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Simulating LPF with matched stiffness involves bringing together the details of the previous section. The following code snippet builds two versions of the LPF model: one with matched stiffness, one with unmatched stiffness.

% Configuration plist for building our model with matched stiffness modelPlistMatched = plist(... 'built-in', 'LPF', ... 'EOM_TM1_STIFF_XX', 2e-6, ... 'EOM_TM2_STIFF_XX', 2e-6 ... ); % Configuration plist for building our model with unmatched stiffness modelPlistUnmatched = plist(... 'built-in', 'LPF', ... 'EOM_TM1_STIFF_XX', 1e-6, ... 'EOM_TM2_STIFF_XX', 5e-6 ... ); % Build the LPF model with our configuration plists lpfMatched = ssm(modelPlistMatched); lpfUnmatched = ssm(modelPlistUnmatched);

% Create a covariance matrix and port list sized for our LPF model cov_matrix = lpfMatched.generateCovariance(); % Define the simulation plist for a 100,000s simulation simPlist = plist(... 'CPSD Variable Names', cov_matrix.find('names'), ... 'CPSD', cov_matrix.find('cov'), ... 'Return outputs', {'IFO.x1', 'IFO.x12', 'DFACS.sc_x', 'DFACS.tm2_x'}, ... 'Nsamples', 1000000 ... ); % Run the simulations outMatched = simulate(lpfMatched, simPlist); outUnmatched = simulate(lpfUnmatched, simPlist);

% Compare the coherence between force on SC and the diff. displacement % Unpack the outputs from the simulations [o1m, o12m, F_cmd_Xm, F_cmd_x2m] = unpack(outMatched); [o1u, o12u, F_cmd_Xu, F_cmd_x2u] = unpack(outUnmatched); % Compute the coherence coherePlist = plist(... 'navs', 16, ... 'order', 1 ... ); Cm = cohere(F_cmd_Xm, o12m, coherePlist); Cm.setName('SC Jitter to X12 coherence (matched stiffness)'); Cu = cohere(F_cmd_Xu, o12u, coherePlist); Cu.setName('SC Jitter to X12 coherence (unmatched stiffness)'); % Bin the data to do some frequency-domain averaging Cm_binned = Cm.bin_data; Cu_binned = Cu.bin_data; % Plot the results with error bars iplot(Cm_binned, Cu_binned)

Changing system parameters | Topic 3 - Estimation of equivalent acceleration. |

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