[Elecraft] Diversity Receive as Noise Canceling?

[Erik Basilier]

I am not familiar with the ANC-4, but I assume it is similar to the MFJ
noise cancellers. Those units are not "receivers" but work with the weak
antenna signals at the originally transmitted frequencies. Aside from some
signal buffering, such a unit essentially provides the capability to
continuously adjust the phase difference and relative gain between the two
inputs, and to do this at a wide variety of ham band frequencies. If you
instead feed the two antennas into twin receivers, you would have to adjust
amplitude and phase at the output. At audio frequency it is hard enough to
build a phase shifting network that maintains constant phase shift over a
reasonable audio frequency range, but if you want to make that phase shift
continuously knob adjustable it becomes really hard. The DSP in the K3 has
potential as a precision phase shifter, but consider that the
frequency-dependent phase shifts that may be caused by the different xtal
filter specimens and analog components in each receiver may have already
messed up the phase relationships by the time the signal gets to DSP or
receiver output.

 

73,

Erik K7TV