What is the difference between Scan and TWS radar modes?

[kontiuka]

In the manual, under TWS, it says ...

 

The main distinction from SCAN mode is that the radar retains target parameters, like elevation and velocity vector, while continuing to search for additional targets.

 

What I'm confused about is that the radar maintains elevation and velocity in scan mode as well so i'm not sure what the real difference is.

EDIT: sorry, this should be in the Su-27 forum.

[ricktoberfest]

TWS means you can launch a missile at a locked target while still scanning for other targets. Useful for multiple bogies

[kontiuka]

TWS means you can launch a missile at a locked target while still scanning for other targets. Useful for multiple bogies

But once you lock a target, aren't you in Single Target Track mode then? Again, this is for the Su-27. I know the F-15C works differently.

[ricktoberfest]

I don't know specifically for the su27, but the whole idea is locking multiple targets at once so it shouldn't enter single track mode or it's not really track while scan

[GGTharos]

The SNP mode of the Su-27 is intended to be used as a Situational Awareness aid.

 

It is not capable of directing weapons at multiple targets, however it will give you a good idea of what the battlefield looks like.

 

@ricktoberfest: Yes, it is Track While Scan. Read the words: It's Track While Scan, not Attack Multiple Targets While Scan. Just because the TWS has sub-modes capable of this on the eagle, it doesn't mean the flanker has to.

 

The SNP mode gives you great SA by showing speeds, altitudes and headings of contacts. Since this requires generating a track for each contact, while scanning for others, it really is Track While Scan.

Edited November 17, 2014 by GGTharos

[karambiatos]

Is it realistic that the TWS turns off and switches to scan, when it spots a ECM

[GGTharos]

Yes, because generating and storing the target tracks requires just about all of the processing and memory capability of that radar processor - so when ECM pops up, it overwhelms it with targets, and the software bounces it out of SNP mode so it doesn't freeze up/become useless.

[kontiuka]

The SNP mode gives you great SA by showing speeds, altitudes and headings of contacts. Since this requires generating a track for each contact, while scanning for others, it really is Track While Scan.

This comes back to my original question of how does TWS (I assume this is what you mean by SNP) differ from the regular scan mode since in the regular scan mode, you also get speeds, altitudes, and headings.

[GGTharos]

You don't get speeds altitudes and headings in Scan mode unless you go to STT. You only get them in SNP.

 

Perhaps you're getting data-linked contacts from an EWR or AWACS?

[srky]

This comes back to my original question of how does TWS (I assume this is what you mean by SNP) differ from the regular scan mode since in the regular scan mode, you also get speeds, altitudes, and headings.

No... STT gives you that, not the Long Range Scan.

[kontiuka]

You don't get speeds altitudes and headings in Scan mode unless you go to STT. You only get them in SNP.

 

Perhaps you're getting data-linked contacts from an EWR or AWACS?

I tried a mission without AWACS or EWR and thought I saw velocity vectors on the radar contacts in scan mode. Could be wrong. I'll test again tonight. The manual is a little misleading because in the scan mode section it shows the HDD with altitudes/velocities on the radar returns.

[kontiuka]

A screenshot of the HDD in scan mode. No TWS or AWACS or EWR.

[GGTharos]

I'll have to check, I believe it's a bug.

[GenericFloat]

The SNP mode of the Su-27 is intended to be used as a Situational Awareness aid.

 

It is not capable of directing weapons at multiple targets, however it will give you a good idea of what the battlefield looks like.

 

@ricktoberfest: Yes, it is Track While Scan. Read the words: It's Track While Scan, not Attack Multiple Targets While Scan. Just because the TWS has sub-modes capable of this on the eagle, it doesn't mean the flanker has to.

 

The SNP mode gives you great SA by showing speeds, altitudes and headings of contacts. Since this requires generating a track for each contact, while scanning for others, it really is Track While Scan.

 

Ok, firstly what does the abbreviation SNP mean?

 

Secondly, how does the SNP mode give speed, altitude, and heading in the Su-27? When I lock a target in STT, I am given the aspect, speed (top left of the HUD), and altitude (top right of the HUD). But in TWS mode, I am given none of this information except distance? Am I missing something?

 

I know in the F-15 this is all given in TWS, but in the Flanker I don't see it.

[Weta43]

Interesting

 

SNP = СНП ~ TWS

 

The TWS scan tracks are possible because each individual scan of the radar gives you the return's range, altitude and closing speed.

 

Assuming the worst case - that the beam's transit across the target is so quick as to be essentially instantaneous, then you need at least 2 consecutive 'polls' to create a TWS track that gives absolute speed & direction (you know where it was, you know where it is, and you know how long it took to get there - you're tracking it).

 

According to the manual, 'The radar can correlate tracks for up to 10 targets simultaneously in "СНП" (TWS)', so the HDD can give you the range, altitude, speed and direction of 10 aircraft simultaneously while in TWS

 

What's interesting to me is that you can only make these tracks because each pass of the radar gives you range, altitude and closing speed - so surely even in OBZ (ОБЗ ~ scan), there should be range altitude and closing speed indications for every return even without a track (but all the tails should point directly at you) ?

[GenericFloat]

Interesting

 

 

According to the manual, 'The radar can correlate tracks for up to 10 targets simultaneously in "СНП" (TWS)', so the HDD can give you the range, altitude, speed and direction of 10 aircraft simultaneously while in TWS

 

but where is this information displayed in TWS mode? I literally don't see this anywhere.

[Weta43]

The length of the line in front of the target is proportional to speed, and the width of the 'wings' to altitude.

[GenericFloat]

The length of the line in front of the target is proportional to speed, and the width of the 'wings' to altitude.

 

Ah, yes. Thank you. It would be nice if this was an "exact" measurement like the f-15. Oh well, we work with what we have.

[GGTharos]

It's a situational awareness tool.

[kontiuka]

I'm wondering if anything should be shown on the HDD at all if only in scan mode, not TWS. From the manual ...

 

"The TWS mode provides more detailed target information, permits a tactical situation picture to be displayed on the Head Down Display (HDD), and can lock targets in an automated mode."

[GGTharos]

The trick here is that we don't know how SCAN, SNP and data-link are fused on the HDD, or rather, I don't know.

[GrEaSeLiTeNiN]

This might help...

[ame]

[/ame]

[lmp]

It doesn't, because the mode in the video is specific to the MiG-29S and not available on the Su-27...

[holimoli]

I tried a mission without AWACS or EWR and thought I saw velocity vectors on the radar contacts in scan mode. Could be wrong. I'll test again tonight. The manual is a little misleading because in the scan mode section it shows the HDD with altitudes/velocities on the radar returns.

 

yes, you see speed and alt in STT. TWS in the flanker is pretty useless since you see the contacts on the HDD like in TWS anyway.. Reported bandits by AWACS will have an open triangle. As long as you see the bandit as a "T" and only has 1 number next to it, it is only seen by your radar.

[DarkFire]

A screenshot of the HDD in scan mode. No TWS or AWACS or EWR.

 

Did you have wingmen? The 1, 2 and 4 symbols can represent which of your wingmen are providing datalink information for those specific targets.