Previous Thread
Next Thread
Print Thread
Rate This Thread
Hop To
Page 14 of 14 1 2 12 13 14
#4294399 - 09/08/16 09:07 AM Re: S-75M3 Volhov (SA-2E Guideline) ***** [Re: Cat]  
Joined: Apr 2012
Posts: 592
Alien_MasterMynd Offline
Member
Alien_MasterMynd  Offline
Member

Joined: Apr 2012
Posts: 592
Czech Republic
Regarding jamming, I've read here, that Volchov contains GShV module to counter impulse jamming. Is it simulated? How does it work?

Inline advert (2nd and 3rd post)

#4294466 - 09/08/16 02:22 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Feb 2015
Posts: 29
Jonas85 Offline
Junior Member
Jonas85  Offline
Junior Member

Joined: Feb 2015
Posts: 29
Ontario
GShV is an ECCM fix against AM-modulated jamming in angles.

It was introduced for the first time in C-25 Berkut, later - into C-75 Volkhov and C-125 Neva. In Berkut, this mode was called GSh, in Neva - GShN. I guess that the abbreviation GSh stands for the Russian Gashenie Shumov - that is, noise reduction, letters V and N means the implementation in Volkhov and Neva systems.

GShV is a side-lobe blanking and AM-demodulation scheme based on the comparison of the signal from the narrow-beam antenna, epsilon or beta (this is called main channel) with a reference signal coming from the wide-beam antenna (this is called auxiliary, or compensation channel).

In order to understand the main idea, you need some basic math.

Let

Umain(O) - target return (no jamming) in by main receiving channel.
Uaux(O) - target return (no jamming) in auxiliary receiving channel.
Ujam(O) - AM-modulated signal, introduced by jammer.

Here, letter U means voltage (corresponds to the signal strength in respective channel), O - means angle (O=beta or O=epsilon)

When tracking a jamming target, the return from the target in the main channel is

Umain(O)*Ujam(O),

where the factor Ujam(O) accounts for the parasite AM-modulation. Jamming is so strong, that Ujam(O) might obscure target return Umain(O).

In auxiliary channel, the return is

Uaux(O)*Ujam(O)

(note that you have same Ujam(O) in the auxiliary and main channels because jammer signal is very powerful).

You get rid of parasite modulation by dividing the two signals:

Umain(O)*Ujam(O) / (Uaux(O)*Ujam(O)) = Umain(O)/Uaux(O).

Now comes the trick: since Uaux(O) comes from the wide beam antenna, its graph is much "flatter", than the Umain(O), so one can assume that Uaux(O) = const (this is not very precise, but enough to understand the idea).

Uaux(O) is amplified in such a way, that the ratio

Umain(O)/Uaux(O) = 1

for any return coming from the first side lobe of narrow beam antenna (this is called the threshold, or base level).

Then the signal is passed to the filter with a cut-off at or below the base level

Umain(O)/Uaux(O) <= 1,

so you get a side lobe blanking as a bonus. This process is illustrated below (the form of the curves correspond to the antenna gain diagrams in the corresponding plane).




GSh was first implemented in C-25 Berkut M2 system in 1964. After Vietnam war experiences with Dvina, in 1970 it was introduced to Volkhov (C-75V-M3) and C-125-M Neva. In different systems, they use different antennas are for the main and aux channels, also the wiring for demodulation is done differently (in Berkut - by cutting of the signal at lower threshold, in Volkhov and Neva - by using logarithmic amplifiers in the subtraction scheme).

In C-75M3, separate GShV circuits are used for azimuth and elevation angle tracking.

In azimuth (beta),
main channel is connected to P-11V (azimuth wide beam) antenna,
aux channel is connected to P-13V (azimuth narrow beam) antenna.

In elevation (epsilon),
main channel is connected to P-12V (elevation wide beam) antenna,
aux channel is connected to P-14V (elevation narrow beam) antenna.

At first this might seem confusing, because one expects narrow beam antenna to function as main receiver and wide beam to function as aux receiver. But the notion of "wide" and "narrow" depends in what plane you are looking! For instance, in beta-plane, P-11 beam dimensions (vertical x horizontal) are 7.5 x 1.1] degrees, P-13 beam dimensions are 1.5 x 1.5; since 1.1 < 1.5 , the P-13 beam is actually wider than P-11 beam in azimuth plane.

