passive radar theory refrence needed

Hi,

I heard there are some types of radar which operate passively, this
means, they dont send any signal and dont wait for the echo, but they
get some random electromagnetic waves from the air which are reflected
on objects as well and it is possible get some image in exchange of
some computation.
I also heard of a swiss company who are using the same principle but in
geology, seismology, oil exploration. They dont produce any signal
(like explosion under the surface) but instead use very sensitive
detectors and catch the random seismic noise from the earth which
reflects as well and get the image based on this.

So. I am interested in the mathematical and algorithmical part of the
topic. Does anyone know any good references? Like keywords or book
titles.

Many thanks
Peter

Peter Divos wrote:

> Hi,
> 
> I heard there are some types of radar which operate passively, this
> means, they dont send any signal and dont wait for the echo, but they
> get some random electromagnetic waves from the air which are reflected
> on objects as well and it is possible get some image in exchange of
> some computation.

Yes, there are some systems like that. They operate like a radio 
direction finders using the emissions of the target itself or 
reflections of some other source. The performance is very limited 
compared to conventional radars.


> I also heard of a swiss company who are using the same principle but in
> geology, seismology, oil exploration. They dont produce any signal
> (like explosion under the surface) but instead use very sensitive
> detectors and catch the random seismic noise from the earth which
> reflects as well and get the image based on this.

In our days, mechanical tampers are used instead of explosives.

> 
> So. I am interested in the mathematical and algorithmical part of the
> topic. Does anyone know any good references? Like keywords or book
> titles.

This is the geophysics. It is very different from the radar science.


Vladimir Vassilevsky

DSP and Mixed Signal Design Consultant

http://www.abvolt.com

Peter Divos skrev:
> Hi,
>
> I heard there are some types of radar which operate passively, this
> means, they dont send any signal and dont wait for the echo, but they
> get some random electromagnetic waves from the air which are reflected
> on objects as well and it is possible get some image in exchange of
> some computation.

The idea is to use emissions from civilian radio sources. The source
position is known, so one gets a head start.

> I also heard of a swiss company who are using the same principle but in
> geology, seismology, oil exploration. They dont produce any signal
> (like explosion under the surface) but instead use very sensitive
> detectors and catch the random seismic noise from the earth which
> reflects as well and get the image based on this.

Earthquake seismology is based on this principle. The sensor
locations are known, the source positions are found by other
means (collapsed buildings and other structures cand be very
conspicuous), so any tomographic image you see for the deep
eart is produced this way.

> So. I am interested in the mathematical and algorithmical part of the
> topic. Does anyone know any good references? Like keywords or book
> titles.

"Quantitative seismology" by Aki and Richards,

anything on tomography.

Rune

Rune Allnor wrote:
> Peter Divos skrev:
> 
>>Hi,
>>
>>I heard there are some types of radar which operate passively, this
>>means, they dont send any signal and dont wait for the echo, but they
>>get some random electromagnetic waves from the air which are reflected
>>on objects as well and it is possible get some image in exchange of
>>some computation.
> 
> 
> The idea is to use emissions from civilian radio sources. The source
> position is known, so one gets a head start.
> 
> 
>>I also heard of a swiss company who are using the same principle but in
>>geology, seismology, oil exploration. They dont produce any signal
>>(like explosion under the surface) but instead use very sensitive
>>detectors and catch the random seismic noise from the earth which
>>reflects as well and get the image based on this.
> 
> 
> Earthquake seismology is based on this principle. The sensor
> locations are known, the source positions are found by other
> means (collapsed buildings and other structures cand be very
> conspicuous), so any tomographic image you see for the deep
> eart is produced this way.
> 
> 
>>So. I am interested in the mathematical and algorithmical part of the
>>topic. Does anyone know any good references? Like keywords or book
>>titles.
> 
> 
> "Quantitative seismology" by Aki and Richards,
> 
> anything on tomography.
> 
> Rune
> 

*ANYTHING* ?
Courtesy of http://en.wikipedia.org/wiki/Tomography we have
     * Atom probe tomography (APT)
     * Computed tomography (CT)
     * Confocal laser scanning microscopy (LSCM)
     * Cryo-electron tomography (Cryo-ET)
     * Electrical capacitance tomography (ECT)
     * Electrical impedance tomography (EIT)
     * Functional magnetic resonance imaging (fMRI)
     * Magnetic induction tomography (MIT)
     * Magnetic resonance imaging (MRI), formerly known as magnetic
       resonance tomography (MRT) or nuclear magnetic resonance
       tomography
     * Neutron tomography
     * Optical coherence tomography (OCT)
     * Optical projection tomography (OPT)
     * Positron emission tomography (PET)
     * Quantum tomography
     * Single photon emission computed tomography (SPECT)
     * Seismic tomography
     * X-ray Tomography


More seriously, http://en.wikipedia.org/wiki/Seismic_tomography has just 
enough to be a teaser. Can earthquakes be essentially used to "map" 
other faults?

I'm thinking two distinct cases:
A. Active areas such as California with many nearby quakes to
    "illuminate" a fault.
B. "Quiet" areas such as New Madrid in SE Mo.
    [Personal interest - I live in Springfield, MO which is a designated
    "reception area" (proper term?) in case of the *BIG ONE*]

Do I assume correctly that seismic waves would reflected/refracted by
a fault as waves generally do when encountering a discontinuity?

