Logarithmic amplitude scaling of a signal
5 views (last 30 days)
Show older comments
Lorenzo Lellini
on 13 Feb 2023
Answered: Jeffrey Clark
on 14 Feb 2023
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).
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1294185/image.png)
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1294190/image.png)
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
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1294225/image.jpeg)
3 Comments
Jeffrey Clark
on 13 Feb 2023
@Lorenzo Lellini, you are also using the length of sweep four your amp but sweep includes the silence duration as indicated in sweeptone documentation.
Accepted Answer
Jeffrey Clark
on 14 Feb 2023
@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.
0 Comments
More Answers (0)
See Also
Categories
Find more on Octave in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!