Logarithmic amplitude scaling of a signal

Question

Lorenzo Lellini 2023-2-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1911640-logarithmic-amplitude-scaling-of-a-signal

回答： Jeffrey Clark 2023-2-14

采纳的回答： Jeffrey Clark

在 MATLAB Online 中打开

I need to logarithmically scale the amplitude a sinesweep signal from

at the starting frequency to

at the lastest frequency (it should be 12 dB per octave).

Is this code wrong? Why if I plot the exponential shape and the scaled signal the profiles does not overlap?

duration_sweep = 2;   % Seconds
% Sine sweep frequency range
f_start = 100;
f_end = 10000;
%--------------------------------------------
% Settings sweeptone
duration_final_silence_sweep = 0.1; % Secondi
total_duration_sweep = duration_sweep + duration_final_silence_sweep ;
sweep = sweeptone(duration_sweep,duration_final_silence_sweep,Fs,"SweepFrequencyRange",[f_start f_end]);
% Time axis
t_input = (0:numel(sweep)-1); 
% Scaling factor
amp = logspace(log10(0.1*10^-3), log10(10), length(sweep)); 
% amplitude scaling
out = sweep.*amp';
% Plot
figure(1)
plot (out, 'LineWidth', 1.5)
hold on
plot(t_input, amp)
grid minor

3 个评论
显示 1更早的评论隐藏 1更早的评论

Jeffrey Clark 2023-2-13

@Lorenzo Lellini, you are also using the length of sweep four your amp but sweep includes the silence duration as indicated in sweeptone documentation.

Lorenzo Lellini 2023-2-13

ok, thank you! I forgot to specify Fs but I had already considered it...

How can I perform the procuct between amp and the sweeptone in a correct way since I must specify a silence duration in the sweep and vectors must have the same length?

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Jeffrey Clark 2023-2-14

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1911640-logarithmic-amplitude-scaling-of-a-signal#answer_1171575

@Lorenzo Lellini, note that your curve is assuming a full scale sweep of +/- 1 whereas sweeptone produces +/- 0.5 so you need to plot 0.5*amp. And as in my comments above, you need to exclude fix(duration_final_silence_sweep*Fs) bins from the end of sweep.