Pulse vs Pulse Doppler

[eatthis]

SARH = "Semi active" not "non-active". Which means, ofc you can noth an aim7, as you can notch every missile. An Aim7 would also relock a friendly or any target in the way, if it lost its radar contact in real life, if it is in the general vincinity of the radar target, it would be way less discriminate as it is in DCS. The "fire a sparrow, so it does not accidentally lock a friendly" for example is a total DCS-ism, hence it is easy to have the impression that an aim7s seeker head does not matter. It does, twice in real life, but in DCS as well. Aim7s can relock a target close in in DCS, if radar track is lost.

 

im not following you, do you mean if i lost lock/turned radar off and the aim7 is close to target it would still guide itself in? if so how? does it have its own small radar in it??

[key_stroked]

im not following you, do you mean if i lost lock/turned radar off and the aim7 is close to target it would still guide itself in? if so how? does it have its own small radar in it??

 

The way I always understood it was that the Sparrow can't guide itself. The missile uses targeting supplied by the aircraft's radar. If the aircraft loses lock, the missile loses its tracking but continues "listening" for another lock if the aircraft radar locks onto something else.

To my knowledge, the Sparrow doesn't have any radar onboard the missile, which is why it's classified as Semi-active.

 

IronMike made it sound like the missile behaves like an AIM-120 would, which does have onboard radar.

Edited June 1, 2020 by Halcyon

[draconus]

Guys, all that was said by Mike is that:

- AIM-7 can be notched (ground clutter + doppler range gate)

and

- targets can change for AIM-7 during the engagement - aircraft are just blobs on radar, they have no unique ID - if your wingman happens to fly through the LOS, being similar RCS, speed and maneuvering vector he can be tracked now on instead of the original target.

 

Pulse-Doppler is used best in look down situation (but have range gate so can be notched and cannot maintain all tracks).

Pulse is used best against the sky (cannot be notched but ground clutter can make it lose track).

 

AIM-7 is SARH so it only has receiver antenna in front and depending on the model... best to ask GGTharos ;)

 

In F-14, if the AWG-9 loses track for AIM-7 it uses Flood mode and the pilot can point the Flood cone onto the area with a small chance of reacquiring but again, it may be different target this time.

Edited June 2, 2020 by draconus

[Jedrzej]

Guys, all that was said by Mike is that:

- AIM-7 can be notched (ground clutter + doppler range gate)

and

- targets can change for AIM-7 during the engagement - aircraft are just blobs on radar, they have no unique ID - if your wingman happens to fly through the LOS, being similar RCS, speed and maneuvering vector he can be tracked now on instead of the original target.

 

Pulse-Doppler is used best in look down situation (but have range gate so can be notched and cannot maintain all tracks).

Pulse is used best against the sky (cannot be notched but ground clutter can make it lose track).

 

AIM-7 is SARH so it only has receiver antenna in front and depending on the model... best to ask GGTharos ;)

 

In F-14, if the AWG-9 loses track for AIM-7 it uses Flood mode and the pilot can point the Flood cone onto the area with a small chance of reacquiring but again, it may be different target this time.

 

 

Resume:

 

 

- AIM-7 is not guaided, just follows to the strongest signal or rather echo, just running to the light :). During poreperation "plane" injects CW radar video from the radar to the missiles, this video is used to tune the AIM-7 missile to the selected CW frequency on the RIO DDD panel, so every Plane/radar has its own signature of CW. During all the way missile the taget must by paints by radar (CW) to see/hear echo.

 

 

 

- I don't undesrtand how is posiible to notch missile AIM-7. The notching is matter of logic, filter, not disapper the target. He is still there. I would rather say, that radar lost lock in the matter of his logic, but if radar still works the reflection still exists

[draconus]

- I don't undesrtand how is posiible to notch missile AIM-7. The notching is matter of logic, filter, not disapper the target. He is still there. I would rather say, that radar lost lock in the matter of his logic, but if radar still works the reflection still exists

...and so does exist the ground clutter which then happens to be the same as the target reflections with no doppler shift between them.

