SPO15 feedback

[Dudikoff]

On 9/22/2025 at 2:14 PM, Кош said:

Radar cuts off even itself, not just SPO. It cuts off itself. And then this signal is just copied to SPO too. Othervise radar would have shown only a white wall at all times instead of contacts and clutter. So yes when radar is emitting, SPO is "closed". Indeed. You just have to understand this "disabling" lasts for 3 microseconds every next 3 microsecons. This is HPRF duty cicle, MPRF is much much easier. 

Radar switches itself between transmit and receive periods constantly (so it can receive the reflections), that's normal.

I don't see any mention here that these periods are synced with the SPO.

[Кош]

14 минут назад, Dudikoff сказал:

Radar switches itself between transmit and receive periods constantly (so it can receive the reflections), that's normal.

I don't see any mention here that these periods are synced with the SPO.

Signal called same on other page in same document regarding SPO, and in SPO document the graph of duty cycle sync looks similar. Also, in tech plackards, signal generator simulating radar overspill is mentioned, used to test SPO for radar-proofness without turning the actual radar on in the workshop. There is not a single word about SPO being unreliable in the 9.12 avionics book. It just states that SPO is synced to blanking signal without elaboration, and I started to look for that naming on any graph, and found it. And not just anywhere - on HPRF graph!

Edited yesterday at 02:08 PM by Кош

[Кош]

4 часа назад, Flyout сказал:

This SPO-15 manual isn't specific to any particular aircraft. 

But MiG 9.12 avionics manual corresponds to this. That's a very particular aircraft.

[Dudikoff]

17 minutes ago, Кош said:

Signal called same on other page in same document regarding SPO, and in SPO document the graph of duty cycle sync looks similar. Also, in tech plackards, signal generator simulating radar overspill is mentioned, used to test SPO for radar-proofness without turning the actual radar on in the workshop. There is not a single word about SPO being unreliable in the 9.12 avionics book. It just states that SPO is synced to blanking signal without elaboration, and I started to look for that naming on any graph, and found it. And not just anywhere - on HPRF graph!

It's probably how it's supposed to function in theory, but given all the references from various flight manuals mentioned in this thread, I guess in practice this sync is not guaranteed and overspills would obviously occur.

Given the state of Soviet electronics, the question is if this would occur constantly or randomly (i.e. couldn't be avoided with the systems used being not reliable or precise enough to avoid this) or perhaps the equipment would get out of tune in time (so it's kind of a maintenance issue where the ground crew would need to tinker with it).

Edited yesterday at 02:23 PM by Dudikoff

[BIGNEWY]

Hi all,

Firstly regarding the device limitations and how the device handles launch warning.

The detection of launch warnings is handled by the subsystem called "Type 10 forming system" on board 55. This system actually does two things.
- It receives raw pulse train envelope as well as information from board 57 (threat program) about detection of type N (Nike-Hercules) in track mode, and tries to detect the pattern of coding pulses corresponding to guidance commands sent to the missile through the MTR. If detected, it sends a signal labelled "Type 10 impulse" which triggers the launch warning.
- It processes raw pulse train to detect M/HPRF signals, as the regular PRI measurement circuit cannot process signals with PRF > 10kHz due to aliasing (the reference clock is 100kHz and the measurement procedure is suboptimal as it was not designed for M/HPRF signals, requires picking up the same PRI at least 3 times in a row). Keyword is detect not measure: it can only determine if PRF is lower than 26kHz and if it's higher than 50kHz. That means the ability of a production SPO-15LM to categorize the threat based on PRF is limited to 3 bins, 10-26kHz, 26-50kHz and above 50kHz. The threat program board (57) would require a major redesign to handle more PRF bins, rather than the typical modifications it was designed for to update the threat type assignments. The bins themselves could be modified by doing some rewiring, (100 and 200kHz for instance could be achieved) but that wouldn't change categorization of typical gen 4 fighter radars at all (these are above 200kHz in HPRF modes).

See the excerpts from signal flow schematic (from Polish docs available at MUT in Warsaw where the documentation is declassified there).

Board 55, specifically the specimen we've seen is dominated with discrete logic gates packed by 4s into ICs, with the remaining space filled by printed circuits. With that, in addition to the above board 55 implements a lot of binary logic including 2 bit memory for the elevation channel (and handling of that channel in general), synchronization of individual azimuth channels with sequential part of the processing, part of the PRI measurement logic for signals below 10 kHz PRF, etc.

As for what would need to be done: to detect AMRAAM or PD variants of AIM-7, the whole board would likely need to be replaced with a new one, as it would require measuring frequencies that aren't multiplicities of the reference clock - it would require pretty much another copy of the entire PRI circuit from board 56, but using a different measurement procedure. It would be difficult to squeeze 2 more counters on this board (board 56 uses 8 bit counters built with 4 bit counter ICs, so that's what was originally available).

