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Re: Re: [psk31] PSK-31 Satellite Donwlink Opportunity?



On Mon, 26 Feb 2001, Jon Ogden wrote:

> > Ah, another very good point.  So if the INBAND is not such a great idea,
> > then maybe 15 meters UP and 10 meters down. This solves many problems
> 
> Why are we insistent on using HF for this satellite?
> 
> If you are going to do this, why not use a simple 2m transceiver as the
> uplink and 10m as the downlink.  Then it fits in the band plans and so
> forth.  As for Doppler, well, heck, it can all be adjusted for in software

Good Question. The answer is Doppler, and also cheap $99 HF SSB XCVR kits.
At 10m and below the DOppler is less than 600 Hz and so the Software can
correct for it without having to have any radio control interface...  At
2m and above, the Doppler is 3 to 6 Khz and so there is no way to account
for it in Software without having to re-tune the rig.  (or design a 6 Khz
SSB xcvr)

There are many problems with trying to re-tune the rig under software
control.

1) It takes a hardware interface
2) It requires a computer controllable $700 to $2000 ALL mode Rig
3) Every radio is different, requiring multiple software modules
4) Most of the radios can not tune to 1 Hz precision

So it changes a simple concept (audio to a sound card) and maybe a $99
xtal controlled SSB XCVR (see Warbler in this months QST) to the
requirement for a $3000 Oscar class station...

My objective was to find a satellite design that would let many
people use it easily per pass with simple equipment and such that the
satellite can be built in a 4" cube and thus get an easy ride to space...

Also, by the time this gets to space, 10m and 15m will again be dead bands
most of the time, hi hi.  By the way, I have not checked to see if
satellite opertions is permitted in the new 12 m band under the ITU
rules...

de WB4APR, Bob


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