Browsing by Subject "Array signal processing"

Now showing 1 - 6 of 6

Open Access
Çokyollu kanal parametre kestirimi için yeni bir dizilim sinyal işleme tekniği
(IEEE, 2007-06) Güldoǧan, Mehmet Burak; Arıkan, Orhan
Bu bildiride, çarpraz belirsizlik işlevinin kullanıldığı yeni bir dizilim sinyal işleme tekniği önerilmektedir. Geliştirilen teknik bir algılayıcı dizilimine gelen sinyallerden herbirinin geliş yönünü (GY), zaman gecikmesini Doppler kaymasını ve genliğini dürümlü bir sekilde kestirir. Önerilen Çarpraz Belirsizlik İşlevi - Yön Bulma (ÇBI-YB) tekniği ile Çoklu Sinyal Sınıflandırması (MUSIC) algoritmasının performansları sentetik sinyaller kullanılarak kök Ortalama Karesel Hata (kOKH) cinsinden değişik işaret Gürültü Oranı (İGO) değerleri için karşılaştırılmıştır. Önerilen tekniğin başarımı kayıt edilmiş çokyollu yüksek-enlem iyonosfer verileri üzerinde irdelenmiştir. Elde edilen sonuçlar, düşük İGO değerlerinde dahi çokyollu sinyal kaynaklarını ayırmada önerilen ÇBİ-YB tekniğinin ciddi başarım artışı sağladığını göstermektedir.
Open Access
Joint multi-emitter signal seperation and angle of arrival estimation via variational mode decomposition
(IEEE, 2017) Soğanlı, Abdurrahim; Arıkan, Orhan
In this work, we propose a framework which separates multi-emitter signals arriving to uniform linear antenna receiver system. Proposed model uses a combination of variational mode decomposition (VMD) and space alternating expectation maximization (SAGE) algorithms. Former one separates emitter signals and estimates their frequencies while in the second part channel parameters (relative phases, angle of arrivals) are estimated using SAGE algorithm. Experimental results have showed that the proposed model can simultaneously estimates angle of arrivals of the multi-emitter signals working at the same frequencies.
Open Access
A new technique for direction of arrival estimation for ionospheric multipath channels
(ELSEVIER, 2009) Guldogan, M. B.; Arıkan, Orhan; Arikan, F.
A novel array signal processing technique is proposed to estimate HF channel parameters including number of paths, their respective direction of arrivals (DOA), delays, Doppler shifts and amplitudes. The proposed technique utilizes the Cross Ambiguity Function (CAF), hence, called as the CAF-DF technique. The CAF-DF technique iteratively processes the array output data and provides reliable estimates for DOA, delay, Doppler shift and amplitude corresponding to each impinging HF propagated wave onto an antenna array. Obtained results for both real and simulated data at different signal to noise ratio (SNR) values indicate the superior performance of the proposed technique over the well known MUltiple SIgnal Classification (MUSIC) technique.
Open Access
A novel array signal processing technique for multipath channel parameter estimation
(2006) Güldoğan, Mehmet Burak
Many important application areas such as mobile communication, radar, sonar and remote sensing make use of array signal processing techniques. In this thesis, a new array processing technique called Cross Ambiguity Function - Direction Finding (CAF-DF) is developed. CAF-DF technique estimates direction of arrival (DOA), time delay and Doppler shift corresponding to each impinging signals onto a sensor array in an iterative manner. Starting point of each iteration is CAF computation at the output of each sensor element. Then, using incoherent integration of the computed CAFs, the strongest signal in the delay-Doppler domain is detected and based on the observed phases of the obtained peak across all the sensors, the DOA of the strongest signal is estimated. Having found the DOA, CAF of the coherently integrated sensor outputs is computed to find accurate delay and Doppler estimates for the strongest signal. Then, for each sensor in the array, a copy of the strongest signal that should be observed at that sensor is constucted and eliminated from the sensor output to start the next iteration. Iterations continue until there is no detectable peak on the incoherently integrated CAFs. The proposed technique is compared with a MUSIC based technique on synthetic signals. Moreover, performance of the algorithm is tested on real high-latitude ionospheric data where the existing approaches have limited resolution capability of the signal paths. Based on a wide range of comparisons, it is found that the proposed CAF-DF technique is a strong candidate to define the new standard on challenging array processing applications.
Open Access
A VLSI receive beamformer for digital ultrasound imaging
(IEEE, 1992-03) Karaman, Mustafa; Kolağasıoğlu, Ertuğrul; Atalar, Abdullah
A VLSI architecture for real-time digital receive beamforming in phased array ultrasound imaging is proposed. The architecture is an inverse binary tree like structure with N stages where N is the number of array elements. The sampled signals from the phased array channels are coherently added in a pairwise manner within the stages of the architecture in a pipelined data flow scheme. The storage requirement for the synchronization of the asynchronously received samples corresponding to a focal point is significantly reduced. The architecture is modular and has a regular communication scheme which make the VLSI implementation rather easy and straightforward.
Open Access
Wideband maximum likelihood direction finding and signal parameter estimation by using the tree-structured EM algorithm
(Institute of Electrical and Electronics Engineers, 1999-01) Çadallı, N.; Arıkan, Orhan
The expectation maximization (EM) algorithm is presented for the case of estimating direction of arrivals of unknown deterministic wideband signals. Alternative regularized least squares estimation techniques for the required signal estimation and a tree structure for the data mapping in the EM algorithm are proposed. Extensive simulation results are presented for comparison of the proposed algorithms with the conventional EM approach and the current high-resolution methods of wideband direction finding.