Datalink for the Viggen?

[slundal]

I know that both the J35 and JA37 were equipped with datalink (STRIL). The J35 could receive commands directly from ground operator displayed on their instruments for example. And JA37 could even overlay each others radar information, if I'm not mistaken.

 

Was there any datalink systems active in the AJS37? If so do we have any chance on seeing them integrated in the sim?

[QuiGon]

The AJ(S)-37 was never equipped with a datalink, unlike the JA-37.

[slundal]

I was under the assumption the one of the main design requirements of "System 37" was a STRIL integration.

 

Source (Swedish)

https://www.aef.se/Flygvapnet/Notiser/FPL37_Viggen.htm

[QuiGon]

I was under the assumption the one of the main design requirements of "System 37" was a STRIL integration.

 

Source (Swedish)

https://www.aef.se/Flygvapnet/Notiser/FPL37_Viggen.htm

I think this only applies to the JA variant, but I'm not an expert on this topic, so maybe someone of the other swedish guys here can shed some more light on this?

[renhanxue]

While the data link was one of the major new features of Stril 60, it was not required for air combat control. Also, “system 37” was not multi-role - the various aircraft variants had completely different requirements. The AJ(S) 37 never had a data link receiver because it wasn’t an air defense aircraft. GCI with plain old talk radio was sufficient for its very modest air to air capability.

[SnorreSelmer]

As STRIL 60 was a ground-based air intercept director system, it might have been useful for the AJ-37 until the JA-37 came along.

 

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[QuiGon]

As STRIL 60 was a ground-based air intercept director system, it might have been useful for the AJ-37 until the JA-37 came along.

 

Sent from my SM-G950F using Tapatalk

 

The Draaken was still in service and the primary fighter aircraft untill the JA-37 came along. The AJ-37 could have been used in the air defense role in concjungtion with STRIL 60 if necessary, but only through radio talk-on as it had no data link capabilities as renhanxue said.

[SnorreSelmer]

Copy that, thanks!

 

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[QuiGon]

Actually, I don't even know if the JA-37 data link could be linked to the STRIL 60 data link system. So far I have only heard of the JA-37 data link as a fighter to fighter data link. Does someone know if it was actually possible to send GCI data to the JA-37 data link system? I only know that this was the case with the J-35 Draaken.

[renhanxue]

The Swedish Air Force data link system (it doesn't have a name, the literature only refers to it as "Flygvapnets styrdatasystem") maintained the same 103-bit packet format and general infrastructure for over 40 years - the signal multiplexers in the ground stations stayed the same from installation in the early 60's to retirement in the early 2000's. The JA 37 fighter to fighter link also used the same packet format and transmission tech, but I believe on other frequencies. An early 1960's Stril 60 ground installation could talk to an early 80's JA 37 as if it was a J 35B and it'd work, but in the early 80's the ground installations were upgraded to be able to send a variant of the data link packet that modified the structure slightly and used some previously reserved bits to send an identically structured message but with different meaning and a bit more data.

 

In the Draken days, the ground installation would calculate the intercept vector based on the intercepting aircraft's radar-measured position and transmit the target's altitude as well as its bearing and distance relative to the intercepting aircraft. For the JA 37 however you could also choose to transmit the target's absolute position and altitude instead and let the onboard computer do the intercept vector calculations instead, for higher precision. On upgraded ground installations there were a few switches that controlled what to send, and since the general packet structure and addressing etc was compatible, messages for JA 37's and J 35's could share the same cabling, multiplexers, transmitters, frequencies etc etc. I have a few photos of an operator's station from the missile museum in Arboga somewhere, I'll see if I can dig them up.

 

This report from FHT has a ton of detail, but it's from 2005 and mainly centered on the early days. The extensions for the then recently retired JA 37 are discussed only briefly.

