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radar:tracking [2018/06/05 11:21] – [Monopulse Accuracy] anubabyradar:tracking [2026/04/28 15:13] (current) – external edit 127.0.0.1
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 This kind of phase comparison monopulse tracker is often called the half-angle tracker. This kind of phase comparison monopulse tracker is often called the half-angle tracker.
  
-<figure label> {{:media:phase_radar.png?550*70}}<caption>Block diagram of a phase comparison monopulse radar (one angle coordinate).[(cite:Image4>)]</caption></figure>+<figure label> {{ :media:phase_radar.png?450*60 }}<caption>Block diagram of a phase comparison monopulse radar (one angle coordinate).[(cite:Image4>)]</caption></figure>
  
  
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 of these implementations, returns from a single transmission are received in simultaneously formed sum and difference beams and processed coherently. In the full-vector monopulse of Figure 16.a, two complex (I, Q) samples are fully utilized to calculate a complex monopulse ratio statistic. This calculated statistic, the measured monopulse ratio, provides the basis for a computer table lookup of the target angle of arrival relative to the null in the delta beam. The computer lookup function is simply a tabulated version of the assumed monopulse ratio consisting of the assumed delta beam antenna pattern to that of the assumed sum beam versus angle off-beam boresight. The tabulated monopulse ratio is inverted in the lookup process by entering the table with the measured monopulse ratio and finding the corresponding off-boresight angle. The full-vector monopulse processing in Figure 16.b differs somewhat from that in Figure 16.a, in that after low-noise amplification to establish the system noise figure, an RF quadrature hybrid device is used to combine the delta and sum beam signals 90° out of phase, i.e., as Σ + jΔ. The purpose of this combining in the difference channel is to bring the signal strength in the difference channel to approximately the same amplitude at that in the sum channel. This causes unavoidable receiver nonlinearities to have nearly the same effect in the two channels, resulting in less degradation in accuracy performance attributable to receive-string nonlinearities. In the absence of nonlinearities, the two techniques in Fig. 16.a and b are mathematically identical because of these implementations, returns from a single transmission are received in simultaneously formed sum and difference beams and processed coherently. In the full-vector monopulse of Figure 16.a, two complex (I, Q) samples are fully utilized to calculate a complex monopulse ratio statistic. This calculated statistic, the measured monopulse ratio, provides the basis for a computer table lookup of the target angle of arrival relative to the null in the delta beam. The computer lookup function is simply a tabulated version of the assumed monopulse ratio consisting of the assumed delta beam antenna pattern to that of the assumed sum beam versus angle off-beam boresight. The tabulated monopulse ratio is inverted in the lookup process by entering the table with the measured monopulse ratio and finding the corresponding off-boresight angle. The full-vector monopulse processing in Figure 16.b differs somewhat from that in Figure 16.a, in that after low-noise amplification to establish the system noise figure, an RF quadrature hybrid device is used to combine the delta and sum beam signals 90° out of phase, i.e., as Σ + jΔ. The purpose of this combining in the difference channel is to bring the signal strength in the difference channel to approximately the same amplitude at that in the sum channel. This causes unavoidable receiver nonlinearities to have nearly the same effect in the two channels, resulting in less degradation in accuracy performance attributable to receive-string nonlinearities. In the absence of nonlinearities, the two techniques in Fig. 16.a and b are mathematically identical because
  
-Im($\frac {Σ + jΔ} {Σ}$) = Im|$\frac{Δ}{Σ}|cosϕ)$+\begin{equation} 
 +Im(\frac {Σ + jΔ} {Σ}) = Im|\frac{Δ}{Σ}|cosϕ) 
 +\end{equation} 
  
 Hence, they both provide the fundamental accuracy performance of full-vector monopulse processing, given by Hence, they both provide the fundamental accuracy performance of full-vector monopulse processing, given by
  
-rmse = $\frac{||{W_Δ} - f{W_Σ}||}{|f|(2x)^{\frac{1}{2}}}$+\begin{equation} 
 +rmse = \frac{||{W_Δ} - f{W_Σ}||}{|f|(2x)^{\frac{1}{2}}} 
 +\end{equation}
  
-<figure label> {{:media:monopulseaccuracy1.png?550*60}}{{:media:monopulseaccuracy2.png?550*60}}{{:media:monopulseaccuracy3.png?550*60}}{{:media:monopulseaccuracy4.png?550*60}}<caption>Functional monopulse processing implementations, (a) Full-vector monopulse processing,(b) Full-vector monopulse with prehybrid combining,( c) Amplitude-only monopulse processing,(d) Phase-only monopulse processing.</caption></figure>+<figure label> {{ :media:monopulseaccuracy1.png?400*60 }}{{ :media:monopulseaccuracy2.png?400*60 }}{{ :media:monopulseaccuracy3.png?400*60 }}{{ :media:monopulseaccuracy4.png?400*60 }}<caption>Functional monopulse processing implementations, (a) Full-vector monopulse processing,(b) Full-vector monopulse with prehybrid combining,( c) Amplitude-only monopulse processing,(d) Phase-only monopulse processing.</caption></figure>
  
  
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