SPO15 feedback

[AeriaGloria]

50 minutes ago, Dača said:

Wow, a lot of information to process.

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

change to automatic mode 

Okay, so the problem is that HPRF is over 200 kHz, and SPO begins to have trouble over 50 kHz in regards to its bins. 
 

This says that MPRF is much below 50 kHz in terms of PRF. How could SPO have a problem with it? 

Edited 22 hours ago by AeriaGloria

[Rhinozherous]

Wow, there is a ton of deep technical info about this topic... But what is the more superficial point of the discussion, for not that tech savvy people? I dont get it what SPO is not able to detect? 

1 - Is there no warning when we are locked by an Fox3 because it is more modern then the MiG29?

2 - Are we not warned when we are locked by blue side SAM? What about red side SAM?

3 - What is Automatic mode? 

Thank you!

[AeriaGloria]

7 minutes ago, Rhinozherous said:

Wow, there is a ton of deep technical info about this topic... But what is the more superficial point of the discussion, for not that tech savvy people? I dont get it what SPO is not able to detect? 

1 - Is there no warning when we are locked by an Fox3 because it is more modern then the MiG29?

2 - Are we not warned when we are locked by blue side SAM? What about red side SAM?

3 - What is Automatic mode? 

Thank you!

1. It will seem like host radar is getting stronger and stronger in lock mode when it appears 

 

2. yes. Red side Sam won’t show in automatic 

3. in ME you can set stock or automatic. Stock is a default Warsaw pact setting. Automatic assumes it is reprogrammed with all enemy threats in mission and told to ignore all friendly radars. It might still mistake friendly radars for enemy though, such as F-16 for F14/15/18. 

[Rhinozherous]

5 minutes ago, AeriaGloria said:

1. It will seem like host radar is getting stronger and stronger in lock mode when it appears 

 

2. yes. Red side Sam won’t show in automatic 

3. in ME you can set stock or automatic. Stock is a default Warsaw pact setting. Automatic assumes it is reprogrammed with all enemy threats in mission and told to ignore all friendly radars. It might still mistake friendly radars for enemy though, such as F-16 for F14/15/18. 

This clears it up for me! Thank you!

[Harlikwin]

1 hour ago, AeriaGloria said:

change to automatic mode 

Okay, so the problem is that HPRF is over 200 kHz, and SPO begins to have trouble over 50 kHz in regards to its bins. 
 

This says that MPRF is much below 50 kHz in terms of PRF. How could SPO have a problem with it? 

 

Again, the thing here is building a blanking circuit at ANY of these PRF's is trivial with 70's era electronics. So we need to disambiguate  the whole "detection/classification" of signals. From turn the thing on/off real fast (aka the blanker). The SPO-15 was modular. The blanker circuit was modular. Its trivial to build, the issue IMO is how they synched it, if they were doing it really simply using the "1 wire" (come on guys, this is clearly a RF coax cable). Then you use the rising edge of the radar pulse to blank the SPO. This is not elegant but if it has a concomitant delay to synch it, it will prolly work "ok"... 

And honestly the synch part is where it seems to go wrong, which tracks with the "not elegant" coax cable solution. But it "should work" in a perfect (DCS is always perfect when it comes to western electronics) world.

 

 

Edited 21 hours ago by Harlikwin

[Muchocracker]

The claim being made by the dev is that the synchronization circuit itself can't handle HPRF or CW signals.
 

Quote

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

[Harlikwin]

1 hour ago, Muchocracker said:

The claim being made by the dev is that the synchronization circuit itself can't handle HPRF or CW signals.
 

I mean, there is nothing particularly complex about making a blocking signal thats measured in khz in the 1970's. Like I could build one using 70's era components today for like 10 bucks. So that argument doesn't really sound realistic. Its a simple crystal oscillator and divider circuit. 

Maybe they have a circuit from something that isn't a mig29 tho. Since the SPO-15 was modular for many good reasons. The blanking circuits would certainly be modular depending on what platform it was installed on. If you are using a mig23 blanker on a mig29 I'm sure that doesn't work. But its pretty far from "rokit/elektronik" science to make a blanker circuit work at the desired PRF, be it LPRF/MPRF/HPRF from an electronics standpoint. There might some additional caveats synching it which might explain the various "abberant" behaviors tho. Also to address the "1 cable" thing that was brought up, thats like a non issue. Its a coax cable sending a timed signal, like ever other radio cable on earth, nothing "primitive or advanced about it"

 

[Muchocracker]

Okay, so it should be easy to present evidence to prove that the blanking circuit installed on SPO-15LM's for 9.21A mig-29's can handle the HPRF waveform then 

[AeriaGloria]

2 hours ago, Muchocracker said:

Okay, so it should be easy to present evidence to prove that the blanking circuit installed on SPO-15LM's for 9.21A mig-29's can handle the HPRF waveform then 

I feel like we basically need color video by this point lol, or a bunch of SME’s 

[SlipHavoc]

So many experts here on the SPO-15, too bad none of them can agree on how it works.

[Pavlin_33]

I guess in this kind of situation ot would be advisable to ask RL pilots for their input.

[MicroShket]

Только что, Pavlin_33 сказал:

I guess in this kind of situation ot would be advisable to ask RL pilots for their input.

Both sides support their statements with real MiG-29 pilots experience. Dead end.

But it's interesting who are ED's SMEs: from what timeline and countries. Could they relate to the new Soviet aircraft or decades old and secondhand?..

[okopanja]

On 9/23/2025 at 4:45 PM, BIGNEWY said:

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 

[Aroe]

22 hours ago, DD_Fenrir said:

it is therefore up to the MiG-29 fans to find unclassified documentation to corroborate this claim.

 

Or someone could take one for the team and just pull the warthunder strat.

[Harlikwin]

16 hours ago, Muchocracker said:

Okay, so it should be easy to present evidence to prove that the blanking circuit installed on SPO-15LM's for 9.21A mig-29's can handle the HPRF waveform then 

 

I mean  if you happen to have an actual schematic of the blanker boards along with a technical description from the 9.12  you could just post those for us too. That would clear this up.  There are people working on finding em, but if you got em already that would save a ton of time.