06-10-2012, 01:40 PM
Smart Antenna
smartantenna1(2).doc (Size: 1.21 MB / Downloads: 125)
Abstract: :
The present wireless video camera described in this is designed using wireless video monitoring system, for detecting the presence of a person who is inside the restricted zone. This type of automatic wireless video monitors is quite suitable for the isolated restricted zones, where the tight security is required. Once upon a time much importance is not given for the security system. But as we see today lot of terrorism has grown up across the country and need has aroused to develop different types of security systems for various applications to safe guard the zones of various types like, military zones, railway yards, scrap yards, borders etc., this kind of automatic video monitoring systems can be installed at indo-pak borders, where the terrorists are crossing borders. In fact our country is spending lot of its revenue to safe guard the borders. By installing this type of security systems everywhere at critical points, lot of revenue can be saved by minimizing the manpower.
BEAM FORMING BASICS
Beam forming is the term used to describe the application of weights to the inputs of an array of antennas to focus the reception of the antenna array in a certain direction, called the look direction or the main lobe. More importantly, other signals of the same carrier frequency from other directions can be rejected. These effects are all achieved electronically and no physical movement of the receiving antennas is necessary. In addition, multiple beam formers focused in different directions can share a single antenna array one set of antennas can service multiple calls of the same carrier. It is no coincidence that the number of elements in the above diagram equals the number of incoming signals. A beam former of L antenna elements is capable of accepting one signal and reliably rejecting L-1 signals. A greater number of interfering signals will diminish the performance of the beam former. Beam forming presents several advantages to antenna design .Firstly, space division multiple access (SDMA) is achieved since a beamformer can steer its look direction towards a certain signal.
SPATIAL STRUCTURE METHODS
As mentioned before, spatial structure methods exploit the information in the steering vector ...»._¼. The spatial structure is used to estimate the direction of arrivals (DOAs) of
the signals impinging on the sensor array. The estimated directions of arrivals are then used to determine the weights in the pattern forming network. This is called beam forming. Spatial structure methods only exploit spatial structure and training signals and the temporal structure of the signals is ignored. In the following an overview will be given about the three main spatial structure methods, namely conventional beam forming methods, maximum likelihood estimation and the so-called subspace-based methods.
CONCLUSION
In conclusion to this paper “Smart Antenna” systems are the antennas with intelligence and the radiation pattern can be varied without being mechanically changed. With appropriate adaptive algorithms such as Recursive Least Square Algorithm (RLS) the beam forming can be obtained. As the system uses a DSP processor the signals can be processed digitally and the performance is with a high data rate transmission and good reduction of mutual signal interference.
smartantenna1(2).doc (Size: 1.21 MB / Downloads: 125)
Abstract: :
The present wireless video camera described in this is designed using wireless video monitoring system, for detecting the presence of a person who is inside the restricted zone. This type of automatic wireless video monitors is quite suitable for the isolated restricted zones, where the tight security is required. Once upon a time much importance is not given for the security system. But as we see today lot of terrorism has grown up across the country and need has aroused to develop different types of security systems for various applications to safe guard the zones of various types like, military zones, railway yards, scrap yards, borders etc., this kind of automatic video monitoring systems can be installed at indo-pak borders, where the terrorists are crossing borders. In fact our country is spending lot of its revenue to safe guard the borders. By installing this type of security systems everywhere at critical points, lot of revenue can be saved by minimizing the manpower.
BEAM FORMING BASICS
Beam forming is the term used to describe the application of weights to the inputs of an array of antennas to focus the reception of the antenna array in a certain direction, called the look direction or the main lobe. More importantly, other signals of the same carrier frequency from other directions can be rejected. These effects are all achieved electronically and no physical movement of the receiving antennas is necessary. In addition, multiple beam formers focused in different directions can share a single antenna array one set of antennas can service multiple calls of the same carrier. It is no coincidence that the number of elements in the above diagram equals the number of incoming signals. A beam former of L antenna elements is capable of accepting one signal and reliably rejecting L-1 signals. A greater number of interfering signals will diminish the performance of the beam former. Beam forming presents several advantages to antenna design .Firstly, space division multiple access (SDMA) is achieved since a beamformer can steer its look direction towards a certain signal.
SPATIAL STRUCTURE METHODS
As mentioned before, spatial structure methods exploit the information in the steering vector ...»._¼. The spatial structure is used to estimate the direction of arrivals (DOAs) of
the signals impinging on the sensor array. The estimated directions of arrivals are then used to determine the weights in the pattern forming network. This is called beam forming. Spatial structure methods only exploit spatial structure and training signals and the temporal structure of the signals is ignored. In the following an overview will be given about the three main spatial structure methods, namely conventional beam forming methods, maximum likelihood estimation and the so-called subspace-based methods.
CONCLUSION
In conclusion to this paper “Smart Antenna” systems are the antennas with intelligence and the radiation pattern can be varied without being mechanically changed. With appropriate adaptive algorithms such as Recursive Least Square Algorithm (RLS) the beam forming can be obtained. As the system uses a DSP processor the signals can be processed digitally and the performance is with a high data rate transmission and good reduction of mutual signal interference.
