe
Sorry for the reply only now…was away for a while.
Some corrections and clarifications from my end:Channel: There are three channels available in LINK 16, MC, FC, SC
You are mixing up Channels in the Link 16 network with the Channels in the MIDS/JTIDS.
There are 128 channels in a Link 16 network. These are subnets or simply nets.
The MIDS/JTIDS can listen to up to 3 channels with 3 specific NPGs. Not all platforms can do that though. The Eagles in BMS and non-USAF/old tapes Vipers cannot listen to the special channel (=EW).
Mission Channel (MC): (Automatically set by BMS), can be manually set between 0 and 127. Responsible for exchanging information with AWACS or other Command and Control platforms (SURV air track data)
This is not correct. SURV tracks will be always received independent of the MC.
SURV: …(such as pending, unknown, assumed friend, friend, neutral, suspect, hostile), IFF codes, air platform type (generic categories like fighter, bomber, attack etc.) a…
IFF codes are not shared in a SURV message. Only if the track replied correctly to a M4 or not.
As above, MC is not required. Appears a couple times in other graphs and text.
Flight, team or donor lock lines, secondary fighter air target tracks and AMRAAM shot lines are not currently implemented
Shot-lines are only present for Flight members in RL. (i.e. #1-#4)
Donor secondary fighter air target tracks, lock lines and AMRAAM shot lines have not yet been implemented.
As above…no shot-lines for Donors. Only for Flight Members.
Also SURV tracks are not shown in HUD/HMS, only the one designated as PDLT.
Cheers und Vielen Dank!
-
@tiag said in Helping To Understand LINK 16:
Hi Tiag,
Thanks for this, I will address what I can over the weekend.However, be aware the following lines are taken from the BMS documentation, so if wrong please could you provide the exact wording needed (you may also wish to update the documents)?
“SURV: …(such as pending, unknown, assumed friend, friend, neutral, suspect, hostile), IFF codes, air platform type (generic categories like fighter, bomber, attack etc.) a…”
- This is from the 31-1-1, P254 and the training manual p.281
“Mission Channel (automatically set by BMS), can be manually set between 0 and 127-> is responsible for exchanging information with AWACS or other C2 platforms (SURV air track data).”
- This is from the 31-1-1, P254 and the training manual p.281
-
@Sharpe Yes, manual needs some polishing. Replied to your msg on discord with correct formulation. Ty.
-
This post is deleted! -
M Micro_440th unpinned this topic on
-
@tiag i hope you had a good Christmas
Would it be possible to update this topic with the latest things added in 4.37.5Thanks
