Re: Two examples of failure...
> > I was flipping out for about an hour at work...then I
> > realized that NO ONE is stupid enough to have every
> freaking
> > affiliate across the country realign their dishes.
> They'll
> > probably de-orbit amc-8 and move someone else over with
> less
> > usage.
>
> It has happened in the past.
> Two good example of high profile/high usage satellites which
> failed, causing MAJOR impact.
>
> Galaxy 4. When Galaxy 4 failed, 90% of the US paging
> companies lost satellite reception, along with PBS, WB
> networks (before the WB network itself), and several
> syndicated content including Regis & Kathy Lee (at the
> time).
>
> Telstar 4. When Telstar 4 failed, it was ABC's main primary
> satellite, and FOX's backup. All the ABC affiliates
> nationwide had to scramble to get alternate feeds up until
> both fired up on the , then new, Telstar 6. (Now IA-6).
> (Fortunatley ABC and FOX all had feeds on Telstar 5)
>
Sometimes a single tramsponder can also fail. Usually there is a way to roll in or switch in a transponder from ground control, but that may not always work.
I was on duty at the satellite control center for Americom back in the 80's when TWC, The Weather Channel went off the air. We had a local station engineer in the Atlanta area who ran that earth station go in and try flipping HPA's (High Power Amps)(what the klystron transmitters are called)until we figured out the satellite's transponder went bad. After rolling in a backup was unsuccesful, they wound up staying on the same bird but switching to a different transponder and bumping CSPAN in the process. It all depends what level of backup you pay for when you lease the transponder. CSPAN eventually moved over to a different bird since they where under a less protected rate structure. I'm thinking the satellite in question was C4, which eventually was replaced with a newer bird, but did have 1 transponder out for several years until then.
There are also spare receivers onboard the satellite that can be switched in from ground control (TT&C) if needed.
George Kowal CBNT