论坛 › 信号处理方法 › 请教功率谱密度问题

jingrenzhi 发表于 2007-8-30 10:34

请教功率谱密度问题

对时域离散信号求取功率谱密度,得到的共振频率是否是结构的固有频率?直接做FFT得到的共振频率是否是结构的固有频率?谢谢

[ 本帖最后由 zhangnan3509 于 2007-9-3 09:34 编辑 ]

pengweicai 发表于 2007-8-30 12:31

理论上应该是，但是信号中会存在干扰，所以有些可能不是。需要识别。才能判断。

jingrenzhi 发表于 2007-8-30 16:02

回复 #2 pengweicai 的帖子

谢谢!我现在有这样一组数据,请帮忙求一下功率谱密度!
x=[3.108450e-02
6.311096e-03
6.122705e-03
1.987524e-02
2.496180e-02
3.579427e-03
-2.769346e-02
-2.175915e-02
-4.709773e-04
-2.354886e-02
-6.122705e-02
-2.204174e-02
1.205702e-02
-9.419546e-04
-4.427187e-03
-1.130346e-03
3.862014e-03
1.610742e-02
1.281058e-02
-1.883909e-04
3.664203e-02
6.292257e-02
3.099030e-02
-9.419546e-05
3.617106e-02
7.205953e-02
1.902748e-02
-1.667260e-02
2.006363e-02
4.464865e-02
9.419546e-04
-5.058296e-02
-4.738031e-02
-2.590375e-02
-4.304732e-02
-8.100809e-02
-9.636195e-02
-8.383396e-02
-6.085027e-02
-3.249743e-02
-3.428715e-02
2.693990e-02
6.216900e-02
-1.130346e-03
-1.460030e-02
4.832227e-02
8.647143e-02
3.099030e-02
-8.100810e-03
2.957737e-02
7.130596e-02
3.174387e-02
-4.738031e-02
-5.793021e-02
-8.477591e-04
2.185335e-02
-5.708245e-02
-7.837062e-02
-7.064659e-03
1.817972e-02
-4.285893e-02
-6.292257e-02
7.912419e-03
1.356415e-02
-7.064659e-03
-4.285893e-02
1.799133e-02
6.113285e-02
-4.898164e-03
-4.088083e-02
1.601323e-03
4.596738e-02
1.092667e-02
-4.248215e-02
-1.610742e-02
3.438134e-02
9.136959e-03
-3.852594e-02
-1.987524e-02
3.193226e-02
2.816444e-02
-1.309317e-02
-1.770875e-02
1.224541e-03
9.419546e-05
-7.535637e-04
-9.513741e-03
1.723777e-02
5.124233e-02
1.507127e-02
-7.441441e-03
2.288950e-02
5.435078e-02
3.259163e-02
-2.260691e-03
1.733196e-02
4.945261e-02
3.551169e-02
6.499487e-03
7.912419e-03
3.475812e-02
3.136709e-02
8.948568e-03
4.144600e-03
1.130345e-02
2.298369e-02
7.441441e-03
-2.571536e-02
-1.912168e-02
-4.521382e-03
-7.064659e-03
-2.665731e-02
-2.354886e-02
1.525966e-02
7.912419e-03
-2.449082e-02
-1.695518e-02
1.686099e-02
2.251271e-02
1.422351e-02
1.111506e-02
5.745923e-03
1.007891e-02
1.525966e-02
-1.883909e-04
3.014255e-03
2.458501e-02
2.835283e-02
-3.956209e-03
-1.591903e-02
5.745923e-03
7.912419e-03
-1.478869e-02
-3.287422e-02
-1.318736e-03
4.427187e-03
-3.164968e-02
-5.510434e-02
-5.510434e-02
-5.246687e-02
-5.246687e-02
-2.948318e-02
1.328156e-02
5.095974e-02
4.992359e-02
2.533858e-02
2.825864e-02
6.480648e-02
7.168274e-02
2.515019e-02
-3.391037e-03
3.306261e-02
4.314152e-02
-1.233961e-02
-4.097502e-02
-6.216900e-03
1.450610e-02
-1.375254e-02
-4.709773e-02
-5.632888e-02
-3.004835e-02
-1.054989e-02
-4.615577e-02
-3.419295e-02
3.296841e-02
9.231155e-03
-2.901220e-02
-2.345467e-02
3.117870e-02
4.125761e-02
-1.036150e-02
-1.092667e-02
3.343939e-02
4.285893e-02
1.120926e-02
-3.202646e-03
2.750507e-02
4.295313e-02
1.111506e-02
-3.391037e-03
1.582484e-02
-1.733196e-02
-9.994138e-02
-6.499486e-02
-2.119398e-02
-1.480753e-01
