• Journal of the Korea Institute of Military Science and Technology
• /
• v.13 no.4
• /
• pp.673-682
• /
• 2010

This paper describes and analyzes a various generation methods of the mutually orthogonal polyphase sequences with low cross-correlation peak sidelobe and low autocorrelation peak sidelobe levels. The mutual orthogonality is the key requirement of multi-static or MIMO(Multi-Input Multi-Output) radar systems which provides the good target detection and tracking performance. The polyphase sequences, which are generated by SA(Simulated Annealing) and GA(Genetic Algorithm), have been analyzed with ACF(Autocorrelation Function) PSL(Peak Sidelobe Level) and CCF(Crosscorrelation Function) level at the matched filter output. Also, the ambiguity function has been introduced and simulated for comparing Doppler properties of each sequence. We have suggested the phase selection rule for applying multi-static or MIMO systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1493-1510
• /
• 2000

Theoretical models that can be used to predict the range of main lobe widths and the probability distribution of the peak sidelobe levels of two-dimensionally sparse arrays are presented here. The arrays are considered to comprise microphones that are randomly positioned on a segmented grid of a given size. First, approximate expressions for the expected squared magnitude of the aperture smoothing function and the variance of the squared magnitude of the aperture smoothing function about this mean are formulated for the random arrays considered in the present study. By using the variance function, the mean value and the lower end of the range i.e., the first I percent of the mainlobe distribution can be predicted with reasonable accuracy. To predict the probability distribution of the peak sidelobe levels, distributions of levels are modeled by a Weibull distribution at each peak in the sidelobe region of the expected squared magnitude of the aperture smoothing function. The two parameters of the Weibull distribution are estimated from the means and variances of the levels at the corresponding locations. Next, the probability distribution of the peak sidelobe levels are assumed to be determined by a procedure in which the peak sidelobe level is determined as the maximum among a finite number of independent random sidelobe levels. It is found that the model obtained from the above approach predicts the probability density function of the peak sidelobe level distribution reasonably well for the various combinations of two different numbers of microphones and grid sizes tested in the present study. The application of these models to the design of random, sparse arrays having specified performance levels is also discussed.

• ETRI Journal
• /
• v.43 no.4
• /
• pp.650-659
• /
• 2021

Multi-carrier waveforms have several advantages over single-carrier waveforms for radar communication. Employing multi-carrier complementary phase-coded (MCPC) waveforms in radar applications has recently attracted significant attention. MCPC radar signals take advantage of orthogonal frequency division multiplexing properties, and several authors have explored the use of MCPC signals and the difficulties associated with their implementation. The sidelobe level and peak-to-mean-envelope-power ratio (PMEPR) are the key issues that must be addressed to improve the performance of radar signals. We propose a scheme that applies pattern-based scaling and geometric progression methods to enhance sidelobe and PMEPR levels in MCPC radar signals. Numerical results demonstrate the improvement of sidelobe and PMEPR levels in the proposed scheme. Additionally, autocorrelations are obtained and analyzed by applying the proposed scheme in extensive simulation experiments.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.19 no.5
• /
• pp.43-47
• /
• 1982

In this paper, we derived to anlyze the correlation between the peak sidelobe of the linear isotropic random array and the design parameters, such as the element numbers, wavelength, scanning angle, confidence level and the length of aperture, with the statistical theory of random processes. The Peak sidelobe estimator was tested by the computer simulations using Honte Carlo method. Consequently, it was evident that the results of the peak lidelobe estimator were consistent with those of the computer simulations over confidence level 0.7.

