[time-nuts] Sun Outage
brooke at pacific.net
Thu Oct 9 18:28:18 EDT 2014
The small size of the Ku-band TV dish and that it's surface is covered with a "flat" type paint means there's little or
no thermal heating of the receiver or feed.
There were cases with the early C-band TVRO systems where they did melt the receiver.
Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
> 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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