-1.990350e-01
-9.410126e-02
-1.477927e-01
-3.462625e-01
-4.149310e-01
-4.708831e-01
-1.010811e+00
-1.103029e+00
-6.396813e-01
-7.681640e-01
-1.074111e+00
-9.226445e-01
-6.099156e-01
-5.410587e-01
-2.343583e-01
-9.155799e-02
2.392565e-02
3.492768e-01
6.162267e-01
5.984237e-01
6.337470e-01
9.224561e-01
5.990831e-01
2.632763e-01
1.882967e-01
1.601323e-03
-3.008603e-01
-5.423774e-01
-7.700478e-01
-8.698950e-01
-7.590270e-01
-8.123416e-01
-9.312163e-01
-7.183346e-01
-4.387624e-01
-2.159902e-01
-2.920059e-03
2.816444e-01
5.791137e-01
6.409059e-01
7.160739e-01
6.838590e-01
6.871558e-01
6.669039e-01
3.880853e-01
6.414711e-02
-8.477591e-04
-1.154836e-01
-4.481820e-01
-6.384568e-01
-6.319573e-01
-6.480647e-01
-6.588030e-01
-6.127415e-01
-5.111045e-01
-3.375965e-01
-9.843425e-02
1.275406e-01
2.497122e-01
5.420948e-01
7.206894e-01
6.485357e-01
6.254578e-01
6.685051e-01
6.429782e-01
4.123877e-01
1.985640e-01
4.483704e-02
-1.077596e-01
-2.544219e-01
-5.232558e-01
-6.913946e-01
-6.123646e-01
-5.926778e-01
-6.285663e-01
-5.580139e-01
-4.430954e-01
-4.162497e-01
-1.441191e-01
3.473929e-01
5.938082e-01
7.035459e-01
7.856843e-01
7.666568e-01
7.484771e-01
6.509848e-01
5.024385e-01
2.742972e-01
1.444958e-01
1.660666e-01
6.311096e-02
-3.172503e-01
-7.228559e-01
-6.589914e-01
-6.220668e-01
-6.392103e-01
-5.240093e-01
-3.636886e-01
-9.165218e-02
1.710590e-01
3.617105e-01
5.111988e-01
7.097628e-01
7.380214e-01
7.574257e-01
7.056181e-01
6.662444e-01
5.089381e-01
2.451908e-01
9.381867e-02
2.006363e-02
-2.009189e-01
-5.425658e-01
-6.525861e-01
-6.664329e-01
-6.168860e-01
-5.627236e-01
-4.925480e-01
-2.679861e-01
-2.232432e-02
1.230193e-01
2.679861e-01
4.416825e-01
5.847654e-01
7.668452e-01
7.397169e-01
7.059007e-01
6.506080e-01
4.878383e-01
3.393862e-01
1.306491e-01
-6.405291e-02
-1.552341e-01
-3.743328e-01
-5.758168e-01
-5.301321e-01
-4.913235e-01
-4.028740e-01
-3.554937e-01
-2.369958e-01
-2.637473e-03
2.501831e-01
3.489942e-01
4.788897e-01
6.279069e-01
7.007200e-01
6.785841e-01
5.703535e-01
4.491239e-01
3.404224e-01
1.725661e-01
8.760178e-03
-1.404454e-01
-3.035920e-01
-4.121993e-01
-5.528331e-01
-5.663031e-01
-4.977288e-01
-3.721662e-01
-2.665731e-01
-1.639943e-01
3.004835e-02
3.081133e-01
4.684340e-01
5.241977e-01
6.519268e-01
6.965754e-01
6.727440e-01
5.637598e-01
4.784187e-01
3.998597e-01
2.172147e-01
-4.059824e-02
-1.877315e-01
-2.807025e-01
-3.672681e-01
-4.364076e-01
-4.491239e-01
-3.747095e-01
-2.710003e-01
-1.587193e-01
-2.562116e-02
1.677621e-01
3.605802e-01
4.660791e-01
5.221254e-01
6.086910e-01
6.474996e-01
6.124589e-01
5.332405e-01
3.999539e-01
2.854122e-01
1.322504e-01
9.042764e-03
-5.416239e-02
-2.331337e-01
-4.090909e-01
-4.108806e-01
-4.480878e-01
-4.073012e-01
-3.530446e-01
-2.302137e-01
3.174387e-02
1.948904e-01
3.465451e-01
4.784187e-01
5.242919e-01
5.767588e-01
6.015322e-01
