Unified Time- and Frequency-Domain Study on Time-Modulated Arrays

Zhang

et al. 2016

Entropy

Abstract:In order to detect hearing loss more efficiently and accurately, this study proposed a new method based on fractional Fourier transform (FRFT). Three-dimensional volumetric magnetic resonance images were obtained from 15 patients with left-sided hearing loss (LHL), 20 healthy controls (HC), and 14 patients with right-sided hearing loss (RHL). Twenty-five FRFT spectrums were reduced by principal component analysis with thresholds of 90%, 95%, and 98%, respectively. The classifier is the single-hidden-layer feed-forward neural network (SFN) trained by the Levenberg-Marquardt algorithm. The results showed that the accuracies of all three classes are higher than 95%. In all, our method is promising and may raise interest from other researchers.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Detection of Left-Sided and Right-Sided Hearing Loss via Fractional Fourier Transform

Wang

Zhang

et al. 2016

Entropy

“…For a plane wave with a frequency of f 0 and incident angle of with respect to the broadside of the array, the array factor of the 4-element subarray can be given as [16] ( ) ( )…”

Section: B Phase-comparison Monopulse Based On a 4d Arraymentioning

confidence: 99%

A phase-comparison monopulse system based on a 4D antenna array

Zhu

The 8th European Conference on Antennas and Propagation (EuCAP 2014)

Yao

et al. 2014

Self Cite

Conventional monopulse systems based on sum and difference patterns produced by traditional arrays face the contradiction of angle-resolution and angle-searching range, and a compromise between them usually has to be made. In fourdimensional (4D) antenna arrays, multiple pairs of sum and difference patterns can be produced simultaneously at the center frequency and low sidebands. By designing the time sequences reasonably, the multiple sum and difference patterns point in different directions, covering a much wider angle-range. In this paper, the conventional phase-comparison monopulse is introduced into a 4D array to form a novel monopulse system by which both high angle-resolution and wide angel-searching range are realized. Theoretical analysis shows that the novel monopulse system covers a ±60º angle-searching range without beamscanning. An experiment system based on an 8-element 4D array is established, and measurement results validate the effectiveness of the proposed system. Index Terms-4D arrays, time-modulated arrays, direction finding, differential evolution, monopulse system, sum and difference pattern.

“…On the other hand, sidebands are enhanced for the application of direction of arrival (DOA) estimation or secure communication in physical layer [4,5]. As for the fundamental operating principle of 4D antenna arrays, only the forms of sinusoidal signal and amplitude modulation (AM) signal have been studied [6,7]. When a LFM signal is transmitted through a 4D-antenna array, some problems may arise.…”

Section: Introductionmentioning

confidence: 99%

“…To avoid the aliasing in frequency domain as in [7], the time-modulation frequency f p should be no less than the chirp signal bandwidth B, which is the first constraint to 4D antenna arrays. Furthermore, the pulse duration of a chirp signal should be of integer multiples of time-modulation period as T=KT p =K/f p (K is a constant), which is the second constraint.…”

Section: Introductionmentioning

confidence: 99%

4D antenna arrays for LFM signal transmission

Guo

2015 IEEE International Symposium on Antennas and Propagation &Amp; USNC/URSI National Radio Science Meeting

Zhu

et al. 2015

Self Cite

The application of four-dimensional (4D) antenna arrays for linear frequency modulation (LFM) signal transmission is investigated in this paper. LFM pulse is used as the input of 4D antenna arrays and the influence brought by the periodic on/off switches are analyzed. The relationship among pulse duration, chirp rate, sample frequency, time-modulation frequency and propagation direction is analyzed, and then two constraints and two conditions are highlighted. Numerical examples with two different time schemes, including the pulse shifting (PS) scheme and binary phase center motion (BPCM) scheme, are presented and compared to demonstrate the effectiveness of the LFM signal transmission by 4D arrays. Simulation results validate that original chirp signal can be correctly recovered with low side lobe power patterns, as long as the proposed limitations are satisfied.