[time-nuts] Sun Outage
Dr. David Kirkby (Kirkby Microwave Ltd)
drkirkby at kirkbymicrowave.co.uk
Thu Oct 9 17:53:22 EDT 2014
On 9 Oct 2014 22:17, "Andrew Rodland" <andrew at cleverdomain.org> wrote:
> You pick up satellite TV with a parabolic dish that points at one spot
> in the sky where the geostationary satellite lives. A sun outage
> happens when the sun wanders into the focus and overloads the receiver
> with noise that drowns out the satellite signal (at least, it raises
> the noise floor enough that you can't receive the high bitrates needed
> for a TV picture).
> You pick up GPS with a whole-sky antenna that receives signals from
> the constantly-moving swarm of GPS satellites. It undoubtedly receives
> some noise from the sun, but the only factor in how much of that you
> get is the sun's elevation above the horizon. It's not really relevant
> whether the sun is "aligned with a satellite" or not. Even if it was,
> the satellite would be somewhere else a minute later. :)
Also the much higher gain of the satellite antenna means if the Sun is in
its beamwidth, a much larger increase in noise will occur.
I would actually be concerned about the Sun heating (melting ??) the
receiver, like I expect we have all done with a magnifying glass. The
capture area of a dish is a lot more than any "normal" magnifying glass.
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