From 21bcc8b639e5b0a42d4b98a0f759a6eceeb3be7d Mon Sep 17 00:00:00 2001
From: Bastian Bloessl <mail@bastibl.net>
Date: Mon, 6 Mar 2017 12:46:28 +0100
Subject: [PATCH] equalizer: exclude guards from SNR calculation

Thanks to Stephen Wolfe for reporting
---
 lib/equalizer/lms.cc | 10 +++++-----
 lib/equalizer/ls.cc  | 10 +++++-----
 lib/equalizer/sta.cc | 13 ++++++++-----
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/lib/equalizer/lms.cc b/lib/equalizer/lms.cc
index 395dfc0..fa6396b 100644
--- a/lib/equalizer/lms.cc
+++ b/lib/equalizer/lms.cc
@@ -30,17 +30,17 @@ void lms::equalize(gr_complex *in, int n, gr_complex *symbols, uint8_t *bits, bo
 		double signal = 0;
 		double noise = 0;
 		for(int i = 0; i < 64; i++) {
+			if((i == 32) || (i < 6) || ( i > 58)) {
+				continue;
+			}
 			noise += std::pow(std::abs(d_H[i] - in[i]), 2);
 			signal += std::pow(std::abs(d_H[i] + in[i]), 2);
-		}
-
-		d_snr = 10 * std::log10(signal / noise / 2);
-
-		for(int i = 0; i < 64; i++) {
 			d_H[i] += in[i];
 			d_H[i] /= LONG[i] * gr_complex(2, 0);
 		}
 
+		d_snr = 10 * std::log10(signal / noise / 2);
+
 	} else {
 		int c = 0;
 		for(int i = 0; i < 64; i++) {
diff --git a/lib/equalizer/ls.cc b/lib/equalizer/ls.cc
index e8bdc68..df6043c 100644
--- a/lib/equalizer/ls.cc
+++ b/lib/equalizer/ls.cc
@@ -30,17 +30,17 @@ void ls::equalize(gr_complex *in, int n, gr_complex *symbols, uint8_t *bits, boo
 		double signal = 0;
 		double noise = 0;
 		for(int i = 0; i < 64; i++) {
+			if((i == 32) || (i < 6) || ( i > 58)) {
+				continue;
+			}
 			noise += std::pow(std::abs(d_H[i] - in[i]), 2);
 			signal += std::pow(std::abs(d_H[i] + in[i]), 2);
-		}
-
-		d_snr = 10 * std::log10(signal / noise / 2);
-
-		for(int i = 0; i < 64; i++) {
 			d_H[i] += in[i];
 			d_H[i] /= LONG[i] * gr_complex(2, 0);
 		}
 
+		d_snr = 10 * std::log10(signal / noise / 2);
+
 	} else {
 
 		int c = 0;
diff --git a/lib/equalizer/sta.cc b/lib/equalizer/sta.cc
index 54f9e57..6eee846 100644
--- a/lib/equalizer/sta.cc
+++ b/lib/equalizer/sta.cc
@@ -30,17 +30,17 @@ void sta::equalize(gr_complex *in, int n, gr_complex *symbols, uint8_t *bits, bo
 		double signal = 0;
 		double noise = 0;
 		for(int i = 0; i < 64; i++) {
+			if((i == 32) || (i < 6) || ( i > 58)) {
+				continue;
+			}
 			noise += std::pow(std::abs(d_H[i] - in[i]), 2);
 			signal += std::pow(std::abs(d_H[i] + in[i]), 2);
-		}
-
-		d_snr = 10 * std::log10(signal / noise / 2);
-
-		for(int i = 0; i < 64; i++) {
 			d_H[i] += in[i];
 			d_H[i] /= LONG[i] * gr_complex(2, 0);
 		}
 
+		d_snr = 10 * std::log10(signal / noise / 2);
+
 	} else {
 
 		gr_complex H_update[64];
@@ -81,6 +81,9 @@ void sta::equalize(gr_complex *in, int n, gr_complex *symbols, uint8_t *bits, bo
 		}
 
 		for(int i = 0; i < 64; i++) {
+			if((i < 6) || ( i > 58)) {
+				continue;
+			}
 			d_H[i] = gr_complex(1-alpha,0) * d_H[i] + gr_complex(alpha,0) * H_update[i];
 		}
 	}