[Jedrzej]

...and so does exist the ground clutter which then happens to be the same as the target reflections with no doppler shift between them.

 

 

:thumbup:

[GGTharos]

Resume:

 

 

- AIM-7 is not guaided, just follows to the strongest signal or rather echo, just running to the light :).

 

Yes it is guided. What do you think guidance is? :) The missile locks onto some signal with given parameters and uses various information from there to steer into a collision course.

 

During poreperation "plane" injects CW radar video from the radar to the missiles, this video is used to tune the AIM-7 missile to the selected CW frequency on the RIO DDD panel, so every Plane/radar has its own signature of CW. During all the way missile the taget must by paints by radar (CW) to see/hear echo.

 

CW is not required, and in fact not even available on a bunch of modern radars as the main guidance method. AIM-7M and above prefers PD. But that doesn't matter much -yep, the launching aircraft must illuminate the target.

 

- I don't undesrtand how is posiible to notch missile AIM-7. The notching is matter of logic, filter, not disapper the target. He is still there. I would rather say, that radar lost lock in the matter of his logic, but if radar still works the reflection still exists

 

The AIM-7 has a radar onboard, so of course you can notch it. Just because the AIM-7 radar does not EMIT (it is receive only), does not mean that it is not subject to the same tracking problems as any radar that can both emit and receive.

It still has all the tracking logic and filters that are needed to guide the missile. This is a HOMING missile, meaning it has its own independent guidance.

Edited June 4, 2020 by GGTharos

[Jedrzej]

Yes it is guided. What do you think guidance is? :) The missile locks onto some signal with given parameters and uses various information from there to steer into a collision course.

 

Ok, You right however talking about "guided" I thought about "guidence command" from mother-ship sending to missile (like AIM-54) :)

 

 

The AIM-7 has a radar onboard, so of course you can notch it. Just because the AIM-7 radar does not EMIT (it is receive only), does not mean that it is not subject to the same tracking problems as any radar that can both emit and receive.

It still has all the tracking logic and filters that are needed to guide the missile. This is a HOMING missile, meaning it has its own independent guidance.

I was thinking about AIM-7 an his/her receiver like simple stuff, just going to strongest source of signal, without any sophisticated logic. But got question, as we know AIM-7 is semiactive, so when target notching main radar (plane), he breaks STT, when he breaks STT reflection just stops, so AIM-7 lost his/her "way"?

Another question is that angle between plane <-> target and AIM-7 <-> target can be diffirent - so in the same time target can notch plane radar but do not notch AIM-7 or vice versa in the same time the target is seeing by the plane (STT) but notch AIM-7?

 

 

hmmmm.. it make sens :), so now I (hope) do undertstand, that AIM-7 should have filters and more advanced logic :)

[GGTharos]

I was thinking about AIM-7 an his/her receiver like simple stuff, just going to strongest source of signal, without any sophisticated logic.

 

A SARH seeker can be very sophisticated.

 

But got question, as we know AIM-7 is semiactive, so when target notching main radar (plane), he breaks STT, when he breaks STT reflection just stops, so AIM-7 lost his/her "way"?

 

Yes, most likely. There are ways to keep the radar on the target sometimes, like FLOOD mode or say, the F-14's TCS pointing the radar at a target it has locked on to.

 

Another question is that angle between plane <-> target and AIM-7 <-> target can be diffirent - so in the same time target can notch plane radar but do not notch AIM-7 or vice versa in the same time the target is seeing by the plane (STT) but notch AIM-7?

 

Yes, this could happen.

 

hmmmm.. it make sens :), so now I (hope) do undertstand, that AIM-7 should have filters and more advanced logic :)

 

Most missiles do, you have to go very far back in time to have something that's truly simple :)