[Elecraft] Sensitivity - Was K4 Observations

[Robert Rennard]

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