SA15 TOR

[Stingray66]

Are we talking about a WW2 radar or something? ... modern radars don't lose track just because of a mode switch - not that removing the filter should have any effect on the track one way or the other to begin with.

 

Why would beaming and notching then exist if it was such useless - there are many quite old systems out there - no need to become harsh. Filtering requires Fourier transformation in digital computers which was introduced quite late - and as such you do not turn off the filter you turn off the Doppler pulse and just scan in normal radar mode (cw or p) like in the old days (=WW2 ;)). Why that? Because making the Doppler pulse amenable for detection the radar has to fulfil some special requirements - it is not that it's always there and you just get the info when you want. The Doppler pulse as such IS always there - that's physics - but it wouldnt be good enough for a radar to work with it. Measuring doppler effects in that tiny hertz region is actually quite tricky.

 

 

 

Yes, you do. Just because you're not filtering it out doesn't mean you're not measuring the velocity. It's a pulse doppler radar and the information is right in there.

 

 

 

 

As mentioned above. Besides, how do you measure the velocity directly out of a single radar contact, then? Velocity is the first derivative of the location. That is how you "measure" -> you calculate based on at least two positions. And moreover you cannot track with a "normal" radar. You just have subsequent little dots/ squares on your screen. Nowadays you can -> because of Mr. Doppler. Therein, the velocity is a direct measurement of the radar not something you have to calculate based on previous positions. (though admitted, you need a computer to extract the velocity out the pulses' frequency).

 

 

 

 

If it's useless, why are you continuing to discuss it? ;)

 

For the sake of clarity. I think taken all together we keep quite a high standard in this forum just like you guys did in the sim - btw awesome job :thumbup:.

 

Why I said useless? Because all this does not add anything to the gameplay any more - although we agreed that beaming is not that bad after in some conditions. :D

[Fish]

If you turn that off (pulse Doppler, even if you could) however, you have no exact measurement of the object's velocity. You can only interpolate between subsequent positions.

 

Agree,

.....and you would not be able to tell if it was a bird close by, or a plane far away. And most command guidance systems work on complex lead pursuit geometry, to maximise the kill probability.

 

"Systems without Doppler capability will detect tree leaves blowing in the wind, wavetops, birds, bats, mountains, buildings, clouds, snow flakes, hail, and raindrops. These false signals are called clutter. A 1 degree antenna beam will spread to a width of about 2000 feet by the time it reaches the horizon with a radar height of about 100 feet above the surface. This will illuminate millions of square feet of surface and the target reflection will be buried in the interference. This interference produces thousands of false alarms that will crash computers and overwhelm operators."

[GGTharos]

Just because you removed the clutter notch doesn't mean you removed the doppler shift ... :D

[Stingray66]

Just because you don't know the Doppler shift doesn't mean you don't now ranging. Ranging doesn't use the Doppler effect. A reflection off a close bird comes back sooner than a reflection off a plane far away.

 

 

True, but Fish was talking about interference effects - if I understood it correctly. Which adds another layer of complexity. For sure, clouds etc give a radar signal as well - you just do not talk about ground clutter - call it sky clutter ;)

 

Just a little anectode: When I was sailing last year in the Bretagne the radar gave off signal derived from the froth - not talking about waves. Radars are very sensitive...today up to two dozens of correction algorithms are applied to extract a somewhat useful signal.

Edited July 24, 2011 by Stingray66