5.874029e-01
4.758754e-01
3.052875e-01
1.820798e-01
7.799384e-02
-4.182278e-02
-1.996002e-01
-3.560588e-01
-3.688694e-01
-4.008959e-01
-4.217131e-01
-3.473929e-01
-1.977163e-01
-6.066187e-02
-1.328156e-02
9.655035e-02
3.399514e-01
4.903815e-01
5.199589e-01
5.665857e-01
5.533041e-01
5.096916e-01
3.938312e-01
2.618634e-01
1.332866e-01
1.186863e-02
-9.400707e-02
-1.466623e-01
-2.459443e-01
-4.071128e-01
-3.938312e-01
-3.575659e-01
-3.035920e-01
-1.600381e-01
-4.012727e-02
7.140016e-02
1.781236e-01
3.603918e-01
4.743683e-01
5.070542e-01
5.134594e-01
4.803026e-01
4.412115e-01
3.435308e-01
2.045925e-01
5.906055e-02
-5.670566e-02
-1.522199e-01
-2.858832e-01
-3.852594e-01
-3.998597e-01
-3.975990e-01
-3.581311e-01
-3.034978e-01
-1.726603e-01
-4.530802e-02
-5.651727e-03
1.490172e-01
3.380675e-01
3.815858e-01
4.732380e-01
4.824691e-01
4.226550e-01
3.752747e-01
3.013313e-01
2.530090e-01
4.879325e-02
-1.430829e-01
-1.972453e-01
-2.856948e-01
-3.616164e-01
-3.668913e-01
-3.487116e-01
-3.018965e-01
-2.438720e-01
-1.992234e-01
-6.640780e-02
1.382789e-01
2.235258e-01
2.946434e-01
3.540807e-01
3.631235e-01
3.611454e-01
3.061352e-01
2.321918e-01
1.268813e-01
3.843175e-02
-5.529273e-02
-1.645595e-01
-2.519729e-01
-2.973751e-01
-3.060410e-01
-3.043455e-01
-2.850355e-01
-2.314382e-01
-1.693634e-01
-8.091389e-02
3.504071e-02
1.245264e-01
2.131643e-01
2.616750e-01
2.985054e-01
2.910640e-01
2.522554e-01
2.259749e-01
1.455320e-01
3.993887e-02
-3.504071e-02
-1.083248e-01
-1.716241e-01
-2.385971e-01
-2.844703e-01
-2.672325e-01
-2.684571e-01
-2.352061e-01
-1.786888e-01
-9.306511e-02
4.427187e-03
7.262470e-02
1.165198e-01
1.704938e-01
2.217361e-01
2.276704e-01
1.958324e-01
1.590019e-01
1.160488e-01
4.681514e-02
-3.033094e-02
-8.957988e-02
-1.108681e-01
-1.152952e-01
-1.788772e-01
-2.616750e-01
-2.533858e-01
-2.291775e-01
-1.937601e-01
-1.280116e-01
-7.780544e-02
5.651728e-04
5.906055e-02
1.019195e-01
1.567412e-01
1.634291e-01
1.410106e-01
1.215121e-01
1.032382e-01
5.463336e-02
-2.590375e-02
-8.345717e-02
-9.843425e-02
-9.259413e-02
-9.353609e-02
-9.363028e-02
-1.205702e-01
-1.848115e-01
-1.929123e-01
-1.437423e-01
-1.007891e-01
-4.022146e-02
1.346995e-02
5.736503e-02
8.534108e-02
1.218889e-01
1.190631e-01
9.221735e-02
6.103865e-02
4.238795e-02
1.130346e-03
-6.216900e-02
-1.013543e-01
-1.188747e-01
-1.569296e-01
-1.797249e-01
-1.813263e-01
-1.862244e-01
-1.592845e-01
-1.273523e-01
-1.184037e-01
-1.057815e-01
-4.135181e-02
4.125761e-02
6.085027e-02
7.799384e-02
9.909362e-02
8.430494e-02
6.612521e-02
3.720720e-02
1.007891e-02
-2.665731e-02
-6.480648e-02
-9.626776e-02
-1.183095e-01
-1.295187e-01
-1.400687e-01
-1.469449e-01
-1.488288e-01
-1.296130e-01
-9.202896e-02
-6.094446e-02
-2.938898e-02
2.882381e-02
3.956209e-02
5.604630e-02
7.761706e-02
6.640780e-02
4.860486e-02
3.240324e-02
2.006363e-02
-8.006614e-03
