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Arrays are used in various applications

Although this example was admittedly somewhat contrived, it is not far fetched. Arrays similar to those that I have been discussing are widely used inthe technology area of spatial signal processing.

Radio astronomy

Perhaps the application that is most familiar to the general public (due to widespread publicity and a very popular movie) is the Paul Allen radio telescope used in the Search for Extraterrestrial Intelligence (SETI) .

In the past, much of this work has been done using a very large dish antenna known as the Arecibo Radio Telescope in Puerto Rico. Efforts are now underway involving an alternative approach that uses a large array of small dishes instead of one large dish.

By properly processing and then summing the outputs produced by the dishes in the array, the users will be able to steer the telescope and possibly to alsoeliminate strong sources of interference.

Seismology

Arrays of seismometers are used by U.S. government agencies to monitor for seismic signals produced by earthquakes in locations nearly halfway around theearth.

By applying complex, frequency dependent weighting factors to the seismometer outputs before summing them, the arrays can be tuned to provide a complexresponse in wavenumber space. For example, the arrays can be processed to form response beams looking in different directions with a beam width that isrelatively constant across a wide band of interesting frequencies. In addition, null points in the wavenumber response can be created to suppress seismic noisethat originates from specific points on the earth such as mines, rock quarries, and cities.

The design and analysis of such array systems use 2D (and sometimes 3D) Fourier transforms. Because the weights that are applied are produced by complexfrequency filters, the transform programs that are used must treat both the space domain data and the wavenumber data as complex (instead of being purely real as in the examples in this module) .

Sonar

Probably ninety percent of all sonar systems currently installed on surface ships and submarines use arrays for steering and processing both active andpassive sonar. In almost all cases, these are 3D arrays. Some of the arrays contain multiple sensors on the surface of a portion of a sphere. Some containmultiple sensors located along slats that are mounted on a frame much like the staves on a barrel. Some are located on the sides of the vessel. There areprobably numerous other geometries in use as well.

A Fourier transform program used with these arrays would normally have to be a 3D Fourier transform program capable of transforming from complex spacefunctions to complex wavenumber functions.

Radar

One of the reasons that sonar is typically processed using arrays has to dowith the wavelength of the signals and the operating environment. It is usually not practical to physically move a sonar sensor large enough to do the job inorder to cause it to look in different directions. Thus arrays of small sensors are used with the ability to steer beams electronically in order to look indifferent directions.

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
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