For older SARH missiles that use CW illumination for guidance, it could be possible to rewire board 55 in a way that outputs simultaneous CW and pulsed detection as Type 10, effectively causing presence of type P to also trigger launch warning every single time (but with more false positives). This was not done originally because at the time the device was designed, the CW illuminators were typically controlled manually by the operator. And we do not currently have any evidence this was done. But this is the most realistic modification that could potentially be implemented as an option.

As for systems that use CW exclusively absolutely nothing can be done - the device simply doesn't capture any information about the CW signals other than their presence and average amplitude. Changing this would require such a major redesign of the whole device that it would no longer be the LM variant.

AIM-54 is likely similarly undetectable, likely due to parameter overlap making it indistinguishable from AWG-9 even with potential modifications, it is listed as a known threat in a lot of MiG-29 documentation but with no launch warning for it, it is simply thrown under "type F".

Alternatively to the above, a separate board could be designed that would take any necessary inputs from around the device and then trigger launch warning by directly sending the signal to the threat priority circuit of board 59. We're talking fantasy modifications here however.

The launch warning can also be by an external MLWS connected to SPO-15, but the MiG-29 doesn't have one - it's basically the same situation as above.

Command signals are out of the question for most systems as even if they were powerful enough, they're way out of band. NH is special in that the command signal is encoded in MTR's tracking signal.

Overall, there's not enough info to implement any of this, if docs were produced for an upgraded cartridge 55 it could be considered as an additional threat program option, but pilot anecdotes are not a viable source, especially since it could be explained away by proper training and interpretation of incoming signals. A TWS capable fighter suddenly producing a lock on usually means that either they're about to launch a Sparrow or an AMRAAM went active. The same is the case for most SAM tracking radars: in DCS in particular a lock by a SAM almost always means launch. As for the device itself, it absolutely is hardwired, all logic is implemented directly in hardware.

As for synchronization with radar, SPO-15 features a synchronization circuit on board 51, but it was designed for older radars such Sapfir-23. The principle of operation is the same as in older SPO-10, the receivers are blocked in rhythm with own radar's pulses. It cannot handle CW or HPRF signals (which trigger CW circuits anyway, followed by them being disabled completely in all channels once HPRF is recognized), so if they are emitted the affected hemisphere is shut down completely. According to electrical schematics for the aircraft, the N019 produces a single signal wire, which is used to block forward hemisphere, so that SPO can be left on and at least the rear hemisphere remains usable. Radio equipment manual confirms this. Full synchronization would require additional signals, so even if Cartridge 51 was modernized it would also require additional changes to wiring and to radar itself. Additionally every single channel in forward hemisphere on both boards #54 would need to be modified, so only CW signals were blocked, which is not avoidable. Failure of this system would cause the device to be flooded by own radar, making it completely unusable with radar on.


hope that helps clarify some points. 

thank you 

[Raven (Elysian Angel)]

@BIGNEWY Is it possible to implement a simplified version of this logic for AI MiG-29s? This would go a long way to make single player feel more alive and variable instead of just fighting a slightly different version of Generic Opponent with slightly different FM characteristics.

[Кош]

20 минут назад, BIGNEWY сказал:

It cannot handle CW or HPRF signals

Why? Latency? Frequency limits? What's difference with how radar deals with HPRF shutoff signal?

[Thirsty]

Alright, so we have a out of sync, unserviced MiG-29 lacking parts for the SPO-15 post WP.
Even when multiple real pilots that are confirmed real pilots talking that yes it would still work if the radar is on, and documents are proving it.

Meanwhile there is also the magic RWR for all F-16 and such.

Man I had my hopes up for this release, but now its pointless.

[DD_Fenrir]

41 minutes ago, Thirsty said:

Alright, so we have a out of sync, unserviced MiG-29 lacking parts for the SPO-15 post WP.
Even when multiple real pilots that are confirmed real pilots talking that yes it would still work if the radar is on, and documents are proving it.

Meanwhile there is also the magic RWR for all F-16 and such.

Man I had my hopes up for this release, but now it’s pointless.

Hint: third hand anecdotes from unverified sources do not constitute evidence. 

I could claim to be a MiG-29 pilot and announce that it should explode at anytime a western radar washes over it. I’m sure you’d suddenly find a reason to discount my testimony, hmm?

Ultimately, there is documentary unclassified evidence that the radar interfered with the SPO.

Now, your argument is that this was a maintenance and parts factor; it is therefore up to the MiG-29 fans to find unclassified documentation to corroborate this claim.

It really is that simple 

[Thirsty]

32 minutes ago, DD_Fenrir said:

Hint: third hand anecdotes from unverified sources do not constitute evidence. 