-3.249743e-02
-5.651727e-02
-7.130596e-02
-8.100809e-02
-1.015427e-01
-9.014505e-02
-7.997194e-02
-7.130596e-02
-6.989303e-02
-6.113285e-02
-2.703410e-02
8.477591e-03
1.290478e-02
3.711301e-02
5.011198e-02
3.315680e-02
2.637473e-02
2.420823e-02
1.582484e-02
-9.796328e-03
-2.618634e-02
-3.419295e-02
-4.304732e-02
-4.709773e-02
-4.530802e-02
-5.105394e-02
-5.566952e-02
-5.077135e-02
-4.502543e-02
-3.372197e-02
-1.968685e-02
-5.180750e-03
2.920059e-03
1.224541e-03
1.582484e-02
1.563645e-02
7.818223e-03
1.064409e-02
7.347246e-03
-1.186863e-02
-2.015783e-02
-1.507127e-02
-2.515019e-02
-2.882381e-02
-2.562116e-02
-2.656312e-02
-2.411404e-02
-2.486760e-02
-2.496180e-02
-2.100559e-02
-1.215121e-02
-6.311096e-03
-1.667260e-02
-1.968685e-02
-8.571787e-03
-4.521382e-03
-1.243380e-02
-9.419546e-03
2.825864e-04
-4.521382e-03
-9.042764e-03
-4.144600e-03
1.130346e-03
-3.579427e-03
-3.202646e-03
9.419546e-04
9.419546e-05
-6.876268e-03
-1.497708e-02
-1.770875e-02
-2.204174e-02
-1.846231e-02
-1.346995e-02
-1.573064e-02
-9.607936e-03
-2.543277e-03
-1.252800e-02
-1.497708e-02
-1.281058e-02
-1.281058e-02
-8.100810e-03
-5.557532e-03
9.419546e-05
-1.978105e-03
-4.050405e-03
-3.767818e-04
1.883909e-04
-1.318736e-03
-1.036150e-03
-3.108450e-03
-3.485232e-03
2.260691e-03
-1.883909e-04
-9.702132e-03
-1.045570e-02
-7.629832e-03
-8.477591e-03
-8.760178e-03
-7.724028e-03
-8.665982e-03
-1.215121e-02
-1.243380e-02
-1.507127e-02
-9.702132e-03
-3.956209e-03
-8.289200e-03
-9.607936e-03
-1.412932e-03
-1.883909e-03
-4.050405e-03
-3.202646e-03
-1.601323e-03
2.449082e-03
2.543277e-03
-2.543277e-03
8.477591e-04
4.521382e-03
1.036150e-03
1.036150e-03
3.673623e-03
4.709773e-04
-4.050405e-03
1.318736e-03
7.535637e-04
-4.050405e-03
-5.840119e-03
-1.149185e-02
-7.158855e-03
-4.521382e-03
-1.168024e-02
-1.064409e-02
-8.948568e-03
-8.760178e-03
-6.499487e-03
-5.745923e-03
-1.412932e-03
3.673623e-03
-4.709773e-04
2.072300e-03
5.369141e-03
1.695518e-03
1.318736e-03
2.260691e-03
9.796328e-03
1.111506e-02
3.862014e-03
1.789714e-03
-7.535637e-04
-1.130346e-03
-3.767818e-04
-3.956209e-03
-5.086555e-03
-3.391037e-03
-2.825864e-03
-6.405291e-03
-6.122705e-03
-7.629832e-03
-9.042764e-03
-1.412932e-03
-8.477591e-04
-2.260691e-03
3.296841e-03
4.238795e-03
3.202646e-03
8.195004e-03
5.369141e-03
3.485232e-03
0.000000e+00
-4.427187e-03
3.579427e-03
3.296841e-03
-6.593682e-04
7.535637e-04
-1.318736e-03
1.036150e-03
3.391037e-03
-8.477591e-04
1.695518e-03
-2.825864e-03
-3.296841e-03
4.144600e-03
-6.593682e-04
9.419546e-04
2.543277e-03
5.651728e-04
-5.180750e-03
-1.073828e-02
-4.898164e-03
-6.876268e-03
-8.383396e-03
-9.419546e-05
-1.601323e-03
7.535637e-04
7.253050e-03
3.202646e-03
3.485232e-03
6.876268e-03
4.615577e-03
6.593682e-03
7.535636e-03
4.144600e-03
2.825864e-03
-4.709773e-03
-4.144600e-03
6.122705e-03
9.419546e-04
-3.296841e-03
-2.543277e-03
