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

Larry W4CSC wrote:

"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote in news:gp-
:


So the antennas on the bird are directional targeted at the US? Otherwise
I would think that an equal area below the equator would be covered.

Doug



No, most US-targeted satellite services have directional antennas pointed
this way. It's bad enough trying to get enough field strength to lock up
the cheap XM/Sirius receivers with miniscule antennas so tiny. They're
pointed to the States, all right.

Wonder how they'd work duct taped to the side of the feedhorn of the Dish
Network antenna pointed at the XM bird?....hmm....

Having a more serious receiver antenna capture area would seem to extend
their range much farther than that little plastic blob magmounted to the
fire extinguisher.

The antennas are directional in what is called a spot beam. If they were
omni they would cover equal distance North/South but a LOT more power
would be required to have the required EIRP to be received by the auto
antennas.
krj

Doug Dotson wrote:

So the antennas on the bird are directional targeted at the US? Otherwise
I would think that an equal area below the equator would be covered.

Doug

"krj" wrote in message
...

There are two satellites in geosynchronous orbit, XM-1 (named Roll) at 85
degrees and XM-2 (names Rock) at 115 degrees. Both are 24 transponder C
band satellites with antennas that are positioned to have a footprint for
the CONUS. The footprints extend slightly into Canada and Mexico and about
100 miles offshore.
krj

Doug Dotson wrote:

I thought Sirius and XM worked off of geosynchronous sats over the
equator.

"krj" wrote in message
.. .


Problem is that XM and Sirius only work in the US and near coastal
waters. No Coverage in the BVI and south.
krj

Larry W4CSC wrote:


Terry Spragg wrote in
:




Normally, I would want my entertainment radio to have excellant
reception, and could not bear to be at anchor on a hot, buggy night
with a nice new tune just barely distinguishable through a bad, noisy
antenna.



Is now a good time to show off the XM Radio satellite antenna magnet
stuck to the side of the fire extinguisher next to the hatch?...(c; One
of these days I gotta actually find a place to put it but it works so
good stuck to the fire extinguisher I hate to screw around with
something that always works. It's even sideways from the way it's
supposed to be stuck.....go figure??

XM is the way to fly, not that damned string of continuous commercials
spaced with minor bits of "programming" playing in between......on USA
commercial FM from Clear Channel.

Dennis Pogson wrote:
wrote:
Hello:

I want to install a new FM radio / CD player on my boat. Thought I
would mount the antenna in the stern area. I also like the idea of
having a redundant marine VHF antenna.

Is it reasonable to use a marine VHF antenna for an FM car radio
antenna? Other sugestions that will alow me to get the local tunes
and
news and also have secondary VHF antenna?

Thanks
Chris

You can get a splitter to have the VHF antenna serve both units, but
it
isn't as good as dedicated VHF + FM antennas. Chandlers can usually
supply
the splitter.

Does the problem lie with mucking about with a splitter or less than
optimal reception for FM radio using VHF antenna? I like the mast head
idea to help the FM peak over the horizon but would that simply be a
wash if VHF antenna doesnt match well with the FM radio?
Chris


- - -
Satellite photocharts of the UK & Ireland
available, excellent detail and accurate
calibration using Oziexplorer.
Remove *nospam* to reply.

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.

Shakespeare makes a device that allows the VHF antenna to be used
for both the VHF and FM. Works well, but they do seem to fail after
a while. I've twice isolated VHF transmit problems to a fail one of
these devices. Best to have 2 separate antennas, but the device is
a reasonable compromise.

Doug

wrote in message
oups.com...
Dennis Pogson wrote:
wrote:
Hello:

I want to install a new FM radio / CD player on my boat. Thought I
would mount the antenna in the stern area. I also like the idea of
having a redundant marine VHF antenna.

Is it reasonable to use a marine VHF antenna for an FM car radio
antenna? Other sugestions that will alow me to get the local tunes
and
news and also have secondary VHF antenna?

Thanks
Chris

You can get a splitter to have the VHF antenna serve both units, but
it
isn't as good as dedicated VHF + FM antennas. Chandlers can usually
supply
the splitter.

Does the problem lie with mucking about with a splitter or less than
optimal reception for FM radio using VHF antenna? I like the mast head
idea to help the FM peak over the horizon but would that simply be a
wash if VHF antenna doesnt match well with the FM radio?
Chris


- - -
Satellite photocharts of the UK & Ireland
available, excellent detail and accurate
calibration using Oziexplorer.
Remove *nospam* to reply.

In article ,
"Doug Dotson" dougdotson@NOSPAMcablespeedNOSPAMcom wrote:

I thought Sirius and XM worked off of geosynchronous sats over the equator.

"krj" wrote in message
...
Problem is that XM and Sirius only work in the US and near coastal waters.
No Coverage in the BVI and south.
krj

Larry W4CSC wrote:
Terry Spragg wrote in
:


Normally, I would want my entertainment radio to have excellant
reception, and could not bear to be at anchor on a hot, buggy night with
a nice new tune just barely distinguishable through a bad, noisy antenna.



Is now a good time to show off the XM Radio satellite antenna magnet
stuck to the side of the fire extinguisher next to the hatch?...(c; One
of these days I gotta actually find a place to put it but it works so
good stuck to the fire extinguisher I hate to screw around with something
that always works. It's even sideways from the way it's supposed to be
stuck.....go figure??

XM is the way to fly, not that damned string of continuous commercials
spaced with minor bits of "programming" playing in between......on USA
commercial FM from Clear Channel.



XM is geosynch using SpotBeams, but Sirius is using none-geosynch, and
the farther north you go the bigger the dropout when the Sat
Constellation can't cover the area. for southeastern alaska we lose
signal about 2 hours out of 12 with what Sirius has running now.


Bruce in alaska
--
add a 2 before @

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.

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.

krj wrote in
:

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.



Hmm...This may explain why the signals to it at Best Buy's store here
sometimes works and sometimes dies. That high elliptical orbit put the
satellite at some serious distance (read that attenuation) when it's "way
out there" at apogee. We have several ham radio satellites with orbits
like these. You can talk to them a long time as they go over the apogee
hump.

Thanks for the info. All I knew about Sirius was it was near bankruptcy
with much-lower-than-expected subscriptions.
http://finance.yahoo.com/q/cf?s=SIRI
It just bleeds money.....even though some keep priming the pump.