Fwd: Re: [amsat-bb] NB96/PSK-1 Combo

[Jim White <jim@xxxxxxxxxxxxxxxxxxxxx>]

>
>  Jon Ogden writes:
>
> > So for looking toward the future, who knows how much longer the 1200 baud
> > birds will stay in operation (let's hope for years), but 9600 baud 
> birds are
> > going up all the time.
>
>I understand thr RUDAK on P3D will have a 1200PSK capability as well as
>several higher speeds. I don't recall seeing anything in the RUDAK write-
>ups about a digipeating capability (although I'm sure it will be there).

The default mode for RUDAK will be 9k6 GMSK (G3RUH compatible) because that 
is the mode/speed in hardware.  1200 PSK is an option we are working toward 
for use when conditions make 9k6 difficult.  However this has to be done in 
DSP which draws more current.  It may be that the same conditions (off 
pointing, spinning, whatever) that make 1200 PSK desirable will also be low 
power generation modes where we can't run the DSP.

There is 153k6 with and without encoding in hardware also, but at this 
point little equipment on the ground to use against it.  All other modes 
and speeds are done in DSP.

As is the case with all new birds, there will be a period of testing and 
commissioning for RUDAK before it is available for general use.  This will 
come at some point after bus hardware and software is tested and 
commissioned, and when there is power available. During that checkout 
various modes and software capabilities will be tested along with all the 
experiments.

There are two processors in RUDAK and it is technically possible to have 
both running:  Perhaps one as a general use BBS like the store-and-forward 
LEO birds and the other dedicated to the experiments (GPS, SCOPE, Monitor, 
CDEX).  But that would require two digital signals in the pass band with 
half the power of a single signal.  We just won't know if this is feasible 
until the bird is on orbit and operating.  The possibilities for mixtures 
of modes, speeds and experiment arrangements are many and pretty 
exciting.  But patience will be necessary because there is no doubt we will 
start out simple.

As for digipeating, the facility is there (in software) and is easy to turn 
on and off.  It would certainly be fun to use with a 'near-geo' bird.  But 
there is always the issue about sharing links (mostly the issue is uplinks) 
between folks using the digi and folks using the BBS or other 
facilities.  We will just have to see how it plays out.  The interesting 
thing to note is that while the LEO birds see at most a few tens of uses at 
once, P3d will see a few hundreds.  An interesting paper might be written 
on the subject of usage profiles, queuing theory applied, and link . . .

BTW, there is still much DSP code to be written for RUDAK.  The RUDAK team 
would be interested in hearing from experienced and enthusiastic DSP 
programmers.

Jim White
RUDAK Operations
jim@coloradosatellite.com
wd0e@amsat.org
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