[amsat-bb] Re: HF Satellite Relay
domenico.i8cvs at tin.it
Tue Jun 29 11:05:41 PDT 2010
Hi Greg, KO6TH
Echo-1 A was a passive communication satellite launched on 12 august 1960
in a circular orbit at 1519 - 1687 km and it was a balloon 30.5 meters in
diameter made of 0.0127 mm thick metallized mylar polyester film to reflects
signals transmitted from the earth at 960 MHz and 2390 MHz
Echo-1 A was also carrying two VHF TLM beacons at 108.000 and 108.03 MHz
with a power of 45 mW and I was receiving both of them for several days
using a homebrewed downconverter with two low noise triodes 6AN4 in a
cascode input stage and a simple three elements yagi.
At that epoch time the 108 MHz band was used only for aeronautical and space
communications but not for FM broadcasting as novadays so that it was free
of interfering signals and man made noise and the only existing noise was
the galactic noise.
By the way in the early 1960 it was my first received satellite signal and
it was very exiting to receive the 45 mW beacons using only a three elements
yagi and a downconverter with a noise figure at best of 6 dB while to see
the balloon as a bright star by naked eye flying in the night.
For more technical informations on ECHO-1 ,ECHO-1A and ECHO-2 look at
the following web page:
----- Original Message -----
From: "Greg D." <ko6th_greg at hotmail.com>
To: <bruninga at usna.edu>; <amsat-bb at amsat.org>
Sent: Tuesday, June 29, 2010 7:03 AM
Subject: [amsat-bb] Re: HF Satellite Relay
> Well, it's finally happened. We've come full circle. They've reinvented
> Of course, that one was 10x larger. What makes this a 10m (band)
operation? I expect it would work on the higher bands too, especially with
the smaller size. What band did they use ~50-ish years ago?
> Greg KO6TH
> > From: bruninga at usna.edu
> > To: amsat-bb at amsat.org
> > Date: Mon, 28 Jun 2010 13:44:45 -0400
> > Subject: [amsat-bb] HF Satellite Relay
> > Heard today of a Passive HF relay satellite being proposed.
> > Wondered if Hams could relay off of it.
> > It's a 10m diameter sphere.
> > I assumed a 10m signal and 1000 Watts
> > And antenna gains at both ends of 10 dB.
> > Unless I made a dumb error, it looks impossible?
> > I get a received signal of -170 dBm
> > Compared to a good HF receiver of -122 dBm
> > So its 48 dB down in the noise.
> > Going to narrow band, could improve things, but the Doppler of
> > +/- 600 Hz would make that difficult.
> > Anyway, if someone else wants to double check the link budget
> > using the radar range equation, go for it.
> > The beauty of this system is that it is perfectly spherical, so
> > the reflection coefficient would be constant within 1 dB. That
> > is the advantage over trying to use the ISS or other large
> > rocket body... They vary by 20 dB making communication by
> > reflection impossible.
> > Oh, and it would be in space for 30 years or more. So with
> > something that reliable, it would be worth developing an amateur
> > capability to use it.
> > It is not designed for comms, but as a calibration sphere for
> > over the horizon radars that have LOTS more power and LOTS more
> > gain than we do.
> > Bob, Wb4APR
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