Noise.py
108 lines
| 2.7 KiB
| text/x-python
|
PythonLexer
Victor Sarmiento
|
r83 | import numpy | ||
| from Model.JROHeader import * | ||||
| from Model.Voltage import Voltage | ||||
| def hildebrand_sekhon(Data, navg=1 ): | ||||
| """ | ||||
| This method is for the objective determination of de noise level in Doppler spectra. This | ||||
| implementation technique is based on the fact that the standard deviation of the spectral | ||||
| densities is equal to the mean spectral density for white Gaussian noise | ||||
| Inputs: | ||||
| Data : heights | ||||
| navg : numbers of averages | ||||
| Return: | ||||
| -1 : any error | ||||
| anoise : noise's level | ||||
| """ | ||||
| divisor = 8 | ||||
| ratio = 7 / divisor | ||||
| data = Data.reshape(-1) | ||||
| npts = data.size #numbers of points of the data | ||||
| if npts < 32: | ||||
| print "error in noise - requires at least 32 points" | ||||
| return -1.0 | ||||
| # data sorted in ascending order | ||||
| nmin = int(npts/divisor + ratio); | ||||
| s = 0.0 | ||||
| s2 = 0.0 | ||||
| data2 = data[:npts] | ||||
| data2.sort() | ||||
| for i in range(nmin): | ||||
| s += data2[i] | ||||
| s2 += data2[i]**2; | ||||
| icount = nmin | ||||
| iflag = 0 | ||||
| for i in range(nmin, npts): | ||||
| s += data2[i]; | ||||
| s2 += data2[i]**2 | ||||
| icount=icount+1; | ||||
| p = s / float(icount); | ||||
| p2 = p**2; | ||||
| q = s2 / float(icount) - p2; | ||||
| leftc = p2; | ||||
| rightc = q * float(navg); | ||||
| if leftc > rightc: | ||||
| iflag = 1; #No weather signal | ||||
| # Signal detect: R2 < 1 (R2 = leftc/rightc) | ||||
| if(leftc < rightc): | ||||
| if iflag: | ||||
| break | ||||
| anoise = 0.0; | ||||
| for j in range(i): | ||||
| anoise += data2[j]; | ||||
| anoise = anoise / float(i); | ||||
| return anoise; | ||||
| class Noise(): | ||||
| """ | ||||
| Clase que implementa los metodos necesarios para deternimar el nivel de ruido en un Spectro Doppler | ||||
| """ | ||||
| m_DataObj = None | ||||
| def __init__(self, m_Voltage=None): | ||||
| """ | ||||
| Inicializador de la clase Noise para la la determinacion del nivel de ruido en un Spectro Doppler. | ||||
| Affected: | ||||
| self.m_DataObj | ||||
| Return: | ||||
| None | ||||
| """ | ||||
| # if m_Voltage == None: | ||||
| # m_Voltage = Voltage() | ||||
| # | ||||
| # if not(isinstance(m_Voltage, Voltage)): | ||||
| # raise ValueError, "in Noise class, m_Voltage must be an Voltage class object" | ||||
| self.m_DataObj = m_Voltage | ||||
| def getNoiseLevelByHildebrandSekhon(self): | ||||
| """ | ||||
| Determino el nivel de ruido usando el metodo Hildebrand-Sekhon | ||||
| Return: | ||||
| noise level | ||||
| """ | ||||
| data = self.m_DataObj.data # heights x perfiles | ||||
| #heights = numpy.transpose( Data, (2,0,1) ) # channel x profile x height | ||||
| #data = Data[0,0,:] | ||||
| noiselevel = hildebrand_sekhon(data) | ||||
| print noiselevel | ||||