diff options
| author | Tom Rondeau <trondeau@vt.edu> | 2011-12-29 15:38:49 -0500 |
|---|---|---|
| committer | Tom Rondeau <trondeau@vt.edu> | 2011-12-29 15:38:49 -0500 |
| commit | 886e3c258ff40b4d10e7e8fc28912f14565a4fd1 (patch) | |
| tree | befcf76a159a74300d4ef7aef93664cfc3c9095c /gr-digital/lib/digital_impl_mpsk_snr_est.cc | |
| parent | 2db40bb40eda996bf47417a04ec001acb422d3d9 (diff) | |
digital: adding documentation for SNR estimators; added an estimator for M2M4 type that allows the user to set the kurtosis of the signal and noise, if known, to work with non-MPSK and non-AWGN channels (untested).
Also, the technique is signal to variation ratio (SVR), not SVN. Couldn't read my own writing.
Diffstat (limited to 'gr-digital/lib/digital_impl_mpsk_snr_est.cc')
| -rw-r--r-- | gr-digital/lib/digital_impl_mpsk_snr_est.cc | 50 |
1 files changed, 47 insertions, 3 deletions
diff --git a/gr-digital/lib/digital_impl_mpsk_snr_est.cc b/gr-digital/lib/digital_impl_mpsk_snr_est.cc index 8adc6ffed1..87ac84e044 100644 --- a/gr-digital/lib/digital_impl_mpsk_snr_est.cc +++ b/gr-digital/lib/digital_impl_mpsk_snr_est.cc @@ -187,7 +187,51 @@ digital_impl_mpsk_snr_est_m2m4::snr() /********************************************************************/ -digital_impl_mpsk_snr_est_svn::digital_impl_mpsk_snr_est_svn( +digital_impl_snr_est_m2m4::digital_impl_snr_est_m2m4( + double alpha, double ka, double kw) : + digital_impl_mpsk_snr_est(alpha) +{ + d_y1 = 0; + d_y2 = 0; + d_ka = ka; + d_kw = kw; +} + +int +digital_impl_snr_est_m2m4::update( + int noutput_items, + gr_vector_const_void_star &input_items) +{ + const gr_complex *in = (const gr_complex *) input_items[0]; + + for (int i = 0; i < noutput_items; i++) { + double y1 = abs(in[i])*abs(in[i]); + d_y1 = d_alpha*y1 + d_beta*d_y1; + + double y2 = abs(in[i])*abs(in[i])*abs(in[i])*abs(in[i]); + d_y2 = d_alpha*y2 + d_beta*d_y2; + } + return noutput_items; +} + +double +digital_impl_snr_est_m2m4::snr() +{ + double M2 = d_y1; + double M4 = d_y2; + double s = M2*(d_kw - 2) + + sqrt((4.0-d_ka*d_kw)*M2*M2 + M4*(d_ka+d_kw-4.0)) / + (d_ka + d_kw - 4.0); + double n = M2 - s; + + return 10.0*log10(s / n); +} + + +/********************************************************************/ + + +digital_impl_mpsk_snr_est_svr::digital_impl_mpsk_snr_est_svr( double alpha) : digital_impl_mpsk_snr_est(alpha) { @@ -196,7 +240,7 @@ digital_impl_mpsk_snr_est_svn::digital_impl_mpsk_snr_est_svn( } int -digital_impl_mpsk_snr_est_svn::update( +digital_impl_mpsk_snr_est_svr::update( int noutput_items, gr_vector_const_void_star &input_items) { @@ -215,7 +259,7 @@ digital_impl_mpsk_snr_est_svn::update( } double -digital_impl_mpsk_snr_est_svn::snr() +digital_impl_mpsk_snr_est_svr::snr() { double x = d_y1 / (d_y2 - d_y1); return 10.0*log10(2.*((x-1) + sqrt(x*(x-1)))); |