请教matlab高手:拟合或变换问题
下面的数据第一列表示时间,第二列表示函数值,表示一个周期信号.请为能否用一个比较精确的方法求出其相位?本人用数据拟合的方法求出的相位感觉不是很精确.能否用FFT变换,请赐教,不胜感谢!!!0.10000E-02 0.775707E-06
0.25075 0.281535E-01
0.50050 0.743086E-01
0.75025 0.132678
1.0000 0.199235
1.2500 0.270819
1.5000 0.344514
2.0000 0.487779
2.5000 0.608510
3.0000 0.692186
3.5000 0.728691
4.0000 0.712969
4.5000 0.645359
4.7500 0.598614
5.0000 0.540465
5.2500 0.472500
5.5000 0.396445
6.0000 0.222964
6.5000 0.440217E-01
7.0000 -0.123694
7.5000 -0.264443
8.0000 -0.365019
8.5000 -0.416069
9.0000 -0.413024
9.5000 -0.356556
9.7500 -0.315027
10.000 -0.261771
10.250 -0.198401
10.500 -0.126663
10.750 -0.484520E-01
11.000 0.342116E-01
11.250 0.119217
11.500 0.204408
12.000 0.365744
12.500 0.501199
13.000 0.597192
13.500 0.644196
14.000 0.637536
14.500 0.577803
14.750 0.534716
15.000 0.479971
15.250 0.415172
15.500 0.342059
15.750 0.262523
16.000 0.178578
16.250 0.923325E-01
16.500 0.593784E-02
17.000 -0.157671
17.500 -0.295279
18.000 -0.393305
18.500 -0.442220
19.000 -0.437334
19.500 -0.379225
19.750 -0.336908
20.000 -0.282889
20.250 -0.218772
20.500 -0.146296
20.750 -0.673514E-01
21.000 0.160469E-01
21.250 0.101792
21.500 0.187730
22.000 0.350587
22.500 0.487591
23.000 0.585141
23.500 0.633676
24.000 0.628479
24.500 0.570094
24.750 0.527641
25.000 0.473483
25.250 0.409224
25.500 0.336599
25.750 0.257496
26.000 0.173929
26.250 0.880033E-01
26.500 0.187135E-02
27.000 -0.161420
27.500 -0.298903
28.000 -0.396961
28.500 -0.446017
29.000 -0.441328
29.500 -0.383414
29.750 -0.341181
30.000 -0.287226
30.250 -0.223148
30.500 -0.150684
30.750 -0.717182E-01
31.000 0.117365E-01
31.250 0.975747E-01
31.500 0.183644
32.000 0.346903
32.500 0.484438
33.000 0.582617
33.500 0.631839
34.000 0.627336
34.500 0.569600
34.750 0.527446
35.000 0.473559
35.250 0.409537
35.500 0.337112
35.750 0.258167
36.000 0.174714
36.250 0.888579E-01
36.500 0.274998E-02
37.000 -0.160660
37.500 -0.298413
38.000 -0.396866
38.500 -0.446393
39.000 -0.442203
39.500 -0.384760
39.750 -0.342741
40.000 -0.288976
40.250 -0.225058
40.500 -0.152720
40.750 -0.738419E-01
41.000 0.956494E-02
41.250 0.953972E-01
41.500 0.181503
42.000 0.344991
42.500 0.482898
43.000 0.581563
43.500 0.631341
44.000 0.627413
44.500 0.570218
44.750 0.528313
45.000 0.474648
45.250 0.410816
45.500 0.338546
45.750 0.259717
46.000 0.176339
46.250 0.905149E-01
46.500 0.439488E-02
47.000 -0.159198
47.500 -0.297284
48.000 -0.396185
48.500 -0.446235
49.000 -0.442590
49.500 -0.385661
49.750 -0.343878
50.000 -0.290322
50.250 -0.226583
50.500 -0.154389
50.750 -0.756169E-01
51.000 0.772522E-02
51.250 0.935353E-01
51.500 0.179663
52.000 0.343350
52.500 0.481604
53.000 0.580731
53.500 0.631045
54.000 0.627674
54.500 0.571005
54.750 0.529340
55.000 0.475890
55.250 0.412242
55.500 0.340121
55.750 0.261403
56.000 0.178094
56.250 0.922962E-01
56.500 0.615917E-02
57.000 -0.157627
57.500 -0.296052
58.000 -0.395409
58.500 -0.445990
59.000 -0.442897
59.500 -0.386489
59.750 -0.344945
60.000 -0.291602
60.250 -0.228046
60.500 -0.155999
60.750 -0.773364E-01
61.000 0.593760E-02
61.250 0.917223E-01
61.500 0.177868
62.000 0.341750
62.500 0.480344
63.000 0.579931
63.500 0.630776
64.000 0.627960
64.500 0.571813
64.750 0.530389
65.000 0.477153
65.250 0.413688
65.500 0.341716
65.750 0.263108
66.000 0.179868
66.250 0.940967E-01
66.500 0.794269E-02
67.000 -0.156036
67.500 -0.294801
68.000 -0.394615
68.500 -0.445726
69.000 -0.443187
69.500 -0.387302
69.750 -0.345998
70.000 -0.292869
70.250 -0.229496
70.500 -0.157599
70.750 -0.790459E-01
71.000 0.415880E-02
71.250 0.899169E-01
71.500 0.176079
72.000 0.340153
72.500 0.479087
73.000 0.579130
73.500 0.630507
74.000 0.628244
74.500 0.572621
74.750 0.531437
75.000 0.478415
75.250 0.415135
75.500 0.343311
75.750 0.264814
76.000 0.181645
76.250 0.959001E-01
76.500 0.972990E-02
77.000 -0.154439
77.500 -0.293543
78.000 -0.393814
78.500 -0.445455
79.000 -0.443470
79.500 -0.388108
79.750 -0.347045
80.000 -0.294131
80.250 -0.230942
80.500 -0.159194
80.750 -0.807523E-01
81.000 0.238213E-02
81.250 0.881127E-01
81.500 0.174291
82.000 0.338555
82.500 0.477827
83.000 0.578326
83.500 0.630233
84.000 0.628524
84.500 0.573424
84.750 0.532481
85.000 0.479674
85.250 0.416578
85.500 0.344905
85.750 0.266519
86.000 0.183420
86.250 0.977040E-01
86.500 0.115184E-01
87.000 -0.152840
87.500 -0.292281
88.000 -0.393007
88.500 -0.445179
89.000 -0.443747
89.500 -0.388910
89.750 -0.348087
90.000 -0.295388 如果想要用FFT的方法求出信号的相位，首先数据采样j后各样点之间的时间间隔是等距的，即x(0),x(ΔT),x(2ΔT),x(3ΔT),…，ΔT便是采样周期。但楼主提供的数据，采样周期是在变化的，有时是0.25，有时是0.5（以下给出前50点的图，可明显看到采样周期不是一个常数）， 这样是没有办法用FFT来计算的。同时我怀疑采样周期不是一个常数的条件下用数据拟合的方法是否可行。
回复 #2 songzy41 的帖子
谢谢老兄的启发，我明白了！！！:handshake
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