MATLAB Examples

# Figure 26. SINR for the optimum and tapered fully adaptive STAP, including Doppler straddling losses.

## Contents

```clc; clear; close all; ```

```radar_oper_params; ```

## Thermal Noise Power Computation

```thermal_noise_power; ```

## Thermal Noise Covariance Matrix

```Rn = sigma2*eye(M*N); ```

## Clutter Patch RCS Computation

```clutter_patch_rcs; ```

## Calculate the Array Transmit and Element Receive Power Gains

```Tx_Rx_power_gains; ```
```Warning: The value of local variables may have been changed to match the globals. Future versions of MATLAB will require that you declare a variable to be global before you use that variable. ```

## Calculate the Clutter to Noise Ratio (CNR) for each clutter patch

```ksi = Pt*Gtgain.*Grec*lambda^2*sigma/((4*pi)^3*Pn*10^(Ls/10)*Rcik^4); % Eq. (58) ```

## Clutter Covariance Matrix Computations

```beta = 1; % beta parameter. phia = 0; % Velocity Misalignment Angle. Rc = clutt_cov(ksi,beta); ```

## Jamming Covariance Matrix Calculation

```jamm_cov; ```

## Total Interference Covariance Matrix

```Ru = Rc + Rj + Rn; % Eq. (98) ```

## SINR calculation for Optimum and Tapered Fully Adaptive STAP

```ta = chebwin(N,30); % 30 dB Chebychev Spatial Tapper. tb = chebwin(M,40); % 40 dB Chebychev Doppler Taper. phit = 0; thetat = 0; % Target Azimuth and Elevation Angles. fspt = d/lambda*cos(thetat*pi/180)*sin(phit*pi/180); % Target Spatial Frequency. a = exp(1i*2*pi*fspt*(0:N-1)).'; % Target Spatial Steering Vector. fd = 0:.5:300; Lfd = length(fd); omega = fd/fr; dopplerfilterbank = linspace(0,300,M+1); % Doppler Filterbank frequencies. omegadopplerbank = dopplerfilterbank/fr; SINRopt_mat = zeros(length(dopplerfilterbank),Lfd); SINRtap_mat = zeros(length(dopplerfilterbank),Lfd); InvRu = inv(Ru); for m=1:length(dopplerfilterbank) bm = exp(1i*2*pi*omegadopplerbank(m)*(0:M-1)).'; % Doppler Filter Steering Vector vm = kron(bm,a); gt = kron(tb.*bm,ta.*a); wm = InvRu*vm; %#ok<*MINV> % Eq. (116) wmtap = InvRu*gt; for n=1:Lfd b = exp(1i*2*pi*omega(n)*(0:M-1)).'; % Dummy Target Doppler Steering Vector v = kron(b,a); SINRopt_mat(m,n) = wm'*v; % Eq. (114) SINRtap_mat(m,n) = abs(wmtap'*v)^2/real(wmtap'*gt); % Eq. (115) end end SINRopt = max(abs(SINRopt_mat)); % Eq. (117) for Optimum Fully Adaptive Case SINRtap = max(abs(SINRtap_mat)); % Eq. (117) for Tapered Fully Adaptive Case ```

## Plot the SINRs

```figure('NumberTitle', 'off','Name', ... 'Figure 26. SINR for the optimum and tapered fully adaptive STAPs, including Doppler straddling losses.',... 'Position', [1 1 600 500]); plot(fd,10*log10(SINRopt),'LineWidth',1.5) hold on; plot(fd,10*log10(SINRtap),'r','LineWidth',1.5) ylabel('SINR (dB)'); xlabel('Target Doppler Frequency (Hz)'); ylim([-5 26]); xlim([-5 305]); legend('Optimum Fully Adaptive', 'Tapered Fully Adaptive', 'Location','South') grid on; ```