Abstract
Accurate direction of arrival (DOA) estimation of wideband, low-power nonstationary signals is important in many radio frequency (RF) applications. This article analyses the performance of two incoherent aggregation techniques for the DOA estimation of high chirp-rate linear frequency modulated (LFM) signals used in modern radar and electronic warfare (EW) applications. The aim is to determine suitable aggregation techniques for blind DOA estimation for real-time implementation with a frequency channelised signal. The first technique calculates a single pseudospectrum by directly combining the spatial covariance matrices from each of the frequency bins. The second technique first calculates the spatial pseudospectra from the spatial covariance matrix (SCM) from each frequency bin and then combines the spatial pseudospectra into one single estimate. Firstly, for single and multiple signal emitters, we compare the DOA estimation performance of incoherent SCM-based aggregation with that of the incoherent spatial pseudospectra-based aggregation using the root mean-squared error (RMSE). Secondly, we determine the types of signals and conditions for which these incoherent aggregation techniques are more suited. We demonstrate that the low-complexity SCM-based aggregation technique can achieve relatively good estimation performance compared to the pseudospectra-based aggregation technique for multiple narrowband signal detection. However, pseudospectra aggregation is better suited for single wideband emitter detection. Both the incoherent aggregation techniques presented in this article offer a computational advantage over the coherent processing techniques and hence are better suited for real-time implementation.
Highlights
Direction of arrival (DOA) estimation is of paramount importance in modern communication, sonar and radar applications
We present the results from simulations performed using Matrix Laboratory (MATLAB)
In Section 4.2.1, we investigate the effect of the initial frequency on the DOA estimation performance using plots of spatial pseudospectra against DOA at 10 dB signal-to-noise ratio (SNR)
Summary
Direction of arrival (DOA) estimation is of paramount importance in modern communication, sonar and radar applications. To overcome some of the challenges associated with the above-mentioned coherent techniques, several wideband DOA estimation techniques have recently been proposed [12,13,14,15,16,17] Shortcomings of these proposed techniques include the need to perform initial frequency or DOA estimation and the requirement to compute focussing matrices for each frequency bin. We demonstrate that acceptable DOA estimation performance can be achieved with both single and multiple LFM emitters using these two incoherent aggregation techniques with reasonably low computational complexity and show their trade-offs. Pseudospectra-based aggregation yields better estimation performance for a single wideband source Due to their lower computational complexities, the two incoherent aggregation techniques presented are more suitable for real-time implementation than more complex traditional coherent aggregation techniques.
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