Last things:

1) since GShV needs main/aux channels with wide & narrow beam antennas, in Volkhov it can be used only in LORO ('Podsvet') mode.

2) GShV mode is not compatible with SDC (the phase information required to filter targets from clutter is destroyed when transforming the signal).

3) GSh modes were designed to counter single jamming target; I've no idea if it works for group targets or in the background of stand-off jamming coming from from EB-66C or similar aircraft.

Sadly, I have found no pictures of the operator view of beta or epsilon indicators of a jamming target with GShV on/off.

Last edited by Jonas85; 09/14/16 11:12 PM.
#4294490 - 09/08/16 05:03 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Apr 2012
Posts: 592
Alien_MasterMynd Offline
Member
Alien_MasterMynd  Offline
Member

Joined: Apr 2012
Posts: 592
Czech Republic
Thanks thumbsup

How does it work at S-25? There are just two antennas for epsilon and beta. What is the source of the second signal?

#4294571 - 09/08/16 08:55 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Jonas85]  
Joined: Sep 2011
Posts: 1,722
piston79 Offline
Member
piston79  Offline
Member

Joined: Sep 2011
Posts: 1,722
Originally Posted By: Jonas85
GShV is an ECCM fix against AM-modulated jamming. For the first time, this technique was introduced into C-25 Berkut, later - into C-75 Volkhov and C-125 Neva systems. In Berkut, this mode was called GSh, in Neva - GShN. I guess that the abbreviation GSh stands for the Russian "Gashenie Shumov" - that is, "noise reduction", letters V and N means the implementation in Volkhov and Neva systems.

In a nutshell, GShV is a side-lobe blanking and AM-demodulation scheme, that is based on comparison of the signal from the narrow-beam antenna, epsilon or beta (this is called main channel) with a reference signal coming from the wide-beam antenna (this is called auxiliary, or compensation channel).

............


1) since GShV needs main/aux channels with narrow & wide beam antennas, in Volkhov it can be used only in LORO ('Podsvet') mode.




Maybe it is the opposite - auxiliary signal received by narrow-beam antenna, main - by wide-beam antenna (as LORO is with narrow-beam antenna transmitting and wide-beam antenna receiving...????

Last edited by piston79; 09/08/16 08:57 PM.
#4294639 - 09/09/16 01:22 AM Re: S-75M3 Volhov (SA-2E Guideline) [Re: piston79]  
Joined: Feb 2015
Posts: 29
Jonas85 Offline
Junior Member
Jonas85  Offline
Junior Member

Joined: Feb 2015
Posts: 29
Ontario
Excellent question, piston 79!

Actually, in describing GSh mode, I used "narrow" and "wide" beam in a different sense!

"wide angle" antenna means = larger or at least equal diagram of reception than that of a "narrow beam" antenna in a particular plane.

So, in case of GSh, azimuth (beta) plane... (vertical x horizontal)

P-11V antenna, main lobe diagram 7.5 x 1.1 degrees
P-13V antanna, main lobe diagram 1.7 x 1.7 degrees

Note that the angles for P-11/P-13 antennas in beta-plane are

1.1 < 1.7!

So, the arrangement is as follows:

main channel receives from P-11 (which is usually called "wide angle")
aux channel receives from P-13 (when it is not transmitting) (which is usually called "narrow angle").

Now you see why the roles of P-11/P-13 are (as "wide"and "narrow" beam) are, technically speaking, reversed!

The same is true for vertical (epsilon plane), using P-12/P-14 pair as main/aux receiving antennas.

Last edited by Jonas85; 09/09/16 11:32 AM.
#4294696 - 09/09/16 09:10 AM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Dec 2009
Posts: 2,660
Hpasp Offline
Hpasp  Offline

Senior Member

Joined: Dec 2009
Posts: 2,660
Hungary, Europe
Here you go with the Volhov GShV operations panel.


Right from the FCO panel, at the wall...


Last edited by Hpasp; 09/09/16 09:15 AM.

