Satellite to Satellite communication ?

In article , says...
Marc 182 wrote:

Multi-jump communications would create unacceptable delay in a voice
conversation due to the speed of light and the distance to the
satellites. Even a single jump causes a noticeable and annoying delay.
That's why trans-Atlantic/Pacific cables remain popular.

Cables are popular because they're *cheaper* than satellites
(per unit of delivered bandwidth) what with the incredible advances
in fiber optics.

Ok, true enough. But the issue of delay still remains. A single hop
conversation is possible but annoying. A multi-hop conversation would be
impossible to hold in a natural way.

Marc

"Marc 182" wrote in message
...
In article , says...
Marc 182 wrote:

Multi-jump communications would create unacceptable delay in a voice
conversation due to the speed of light and the distance to the
satellites. Even a single jump causes a noticeable and annoying delay.
That's why trans-Atlantic/Pacific cables remain popular.

Cables are popular because they're *cheaper* than satellites
(per unit of delivered bandwidth) what with the incredible advances
in fiber optics.

Ok, true enough. But the issue of delay still remains. A single hop
conversation is possible but annoying. A multi-hop conversation would be
impossible to hold in a natural way.

Marc

Not true. It is used in many of the Pacific islands, for one. A single hop,
with minimal extra delays due to compression and processing, is quite
acceptable. Two hops can be a nuisance, but it is actually still quite okay.
It sure beats the heck out of the alternative, which is usually a short-wave
radio-telephone conversation or a telegram!

Ken

Paul F. Dietz wrote:

Cables are popular because they're *cheaper* than satellites
(per unit of delivered bandwidth) what with the incredible advances
in fiber optics.

Paul



Perhaps for large metropolitan areas. I live in a little podunk place 120
miles from Tucson or Phoenix. Folks on the nearby rez who'd have no way
of getting fiber optic or cable are getting dishes.

However the metropolitan markets are much more lucrative. Don't know if
reaching the planet's rural areas justifies comsats.

--
Hop David
http://clowder.net/hop/index.html

"Hop David" wrote in message
...


Paul F. Dietz wrote:

Cables are popular because they're *cheaper* than satellites
(per unit of delivered bandwidth) what with the incredible advances
in fiber optics.

Paul



Perhaps for large metropolitan areas. I live in a little podunk place 120
miles from Tucson or Phoenix. Folks on the nearby rez who'd have no way
of getting fiber optic or cable are getting dishes.

However the metropolitan markets are much more lucrative. Don't know if
reaching the planet's rural areas justifies comsats.

--
Hop David
http://clowder.net/hop/index.html

It's a really dicey proposition. The number of people required in an area to
make it feasible to put in a terrestrial solution tends to be much less than
that required to make the comsat solution viable. While you can get greater
coverage area with comsat than a terrestrial install, you tend to need to
limit your coverage area anyway to raise the power level in your area of
interest to something considered usable by the customer (ie. they want a
small dish!). So it gets hard to get a satellite solution going with a
chance of long-term viability. Companies are still trying though - most
fascinating! :-)

Ken

(replying to wrong article -- didn't see the
original.)

In article ,
Marc 182 wrote:
In article ,
says...
Hello:
1. When you make an international phone call - say from NY to China -
how does the voice data travel ? Does it have to be send to the
satellite and then received at teh ground, some distance away, then
sent to another satellite till it reaches the destination country. ? I
mean is there any direct satellite to satellite communication. Or is
it always bouncing between teh satellite and the ground at an angle.

2. Is this true for international television programming too ? I know
there are live television from Arab countries, Japan etc, in US.

Multi-jump communications would create unacceptable delay in a voice
conversation due to the speed of light and the distance to the
satellites. Even a single jump causes a noticeable and annoying delay.
That's why trans-Atlantic/Pacific cables remain popular.

Note that I didn't actually answer your question, because I don't know.

The "unacceptable delays" come from Geostationary
satellites. Iridium for example does do
satellite-to-satellite switching in the sky. That
turns out to be a bad idea for other reasons
(basically the satellites are little telephone
switches in the sky), but in LEO it doesn't add
noticeable delays.

