diff --git a/demod/mod/README.md b/demod/mod/README.md
index 8efe5d5..3cd0687 100644
--- a/demod/mod/README.md
+++ b/demod/mod/README.md
@@ -60,6 +60,8 @@ alternative decoders using cross-correlation for better header-synchronization
   code does most of the error correction. The concatenated outer Reed-Solomon code kicks in only at low SNR.
 
   soft input:<br />
-  Option `--softin` expects float32 symbols as input
+  Option `--softin` expects float32 symbols as input, with `s>0` corresponding to `bit=1`.<br />
+  (remark/caution: often soft bits are defined as `bit=0 -> s=+1` and `bit=1 -> s=-1` such that the identity element `0`
+  for addition mod 2 corresponds to the identity element `+1` for multiplication.)
 
 
diff --git a/ecc/ecc_hamming.pdf b/ecc/ecc_hamming.pdf
index 5dd986c..31a42c6 100644
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diff --git a/iq/iq_demod.pdf b/iq/iq_demod.pdf
index f61094b..b2bb124 100644
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