I believe there is a bug in file gr-channels/lib/flat_fader_impl.cc,
line 67
according to Eq.4 of paper “Improved Models for the Generation of
Multiple
Uncorrelated Rayleigh Fading Waveforms” published on IEEE COMMUNICATIONS
LETTERS, VOL. 6, NO. 6, JUNE 2002,
that line should be changed from:
float alpha_n = (2*M_PI*n - M_PI + d_theta)/4*d_N;
to:
float alpha_n = (2*M_PI*n - M_PI + d_theta)/(4*d_N);