Indian Missiles News & Discussions - 17 Dec 2018

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manjgu
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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby manjgu » 23 Mar 2020 19:25

1) thanks for the illustrations 2) as per advertised capability of astra...a) is their cooperative engagement ? b) what happens to DL when shooter a/c turns tail ... in opp direction of enemy a/c

ramana
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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby ramana » 24 Mar 2020 02:45

srai, Through as usual. Never a useless post from you.

ramana
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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby ramana » 24 Mar 2020 02:47

I think the DRDO tests should proceed and telemetry and video shared later.

The testing date is set taking a lot of things into consideration.

NachiketM
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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby NachiketM » 31 Mar 2020 04:41

This question is for the seniors here;

How does the Home-on-Jammer (HOJ) mode of modern missiles actually work?
Why didn't the our aircraft use it on 27th Feb?
Does Astra come with this mode too?

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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby nachiket » 01 Apr 2020 06:28

NachiketM wrote:This question is for the seniors here;

How does the Home-on-Jammer (HOJ) mode of modern missiles actually work?
Why didn't the our aircraft use it on 27th Feb?
Does Astra come with this mode too?

In HOJ mode the missile (AAM like R-77 or AMRAAM) switches to a passive homing mechanism similar to that of an anti-radiation missile (ARM) like the Kh-31P Krypton or AGM-88 HARM, although actual ARM's would be much better at doing it.

There are obviously limits to this capability. An older noise jammer which transmits continuously can be easier to locate than a modern DRFM jammer which tries to spoof the radar by mimicking a response to the original signal. With a modern DRFM jammer the missile seeker may not even detect that it is being jammed. Also, it is more difficult to get accurate range to target using HOJ than a real radar-lock.

I'm not sure about your second question. In what context were we supposed to use this? This capability is automated on AAM's I believe. We did not fire any R-77's for a variety of reasons which were discussed in the thread about that incident. HOJ never got into the picture.

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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby NachiketM » 04 Apr 2020 03:49

nachiket wrote:
NachiketM wrote:This question is for the seniors here;

How does the Home-on-Jammer (HOJ) mode of modern missiles actually work?
Why didn't the our aircraft use it on 27th Feb?
Does Astra come with this mode too?

In HOJ mode the missile (AAM like R-77 or AMRAAM) switches to a passive homing mechanism similar to that of an anti-radiation missile (ARM) like the Kh-31P Krypton or AGM-88 HARM, although actual ARM's would be much better at doing it.

There are obviously limits to this capability. An older noise jammer which transmits continuously can be easier to locate than a modern DRFM jammer which tries to spoof the radar by mimicking a response to the original signal. With a modern DRFM jammer the missile seeker may not even detect that it is being jammed. Also, it is more difficult to get accurate range to target using HOJ than a real radar-lock.

I'm not sure about your second question. In what context were we supposed to use this? This capability is automated on AAM's I believe. We did not fire any R-77's for a variety of reasons which were discussed in the thread about that incident. HOJ never got into the picture.



The second question was in context of our communications being jammed by the enemy. Not sure if it was ground station or airborne.

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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby Haridas » 04 Apr 2020 13:15

NachiketM wrote:This question is for the seniors here;

How does the Home-on-Jammer (HOJ) mode of modern missiles actually work?
Why didn't the our aircraft use it on 27th Feb?
Does Astra come with this mode too?

Reminds me of talks I gave to my final year classmates in 1983 on Electronic-warfare , all of them were amazed of possibilities! So were the electronics engineering lecturers

NachiketM
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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby NachiketM » 05 Apr 2020 21:06

Haridas wrote:
NachiketM wrote:This question is for the seniors here;

How does the Home-on-Jammer (HOJ) mode of modern missiles actually work?
Why didn't the our aircraft use it on 27th Feb?
Does Astra come with this mode too?

Reminds me of talks I gave to my final year classmates in 1983 on Electronic-warfare , all of them were amazed of possibilities! So were the electronics engineering lecturers


Please do elaborate and enlighten us for the benefit of this community... :D

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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby Haridas » 06 Apr 2020 06:09

NachiketM wrote:This question is for the seniors here;

How does the Home-on-Jammer (HOJ) mode of modern missiles actually work? ....

Missiles with active seeker typically uses X or K band antenna array at launch or after launch. When enemy counter measure uses Jammer to degrade the seeker SNR (Signal to noise ratio), since the typical jammer is co-located with the target, the missile counter-counter measure could use the jammer as a beacon, so the seeker array could use the beam steering to accurately determine the angular direction of the jammer to continue to move towards jammer. Eventually when the distance to target becomes less than burn-through range of the active seeker radar, the radar is back in action with additional ranging information (in addition to angular position).

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Re: Indian Missiles News & Discussions - 17 Dec 2018

Postby nachiket » 07 Apr 2020 00:14

NachiketM wrote:The second question was in context of our communications being jammed by the enemy. Not sure if it was ground station or airborne.

Communications jamming and Radar jamming are not the same thing although they work on a similar principle.

HOJ mode is only useful AFAIK for a specific case - where the missile's target is itself jamming the missile's radar seeker (and launching aircraft's radar) using a self-protection jammer. Even here there are limitations as I've noted above.


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