randnase.txt

产生随机高斯白噪声

// Debug the sigma through the spectrum
				     sprintf(filename4, "SP_ch%d_1.dat", index_ch[j]);
				    output_spectrum(filename4, field_ch2, f[j], sp_res, wl, lambda, 2.0);
				     double u=0, z=0;
				     for (i=0;i<mnb;i++) 
				       {
				         u += field_ch2.noise[i].re*field_ch2.noise[i].re;
				         u += field_ch2.noise[i].im*field_ch2.noise[i].im;
				       }
				     printf("\n noise power = %g", u);
				   
				     osnr_cal2_n(osnr_1, P_n, field_ch2, f, nch, fsp_n);
				   
				     double sigma1;
				     sigma1 = pow(10.0, 0.1*P_n[j])/12.5;   // ASE power density with two polarization
				     sigma1 *= bwsim/mnb*(mnb-1.0);      // total ASE power in mW 
				     for (i=0;i<mnb;i++) 
				      {
				         u = xrandom();
				         z = sqrt(-0.5*sigma1*2.0*log(1.0-u));
				         u = xrandom();
				         field_ch2.noise[i].re = z*cos(TWOPI*u);
				        field_ch2.noise[i].im = z*sin(TWOPI*u);
				       }
				   
				   u=0;
				     for (i=0;i<mnb;i++) 
				       {
				         u += field_ch2.noise[i].re*field_ch2.noise[i].re;
				         u += field_ch2.noise[i].im*field_ch2.noise[i].im;
				      }
				   printf("\n noise power = %g, bw_step = %g", u, bw_step);
				   
				    sprintf(filename4, "SP_ch%d_2.dat", index_ch[j]);
				    output_spectrum(filename4, field_ch2, f[j], sp_res, wl, lambda, 2.0);
				   
				    sprintf(filename4, "ber_osnr_bb_ch%d_PMD%g.dat", index_ch[j], para_bb);
// Debug the sigma through the spectrum