Re: Transponder outage

Dave Martin <Dave.Martin@...>
 

Alan - I'd have to beg to differ - whilst you can uplink a whole transponder's worth of content from one teleport; you can equally have many parties' traffic carried over the same transponder, uplinked from a variety of locations.

As I understand it, a basic transponder acts as a frequency-multiplexed "bent-pipe" - anything that comes in, within a particular frequency range (which can be hundreds of MHz) and has the correct polarisation, is re-broadcast back to Earth with a frequency shift applied.

Think of VSAT networks - some admittedly have more complex DAMA (demand assigned) channel allocation - but in the basic single channel per carrier you can have as thin as say 32k equivalent bandwidth, and you rent maybe tens of megs (which in itself is only a portion of a transponder) and then uplink from N terminals in the field.

So - I wouldn't rule out transponder problems - now that could be on-board (as in SSPA) but it could also be a command & control issue .....

Dave

----- Original Message -----
From: Alan Sewards
To: MSG-1@...
Sent: Thursday, October 23, 2003 8:18 AM
Subject: Re: [MSG-1] Re: Transponder outage


Ian,
Why? There will be one uplink transmitter for each transponder and all
the traffic for that transponder will go over it, so if the uplink goes
down, so does the lot. Sounds like finger trouble on the ground to me!

Alan

----- Original Message -----
From: "Ian S Deans" <ian@...>
To: <MSG-1@...>
Sent: Wednesday, October 22, 2003 10:55 PM
Subject: Re: [MSG-1] Re: Transponder outage


> David,
>
> Unlikely I think to be the uplink with all other channels out. My guess is
> problem with the satellite.
>
> Regards
>
> Ian
> ----- Original Message -----
> From: "David Taylor" <david-taylor@...>
> To: <MSG-1@...>
> Sent: Wednesday, October 22, 2003 7:35 PM
> Subject: [MSG-1] Re: Transponder outage
>
> > Thanks for that Ian, you are making good use of your facilities!
> > Presumably, the fault could still have been due to the uplink rather
> > than the satellite itself.
>

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