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A description of what direction of arrival is and a discussion of our specific algorithm for determining it

Direction of arrival estimation

Given the basic foundation in beamforming the other modules in this section have established, we would like to extend the usefulness of the technique into new domains. One application of interest outside of simply creating a directional antenna is to identify the direction from which a known source is broadcasting, called Direction of Arrival Estimation.

Basic premise:

In all cases, direction of arrival estimation relies upon an a priori estimate of the signal’s arrival direction. If no estimate can be made, the array’s response is swept around the unit circle, and a decision rule is applied to its output. Locations where this decision rule is satisfied are assumed to correspond to locations of the known source. If an estimate exists, more sophisticated adaptive processing techniques may be applied to determine the source’s location with greater precision.

Specific implementation:

To simplify the process of direction estimation, we make a few assumptions about the configuration of our sensor network and its environment. The first assumption we make is that our source is sufficiently distant from our sensor network for the received wavefront to be considered linear. This first assumption is called the Far Field Approximation, and simplifies the computation of steering and weighting vectors. The second assumption we make pertains to the noise environment the sensor operates within. We assume that noise (if present) is ideal Gaussian noise, simplifying the structure of our signal detection segment.

These assumptions having been made, the detection algorithm is quite simple. We step through angles over which the array can look, feeding an input from a known location. The output of the array is then fed through a matched filter, which has the effect of computing the cross-correlation between the signal received by the array and the known signal of the transmitter. The peak value of that correlation is then stored with its corresponding angle. Upon completing the sweep over angles, the angle with the highest peak correlation is taken to be the most likely location of the signal source. This algorithm is described below in pseudocode:


Function AngleEstimation{ Angle<- 0 Angles<- [] //empty set of anglesMagnitudes<- [] //empty set of peak amplitudesWhile Angle<2*pi { Output<- Beamformer(Angle, input) Output<- Matched_Filter(Output) Angles<- concatenate(Angles, Angle) Magnitudes<- concat(Magnitudes, max(Output)) Angle<- Angle + pi/32 //increment to next angle }SourceAngle<- Angles[index(max(Magnitudes))] Return SourceAngle;}

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
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What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
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Adin Reply
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what school?
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Damian Reply
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Introduction about quantum dots in nanotechnology
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what does nano mean?
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nano basically means 10^(-9). nanometer is a unit to measure length.
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Damian Reply
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s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
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Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
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s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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Source:  OpenStax, Direction of arrival estimation. OpenStax CNX. Dec 18, 2012 Download for free at http://cnx.org/content/col11470/1.2
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