[opendtv] Re: 47 year old television signals bouncing back to earth
- From: Olivier Houot <olho_avatar_i@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Fri, 23 Dec 2011 12:28:57 +0100
Albert Manfredi:
> But I doubt they would opt for DVB-T1 or T2! The PAPR is too much of a
> waste of power, and the fact that you're using a very narrow and
> directed beam, with parabolic transmit and receive antennas, implies
> that you're not banking on a lot of multipath anyway.
>
Indeed, assuming this family of standards, DVB-S2 would be more
appropriate.
However, i see in
http://www.google.fr/url?sa=t&rct=j&q=dvb-s%
20snr&source=web&cd=11&ved=0CDMQFjAAOAo&url=http%3A%2F%
2Fwww.img.lx.it.pt%2F~fp%2Fcav%2FAdditional_material%2FDVB-S2%2520The%
2520Second%2520Generation%2520Standard%
2520for.pdf&ei=zVv0TsGPGs2k-gb81cWrAQ&usg=AFQjCNHyYDLAZJJFXDuzwMB7m_m1R2ztdg&cad=rja
that DVB-S2 would allow for 58.8 Mbps of useful data rate in 27.5 Mhz
(but 36 Mhz transponders ??) with a C/N of 7.8 dB. They mention an EIRP
of 53.7 dBW "at the service area contour" and 60 cm receiving antennas.
I am not sure of the frequency, one reference mentions 11/12 Ghz.
Wouldn't that make for a more optimistic result? Or is it not applicable
to such a long distance link for some reason?
And i suppose some form of doppler effect compensation would be
recommended, too.
In another of his papers, Lou Scheffer, the author of the "aliens can
watch i love lucy" document, suggested frequencies in the vicinity of 60
Ghz for interstellar communication, which would be make high gains even
easier.
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