Magenta turbulence areas on ND

[Hardy Heinlin]

Hello,

I'm working on an improvement of the WXR graphics (more chaos, less patterns, and other modifications).

I'm wondering if it's correct that the magenta areas don't get much bigger when increasing the gain.

As we know, the calculation of a turbulence area is a function of radar detected air mass motion, not of radar return intensity.

The radar detects the motion of water particles. As long as it can detect any particles in an area, it can detect the motion of the air mass in that area. It doesn't matter how intensive the return from these particles is. The intensity says nothing about their motion.

So, if the motion in that area is such that a turbulence warning is desired, the area will be displayed in magenta. And this area will not change its shape when I'm changing the gain. It's just there, or disappears completely -- as long as the gain is high enough to get returns from water particles.

This method is used in the existing PSX versions. I think I shouldn't change this part.

Of course, I'm talking of the manual mode.


Cheers,

|-|ardy

[Michael Benson]

Hi Hardy,

Sorry to thread creep so quickly, but would this update allow the possibility of injecting Activesky radar information for the location of cells?  It's only a minor request but it would be nice to see the build up in P3D in the same places as on the ND?

Like I say only minor but thought I'd get it in early in proceedings!

[Hardy Heinlin]

Do you know the coords and the size of each cell?

[Michael Benson]

Hi Hardy,

It's done via an API which is confusing me to read!  here is the documentation!

[Hardy Heinlin]

OK, short answer: Not possible :-)

Maybe next year ...

Back to the topic :-)

[Michael Benson]

OK, short answer: Not possible :-)

Cool, thanks for looking into it! 

Back on topic - no idea sorry!

[Britjet]

Magenta returns were a rare occurrence, and always small, at least on the radar sets we used. Folks rarely messed with the gain, leaving it on auto, so I never tried it, but my own guess would be that the size wouldn't change, as you say.

Peter

[Hardy Heinlin]

Thanks, Peter.

For reference, here's a nice sample:

http://aviafilms.com/photos/weather-radar-map.jpg


|-|ardy

[John H Watson]

My Engineering notes say (for the older radar systems), the gain was always automatic for turbulence detection, even in manual gain mode (except when in test mode when the gain was fixed). The gain is set at an optimal value. It's not specified what parameters were used to set an optimal gain value for turbulence.

The radar uses different pulses (transmissions) for turbulence and weather. The turbulence pulses were at 1446Hz, the weather pulses were 181 or 362 depending on selected range.

[Hardy Heinlin]

Great, thanks! This confirms the existing model is plausible.


|-|ardy

[United744]

Whilst you are correct that the intensity doesn't tell about motion, the sensitivity does affect the ability for the RADAR to detect the droplets. At high sensitivity, it can detect the edges of such areas, so they grow slightly, but it is relatively small compared with the general ability to see precipitation.

Depending on the auto gain, it will see the majority of the motion, particularly the core, but it won't see all the way to the edge, even if it can see the droplets.