Richard Owlett skrev:
> Rune Allnor wrote:
> > Peter Divos skrev:
> >
> >>Hi,
> >>
> >>I heard there are some types of radar which operate passively, this
> >>means, they dont send any signal and dont wait for the echo, but they
> >>get some random electromagnetic waves from the air which are reflected
> >>on objects as well and it is possible get some image in exchange of
> >>some computation.
> >
> >
> > The idea is to use emissions from civilian radio sources. The source
> > position is known, so one gets a head start.
> >
> >
> >>I also heard of a swiss company who are using the same principle but in
> >>geology, seismology, oil exploration. They dont produce any signal
> >>(like explosion under the surface) but instead use very sensitive
> >>detectors and catch the random seismic noise from the earth which
> >>reflects as well and get the image based on this.
> >
> >
> > Earthquake seismology is based on this principle. The sensor
> > locations are known, the source positions are found by other
> > means (collapsed buildings and other structures cand be very
> > conspicuous), so any tomographic image you see for the deep
> > eart is produced this way.
> >
> >
> >>So. I am interested in the mathematical and algorithmical part of the
> >>topic. Does anyone know any good references? Like keywords or book
> >>titles.
> >
> >
> > "Quantitative seismology" by Aki and Richards,
> >
> > anything on tomography.
> >
> > Rune
> >
>
> *ANYTHING* ?
> Courtesy of http://en.wikipedia.org/wiki/Tomography we have
>      * Atom probe tomography (APT)
>      * Computed tomography (CT)
>      * Confocal laser scanning microscopy (LSCM)
>      * Cryo-electron tomography (Cryo-ET)
>      * Electrical capacitance tomography (ECT)
>      * Electrical impedance tomography (EIT)
>      * Functional magnetic resonance imaging (fMRI)
>      * Magnetic induction tomography (MIT)
>      * Magnetic resonance imaging (MRI), formerly known as magnetic
>        resonance tomography (MRT) or nuclear magnetic resonance
>        tomography
>      * Neutron tomography
>      * Optical coherence tomography (OCT)
>      * Optical projection tomography (OPT)
>      * Positron emission tomography (PET)
>      * Quantum tomography
>      * Single photon emission computed tomography (SPECT)
>      * Seismic tomography
>      * X-ray Tomography

Anything.

The physical phenomena may be different, but the
make-an-image-from-lots-of-measurements reconstruction step
is useful, whatever method you start with.

> More seriously, http://en.wikipedia.org/wiki/Seismic_tomography has just
> enough to be a teaser. Can earthquakes be essentially used to "map"
> other faults?

Depends on what you mean by "map". Random seismic sources
are likely to be too incoherent (or rather, the signature is too fuzzy)
to make clear images as with exploration seismology. However,
mapping the locations of microquakes is an indirect map of active
faults/zones.

> I'm thinking two distinct cases:
> A. Active areas such as California with many nearby quakes to
>     "illuminate" a fault.
> B. "Quiet" areas such as New Madrid in SE Mo.
>     [Personal interest - I live in Springfield, MO which is a designated
>     "reception area" (proper term?) in case of the *BIG ONE*]
>
> Do I assume correctly that seismic waves would reflected/refracted by
> a fault as waves generally do when encountering a discontinuity?

You do. Fracture zones do act as acoustic scatterers, but as far
as faults are concerned, the main scattering mechanism is
differences in acoustic impedances across the face. I would be
very surprised if the "fase slipperyness" across a fault represents
scattering, at least at some depth.

Rune

Peter Divos wrote:
> Hi,
>
> I heard there are some types of radar which operate passively, this
> means, they dont send any signal and dont wait for the echo, but they
> get some random electromagnetic waves from the air which are reflected
> on objects as well and it is possible get some image in exchange of
> some computation.
> I also heard of a swiss company who are using the same principle but in
> geology, seismology, oil exploration. They dont produce any signal
> (like explosion under the surface) but instead use very sensitive
> detectors and catch the random seismic noise from the earth which
> reflects as well and get the image based on this.
>
> So. I am interested in the mathematical and algorithmical part of the
> topic. Does anyone know any good references? Like keywords or book
> titles.
>
> Many thanks
> Peter

Try googling "passive coherent location" (PCL). This is a studied and
reported field using  existing radiators to provide the signal source.
Implementations have used FM broadcast stations, TV stations and cell
stations and more. Applications have included atmospheric research,
aircraft tracking and spacecraft tracking.

Dale B. Dalrymple
http://dbdimages.com

"dbd" <dbd@ieee.org> wrote in message 
news:1167799855.071131.256170@a3g2000cwd.googlegroups.com...
> Peter Divos wrote:
>> Hi,
>>
>> I heard there are some types of radar which operate passively, this
>> means, they dont send any signal and dont wait for the echo, but they
>> get some random electromagnetic waves from the air which are reflected
>> on objects as well and it is possible get some image in exchange of
>> some computation.
>> I also heard of a swiss company who are using the same principle but in
>> geology, seismology, oil exploration. They dont produce any signal
>> (like explosion under the surface) but instead use very sensitive
>> detectors and catch the random seismic noise from the earth which
>> reflects as well and get the image based on this.
>>
>> So. I am interested in the mathematical and algorithmical part of the
>> topic. Does anyone know any good references? Like keywords or book
>> titles.
>>
>> Many thanks
>> Peter
>
> Try googling "passive coherent location" (PCL). This is a studied and
> reported field using  existing radiators to provide the signal source.
> Implementations have used FM broadcast stations, TV stations and cell
> stations and more. Applications have included atmospheric research,
> aircraft tracking and spacecraft tracking.
>
You could try 'bistatic radar' too.
Best of Luck - Mike