[amsat-bb] Re: Has anyone considered???
ka1rrw at yahoo.com
Thu Jul 2 08:21:50 PDT 2009
Yes, Digital is an option.
However, i would want it to pass through the analog transponder unprocessed. The reason is that we can't afford the Million dollar Radiation hardened chips to support digital processing required on satellites.
DSP or SDR will add to the Cost and add many years to the project.
WE need projects much faster than have been delivered in the past, 1-2 year schedules not 10 year schedules.
--- On Thu, 7/2/09, Jack K. <kd1pe.1 at gmail.com> wrote:
> From: Jack K. <kd1pe.1 at gmail.com>
> Subject: Has anyone considered???
> To: bruninga at usna.edu, "'Joe'" <nss at mwt.net>, "'MM'" <ka1rrw at yahoo.com>
> Cc: amsat-bb at amsat.org, kg4zlb at gmail.com
> Date: Thursday, July 2, 2009, 8:40 AM
> Has anyone considered the notion that
> the communications from a HEO or Moon or Mars need not be
> analog? Has anyone considered a digital mode such as WSJT
> for comms? I know for a fact people are running meteor
> scatter and EME using a single beam (albeit a long one) and
> 150 watts. This is not out of the reach of most hams and it
> is not non-viable communications mode... Heck the US Navy
> even ran RTTY in the 60's from Hawaii to Maryland as a
> normal mode of communications (yes it was big and wieldy, I
> just mentioned it as an aside).
> DE - KD1PE - Jack
> >> Why go with the minimal antenna gain?
> >> ... any antenna with a 3 db point that exceeds
> >> 6.5 degrees is just wasting transmitter power.
> > I think that would be about a 24 dB gain
> antenna. Pretty big
> > and would take some careful alignment... Kinda
> like a realy big
> > EME array
> >> Just remember what an Oscar 10 station took
> >> to have reliable communications, At Apogee
> >> it was only 35,000 miles away, the Moon is ...]
> >> [250,000 miles]
> > Which is 7 times farther, squared or 50 times more
> power (about
> > 17 dB).
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