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Added a function to calculate the e-folding time from the noise spectrum.

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Karthik 2024-09-16 18:53:17 +02:00
parent 0d2ce1aa76
commit 9b22207a2d
2 changed files with 92 additions and 27 deletions
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81
Time-Series-Analyzer/computeAndcompareRIN.m
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@ -22,13 +22,13 @@ dirACData = 'C:\\Users\\Karthik\\Documents\\GitRepositories\\Calculations\\Time-
%------------------------------------------------------------------------- %
bgsignal = load( [ dirACData '20240915_Background_AC'] ); %
dcsignal = load( [ dirDCData '20240915_1V_-3Mod_DC_PID_Inactive'] ); %
acsignal_1 = load( [ dirACData '20240915_1V_-3Mod_AC_PID_Inactive'] ); %
acsignal_2 = load( [ dirACData '20240915_1V_-3Mod_AC_PID_Active'] ); %
dcsignal = load( [ dirDCData '20240915_5V_1.1Mod_DC_PID_Inactive'] ); %
acsignal_1 = load( [ dirACData '20240915_5V_1.1Mod_AC_PID_Inactive'] ); %
acsignal_2 = load( [ dirACData '20240915_5V_1.1Mod_AC_PID_Active'] ); %
label_0 = 'Background'; %
label_1 = 'Power = 1 V, Modulation = -3.0 V, PID Inactive'; %
label_2 = 'Power = 1 V, Modulation = -3.0 V, PID Active'; %
label_1 = 'Power = 5 V, Modulation = 1.1 V, PID Inactive'; %
label_2 = 'Power = 5 V, Modulation = 1.1 V, PID Active'; %
%------------------------------------------------------------------------- %
%% Read out the important parameters
@ -81,9 +81,12 @@ spsd_src_smooth_2 = smooth(spsd_src_2,span,'moving');
spsd_bg_smooth = smooth(spsd_bg, span,'moving');
% calculates the RIN given in dB/Hz; the factor delta_f is needed to convert from dB/bin into dB/Hz
RIN_src_smooth_1 = 10*log10(spsd_src_smooth_1/(average_P*delta_f));
RIN_src_smooth_2 = 10*log10(spsd_src_smooth_2/(average_P*delta_f));
RIN_bg_smooth = 10*log10(spsd_bg_smooth /(average_P*delta_f));
spsd_src_smooth_rel_1 = spsd_src_smooth_1/(average_P*delta_f);
spsd_src_smooth_rel_2 = spsd_src_smooth_2/(average_P*delta_f);
spsd_bg_smooth_rel = spsd_bg_smooth /(average_P*delta_f);
RIN_src_smooth_1 = 10*log10(spsd_src_smooth_rel_1);
RIN_src_smooth_2 = 10*log10(spsd_src_smooth_rel_2);
RIN_bg_smooth = 10*log10(spsd_bg_smooth_rel);
% creates an array for the frequencies up to half the sampling frequency
f = f_s/2 * linspace(0,1,N/2+1);
@ -125,6 +128,68 @@ grid on
% saveas(f_,'FileName','png'); %
%------------------------------------------%
%%
compute_eFoldingTime(f_smooth, spsd_src_smooth_rel_2, 100, 1000, label_2)
%%
compute_eFoldingTime(f_smooth, spsd_src_smooth_rel_2, 1000, 5000, label_2)
%%
function compute_eFoldingTime(faxis, Skk, fstart, fend, data_str)
% computes the energy e-folding time: time to increase the energy by a factor e in sec.
[~,idx_ini] = min(abs(faxis-(2 * fstart))); % Find closest index for 2*fstart
[~,idx_fin] = min(abs(faxis-(2 * fend))); % Find closest index for 2*fend
Skk = Skk(idx_ini:idx_fin); % Slice Skk array
freqs = linspace(fstart, fend, length(Skk));
% Calculate e-folding time
e_folding_time = arrayfun(@(idx) 1 / (pi^2 * freqs(idx)^2 * Skk(idx)), 1:length(freqs));
% Plotting
figure('Position', [100, 100, 1200, 800]);
semilogx(freqs, e_folding_time, 'r', 'LineWidth', 2, 'DisplayName', data_str);
hold on;
grid on;
set(gca, 'GridLineStyle', '-'); % Thin grid lines
% Create gridlines for multiples of 10
x_multiples_of_10 = 10.^floor(log10(min(freqs(freqs > 0))):log10(max(freqs(freqs > 0))));
for val = x_multiples_of_10
xline(val, 'k-', 'LineWidth', 2); % Thick lines for multiples of 10
end
legend('show', 'Location', 'southwest', 'FontSize', 12);
xlabel('Frequency [Hz]', 'FontSize', 14);
ylabel('$T_e$ [s]', 'Interpreter', 'latex', 'FontSize', 14);
title(sprintf('Lower Bound= %.5f s', min(e_folding_time)), 'FontSize', 14);
set(gca, 'XScale', 'log');
set(gca, 'FontSize', 12);
hold off;
end

4
Time-Series-Analyzer/computeRIN.m
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@ -20,7 +20,7 @@ dirACData = 'C:\\Users\\Karthik\\Documents\\GitRepositories\\Calculations\\Time-
% - the AC coupled y-t signal to obtain the fluctuations
% - the AC coupled y-t signal with the beam blocked to obtain the background fluctuations
%-------------------------------------------------------------------------%
%--------------------------------------------------------------------------------------------------%
dcsignal = load( [ dirDCData 'IPG1064_100W'] ); %
acsignal = load( [ dirACData 'IPG1064_100W'] ); %
bgsignal = load( [ dirACData 'Background'] ); %
@ -29,7 +29,7 @@ label_0 = 'Picoscope noise floor'; %
label_1 = 'Background (Picoscope + InGaAs PIN PD + Transimp amp + Buffer amp + power supply)'; %
label_2 = 'Laser output power=100 W (Incident on PD=1mW)'; %
label_3 = 'Shot-Noise limit @ 1 mW incident power'; %
%-------------------------------------------------------------------------%
%------------------------------------------------------------------------------------------------- %
%% Read out the important parameters