From 2039af90a2fac44b6593d0a380a2d3f32a713964 Mon Sep 17 00:00:00 2001
From: Ahmet Inan <xdsopl@gmail.com>
Date: Wed, 18 May 2022 12:05:47 +0200
Subject: [PATCH] simplified precision estimation

---
 decode.cc | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/decode.cc b/decode.cc
index 3f593c4..c1a4337 100644
--- a/decode.cc
+++ b/decode.cc
@@ -513,12 +513,9 @@ struct Decoder
 				sp += norm(hard);
 				np += norm(error);
 			}
-			value snr = DSP::decibel(sp / np);
+			precision = sp / np;
+			value snr = DSP::decibel(precision);
 			std::cerr << "init Es/N0: " << snr << " dB" << std::endl;
-			// $LLR=log(\frac{p(x=+1|y)}{p(x=-1|y)})$
-			// $p(x|\mu,\sigma)=\frac{1}{\sqrt{2\pi}\sigma}}e^{-\frac{(x-\mu)^2}{2\sigma^2}}$
-			value sigma = std::sqrt(np / (2 * sp));
-			precision = 1 / (sigma * sigma);
 		}
 		for (int i = 0; i < cons_cnt; ++i)
 			mod_soft(code+mod_bits*i, cons[i], precision);