passive radar theory refrence needed

Started by Peter Divos December 31, 2006
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