-2.825864e-03
1.601323e-03
-5.840119e-03
-6.970464e-03
-2.166495e-03
-4.521382e-03
-4.332991e-03
-2.543277e-03
-1.130346e-03
-2.260691e-03
-2.920059e-03
4.615577e-03
3.956209e-03
-5.651728e-04
1.318736e-03
3.862014e-03
6.028509e-03
5.086555e-03
7.347246e-03
5.934314e-03
2.354886e-03
3.767818e-03
6.593682e-03
3.579427e-03
4.709773e-03
6.687877e-03
1.789714e-03
-1.168024e-02
-1.488288e-02
-9.325351e-03
-3.391037e-03
4.709773e-04
-5.274945e-03
-7.535637e-04
-4.992359e-03
-3.296841e-03
1.507127e-03
1.036150e-03
4.238795e-03
3.862014e-03
9.136959e-03
9.607936e-03
4.803968e-03
4.803968e-03
7.441441e-03
9.419546e-03
8.477591e-03
8.854373e-03
8.760178e-03
3.296841e-03
7.818223e-03
1.130345e-02
6.405291e-03
1.695518e-03
-3.202646e-03
-3.108450e-03
-2.825864e-04
6.593682e-04
3.767818e-04
2.920059e-03
1.412932e-03
2.637473e-03
1.318736e-03
-1.036150e-03
2.731668e-03
-6.593682e-04
3.767818e-04
4.144600e-03
1.007891e-02
6.405291e-03
3.862014e-03
7.441441e-03
8.289200e-03
9.702132e-03
6.216900e-03
5.274945e-03
2.354886e-03
2.637473e-03
0.000000e+00
1.130346e-03
1.978105e-03
6.593682e-04
1.883909e-03
-3.014255e-03
-2.449082e-03
-1.601323e-03
-1.883909e-04
-3.767818e-03
-3.296841e-03
8.477591e-04
7.535637e-04
-3.108450e-03
-6.216900e-03
-1.883909e-04
1.507127e-03
3.296841e-03
3.579427e-03
2.072300e-03
6.782073e-03
8.100810e-03
8.289200e-03
7.064659e-03
8.854373e-03
8.477591e-03
6.216900e-03
3.956209e-03
1.130346e-03
5.651728e-04
-2.260691e-03
-3.202646e-03
-6.876268e-03
-4.238795e-03
2.825864e-04
-2.072300e-03
5.651728e-04
0.000000e+00
-8.477591e-04
2.166495e-03
4.615577e-03
4.803968e-03
5.840119e-03
5.745923e-03
5.369141e-03
2.166495e-03
2.449082e-03
5.840119e-03
5.934314e-03
6.028509e-03
4.427187e-03
3.108450e-03
3.767818e-03
3.956209e-03
5.840119e-03
1.412932e-03
7.535637e-04
1.978105e-03
-2.354886e-03
1.318736e-03
2.166495e-03
4.144600e-03
2.637473e-03
-2.543277e-03
-4.050405e-03
9.419546e-05
-2.166495e-03
2.825864e-03
2.354886e-03
6.593682e-04
2.072300e-03
-6.593682e-04
4.709773e-04
2.637473e-03
7.347246e-03
1.007891e-02
7.724028e-03
6.311096e-03
6.593682e-03
6.593682e-03
7.253050e-03
5.651727e-03
3.673623e-03
2.166495e-03
1.130346e-03
-1.036150e-03
-2.072300e-03
-1.412932e-03
-2.166495e-03
-2.166495e-03
-6.593682e-04
-3.014255e-03
-3.673623e-03
-5.369141e-03
-3.767818e-03
1.601323e-03
5.557532e-03
3.296841e-03
4.238795e-03
4.615577e-03
8.195004e-03
1.054989e-02
7.158855e-03
8.383396e-03
9.419546e-03
6.782073e-03
4.898164e-03
-2.354886e-03
-3.108450e-03
-4.709773e-04
-3.485232e-03
3.391037e-03
6.687877e-03
2.637473e-03
1.036150e-03
-4.898164e-03
4.709773e-04
2.731668e-03
9.419546e-04
-7.535637e-04
-3.485232e-03
4.238795e-03
4.521382e-03
6.687877e-03
8.195004e-03
5.745923e-03
5.745923e-03
4.992359e-03
6.311096e-03
6.687877e-03
3.956209e-03
-1.224541e-03
-5.557532e-03
-3.767818e-03
];

