On 5/19/22 3:34 AM, Rob Atkinson wrote:
Propagation is king, but hams can do things to improve contact
probability and lessen the effects of fading.
This is exactly what the models predict. It turns out that if you model two paths,
separated by 2 milliseconds, with random phase, you get Rayleigh fading with 10-20 dB fades.
I forget what speed the "ionosphere clouds" >move at, but it's related to that
- think of the ionosphere as a very lumpy medium with blobs that are several hundred meters
in size all moving around.
When I was in the Army we employed diversity reception and
transmission to combat this. This method is out of reach for most
hams though.
I'm not so sure that it's out of reach. yes, trying to implement it
with gear from 1980 would be challenging. But with more modern
equipment, where the "radio" is a black box controlled by a "front
panel" or "computer" it gets easier.
And the diversity combining - doing it in analog is hard, but in the
digital domain it's much easier, and for the most part it can be done at
audio (or post down conversion to baseband or low IF).
It *is* true that the design and development work is difficult no matter
what way you go - but not everyone has to do that. I'd hate to have to
design and manufacture a NanoVNA, and the firmware to run it, but I
don't have to - someone else did that and we can all benefit from a $50
VNA now. Will the big dogs in manufacturing (YaeKenCom) do it? Maybe,
if there's demand shown.
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