Talbot Andrew wrote:

[snip]
There seems to be no appreciation on this newsgroup of the real value of
coherent detection - that is, having phase information available when
the signal is decoded and coherently locking to the signal carrier and
bit  timing.   Simple theory, as I covered in a previous email, shows
mathematically the considerable theoretical advantage of coherent
detection over non coherent, there is no dispute about this.
[snip]

Andy,
                from a theoretical point of view you are damn right. But I am
not so sure that LF/HF propagation can preserve phase coherence and
with it the decoding gain achieved with coherent detection, unless you are
willing to use some extra bandwidth to transmit phase information.
But, then, I am not a propagation expert, so my comments stop here.

73,
Alberto   I2PHD