caichengtao 发表于 2007-9-2 23:45

楼上的，希望你能把数据存成一个数据文件，作为附件上传！节省论坛版面空间啊！

jingrenzhi 发表于 2007-9-3 09:06

回复 #4 caichengtao 的帖子

谢谢提醒!可是我不知道怎么贴附件呀?

sunning 发表于 2007-9-3 13:12

在发表帖子时，上传附件就可以了

sunning 发表于 2007-9-3 13:22

你的采样频率是多少？

sunning 发表于 2007-9-3 13:32

我把你的数据分析了一下，用功率谱画了图
不知道你的采样频率是多少，看到你的数据是1024个，我就取采样频率是4096Hz了
第一阶频率大概是200Hz左右

wanyeqing2003 发表于 2007-9-3 13:34

响应的峰值不一定在共振频率处。

共振频率或者固有频率应该由传递函数来确定。

sunning 发表于 2007-9-3 15:10

wanyeqing2003 说的对，共振频率应该是模态的概念，要通过测量FRF来获得
我这个只是将他给的数据进行了自功率谱转换，得到响应的谱线
激励频率为一个（或多个）时的响应谱线的峰值，只代表在此激励频率下的最大响应值，而不一定是该结构的固有频率。如果激励频率中包含有固有频率的话，那这个峰值就是结构的固有频率。不过这似乎有点右果推因的感觉，所以要获得固有频率还是做结构的模态。

jingrenzhi 发表于 2007-9-3 16:09

回复 #10 sunning 的帖子

谢谢,我的采样频率应该是500!
请把您做功率谱的程序共享下好吗?我再学学!谢谢!

查看完整版本: 请教功率谱密度问题