Started by June 13, 2008
```What's the smallest object that can be resolved on radar? eg could a
large model aircraft be seen or would it be confused with say a large
bird? How low does radar go in a city?
Why am I asking? I have reason to believe that the next generation of
terrorists will use UAVs to hit their targets. In fact this is well
known and no secret. So what can be done to stop such an attack?

K.
```
```<kronecker@yahoo.co.uk> wrote in message
> What's the smallest object that can be resolved on radar? eg could a
> large model aircraft be seen or would it be confused with say a large
> bird? How low does radar go in a city?
> Why am I asking? I have reason to believe that the next generation of
> terrorists will use UAVs to hit their targets. In fact this is well
> known and no secret. So what can be done to stop such an attack?
>

The smallest object resolvable and, thus, visible,depends on the radar
wavelength.  One might think of the proverbial "needle in a haystack".  It's
all relative and a needle might be a good target if it's a few wavelenghts
long and if one neglects that it's so skinny.  2" needle, 3 wavelengths
suggests a radar frequency of 19 GHz.  A large model aircraft is often built
with wood and paper, as such, may not provide much of a radar return.  One
can do an "optimum frequency" analysis using the radar equation to decide
what to do.

See:

What's important is that you recognize that the radar cross section or
target strength (from sonar) is frequency dependent as above.

Then you have to know the noise level to get SNR.

Fred

```
```
kronecker@yahoo.co.uk wrote:

> What's the smallest object that can be resolved on radar?

An electron, perhaps. An atom, for sure.

> eg could a
> large model aircraft be seen or would it be confused with say a large
> bird?

This is what is called target recognition. Yes, a bird can be
distingushed from a model aircraft, if there is no other clutter.

> How low does radar go in a city?

Line of sight, basically.

> Why am I asking? I have reason to believe that the next generation of
> terrorists will use UAVs to hit their targets.  In fact this is well
> known and no secret. So what can be done to stop such an attack?

The non-technical problems can't be resolved by any technical methods.

DSP and Mixed Signal Design Consultant
http://www.abvolt.com

```
```On Fri, 13 Jun 2008 00:19:56 -0700 (PDT), kronecker@yahoo.co.uk wrote:

>What's the smallest object that can be resolved on radar? eg could a
>large model aircraft be seen or would it be confused with say a large
>bird? How low does radar go in a city?
>Why am I asking? I have reason to believe that the next generation of
>terrorists will use UAVs to hit their targets. In fact this is well
>known and no secret. So what can be done to stop such an attack?

The first fire-control radars in WWII tracked birds on occassion, and
there's been lots of advances in the technology since then.

As others have said, resolving a UAV is not very problematic.
Recognizing one reliably with a radar would take some effort, I'm
sure.

Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
```
```Eric Jacobsen wrote:
> On Fri, 13 Jun 2008 00:19:56 -0700 (PDT), kronecker@yahoo.co.uk wrote:
>
>> What's the smallest object that can be resolved on radar? eg could a
>> large model aircraft be seen or would it be confused with say a large
>> bird? How low does radar go in a city?
>> Why am I asking? I have reason to believe that the next generation of
>> terrorists will use UAVs to hit their targets. In fact this is well
>> known and no secret. So what can be done to stop such an attack?
>
> The first fire-control radars in WWII tracked birds on occassion, and
> there's been lots of advances in the technology since then.
>
> As others have said, resolving a UAV is not very problematic.
> Recognizing one reliably with a radar would take some effort, I'm
> sure.

Actually, most UAVs are built for stealth, so resolving one is
*supposed* to be problematic. They may look very different from an F-22
or B-2, but the typical diamond shaped fuselage they have is like that
for a reason.

Steve
```
```<kronecker@yahoo.co.uk> wrote in message
> What's the smallest object that can be resolved on radar? eg could a
> large model aircraft be seen or would it be confused with say a large
> bird? How low does radar go in a city?
> Why am I asking? I have reason to believe that the next generation of
> terrorists will use UAVs to hit their targets. In fact this is well
> known and no secret. So what can be done to stop such an attack?

Wouldn't it be easier just to drive a large van?
The idea of Next Gen Terrorism is eccentric, and possibly a little too
analytical! - just my opinion of course.

```
```On 14 Jun, 04:27, Steve Underwood <ste...@dis.org> wrote:
> Eric Jacobsen wrote:
> > On Fri, 13 Jun 2008 00:19:56 -0700 (PDT), kronec...@yahoo.co.uk wrote:
>
> >> What's the smallest object that can be resolved on radar? eg could a
> >> large model aircraft be seen or would it be confused with say a large
> >> bird? How low does radar go in a city?
> >> Why am I asking? I have reason to believe that the next generation of
> >> terrorists will use UAVs to hit their targets. In fact this is well
> >> known and no secret. So what can be done to stop such an attack?
>
> > The first fire-control radars in WWII tracked birds on occassion, and
> > there's been lots of advances in the technology since then.
>
> > As others have said, resolving a UAV is not very problematic.
> > Recognizing one reliably with a radar would take some effort, I'm
> > sure.
>
> Actually, most UAVs are built for stealth, so resolving one is
> *supposed* to be problematic. They may look very different from an F-22
> or B-2, but the typical diamond shaped fuselage they have is like that
> for a reason.

Those are the military UAVs. For some reason I think the
OP thinks about the kind of toys one can buy in a hobby
shop. Some of those can be quite large. Not quite the
payload or range as 'the real thing' but quite capable
of doing bad stuff nonetheless.

Rune
```
```On Sat, 14 Jun 2008 07:54:19 -0700 (PDT), Rune Allnor
<allnor@tele.ntnu.no> wrote:

>On 14 Jun, 04:27, Steve Underwood <ste...@dis.org> wrote:
>> Eric Jacobsen wrote:
>> > On Fri, 13 Jun 2008 00:19:56 -0700 (PDT), kronec...@yahoo.co.uk wrote:
>>
>> >> What's the smallest object that can be resolved on radar? eg could a
>> >> large model aircraft be seen or would it be confused with say a large
>> >> bird? How low does radar go in a city?
>> >> Why am I asking? I have reason to believe that the next generation of
>> >> terrorists will use UAVs to hit their targets. In fact this is well
>> >> known and no secret. So what can be done to stop such an attack?
>>
>> > The first fire-control radars in WWII tracked birds on occassion, and
>> > there's been lots of advances in the technology since then.
>>
>> > As others have said, resolving a UAV is not very problematic.
>> > Recognizing one reliably with a radar would take some effort, I'm
>> > sure.
>>
>> Actually, most UAVs are built for stealth, so resolving one is
>> *supposed* to be problematic. They may look very different from an F-22
>> or B-2, but the typical diamond shaped fuselage they have is like that
>> for a reason.
>
>Those are the military UAVs. For some reason I think the
>OP thinks about the kind of toys one can buy in a hobby
>shop. Some of those can be quite large. Not quite the
>payload or range as 'the real thing' but quite capable
>of doing bad stuff nonetheless.
>
>Rune

Even among the military UAVs most are not stealthy, like the Global
Hawk or Predator, or many of the smaller examples as well.

Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
```
```On Jun 15, 1:04 am, "VelociChicken" <b...@yahoob.com> wrote:
> <kronec...@yahoo.co.uk> wrote in message
>
>
> > What's the smallest object that can be resolved on radar? eg could a
> > large model aircraft be seen or would it be confused with say a large
> > bird? How low does radar go in a city?
> > Why am I asking? I have reason to believe that the next generation of
> > terrorists will use UAVs to hit their targets. In fact this is well
> > known and no secret. So what can be done to stop such an attack?
>
> Wouldn't it be easier just to drive a large van?
> The idea of Next Gen Terrorism is eccentric, and possibly a little too
> analytical! - just my opinion of course.

Ok suppose you needed to blow up the Whitehouse. You couldn't get near
enough in a van. But a model aircraft would do some damage. Not nearly
as much of course but it's the shock that counts and the effect on the
polulation.The sooner officials start looking at this threat the
better.

K.
```
```kronecker@yahoo.co.uk wrote:
> On Jun 15, 1:04 am, "VelociChicken" <b...@yahoob.com> wrote:
>> <kronec...@yahoo.co.uk> wrote in message
>>
>>
>>> What's the smallest object that can be resolved on radar? eg could a
>>> large model aircraft be seen or would it be confused with say a large
>>> bird? How low does radar go in a city?
>>> Why am I asking? I have reason to believe that the next generation of
>>> terrorists will use UAVs to hit their targets. In fact this is well
>>> known and no secret. So what can be done to stop such an attack?
>> Wouldn't it be easier just to drive a large van?
>> The idea of Next Gen Terrorism is eccentric, and possibly a little too
>> analytical! - just my opinion of course.
>
> Ok suppose you needed to blow up the Whitehouse. You couldn't get near
> enough in a van. But a model aircraft would do some damage. Not nearly
> as much of course but it's the shock that counts and the effect on the
> polulation.The sooner officials start looking at this threat the
> better.

Why do you think they aren't? The defense might become useless if its
basis became known. The best kept secrets are those that no one knows
exist.

I made a lock that you can't pick. (Expert locksmiths have tried.) I'm
sure that someone would figure out how to pick it if its insides were
known. It would become worthless if I were to patent it.

Jerry
--
Engineering is the art of making what you want from things you can get.
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```