A Novel Monopulse Angle Estimation Method for Wideband LFM Radars

Abstract

Traditional monopulse angle estimations are mainly based on phase comparison and amplitude comparison methods, which are commonly adopted in narrowband radars. In modern radar systems, wideband radars are becoming more and more important, while the angle estimation for wideband signals is little studied in previous works. As noise in wideband radars has larger bandwidth than narrowband radars, the challenge lies in the accumulation of energy from the high resolution range profile (HRRP) of monopulse. In wideband radars, linear frequency modulated (LFM) signals are frequently utilized. In this paper, we investigate the monopulse angle estimation problem for wideband LFM signals. To accumulate the energy of the received echo signals from different scatterers of a target, we propose utilizing a cross-correlation operation, which can achieve a good performance in low signal-to-noise ratio (SNR) conditions. In the proposed algorithm, the problem of angle estimation is converted to estimating the frequency of the cross-correlation function (CCF). Experimental results demonstrate the similar performance of the proposed algorithm compared with the traditional amplitude comparison method. It means that the proposed method for angle estimation can be adopted. When adopting the proposed method, future radars may only need wideband signals for both tracking and imaging, which can greatly increase the data rate and strengthen the capability of anti-jamming. More importantly, the estimated angle will not become ambiguous under an arbitrary angle, which can significantly extend the estimated angle range in wideband radars.

An edge computing framework based on OFDM radar for low grazing angle target tracking

“…3. shows the monopulse ratio which determines the target elevation angle based on (29). Figure 5 shows the different power allocation schemes applied in the proposed low grazing angle target tracking algorithm.…”

“…We consider the OFDM signaling scheme [18][19][20][21][22][23][24][25], which is one of the ways to accomplish the simultaneous use of several subcarriers. Furthermore, the monopulse method, which has been utilized in many studies for target detection and tracking [26][27][28][29][30][31], has been applied for the angle of arrival estimation. A new adaptive beamforming method has been investigated in [32] for low-angle target tracking under multipath scenarios.…”

Maximum Likelihood Method and Cramer-Rao Low Bound of Angle Estimation for Wide-Band Monopulse Radar

“…Therefore, the challenge of angle estimation for wide-band monopulse radar lies in how to accumulate energy of target echo form high resolution range profiles (HRRP). Zhang et al [10] proposed a estimation method for linear frequency modulated (LFM) radar, in which angle estimation is translated to estimate the frequency of cross-correlation function (CCF). The frequency of the main spectral line can be estimated by fast Fourier transform (FFT) or other frequency estimation methods.…”

Direction Finding for Unmanned Aerial Systems Using Rhombic Antennas and Amplitude Comparison Monopulse

“…Here, the angle θs is the squint angle, which is 45 degrees in the case of this thesis. The tracking axis of the antenna system is along the dotted line from the radar antennas to the target as shown in Figure 3: Amplitude comparison monopulse example [9].…”

“…Amplitude comparison monopulse example[9] below shows the squint angle in relation to the received beam patterns is shown below: Amplitude comparison monopulse example[9] …”