Hpasp
Free SAM Simulator, "Realistic to the Switch"

http://sites.google.com/site/samsimulator1972/home

While Fighter Pilots made movies, SAM Officers made History.
(U-2 over Sverdlovsk, B-52's over Hanoi, F-4 Phantoms over the Sinai, F-16's and the F-117A Stealth bomber over the Balkans.)
thumbsup
#4294724 - 09/09/16 11:48 AM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Hpasp]  
Joined: Feb 2015
Posts: 29
Jonas85 Offline
Junior Member
Jonas85  Offline
Junior Member

Joined: Feb 2015
Posts: 29
Ontario
Dear Hpasp, are you sure it's GShV panel?

I think you are actually showing a panel on block I-57V for a different ECCM feature, called DISKRIMINATOR.

You should look for GShVs on panels I-30(AV, BV, BB), I-31VU, I-330VMI, I-355MV.

#4294796 - 09/09/16 03:39 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Dec 2009
Posts: 2,660
Hpasp Offline
Hpasp  Offline

Senior Member

Joined: Dec 2009
Posts: 2,660
Hungary, Europe
Yes you are right!


Hpasp
Free SAM Simulator, "Realistic to the Switch"

http://sites.google.com/site/samsimulator1972/home

While Fighter Pilots made movies, SAM Officers made History.
(U-2 over Sverdlovsk, B-52's over Hanoi, F-4 Phantoms over the Sinai, F-16's and the F-117A Stealth bomber over the Balkans.)
thumbsup
#4296261 - 09/14/16 11:18 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Feb 2015
Posts: 29
Jonas85 Offline
Junior Member
Jonas85  Offline
Junior Member

Joined: Feb 2015
Posts: 29
Ontario
I updated my post on GShV with more precise notation, pictures and included the answer to piston79's question. Enjoy! thumbsup

#4296301 - 09/15/16 07:02 AM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Dec 2009
Posts: 2,660
Hpasp Offline
Hpasp  Offline

Senior Member

Joined: Dec 2009
Posts: 2,660
Hungary, Europe
Great description!
thumbsup

Keep continue, with the Diskriminator.
biggrin


Hpasp
Free SAM Simulator, "Realistic to the Switch"

http://sites.google.com/site/samsimulator1972/home

While Fighter Pilots made movies, SAM Officers made History.
(U-2 over Sverdlovsk, B-52's over Hanoi, F-4 Phantoms over the Sinai, F-16's and the F-117A Stealth bomber over the Balkans.)
thumbsup
#4296318 - 09/15/16 10:03 AM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Hpasp]  
Joined: Sep 2011
Posts: 1,722
piston79 Offline
Member
piston79  Offline
Member

Joined: Sep 2011
Posts: 1,722
Originally Posted By: Hpasp
Great description!
thumbsup

Keep continue, with the Diskriminator.
biggrin


Maybe we must double it up (in special topic, say "SAM ECCM CAPABILITIES",so having this wonderful info not only in the parigular SA-xx topic, but summarized in a particular one...

How about you, guys...?

#4297448 - 09/19/16 02:27 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: piston79]  
Joined: Apr 2012
Posts: 592
Alien_MasterMynd Offline
Member
Alien_MasterMynd  Offline
Member

Joined: Apr 2012
Posts: 592
Czech Republic
Originally Posted By: piston79
Originally Posted By: Hpasp
Great description!
thumbsup

Keep continue, with the Diskriminator.
biggrin


Maybe we must double it up (in special topic, say "SAM ECCM CAPABILITIES",so having this wonderful info not only in the parigular SA-xx topic, but summarized in a particular one...

How about you, guys...?

I am for the new topic too.

#4298511 - 09/23/16 09:14 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Hpasp]  
Joined: Feb 2015
Posts: 29
Jonas85 Offline
Junior Member
Jonas85  Offline
Junior Member

Joined: Feb 2015
Posts: 29
Ontario
Originally Posted By: Alien_MasterMynd
Thanks thumbsup

How does it work at S-25? There are just two antennas for epsilon and beta. What is the source of the second signal?

This question is now answered at C-25 Berkut (SA-1 Guild) thread...