• Proceedings of the Acoustical Society of Korea Conference
• /
• 1991.06a
• /
• pp.151-156
• /
• 1991

In this paper, we propose a new algorithm for designing the R-G filter that has optimum performance in terms of mean square sidelobe level(MSSL) for the Barker code. The advantage of the conventional R-G filter lies in its simple structure so that it can be easily implemented. However, the conventional R-G filter dose not have optimum performances in terms of peak sidelobe level(PSL), mean sidelobe level(MSL), and MSSL. Recently, a(R-G)LP filter of which filter coefficients are obtained by the linear programming algorithm was proposed and known to have optimum performance in PSL. The proposed (R-G)LS filter keeps the simple structure of the conventional R-G filter and has the filter coefficients that minimizes the sidelobe in the least square sense. The analytic results show that the proposed (R-G)LS filter has better performances than the conventional R-G filter in terms of PSL, MSL, and MSSL. Compared with (R-G)LP filter, the proposed (R-G)LS filter has better performances in terms of MSL and MSSL. The proposed filter design algorithm can be applied to the other binary codes such as truncated pseudonoise(PN) codes and concatenated codes.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.6
• /
• pp.18-22
• /
• 1983

In this paper, we derive and analyze the peak sidelobe estimator of the planar random array antenna by extending the theory of the linear random array antenna. The computer simula-tions, which are based on Monte Carlo method, are programmed and applied easily to cases where a great number of array elements are involved. The results obtained from the computer simulations show that there is a little difference of the maximum 0.8 dB. Consequently, the peak sidelobe estimator is well consistent with the results of the computer simulations over confidence level 0.5.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.10 no.2
• /
• pp.63-70
• /
• 1996

In this paper, we propose the low sldelobe digital doppler filter bank design algorithm which is practically applicable to coherent radar equipment in complex air-defense system. Using the proposed algorithm, we can obtain a digital doppler filter bank of lower peak sidelobe level and higher clutter suppression capability. In this method, it is possible to achieve higher target-detectability without loss of Target SNR. The proposed algorithms are verified by simulations and experiments.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39C no.5
• /
• pp.447-455
• /
• 2014

In this paper, we consider a representative integral imaging method in glasses-free 3D image processing and propose a prioritized transmission scheme for guaranteeing a received video quality in error-prone environments. According to the correlation of pixels consisting of each voxel of integral image, we set the priority differently and apply the modulation level according to this priority value. That is to say, the corresponding pixels with small variance are set to a high priority and transmitted by using a low level modulation that is robust under transmission errors, but the corresponding pixels with greater variance are set to a lower priority and transmitted by using a high level modulation that has a high bit error rate but fast transmission rate. Result shows that the proposed scheme that applies the error-robust modulation level to the important image bit stream with the high priority improves the peak to sidelobe ratio (PSR) of the received 3D image, compared with a typical method that use the same modulation level without distinction of priorities.

• Journal of Korea Society of Industrial Information Systems
• /
• v.27 no.5
• /
• pp.49-59
• /
• 2022

The SHAPE algorithm has the advantage of being able to shape the pulse spectrum as desired and design it not to distort other characteristics, so it was used in the active sonar pulse design. In this paper, we propose a pulse design using the SHAPE algorithm for a multi-static sonar system to reduce the cross-correlation between frequency-adjacent pulses and prevent the performance degradation of the pulses themselves. The boundary function of the SHAPE algorithm is set to be limited to the pulse bandwidth. As a result of applying the proposed design method to the sinusoidal frequency modulated pulse, the peak cross-correlation level (PCCL), which means the degree of cross-correlation, was reduced by 44.23 dB. Although the PCCL decreased by several tens of dB, no significant change in the ambiguity function was observed, and the integrated sidelobe level (ISL), which means the average value of the side lobe, increased by 11.64 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.12
• /
• pp.1351-1358
• /
• 2012

In this paper, an analytical technique is proposed for the design of interleaved thinned planar array with well-behaved and predictable sidelobes. The interleaved arrays are composed of thinned planar subarrays based on cyclic difference sets(DSs). Becauce sidelobes of thinned planar subarrays based on DS are predictable by DS parameters, the subarrays exhibit very similar sidelobe levels by utilizing DS and complementary DS with similar autocorrelations each other. The combinatorial method also allows the design of interleaved placements with simultaneously optimum peak sidelobe levels(PSLs) of subarrays using cyclic shift-a property of DSs. The optimized PSLs of the interleaved array are -12.47 dB and -10.34 dB.