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Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays.

Trucco A, Traverso F, Crocco M - Sensors (Basel) (2015)

Bottom Line: Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance.We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity.A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical, Electronic, Telecommunications Engineering, and Naval Architecture (DITEN), University of Genoa, 5-16126 Genova, Italy. andrea.trucco@unige.it.

ABSTRACT
For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed). In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

No MeSH data available.


Related in: MedlinePlus

Distortion of beam pattern (measured in terms of the percentage error ∑) for beamforming with optimum complex weights versus the upsampling factor U.
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sensors-15-13477-f016: Distortion of beam pattern (measured in terms of the percentage error ∑) for beamforming with optimum complex weights versus the upsampling factor U.

Mentions: For beamforming using optimum complex weights, a sampling frequency fs = 1.5 kHz is set that is slightly higher than the Nyquist rate. Figure 16 shows the measured percentage error, ∑, when the upsampling factor U is increased up to 40. To obtain an error, ∑, that is lower than 5%, an upsampling factor U = 10 is necessary. Instead, if an error, ∑, lower than 2% is desired, the minimum upsampling factor is U = 23. If a sampling frequency similar to the sampling frequency of the oversteered case is adopted without upsampling (i.e., fs = 5 kHz and U = 1), an error ∑equal to 22.7% is achieved and the actual beam pattern exhibits major distortions, as shown in Figure 17.


Maximum Constrained Directivity of Oversteered End-Fire Sensor Arrays.

Trucco A, Traverso F, Crocco M - Sensors (Basel) (2015)

Distortion of beam pattern (measured in terms of the percentage error ∑) for beamforming with optimum complex weights versus the upsampling factor U.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507652&req=5

sensors-15-13477-f016: Distortion of beam pattern (measured in terms of the percentage error ∑) for beamforming with optimum complex weights versus the upsampling factor U.
Mentions: For beamforming using optimum complex weights, a sampling frequency fs = 1.5 kHz is set that is slightly higher than the Nyquist rate. Figure 16 shows the measured percentage error, ∑, when the upsampling factor U is increased up to 40. To obtain an error, ∑, that is lower than 5%, an upsampling factor U = 10 is necessary. Instead, if an error, ∑, lower than 2% is desired, the minimum upsampling factor is U = 23. If a sampling frequency similar to the sampling frequency of the oversteered case is adopted without upsampling (i.e., fs = 5 kHz and U = 1), an error ∑equal to 22.7% is achieved and the actual beam pattern exhibits major distortions, as shown in Figure 17.

Bottom Line: Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance.We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity.A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical, Electronic, Telecommunications Engineering, and Naval Architecture (DITEN), University of Genoa, 5-16126 Genova, Italy. andrea.trucco@unige.it.

ABSTRACT
For linear arrays with fixed steering and an inter-element spacing smaller than one half of the wavelength, end-fire steering of a data-independent beamformer offers better directivity than broadside steering. The introduction of a lower bound on the white noise gain ensures the necessary robustness against random array errors and sensor mismatches. However, the optimum broadside performance can be obtained using a simple processing architecture, whereas the optimum end-fire performance requires a more complicated system (because complex weight coefficients are needed). In this paper, we reconsider the oversteering technique as a possible way to simplify the processing architecture of equally spaced end-fire arrays. We propose a method for computing the amount of oversteering and the related real-valued weight vector that allows the constrained directivity to be maximized for a given inter-element spacing. Moreover, we verify that the maximized oversteering performance is very close to the optimum end-fire performance. We conclude that optimized oversteering is a viable method for designing end-fire arrays that have better constrained directivity than broadside arrays but with a similar implementation complexity. A numerical simulation is used to perform a statistical analysis, which confirms that the maximized oversteering performance is robust against sensor mismatches.

No MeSH data available.


Related in: MedlinePlus