function s_R_tlide = get_downconversion_pulse(s_R, f_n)

    config_parameters;

    s_R_tlide = complex(zeros(1, len));
    real_s_R_tlide = zeros(1, len);
    imag_s_R_tlide = zeros(1, len);

    % down conversion
    for t_idx = 1:len
        t = range_t(t_idx);
    
        p = rem(t, T_r);
    
        % if (p > T_p)
        %     continue
        % end
    
        n = (t - p) / T_r;
        s_R_tlide(t_idx) = s_R(t_idx) * exp(-1 * 1j * 2 * pi * f_n(t_idx) * (t - n * T_r));
        real_s_R_tlide(t_idx) = real(s_R_tlide(t_idx));
        imag_s_R_tlide(t_idx) = imag(s_R_tlide(t_idx));
    end

    if figure_flag_3
        figure(3)
        title("Received signal (after down conversion)")
        subplot(2, 1, 1);
        plot(range_t, imag_s_R_tlide);
        xlabel("Time (s)");
        ylabel("sin(\omega t)");
        ylim([-1, 1]);
    
        subplot(2, 1, 2);
        plot(range_t, real_s_R_tlide);
        xlabel("Time (s)");
        ylabel("cos(\omega t)");
        ylim([-1, 1]);
    end

end