I could claim to be a MiG-29 pilot and announce that it should explode at anytime a western radar washes over it. I’m sure you’d suddenly find a reason to discount my testimony, hmm?

Ultimately, there is documentary unclassified evidence that the radar interfered with the SPO.

Now, your argument is that this was a maintenance and parts factor; it is therefore up to the MiG-29 fans to find unclassified documentation to corroborate this claim.

It really is that simple 

And the same counter argument is also true.

There is an declassified document published in moscow 2011 that mentions the syncing between the radar and SPO.
(Also ascessable on a online classroom website)

So yes, It is as simple as mentioned above.

Edit:
And compered to your intersting claiming logic.
The difference between throwing words around,
that the mentioned SME can prove that they were actual pilots of the well mentioned platform.

Edited 20 hours ago by Thirsty

[Harlikwin]

5 hours ago, Кош said:

This and at least 2 SME's, engineer and fighter pilot, from 2 vastly different air forces.

 

Moreover the repair manual indicates that the blocking circuit is tested with 2us pulse, while the 29 radar runs HPRF at 6us (166khz), so clearly that blanking circuit can handle a PRF 3 fold higher than the radar PRF. 

27 minutes ago, DD_Fenrir said:

Hint: third hand anecdotes from unverified sources do not constitute evidence. 

I could claim to be a MiG-29 pilot and announce that it should explode at anytime a western radar washes over it. I’m sure you’d suddenly find a reason to discount my testimony, hmm?

Ultimately, there is documentary unclassified evidence that the radar interfered with the SPO.

Now, your argument is that this was a maintenance and parts factor; it is therefore up to the MiG-29 fans to find unclassified documentation to corroborate this claim.

It really is that simple 

Sorry man, pretty much every tech manual about the SPO-15 talk about a blanking circuit for the radar. And one that runs fine at HPRF. Like honestly this is not a hard problem to actually solve. Like literally every radar does this. What seems to be an issue is that this blanking circuit due to the way its designed, can become desynched with the radar, which leads to the SPO either giving erratic signals (as documented in a few manuals as "MAY HAPPEN", or ofc if its totally out of whack, the SPO overloads/is damamged and presumably has a protection circuit to shut it off (again, very simple, ham radio level circuit). 

 

[Flyout]

On 9/22/2025 at 6:35 PM, AeriaGloria said:

The specific wording of the Su-27 manual is this sentence 

“When the RLPK and LOO6 operate simultaneously, false information may be displayed on the L006LM indicator (displaying bearing marks 10, 30, 50, 90 from the left and right, type X, power gradation up to 8, marks B, NI CAPTURE).”

Emphasis on the word “may.” Other translators will translate it as “it is possible for false information to be displayed.” 
 

Far from conclusive “this happens 100% of the time” 

You don't speak Russian, but I do. It says there that the information can't be trusted. Quite clearly and unambiguously.

23 hours ago, Dragon1-1 said:

Does it state otherwise? Because just because it doesn't explicitly state that it can't doesn't mean much. It'd be worth mentioning if it didn't work. So far, I've seen it mentioned either in other countries' manuals or in uncertain terms.

Since these are Soviet aircraft, the original manuals in Russian take precedence over all others.

And yes, it clearly states that you cannot use the SPO when the radar or jammer is turned on.

[AeriaGloria]

4 hours ago, BIGNEWY said:

 

Thank you BN, let me say I really appreciate being able to get this long form answer from the devs. It really helps explain why it can’t be set to have launch warnings at all. 
 

Im just confused how HPRF is interfering with the SPO-15 if it is in fact off for the duration of radar transmitting. And does this all include MPRF/ZPS/Dogon mode? 

Edited 20 hours ago by AeriaGloria

[Flyout]

8 hours ago, AeriaGloria said:

I have found atleast 4 sources that attest to MiG-29 having blanking circuits for its radar to RWR, as was standard for any Soviet radar equipped fighter with RWR. It’s basically undeniable it had one at this point. 
 

And I’m probably forgetting one! 

You're wrong. It's not mentioned there.
There's a reference to a blanking feature in the 2011 document about the SPO-15. However, it has nothing to do with the MiG-29 aircraft; it's a general description of the device's capabilities.

It's worth clarifying here. Not all capabilities are always and everywhere utilized.
Recall the R-27R missiles. The manufacturer's description of the missile states that it supports a reduced target illumination frequency to enable a salvo launch of two missiles at two different targets.
But the devil is in the details. Mikoyan and Sukhoi Design Bureaus didn't implement support for this feature in their MiG-29 and Su-27 aircraft. As a result, the missile can be used in a salvo against two targets, but the aircraft don't support this.

