Regarding W0YK/Ed’s comment  – 

The 8-ary FSK of FT-8 may be buried in the ambient noise at my/your/somebody’s 
QTH.  Like LPI communications, knowing where to look in frequency and time 
allows the decoder to combine noisy samples and recover the original; in the 
case of FT-8, a 63 bit message.  Your receiver does not hear the 63 bits, just 
the symbols used in statistically recreating the 63 bits.

The real issue with sensitivity or receiver NF is making sure that the receiver 
is a weak contributor to the overall noise power entering the detection process 
which is generally dominated by ambient noise.  Most of the radios in the top 
Sherwood top 10 are weak contributors in most locations, even in the 
CCIR-defined quiet rural environments.

73  Bob R – N7WY

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