Larry,
I incorrectly used the term LEO. Technically LEO satellites are those
between 300 and 800 miles up. Ic sometimes use the term generically to
indicate a satellite not in geo. orbit. I sometimes refer to GPS birds
as low earth orbit, but they are actually a little over 10,000 nm up.
Sorry if I confused you,but Sirus birds are not geo. They are in an
Elliptical Orbit

A satellite in elliptical orbit follows an oval-shaped path. One part of
the orbit is closest to the center of Earth (perigee) and the other part
is farthest away (apogee). A satellite in this orbit takes about 12
hours to circle the planet. Like polar orbits, elliptical orbits move in
a north-south direction.

krj wrote:
Unlike XM, Sirius does not use GEO satellites. Instead, its three
SS/L-1300 satellites form an inclined elliptical satellite
constellation. Sirius says the elliptical path of its satellite
constellation ensures that each satellite spends about 16 hours a day
over the continental United States, with at least one satellite over the
country at all times. Sirius completed its three-satellite constellation
on November 30, 2000. A fourth satellite will remain on the ground,
ready to be launched if any of the three active satellites encounter
transmission problems.
http://search.netscape.com/ns/boomfr...ite-radio3.htm

Larry W4CSC wrote:

krj wrote in
:


Using an antenna on a dish would work for XM if you put the feed at
the correct focal point for C band (DirectTV and Dish are Ku band),
but would be a problem for Sirius because their three satellites are
not GEO. They are LEO in an eliptical orbit so you would need the
latest Keplers and a tracking antenna. Also they are at 2.3 Ghz.
krj



If Sirius' birds were LEO and they only had 3 of them, you'd only have
service in three 8 minute periods per 90 minute orbits, but only if
those changing orbits caused by the earth's rotation were to happen to
have you in their footprint. No, Sirius is Geosynchronous, too.

You are right about the 2.3G on the C-band dish, but there would be
some reflection. I'd bet the excellent TV hackers across the
Caribbean at fixed locations have some big dishes pointed to XM or
Sirius birds to get enough signal for a lock on exotic islands.