The same is true here. The SPO supports blanking, but for some reason, the aircraft developers didn't implement it.

[AeriaGloria]

5 minutes ago, Flyout said:

You're wrong. It's not mentioned there.
There's a reference to a blanking feature in the 2011 document about the SPO-15. However, it has nothing to do with the MiG-29 aircraft; it's a general description of the device's capabilities.

It's worth clarifying here. Not all capabilities are always and everywhere utilized.
Recall the R-27R missiles. The manufacturer's description of the missile states that it supports a reduced target illumination frequency to enable a salvo launch of two missiles at two different targets.
But the devil is in the details. Mikoyan and Sukhoi Design Bureaus didn't implement support for this feature in their MiG-29 and Su-27 aircraft. As a result, the missile can be used in a salvo against two targets, but the aircraft don't support this.

The same is true here. The SPO supports blanking, but for some reason, the aircraft developers didn't implement it.

It is mentioned in the 9.12B technical manual and 9-12 radio equipment manual, which ED has stated through BN is true.  BN’s post says it is implemented just can’t deal with HPRF for some reason (and MPRF?). My question is for him as it seems the devs have the answer. The blanking circuit is there and it turns off front hemisphere but SPO still gets HPRF. I’m sure BN can provide me with an answer

”N019 produces a single signal wire, which is used to block forward hemisphere, so that SPO can be left on and at least the rear hemisphere remains usable. Radio equipment manual confirms this.”

Edited 20 hours ago by AeriaGloria

[Flyout]

2 hours ago, Thirsty said:

Alright, so we have a out of sync, unserviced MiG-29 lacking parts for the SPO-15 post WP.
Even when multiple real pilots that are confirmed real pilots talking that yes it would still work if the radar is on, and documents are proving it.

You're distorting the facts. There are pilots who report poor performance of the radar. And official documents confirm that SPO information cannot be used when the radar is on.

Edited 20 hours ago by Flyout

[AeriaGloria]

Just now, Flyout said:

You're distorting the facts. There are pilots who report poor performance of the radar. And official documents confirm that SPO information cannot be used when the radar is on.

I’m not saying that, just that there are in fact blanking circuits as confirmed by 9.12 radio equipment manual and 9.12B technical manual and now also confirmed by ED. 

[NineLine]

Hey all, lets try and keep the discussion on feedback about the SPO-15LM, all this arguing with each other or other unhelpful comments makes it hard for our dev team to look over this thread. I may do a clean up pass so if you message vanishes and you dont think it should, you can DM me. 

[Flyout]

1 hour ago, Thirsty said:

There is an declassified document published in moscow 2011 that mentions the syncing between the radar and SPO.
(Also ascessable on a online classroom website)

This document does not apply to the MiG-29. It is a general description of the device.

 

[Flyout]

On 9/22/2025 at 4:14 PM, Кош said:

Radar cuts off even itself, not just SPO. It cuts off itself. And then this signal is just copied to SPO too. Othervise radar would have shown only a white wall at all times instead of contacts and clutter. So yes when radar is emitting, SPO is "closed". Indeed. You just have to understand this "disabling" lasts for 3 microseconds every next 3 microsecons. This is HPRF duty cicle, MPRF is much much easier. 

This is a radar operation cyclogram, the receiver is locked during transmission, it has nothing to do with the SPO.

[Harlikwin]

39 minutes ago, NineLine said:

Hey all, lets try and keep the discussion on feedback about the SPO-15LM, all this arguing with each other or other unhelpful comments makes it hard for our dev team to look over this thread. I may do a clean up pass so if you message vanishes and you dont think it should, you can DM me. 

Ask em about the 2us PW tester and the 6us radar PW... Seems like it can sample and block at about 3x the rate of the radar. 

[Кош]

18 минут назад, Flyout сказал:

This is a radar operation cyclogram, the receiver is locked during transmission, it has nothing to do with the SPO.

Do you have real life experience with MiG-29? We have following FACTS:

- SPO-15 in MiG-29 9.12 is connected to radar for blanking of forward hemisphere.

- Rear is not synced.

- ED agrees SPO-15 can handle MPRF in MiG-29

- Testing for radar overspill of SPO-15 device is performed at 3x the rate of HPRF of MiG-29 radar.

 

What happens here, exclusively in MiG-29, like you insist, to prevent working exactly with HPRF despite SPO clearly being able to work with it?

[Schmidtfire]

Solution: Implement Nike-Hercules so we can enjoy launch warnings over the Cold War Germany map

[Harlikwin]

1 minute ago, Schmidtfire said:

Solution: Implement Nike-Hercules so we can enjoy launch warnings over the Cold War Germany map

LOL, seconded!

[Dača]

Wow, a lot of information to process.

Now the question should be what can SPO detect apart from wingmen radar lock ?