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Re: ECHO Operations Planning



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On Oct 19 2003 19:32 -0400, Bob Bruninga wrote:

> MODE RX   DESCRIPTION               UPLINK      DOWNLINK
> ---- --- -------------------------- ----------  -----------
>  E   RX4 Experimental
>  -       (HF) Multiuser             29.400      S-Band WFM
>          (LV) Lband Voice           12xx.xxx    S-Band WFM
>          (LB) Lband Bent Pipe       12xx.xxx    S-Band WFM
>          (LD) Lband digital         12xx.xxx    S-Band Digital

Just thinking (and, as it looks, it's going to be a while before I can become
active on the amateur satellites), wouldn't using wideband FM be a huge waste
of spectrum? (There are wide S-band amateur allocations, but not infinite.)
Yes, Doppler shift is a concern, but is it really *that* much of a problem?
Also, how would this affect SSB signals (not just voice SSB), and especially
a situation where multiple SSB signals are present throughout the transponder
passband - say, a few CW users around 29.400 and a couple of PSK31
transmitters at 29.402?

I believe that today, computer control of radio equipment is more of the norm
than it has ever been. This makes automatic correction for Doppler shift on
both the up- and downlink quite feasible.

Some modes, especially high-speed packet, could probably benefit a lot from a
wide bandwidth link in terms of tuning ease. But voice and narrow-band
digital modes (CW, PSK31)?

After all, what's the situation on AO-40? I don't hear people complaining
that finding and keeping your frequency relative to e.g. the MB is hard, even
when the satellite is moving very fast relative to the earth.

If tuning is considered a problem for new satellite operators, what about
building your own WFM gear? Wouldn't that put off a lot more people?

Just my 1/50th of a currency unit.


Michael Kjörling

- -- 
Michael Kjörling :: michael@kjorling.com :: SMØYBY JO89  ^..^
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