, . t:
>> t = (0:.01: 2.55);
t 0 2.55 0.01, 100 (). ; ( ) . t, .
y(t), 10 7 , 3 3 :
>> y = 10*sin(2*pi*7*t) + 3*sin(2*pi*3*t);
, , . :
>> randn(state, sum(100*clock));
1.5 2, :
>> yn = 1.5 + sqrt(2)*randn(size(t));
:
>> sig = y + yn;
Matlab sptool. :
>> sptool
, . Signals Spectra. . mtlb, chirp train.
y sig. Import File. y , sampling frequency, 100 . , sig1, sig2 . ʔ sig1. , View, Signals. sig. . ctrl, View. .
Signals Create Spectrum Viewer. . . Matlab pwelch Welch Spectrum Viewer.
:
Nfft .
Nwind D.
Window w.
Overlap D S.
|
|
Apply.
. Options , [0, F/2],
[-F/2, F/2], [0, F].
1. 16 250 . 8 ( ), 7,65 ( ). sptool ( FFT).
.
2. 2,56 :
100 ;
: 1, 40 ;
: 2, 55 .
( FFT).
.
3. 256- : , , , . rectwin(n), triang(n), hanning(n), hamming(n), n . sptool ( FFT). . .
, .
( ) 512- . .
4. 256, 512 1024 :
100 ;
: 10, 15 ;
: 2, 35 .
, (Welch), .
30. .
. ( . 3 ).
5. 256, 512 1024 0.2 .
, , . .
6. , (Ispravn.txt, Neispravn.txt).
File Import Data. Import Open. Next. Finish. , . sptool ( FFT). 1953,125 . 8192.
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15 18 .
1. ().
2. .
3. ?
4. , .
5. () ?
6. () ?
7. ?