<< Chapter < Page Chapter >> Page >
A brief conclusion of our project and an overview of more advanced beamforming techniques

Conclusion

Beamforming is a sizeable and complex sub-study of digital signal processing. While this module has covered the fundamentals of a basic frequency domain implementation, more sophisticated techniques certainly exist. As such, this segment will serve less as a synopsis of the previous sections and more an overview of more advanced techniques in the field.

Synopsis

Beamforming is, at its core, the art of combining multiple omnidirectional sensors into a directional whole with superior characteristics to purpose-built directional sensors. This feat is performed by delaying the sensors’ outputs such that they constructively interfere for signals arriving from a specific direction, and may be done in either the time or frequency domain. While time domain implementations may be simpler for some array topologies, frequency-domain implementations are, by and large, much more efficient due to their ability to create fractional delays (a computationally intensive upsample-delay-downsample process in time domain).

These systems underlie many technologies that we take for granted, from synthetic aperture RADAR used for such disparate applications as weather radar and ICBM tracking, to next-generation cellular technologies seeking to improve connectivity by steering cell signals towards active cell towers.

Advanced beamforming

While the basic techniques described previously yield acceptable results (particularly for our purposes), adaptive processing can be used to far increase the performance of an array. These techniques largely involve a weighting vector w which was not used in our conventional beamforming algorithm. As this weighting vector may be thought of as a windowing function applied to the spatial characteristics of the array, it is clear that careful choice of a weighting function could improve parameters of the beamformer, such as its mainlobe width.

The first method to perform this width reduction is called Minimum Variance beamforming, which can also be known as Capon’s method. This algorithm, as its name implies, seeks to find a weighting vector w such that the expectation value of | w’y | 2 is minimized. This is clearly the equivalent of minimizing the variance of the signal in zero-mean systems. Computing the value of w depends on the propagation direction and the spatiospectral covariance of all the sensors, but the technical details of that computation are outside the scope of this summary. Upon applying this weighting vector, the mainlobe width of the array’s output will be much smaller than that generated by the conventional beamforming algorithm.

Even more advanced techniques, such as Linear Prediction, can yield even better results for the beamformer’s mainlobe width. At a high level, Linear Predication involves expressing the output of one particular sensor as a weighted linear combination of all the others. Again, the mathematical details of this method are beyond the scope of this module.

Further adaptive methods allow for the aggregation of multiple arrays to cancel interference from sidelobes. For instance, creating a secondary array to preferentially receive an offending signal from one of the main array’s sidelobes with the intent of subtracting this signal from the main array’s output. Other applications of multiple arrays include more advanced direction of arrival estimation, including triangulating separate array’s estimates to yield a direction and distance (which can be tracked over time to get a direction of motion estimate).

Questions & Answers

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
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 to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
How can I make nanorobot?
Lily
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
how can I make nanorobot?
Lily
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Direction of arrival estimation. OpenStax CNX. Dec 18, 2012 Download for free at http://cnx.org/content/col11470/1.2
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Direction of arrival estimation' conversation and receive update notifications?

Ask