Slitherine

quote:

ORIGINAL: sandman455

Got to admit that the "hills at the back" statement is rather obtuse. Does the reader really need to be told this? It implies that the writer might not have a firm understanding of the issue. Almost as if it was a revelation that they didn't point the sets directly into the side of the hill.

No matter, yes placing the radar set low would help reduce ground clutter or in this example, returns generated by wave activity.

If you google the SCR271 or any radar set you will notice that it isn't really pointed into the air very much. Consequently, some radio waves are being sent out at a very shallow angle to the surface. To minimize ground clutter you would want a very shallow angle because the radio waves are much more likely to skip off and never to return to the receiver. However, if you elevate the set by putting it on a hill you increase the angle at which these radio waves hit the surface - or more specifically waves on the water. You would be increasing the chance that some radio waves would get reflect back to the receiver and you end up with more ground clutter.

quote:

ORIGINAL: witpqs

I suspect that would impede low altitude contacts simply because of the geometry when mounted higher. The visual metaphor might be hold a flashlight a foot above the ground and point it at a marble on the floor a few feet away (a low altitude contact). Now put the flashlight on the floor and point it at the same marble. In the one case you have the ground/sea all around the contact, in the other case there is clear sky behind the contact - much cleaner. I think that's what they are trying to say. Warning - I am not a subject matter expert!

quote:

ORIGINAL: dorjun driver

quote:

ORIGINAL: sandman455

Got to admit that the "hills at the back" statement is rather obtuse. Does the reader really need to be told this? It implies that the writer might not have a firm understanding of the issue. Almost as if it was a revelation that they didn't point the sets directly into the side of the hill.

No matter, yes placing the radar set low would help reduce ground clutter or in this example, returns generated by wave activity.

If you google the SCR271 or any radar set you will notice that it isn't really pointed into the air very much. Consequently, some radio waves are being sent out at a very shallow angle to the surface. To minimize ground clutter you would want a very shallow angle because the radio waves are much more likely to skip off and never to return to the receiver. However, if you elevate the set by putting it on a hill you increase the angle at which these radio waves hit the surface - or more specifically waves on the water. You would be increasing the chance that some radio waves would get reflect back to the receiver and you end up with more ground clutter.

Cool. I’m glad you were able to take the time to enlighten us all. Would it be too much to ask of you to state the above as a family of partial dif eq’s?

quote:

ORIGINAL: sandman455

quote:

ORIGINAL: witpqs

I suspect that would impede low altitude contacts simply because of the geometry when mounted higher. The visual metaphor might be hold a flashlight a foot above the ground and point it at a marble on the floor a few feet away (a low altitude contact). Now put the flashlight on the floor and point it at the same marble. In the one case you have the ground/sea all around the contact, in the other case there is clear sky behind the contact - much cleaner. I think that's what they are trying to say. Warning - I am not a subject matter expert!

Light waves and eyeballs work a little different but lets try this. Remember that any light coming back to your eyes would be a return to your visual radar set. At short distances, you are getting lots of ground clutter as with any system depending on reflected energy waves. But with eyeballs they have a receiver (cones/rods) that is quite capable of distinguishing between objects. Your radar set can't, a return is anything with a reflection.

As you move further out away from the flashlight/set, can you see how if you mounted it high you would illuminate more ground? Great for eyes, not so good for radar. The objective is to minimize ground clutter. With something flat like the ocean, you are trying to minimize the possibility of a wave creating enough angles to bounce the light/radio waves back to the set.

And I too shall issue the "Warning - I'm not a subject matter expert." I just know what they taught in a simple radar class. This coupled with some basic knowledge of how radar works is enough to assure you that mounting the set high will extend the distance where ground clutter will be an issue.

quote:

ORIGINAL: sandman455

Got to admit that the "hills at the back" statement is rather obtuse. Does the reader really need to be told this? It implies that the writer might not have a firm understanding of the issue. Almost as if it was a revelation that they didn't point the sets directly into the side of the hill.

No matter, yes placing the radar set low would help reduce ground clutter or in this example, returns generated by wave activity.

If you google the SCR271 or any radar set you will notice that it isn't really pointed into the air very much. Consequently, some radio waves are being sent out at a very shallow angle to the surface. To minimize ground clutter you would want a very shallow angle because the radio waves are much more likely to skip off and never to return to the receiver. However, if you elevate the set by putting it on a hill you increase the angle at which these radio waves hit the surface - or more specifically waves on the water. You would be increasing the chance that some radio waves would get reflect back to the receiver and you end up with more ground clutter.