Greg.
--
Greg Rose
232B EC8F 44C6 C853 D68F E107 E6BF CD2F 1081 A37C
Qualcomm Australia: http://www.qualcomm.com.au

"Norris Watkins" wrote in message
om...
Hello:
1. When you make an international phone call - say from NY to China -
how does the voice data travel ? Does it have to be send to the
satellite and then received at teh ground, some distance away, then
sent to another satellite till it reaches the destination country. ? I
mean is there any direct satellite to satellite communication. Or is
it always bouncing between teh satellite and the ground at an angle.

2. Is this true for international television programming too ? I know
there are live television from Arab countries, Japan etc, in US.

Thanks
--sony

The satellites in question are at an orbit 35,000km above the earth and can
'see' a large portion of the Earth's surface. Two ground stations on
separate continents can both see the same satellite if it is correctly
located, and so they can pass a call between them. Hence USA-Europe,
USA-Asia and so forth is possible in one 'hop'. Satellite to satellite can
be done, as in the Iridium system, but I don't know of any other system
off-hand which is commercial and made it to service. There's generally not
actually a need.

Ken

In article ,
Ken Taylor wrote:
...Satellite to satellite can
be done, as in the Iridium system, but I don't know of any other system
off-hand which is commercial and made it to service. There's generally not
actually a need.

Iridium does it, and there is some use of GSO comsats to talk to stuff in
low orbit (notably but not exclusively, NASA's TDRS system), but nobody's
done GSO comsats with intersatellite links, yet. It's been talked about
for some special purposes -- e.g., at one time, the DSP missile-warning
satellites in GSO were going to have laser cross-links so that White Sands
could talk to all of them without needing overseas ground stations -- but
it hasn't actually happened yet. At least, not on anything unclassified.
--
MOST launched 30 June; first light, 29 July; 5arcsec | Henry Spencer
pointing, 10 Sept; first science, early Oct; all well. |

Norris Watkins wrote:

Hello:
1. When you make an international phone call - say from NY to China -
how does the voice data travel ? Does it have to be send to the
satellite and then received at teh ground, some distance away, then
sent to another satellite till it reaches the destination country. ? I
mean is there any direct satellite to satellite communication. Or is
it always bouncing between teh satellite and the ground at an angle.

2. Is this true for international television programming too ? I know
there are live television from Arab countries, Japan etc, in US.

Thanks
--sony

Sometimes there are *multiple* satellite hops, depending.

For a one-way broadcast, it doesn't matter much, but a few years ago,
I had occasion to watch a Presidential address where multiple
televisions were present, and tuned each to a different network. No two
were in sync, implying different speed of light delays between the point
of origin in Washington D.C., and the local stations.

Then there's the noticeable delay on a news program when the anchor
is in 'live' contact (espically with videophones) with the reporter in
the field....


--

You know what to remove, to reply....

"Joann Evans" wrote in message
...
Norris Watkins wrote:

Hello:
1. When you make an international phone call - say from NY to China -
how does the voice data travel ? Does it have to be send to the
satellite and then received at teh ground, some distance away, then
sent to another satellite till it reaches the destination country. ? I
mean is there any direct satellite to satellite communication. Or is
it always bouncing between teh satellite and the ground at an angle.

2. Is this true for international television programming too ? I know
there are live television from Arab countries, Japan etc, in US.

Thanks
--sony

Sometimes there are *multiple* satellite hops, depending.

For a one-way broadcast, it doesn't matter much, but a few years ago,
I had occasion to watch a Presidential address where multiple
televisions were present, and tuned each to a different network. No two
were in sync, implying different speed of light delays between the point
of origin in Washington D.C., and the local stations.

Then there's the noticeable delay on a news program when the anchor
is in 'live' contact (espically with videophones) with the reporter in
the field....

I'd bet that the different delays you noted weren't to do with satellite
delays at all, but processing delays in video compression kit that the
different networks were using. I can't see any reason why a Presidential
address, sent out to a domestic audience, would be multi-hopped on
satellite.

Cheers.

Ken

"Norris Watkins" wrote in message
om...
Hello:
1. When you make an international phone call - say from NY to China -
how does the voice data travel ? Does it have to be send to the
satellite and then received at teh ground, some distance away, then
sent to another satellite till it reaches the destination country. ? I
mean is there any direct satellite to satellite communication. Or is
it always bouncing between teh satellite and the ground at an angle.

Generally ground to sat to ground and that's it.

Sat to sat communication is fairly rare.


2. Is this true for international television programming too ? I know
there are live television from Arab countries, Japan etc, in US.

Thanks
--sony