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Are new clouds influencing AG-radar already?


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Posted (edited)

It seems more difficult to find SEA-target in AG-radar sea mode when flying above the new clouds. Is that correct or just bad luck on my side?


Edited by oho
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I believe it was mentioned in a recent thread that the ranging of SEA mode was adjusted with 2.7 to correct for the earth’s curvature, so this may be the effects you’re seeing. 

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Modern radar can see through and filter out clouds. They should have no effect on the Hornet's radar systems.

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Virpil WarBRD | Thrustmaster Hornet Grip | Foxx Mount | Thrustmaster TWCS Throttle | Logitech G Throttle Quadrant | VKB T-Rudder IV | TrackIR 5

 

 

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The only clouds that would show up are rain clouds with significant water droplets and CB’s / Thunderstorms. 
I imagine the radar might have a few selectable options to adjust gain and calibration to minimise as far as possible the affect of such weather on the display. 
 

In any event, non-rain fair weather clouds would be completely invisible to the radar. 

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4 minutes ago, AvroLanc said:

The only clouds that would show up are rain clouds with significant water droplets and CB’s / Thunderstorms. 
I imagine the radar might have a few selectable options to adjust gain and calibration to minimise as far as possible the affect of such weather on the display. 
 

In any event, non-rain fair weather clouds would be completely invisible to the radar. 

I mean, aren't all clouds rain clouds. Just some less dense than others.

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Posted (edited)
10 minutes ago, Swiftwin9s said:

I mean, aren't all clouds rain clouds. Just some less dense than others.

Nope. If the water droplets haven’t properly condensed it’s not rain yet. The water vapour simply doesn’t produce any radar reflection, until they form droplets and are big enough. I should probably know a bit more technical detail but it’s been a while since I hit the books, (plus far too much furlough.)
 

From personal experience, even dedicated weather radars obviously don’t detect normal clouds. Even drizzly low level stratus doesn’t show that well. But it would depend on how the radar is calibrated I guess. 


Edited by AvroLanc
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Indeed, drop size and composition play a big role in its reflectivity (water being 5x more reflective than ice, for example). Airborne weather radar is tuned to detect precipitation and often misses big buildups still developing, or dispersing thunderstorms. The fact that fighters use ground mapping modes to avoid weather suggests that it must detect returns from water drops in a relatively similar way.

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Posted (edited)

Yes, radars are sensitive to rain/hail/snow not "clouds", although the specifics will vary with the frequency bands used. There are two weather related effects that can happen: weather shadows due to increased attenuation because of scattering (ie weather blocking the signal) and target occlusion due to weather returns (ie the target's returns get lost in weather clutter).

 

Weather shadows are similar to terrain shadows. The more the signal is scattered by rain/hail/snow the more it'll be attenuated, to the point the signal is too weak to be detected past a certain range at that line of sight.

images

 

Possible solutions include using a lower frequency band or increasing the signal's power.

On the other hand, a solution to clearly displaying moving targets that are detected inside weather clutter is using doppler filtering since clouds are relatively static compared to aircraft.

 

The reason this is a problem particularly for A/G radar is that 1. A/G radar's uses low PRFs which make it impossible to calculate doppler, and even if it could, the intended target (terrain) is static so there is nothing to filter. 2. Low PRFs have a lower duty cycle so weather penetration will be worse than medium or high PRFs. A lower frequency band can't be used since that requires a larger antenna and available power is limited, so you're essentially stuck in a case where nothing can really be done about it.

 

A/A radar has the benefits of higher PRFs and doppler filtering, but AFAIK very heavy weather can still cause weather shadows.

 

At least so far in DCS weather interaction with radar isn't modeled but hopefully it could be at some point, especially for A/G radar.


Edited by Santi871
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Inspired by this thread, I headed to base ops to get my flt plan and my IFR clearance was ready by the time I strapped in... It didn't include Harpoon deployment tho:biggrin:

 

Yes, our SEA mode is superb: detects almost everything at 80nm through any weather, including submerged subs.  I never complain about going over the specs and if/when ED decides to tweak it, they'd better not 'adjust' too much... only in the upward direction :wink:

 

https://youtu.be/Vekemzn0b2U

 

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