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Could this device be built?

A

Arny Krueger

Jan 1, 1970
0
No shit?




Yeah, but the implication was the little 4 inch dodad was a megawatt
source. Now it's a receiver front end too?



Not a lot of area there for gigawatts.

Heating of the radome might also be a problem.
 
In sci.physics John Larkin said:
Point totally missed.

Which phase (or frequency) of an Ultra Wide Band transmitter do you use?

You can't use all of them.
[/QUOTE]
Do you have a PhD in what can't be done?

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.

Such a device may make a great wireless LAN at ranges of tens of yards,
but is not the device of choice for building a phased array anything.
 
H

Hal Murray

Jan 1, 1970
0
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.

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

Rich Grise

Jan 1, 1970
0
Jammers have to behave somewhat suicidally. I've tracked real-world jamming
sources and they are very easy to track because they put out one heck of a
signal. In Vietnam, our jamming planes were called "Wild Weasels" and were
often short-lived.

No, the Wild Weasels were recce. The EWO (Electronic Warfare Officer),
ususally the GIB (Guy In Back), had a spectrum-analyzer display, to
sniff out the jammers (and maybe even comm.). I don't know exactly what
they did with the info, other than evasive maneuvers, but it gave a pretty
good idea of the radar environment they were flying into.

I'm sure they carried their own jammers, but so did all of the other
fighters/bombers.

Cheers!
Rich
 
B

Benj

Jan 1, 1970
0
Zappers are great solid state destroyers (transistors make better
fuses than fuses) But you have to get close enough to zap the circuit
boards. (Work great on Computer mother boards!)
CD players don't have antennas. (antennae?)

Yes, although every wire in the player is a potential antenna
especially for high frequency (radar) EMP.

Electronics have antennas. Bugs have antennae!

Benj
 
J

John Larkin

Jan 1, 1970
0
On Tue, 21 Aug 2007 15:41:13 -0500,

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
 
S

Scott Dorsey

Jan 1, 1970
0
Rich Grise said:
No, the Wild Weasels were recce. The EWO (Electronic Warfare Officer),
ususally the GIB (Guy In Back), had a spectrum-analyzer display, to
sniff out the jammers (and maybe even comm.). I don't know exactly what
they did with the info, other than evasive maneuvers, but it gave a pretty
good idea of the radar environment they were flying into.

At the time, the Bad Guys only had a limited number of standard radar
platforms. So with a spiral antenna and a spectrum analyzer, you could
pretty quickly tell what was in the neighborhood from the emission
frequency and the rough envelope. And with a directional antenna and a
little hunting around, you could pretty quickly localize the direction of
the source. So with a pretty limited toolkit, you could tell what the
bad guys were (ie. targetting radar, sky search, airborne radar) and where
they were. Likewise you could very easily tell a legitimate radar system
from a jammer from the spectrum, and the jamming platforms were fairly
standardized.

Doing this while being shot at is left as an exercise to the student and
may not be as easy as identifing spectral envelopes in an air-conditioned
laboratory.
--scott
 
What is the bandwidth of modern radars? I'd expect it to be
wide and using spread spectrum tricks to make jaming harder.

Depends on what bandwidth you are talking about.

For the instananeous transmitted frequency, narrow.

Some military stuff has used frequency hopping since WWII to make it
harder to jam.

Frequency hopping is a spread spectrum technique and the bandwidth
over time is wide.

You could make a spread spectrum, phased array radar, but the frequency,
phase, and amplitude of all the emitters has to be precisely controlled
to form the beam, which implies that for a given pulse, all the
emitters are transmitting very close to the same frequency.

The next pulse may be hundreds of megahertz away, but that's what
processors are for.
 
At a minumum!
Spiffy modern radars hop and chirp, both of which broaden the working
bandwidth.

I would hope so since the techniques have been around for at least
a quarter century.
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.

Narrower pulse widths and good receivers improves resolution.
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.

A search for "mbda hpm" returns:

Your search - "mbda hpm" - did not match any documents.

And "bae hpm" returns:
SIMPLE = T / file conforms to fits standard BITPIX = 16 / number

You are mixing apples, oranges and cherries.

Frequency agile radar, rudimentary spread spectrum, was originally
developed in WWII.

Phased array radars have been around for decades.

And everyone WANTS a death ray, but no one has made a practical one yet.
 
V

Vladimir Vassilevsky

Jan 1, 1970
0
Hal said:
What is the bandwidth of modern radars? I'd expect it to be
wide and using spread spectrum tricks to make jaming harder.


The bandwidth of a radar pulse is determined by the required resolution
of the distance. Thus there is generally no point to increase the pulse
bandwidth beyond ~100Mhz unless for the very special tasks like a target
feature recognition. However the carrier frequency and the spreading
code can vary from pulse to pulse.

Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com
 
F

Fred Bloggs

Jan 1, 1970
0
The TRR was slaved in azimuth and elevation to the TTR.

The TTR had the required hardware to track in azimuth and elevation.

When jammed, the TTR tracked the jamming source.

The TRR provided only range information.

The TTR was X band.

The TRR was Ku band and frequency agile to get around the jamming.

Frequency agile Ku band transmission? What kind of tube did they use for
that? Wondering why the Ku band could not just take a handoff and do the
tracking on its own, must not have been a stable track. What kind of
cheap ill-begotten antenna gets you less angular resolution at Ku band
than X-band?
 
J

John Larkin

Jan 1, 1970
0
A search for "mbda hpm" returns:

Your search - "mbda hpm" - did not match any documents.

And "bae hpm" returns:
SIMPLE = T / file conforms to fits standard BITPIX = 16 / number

Don't type the quote marks. Geez.

John
 
S

Scott Dorsey

Jan 1, 1970
0
And everyone WANTS a death ray, but no one has made a practical one yet.

There are plenty of commercial death rays in the 54-72 MC and 76-88 MC
bands. They don't cause death directly, but transmissions on these
frequencies can cause severe brain damage even at low levels when demodulated
and viewed. A number of studies have shown long-term exposure to cause
all sorts of problems in children.
--scott
 
T

Terry Given

Jan 1, 1970
0
Scott said:
There are plenty of commercial death rays in the 54-72 MC and 76-88 MC
bands. They don't cause death directly, but transmissions on these
frequencies can cause severe brain damage even at low levels when demodulated
and viewed. A number of studies have shown long-term exposure to cause
all sorts of problems in children.
--scott

AIUI they are termed "brain-death rays"

Cheers
Terry
 
Don't type the quote marks. Geez.

Then don't say Google "mbda hpm" and "bae hpm".

And if I don't use quotes, will I get information on phased array
radars, phased array death rays, or phased array, spread spectrum,
death ray radars?
 
T

Tom Potter

Jan 1, 1970
0
John Larkin said:
On Tue, 21 Aug 2007 15:41:13 -0500,


At a minumum!


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 ***
http://home.earthlink.net/~tdp
http://tdp1001.googlepages.com/home
http://no-turtles.com
http://www.frappr.com/tompotter
http://spaces.msn.com/tdp1001
http://www.flickr.com/photos/tom-potter
http://tom-potter.blogspot.com
 
J

JW

Jan 1, 1970
0
CD players don't have antennas. (antennae?)

I would assume that an automotive CD player would also be equipped with an
AM/FM tuner, wouldn't you? The OP just mentions a "stereo", anyway.
 
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