Originally Posted By: Hpasp
Great description!
thumbsup

Keep continue, with the Diskriminator.
biggrin

I have found some bits on Diskriminator copter My info is not very detailed (design projects are missing from PVO website), but I think I have some vague idea how it works (or at least I think I have...). Will post that at some point salute

#4381717 - 09/27/17 05:05 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Dec 2009
Posts: 2,660
Hpasp Offline
Hpasp  Offline

Senior Member

Joined: Dec 2009
Posts: 2,660
Hungary, Europe
Capu Midia range; September of 2017

[Linked Image]
[Linked Image]
[Linked Image]
[Linked Image]
[Linked Image]
[Linked Image]
[Linked Image]
[Linked Image]


Hpasp
Free SAM Simulator, "Realistic to the Switch"

http://sites.google.com/site/samsimulator1972/home

While Fighter Pilots made movies, SAM Officers made History.
(U-2 over Sverdlovsk, B-52's over Hanoi, F-4 Phantoms over the Sinai, F-16's and the F-117A Stealth bomber over the Balkans.)
thumbsup
#4391639 - 11/27/17 06:53 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Sep 2011
Posts: 1,722
piston79 Offline
Member
piston79  Offline
Member

Joined: Sep 2011
Posts: 1,722

#4391646 - 11/27/17 08:34 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: piston79]  
Joined: Apr 2012
Posts: 592
Alien_MasterMynd Offline
Member
Alien_MasterMynd  Offline
Member

Joined: Apr 2012
Posts: 592
Czech Republic
Originally Posted by piston79

Great thumbsup

#4398068 - 01/03/18 10:07 AM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Sep 2011
Posts: 1,722
piston79 Offline
Member
piston79  Offline
Member

Joined: Sep 2011
Posts: 1,722
[video:vimeo]http://www.military.com/video/opera...r/b-52-hit-twice-lands-safe/661837272001[/video]

<iframe width='476 px' height='372 px' src='http://www.military.com/video/operations-and-strategy/persian-gulf-war/b-52-hit-twice-lands-safe/661837272001?snippetVideoId=207dde4ccaaceafaaf15d5b4baf33837' allowfullscreen frameborder=0></iframe> <iframe width='476 px' height='372 px' src='http://www.military.com/video/operations-and-strategy/persian-gulf-war/b-52-hit-twice-lands-safe/661837272001?snippetVideoId=207dde4ccaaceafaaf15d5b4baf33837' allowfullscreen frameborder=0></iframe>

HTML
<iframe width='476 px' height='372 px' src='http://www.military.com/video/operations-and-strategy/persian-gulf-war/b-52-hit-twice-lands-safe/661837272001?snippetVideoId=207dde4ccaaceafaaf15d5b4baf33837' allowfullscreen frameborder=0></iframe>


http://www.military.com/video/opera...r/b-52-hit-twice-lands-safe/661837272001

#4399644 - 01/12/18 09:22 PM Re: S-75M3 Volhov (SA-2E Guideline) [Re: Cat]  
Joined: Sep 2011
Posts: 1,722
piston79 Offline
Member
piston79  Offline
Member

Joined: Sep 2011
Posts: 1,722
[Linked Image]

Page 14 of 14 1 2 12 13 14

Moderated by  Cat, Hpasp, RacerGT 

Quick Search
Recent Articles
Support SimHQ

If you shop on Amazon use this Amazon link to support SimHQ
.
Social


Recent Topics
Russian aerobatic pilot
by KraziKanuK. 04/21/18 05:45 PM
flickr bought by smugmug
by wheelsup_cavu. 04/21/18 04:39 PM
Yes, this is NOT an SNL skit, It's a real product...
by WangoTango. 04/21/18 01:53 AM
main page
by rwatson. 04/20/18 05:26 PM
Cold Waters - South China Sea
by Sluggish Controls. 04/20/18 03:37 PM
Baseball
by PanzerMeyer. 04/20/18 01:48 PM
Another mystery solved
by oldgrognard. 04/19/18 10:02 PM
IT Complaints
by Bill_Grant. 04/19/18 09:14 PM
Copyright 1997-2016, SimHQ Inc. All Rights Reserved.

Powered by UBB.threads™ PHP Forum Software 7.6.0