diff options
Diffstat (limited to 'gr-digital/include/digital_impl_mpsk_snr_est.h')
| -rw-r--r-- | gr-digital/include/digital_impl_mpsk_snr_est.h | 88 |
1 files changed, 84 insertions, 4 deletions
diff --git a/gr-digital/include/digital_impl_mpsk_snr_est.h b/gr-digital/include/digital_impl_mpsk_snr_est.h index a96f3e9c1..e530782bc 100644 --- a/gr-digital/include/digital_impl_mpsk_snr_est.h +++ b/gr-digital/include/digital_impl_mpsk_snr_est.h @@ -29,7 +29,7 @@ enum snr_est_type_t { SNR_EST_SIMPLE = 0, // Simple estimator (>= 7 dB) SNR_EST_SKEW, // Skewness-base est (>= 5 dB) SNR_EST_M2M4, // 2nd & 4th moment est (>= 1 dB) - SNR_EST_SVN // SVN-based est (>= 0dB) + SNR_EST_SVR // SVR-based est (>= 0dB) }; /*! @@ -98,6 +98,21 @@ class DIGITAL_API digital_impl_mpsk_snr_est_m2m4 : double d_y1, d_y2; public: + /*! \brief SNR Estimator using 2nd and 4th-order moments. + * + * An SNR estimator for M-PSK signals that uses 2nd (M2) and 4th + * (M4) order moments. This estimator uses knowledge of the + * kurtosis of the signal (k_a) and noise (k_w) to make its + * estimation. We use Beaulieu's approximations here to M-PSK + * signals and AWGN channels such that k_a=1 and k_w=2. These + * approximations significantly reduce the complexity of the + * calculations (and computations) required. + * + * Reference: + * D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR + * estimation techniques for the AWGN channel," IEEE + * Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000. + */ digital_impl_mpsk_snr_est_m2m4(double alpha); ~digital_impl_mpsk_snr_est_m2m4() {} @@ -106,16 +121,81 @@ class DIGITAL_API digital_impl_mpsk_snr_est_m2m4 : double snr(); }; +class DIGITAL_API digital_impl_snr_est_m2m4 : + public digital_impl_mpsk_snr_est +{ + private: + double d_y1, d_y2; + double d_ka, d_kw; + + public: + /*! \brief SNR Estimator using 2nd and 4th-order moments. + * + * An SNR estimator for M-PSK signals that uses 2nd (M2) and 4th + * (M4) order moments. This estimator uses knowledge of the + * kurtosis of the signal (k_a) and noise (k_w) to make its + * estimation. In this case, you can set your own estimations for + * k_a and k_w, the kurtosis of the signal and noise, to fit this + * estimation better to your signal and channel conditions. + * + * A word of warning: this estimator has not been fully tested or + * proved with any amount of rigor. The estimation for M4 in + * particular might be ignoring effectf of when k_a and k_w are + * different. Use this estimator with caution and a copy of the + * reference on hand. + * + * The digital_mpsk_snr_est_m2m4 assumes k_a and k_w to simplify + * the computations for M-PSK and AWGN channels. Use that estimator + * unless you have a way to guess or estimate these values here. + * + * Original paper: + * R. Matzner, "An SNR estimation algorithm for complex baseband + * signal using higher order statistics," Facta Universitatis + * (Nis), no. 6, pp. 41-52, 1993. + * + * Reference used in derivation: + * D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR + * estimation techniques for the AWGN channel," IEEE + * Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000. + */ + digital_impl_snr_est_m2m4(double alpha, double ka, double kw); + ~digital_impl_snr_est_m2m4() {} + + int update(int noutput_items, + gr_vector_const_void_star &input_items); + double snr(); +}; + -class DIGITAL_API digital_impl_mpsk_snr_est_svn : +class DIGITAL_API digital_impl_mpsk_snr_est_svr : public digital_impl_mpsk_snr_est { private: double d_y1, d_y2; public: - digital_impl_mpsk_snr_est_svn(double alpha); - ~digital_impl_mpsk_snr_est_svn() {} + /*! \brief Signal-to-Variation Ratio SNR Estimator. + * + * This estimator actually comes from an SNR estimator for M-PSK + * signals in fading channels, but this implementation is + * specifically for AWGN channels. The math was simplified to + * assume a signal and noise kurtosis (k_a and k_w) for M-PSK + * signals in AWGN. These approximations significantly reduce the + * complexity of the calculations (and computations) required. + * + * Original paper: + * A. L. Brandao, L. B. Lopes, and D. C. McLernon, "In-service + * monitoring of multipath delay and cochannel interference for + * indoor mobile communication systems," Proc. IEEE + * Int. Conf. Communications, vol. 3, pp. 1458-1462, May 1994. + * + * Reference: + * D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR + * estimation techniques for the AWGN channel," IEEE + * Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000. + */ + digital_impl_mpsk_snr_est_svr(double alpha); + ~digital_impl_mpsk_snr_est_svr() {} int update(int noutput_items, gr_vector_const_void_star &input_items); |