[amsat-bb] Re: P3E transponder and launch

Tony Langdon vk3jed at gmail.com
Fri Mar 23 13:38:20 PST 2007

At 12:29 AM 3/24/2007, Bruce Robertson wrote:

> >From my reading, and I'm not an expert, SDX technology is predicted to be
>indistinguishable from a linear xponder to the ground station: I have read

In its most basic configuration, it will be functionally identical to 
an analog transponder, except somewhat better filter 
performance.  The performance on the Odyssey transponder being built 
for SuitSat 2 looks impressive.  And in this basic configuration, the 
ground station need not know the difference.

>no account of entailed losses. What it *does* aim to provide is a newly
>flexible and configurable bent pipe. One obvious application is to limit
>the amount of output power in a given portion of the passband, thereby
>reducing the impact of alligator stations. The audio files posted on this
>list indicate no unnatural artifacts to my ear, and such transponders are
>routinely built to operate with varying modulation schemes.

That's the real beauty of the technology.

>My point is that SDX allows us to dream of these things, and potentially to
>implement them even after the bird is up. Yes, it entails a risk. We're
>fortunate to be able to mitigate this risk: SuitSatII will fly with SDX
>on-board so that we can test this technology. To my mind, the  satellite
>service/hobby is a branch of the hobby that continues to fulfill the
>experimental origins of amateur radio. We need to do so prudently, given
>the cost of launching the hardware into space, but I think the SDX concept
>fits nicely within that curve.

SuitSat 2 is a handy test platform for the technology, that's for 
sure.  It's good to see ham radio continue innovating.

73 de VK3JED

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