作者:
Bartolomé, DiegoPérez-Neira, Ana I.
c/ Gran Capità 2-4 Planta 2 08034 Barcelona Spain
c/ Jordi Girona 1-3 Mòdul D5 08034 Barcelona Spain
Optimizing a communication of a Q-antenna Access Point (AP) with K single antenna terminals is not straightforward. Since a global optimization might not be solvable in real time, the AP has several alternatives invol...
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Through the wall surveillance is a difficult but important problem for both law enforcement and military personnel. Getting information on both the internal features of a structure and the location of people inside im...
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ISBN:
(纸本)0769520294
Through the wall surveillance is a difficult but important problem for both law enforcement and military personnel. Getting information on both the internal features of a structure and the location of people inside improves the operational effectiveness in search and rescue, hostage, and barricade situations. However, the electromagnetic properties of walls constrain the choices available as sensor candidates. We have demonstrated that a high range resolution radar operating between 450 MHz and 2 GHz can be used with a fixed linear array of antennas to produce images and detect motion through both interior and exterior walls. While the experimental results are good. it has been shown that the linear array causes signalprocessing artifacts that appear as ghosts in the resultant images. By moving toward a sensor concept where the antennas in the array are randomly spaced, the effect of ghost images can be reduced and operational and performance benefits Rained.
We consider the flat fading wireless link where the number of transmitter antennas is greater than the number of receiver antennas and the channel is known to the receiver. For such systems, the currently available li...
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For future high-speed wireless communications using orthogonal frequency division multiplexing (OFDM), two major system requirements will emerge: throughput improvement and rich interference elimination. Because of it...
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For future high-speed wireless communications using orthogonal frequency division multiplexing (OFDM), two major system requirements will emerge: throughput improvement and rich interference elimination. Because of its broadband nature and limited frequency allocations worldwide, interference from co-located wireless LAN's operating in the same frequency band will become a serious deployment issue. Adaptive array antenna can enhance the performance by suppressing the co-channel interference even when interference may have a large amount of multipath and also have similar received power to the desired signal. There are typically two types of adaptive array architecture for OFDM systems, whose signalprocessing is carried out before or after FFT (Fast Fourier Transform). In general, the pre-FFT arrayprocessing has low complexity, but in rich multipath and interference environments, the performance will deteriorate drastically. In contrast, the post-FFT arrayprocessing can provide the optimum performance even in such severe environments at the cost of complexity. Therefore, complexity-reduction techniques combined with the achievement of high system performance will be a key issue for adaptive array antenna applications. This paper proposes novel adaptive array architecture, which is a complexity-reduction technique using subcarrier clustering for post-FFT adaptive array. In the proposed scheme, plural subcarriers can be clustered into a group with the same spatial weight. Simulation results show that the proposed architecture is a promising candidate for real implementation, since it can achieve high performance with much lower complexity even in a rich multipath environment with low signal to noise plus interference ratio (SNIR).
In our previous papers we have introduced the Chirped-Pulsed Frequency Modulation technique (C-PFM);it has been used to allow the multiplexing capability of a multipoint Fiber Bragg Grating (FBG) sensor network. In th...
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ISBN:
(纸本)0819454346
In our previous papers we have introduced the Chirped-Pulsed Frequency Modulation technique (C-PFM);it has been used to allow the multiplexing capability of a multipoint Fiber Bragg Grating (FBG) sensor network. In this paper we report some preliminary experimental results, which confirm the theoretical analyses previously obtained. The innovative multiplexing approach, without to increase the complexity of the acquisition system, is able to address up to 10 independent sensing points on a single fiber. The C-PFM technique is based on the amplitude modulation of the emitted signal (pulsed) from the laser source by a chirped frequency signal and on the demodulation of the reflected signal by means of an adaptive filter (that is only a numerical elaboration). The experimental result are here shown and commented in order to define limitations and capabilities of the approach.
The experimental validation of a numerical technique for temperature/strain sensing, based on frequency domain fiber-optic Brillouin measurements, is presented. In this technique both measurements and the signal proce...
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ISBN:
(纸本)0819454346
The experimental validation of a numerical technique for temperature/strain sensing, based on frequency domain fiber-optic Brillouin measurements, is presented. In this technique both measurements and the signalprocessing are performed in the frequency domain. The algorithm is based on a harmonic expansion of the unknown profile, whose coefficients are determined by means of a multidimensional minimization. Preliminary results prove the validity of the proposed technique.
An Optical fibre based sensor system has been developed for the purpose of examining the colour of food products online as they cook in a large-scale industrial oven. By classifying the colour of each cooking stage it...
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ISBN:
(纸本)0819454346
An Optical fibre based sensor system has been developed for the purpose of examining the colour of food products online as they cook in a large-scale industrial oven. By classifying the colour of each cooking stage it is possible to automatically determine if the food is cooked to an optimum perceived colour. Developments have been made on previous work by the authors [1] by further examining the internal colour of the food and testing the repeatability of the system. Spectroscopic techniques are employed to determine the colour and this signal is interrogated using an Artificial Neural Network.
Space-time adaptive processing (STAP), previously developed in the field of sensorarrayprocessing and applied to radar signalprocessing, has already been shown to exhibit potential when applied on a small scale to ...
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Space-time adaptive processing (STAP), previously developed in the field of sensorarrayprocessing and applied to radar signalprocessing, has already been shown to exhibit potential when applied on a small scale to multidimensional functional magnetic resonance imaging (fMRI) data. In this study, a recursive version of the STAP algorithm, the method of steepest descent, is introduced for application to fMRI data. It is believed to be more suitable for adaptation to larger data sets than is the previous STAP implementation using matrix inversion. Computer simulations incorporating actual MRI noise indicate that it exhibits an improvement over the previous matrix inversion method in detecting activations.
The paper. is devoted to the description and practical verification of a new CCD linear image sensor control method. This method is used for inherent signal preprocessing or processing in the CCD linear image sensor. ...
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ISBN:
(纸本)0780381386
The paper. is devoted to the description and practical verification of a new CCD linear image sensor control method. This method is used for inherent signal preprocessing or processing in the CCD linear image sensor. This new method is suitable for a movement compensation, an one-frame filtration or a two-frame filtration. Because of the similarity between the Non-Recursive Digital Filter with Finite Impulse Response (NRDF FIR) and the new mode it was named FIR mode. Conclusions and hints applicable for operation of CCD image sensor in FIR mode are also included in the paper.
A novel GPR system for stand off landmine detection is discussed. This is a bistatic GPR system, which use a TEM horn antenna for a transmitter and a passive optical electric field sensor as a receiver. A small size p...
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ISBN:
(纸本)9076928045
A novel GPR system for stand off landmine detection is discussed. This is a bistatic GPR system, which use a TEM horn antenna for a transmitter and a passive optical electric field sensor as a receiver. A small size passive optical sensor scans on the ground surface and the acquired signal is used for synthetic aperture processing. Since the receiver is very small, it is suitable for scanning near the ground surfece, where landmines can be buried. Fundamental laboratory test shows its capability of imaging of buried objects.
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