Sidelobe clutter in Pulse ?

[Robin_Hood]

Hi everyone, I hope some people can shed some light on this for me. I was wondering why there seems to be no sidelobe clutter (especially altitude returns) in PULSE SEARCH mode. I have searched but couldn't find anyone mentioning sidelobe clutter except in relation to Pulse Doppler.

I understand that in Pulse Doppler, both main lobe clutter and altitude returns are filtered (MLC filter and Zero-Doppler filter respectively), and that the zero-doppler filter cannot be deactivated. However, it occurs to me that in Pulse Mode, the sidelobes should also be a problem, and shouldn't altitude returns also appear, at a distance roughly equal to the aircraft's current height? A sidelobe pointing at the ground in pulse mode would create a return, wouldn't it?

Is there still some Doppler processing anyway with the zero-doppler filter even in Pulse, or some other way of filtering out aititude returns, or is it simply not implemented? Or am I missing something?

Edited May 2, 2024 by Robin_Hood

[Robin_Hood]

Browsing again through Heatblur's manual, I came across this picture of the Pulse Search mode (page 222), where altitude returns are indicated and displayed approximately in the manner that I would expect. I am guessing then that sidelobe clutter in Pulse Search should be a thing, but is just not implemented (yet?).

Edited May 15, 2024 by Robin_Hood

[Naquaii]

6 minutes ago, Robin_Hood said:

Browsing again through Heatblur's manual, I came across this picture of the Pulse Search mode (page 222), where altitude returns are indicated and displayed approximately in the manner that I would expect. I am guessing then that sidelobe clutter in Pulse Search should be a thing, but is just not implemented (yet?).null

It's a combination of things. One is that that radar model for pulse in the AWG-9 isn't nearly as advanced as the one developed for the APQ-120 in the F-4E. It's only natural that our focus for the AWG-9 was on the pulse-doppler side of things. With time and luck there might be some back port of the tech for the AWG-9 as well as it would be nice to improve where we can. No promises of any sort though.

That said it's also not a straight comparison. The AWG-9 is a different animal all-together and various different factors (especially the antenna design) combine to mean that some factors, like the altitude return and sidelobes weren't as prevalent as they were in the APQ-120. Still factors but not the same as the APQ-120. So even if fully implemented you should not expect it to be the same as the APQ-120.

[Robin_Hood]

Got it, thanks. I wasn't making any comparison with the APQ-120 though, I was only talking about the AWG-9 (and the above image is from the F-14 manual).

Anyway, the AWG-9 is already pretty fun to fiddle around with!

Edited May 15, 2024 by Robin_Hood

[Naquaii]

19 minutes ago, Robin_Hood said:

Got it, thanks. I wasn't making any comparison with the APQ-120 though, I was only talking about the AWG-9 (and the above image is from the F-14 manual).

Anyway, the AWG-9 is already pretty fun to fiddle around with!

 

Yeah, no worries. Was kinda an assumption on my part as there's much talk about the APQ-120 going on atm. Just wanted to make sure people aren't expecting the exact same picture on a different radar like the AWG-9.

[draconus]

On 5/15/2024 at 11:51 PM, Naquaii said:

One is that that radar model for pulse in the AWG-9 isn't nearly as advanced as the one developed for the APQ-120 in the F-4E.

Why? The quality standards changed or you have better info or more performance freedom?

[Naquaii]

On 5/17/2024 at 8:23 AM, draconus said:

Why? The quality standards changed or you have better info or more performance freedom?

It would be strange if HB didn't strive to improve quality standards now wouldn't it?

But it's partly that and partly that the AWG-9 isn't primarily a pulse-radar. And no, I'm not saying that it is bad, just that, naturally, the APG-120 simulation has had a substantial amount of time and effort put into it as you'll be using pulse 100% of the time. Hopefully it's something that might eventually trickle back into the pulse side of the AWG-9.

That said, like I said above, it shouldn't be expected that that means a copy paste as the AWG-9 is a completely different radar with a quite different antenna. (Better side-lobe supression afaik as an example.)

Edited May 18, 2024 by Naquaii