[slundal]

The Swedish Air Force data link system (it doesn't have a name, the literature only refers to it as "Flygvapnets styrdatasystem") maintained the same 103-bit packet format and general infrastructure for over 40 years - the signal multiplexers in the ground stations stayed the same from installation in the early 60's to retirement in the early 2000's. The JA 37 fighter to fighter link also used the same packet format and transmission tech, but I believe on other frequencies. An early 1960's Stril 60 ground installation could talk to an early 80's JA 37 as if it was a J 35B and it'd work, but in the early 80's the ground installations were upgraded to be able to send a variant of the data link packet that modified the structure slightly and used some previously reserved bits to send an identically structured message but with different meaning and a bit more data.

 

In the Draken days, the ground installation would calculate the intercept vector based on the intercepting aircraft's radar-measured position and transmit the target's altitude as well as its bearing and distance relative to the intercepting aircraft. For the JA 37 however you could also choose to transmit the target's absolute position and altitude instead and let the onboard computer do the intercept vector calculations instead, for higher precision. On upgraded ground installations there were a few switches that controlled what to send, and since the general packet structure and addressing etc was compatible, messages for JA 37's and J 35's could share the same cabling, multiplexers, transmitters, frequencies etc etc. I have a few photos of an operator's station from the missile museum in Arboga somewhere, I'll see if I can dig them up.

 

This report from FHT has a ton of detail, but it's from 2005 and mainly centered on the early days. The extensions for the then recently retired JA 37 are discussed only briefly.

Awesome! Thank you renhanxue. This what what wanted to know!! :D Please see if you can dig up those images, would be really interesting to see. :)

 

Also huge thank you for the source! This is going to keep me up for a few nights. ;)

[frosen]

Regarding the usage of the AJ 37 in the Swedish QRF ("incidentberedskapen") I recall from memory that the first time Viggen was used for that purpose was in the late seventies, about five years after entry into service. Because of the limited AAW capabilities it was furthermore only used as QRF during summer when it was nice weather.

[renhanxue]

 

 

Operator's station from a PS-08 radar installation (PS-08 was the Swedish designation for the Decca Type 80 long range air search radar purchased in the late 1950's). I think this is the oldest intercept controller station that supported the data link; it was installed directly at the radar site instead of in an air defense central (Lfc, "luftförsvarscentral") or sector intercept control center (rrgc, "radargruppcentral").

 

 

In the center there's a big orange PPI (of course) - the data link control panel is to the left of the PPI, in the top part of the console. There's two sets of controls so the intercept controller working the station can send orders to two aircraft (or even groups of aircraft) at once.

 

 

For each of the two data link channels: at the top there's three dials, one with the letters of the alphabet and two numeric ones. These are for addressing - you set the dials to the address configured on the receiver in the aircraft and the data link packets will be addressed to that (or those) aircraft. Just under the dials there's a small button labeled "FLYGPL" - it can be set to either J 35 (older message format) or JA 37 (newer message format) depending on which aircraft you're trying to talk to.

 

 

Then there's 20 red buttons that are unlabeled on this console - these let you send one of 20 of pre-arranged informational messages to the aircraft, such as "expect jamming", "caution enemy fighters", "RTB", and so on. These messages were later extended so there were 30 of them, and the buttons had different meanings for J 35 and JA 37 and they also changed over time, so there was a reversible label template that you put on top of them to remember which one was which, like so (on a different console):

 

 

 

 

This one's labeled for JA 37 and has two "priority" modes - red texts are presumably what the message means when sent in high priority mode. If you flip it over there's J 35 message labels on the other side. Example messages on this one are f.ex. 03 - low priority "enemy fighters", high priority "target (has) escort", 10 - low priority "idle", high priority "fire at will".

 

 

 

 

Full console from a more modern rrgc/F installation - the one with the message buttons in close-up above. Data link message buttons in the lower left, with the label template flipped over to the J 35 side. On this one with its fancy-schmancy digital computer, you set the aircraft type etc via keyboard shortcuts instead.

Edited May 8, 2018 by renhanxue

[QuiGon]

That's some very interesting stuff. Thank you very much for sharing this renhanxue! :thumbup: