"John Larkin" wrote in message
...
On Tue, 21 Aug 2007 15:41:13 -0500,
(Hal Murray) wrote:

No, but I have enough years of experience with RF in general and radar
in particular to know building a phased array requires precise phase
(or frequency) control and you can't do that with an ultra wideband
device, which has a bandwidth of 500 Mhz.

At a minumum!


What is the bandwidth of modern radars? I'd expect it to be
wide and using spread spectrum tricks to make jaming harder.

Spiffy modern radars hop and chirp, both of which broaden the working
bandwidth.

With modern signal processing, wider radar bandwidth improves
resolution. You can do all sorts of fun stuff with 1000 antennas and a
few teraflops of compute power.

All the major powers - US, Russia, France, Germany, China, Israel, UK
- are working on HPM weapons and array radars. The Brits call their
projects "Suave" and "Virus." MBDA and BAE are major players.

Google "mbda hpm" and "bae hpm", and believe it or don't.

John

It seems to me,
that with modern electronics and information technology,
that a high resolution, handheld, RADAR system is possible.

You could quasi-randomly modulate (Variable transmit and listen periods),
a solid state microwave oscillator (Gunn Diode)
with a digital code with good correlation properties (Gold Code),

cross-correlate the echoes received when in the listen mode
with the Gold Code, then cross-correlate the correlations
from the echoes with stored geo-patterns downloaded
from a Google-Earth like data base covering the area of operation,

compare adjacent (In time) echo returns to spot moving targets,
then present the pattern on a small, solid state, color display
that shows the Google-Earth like picture of the area,
with super-imposed moving targets.

One would not need a directional antenna,
nor high power for such a device,
but it would be necessary to sweep the device around
to build up a good correlation of
the area as one's body and other things
would block the signals and,
even though the Google-Earth like picture,
and the location of the RADAR would still be valid,
but blocked moving targets would not be detected.

Note that if a map of the area of operation is downloaded
into the system, and a set of times from the radar to fixed
targets is compared to the map, one could quickly correlate the
map with the echoes and determine where one is.

With such a device, one could move around,
and see where they were on a moving Google-Earth-like picture,
and see the moving targets about them,
perhaps even colored and shaped by the RADAR signatures
of the targets. (People, cars, tanks, trains, an incoming missle, etc.)

Note that for many situations that such a device could replace GPS.
Just like GPS, after the device determines where one is,
it would be able to compute changes in position quickly.

Hey maybe, I should patent this device?

As I mentioned in old posts,
I used "Data Mining" back in the 1980's
in my businesses and applied for a patent on "Data Mining"
just when they began to allow software to be patented,
but I decided not to complicate my life,
and didn't complete the patent.

In other words,
if you want to commercialize this idea for non-military applications,
go for it.

As any entrepreneur knows,
ideas are a dime a dozen,
and what requires blood, sweat and tears
is getting an idea to the marketplace.

The bottom line is,
no one should be able to hold progress hostage
with a patent, that is obvious to many,
as the state of the art exposes new approaches.

--
Tom Potter

*** Time Magazine Person of the Year 2006 ***
*** May 2007 Anti-Bigot Award ***
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