Satellite to Satellite communication ?

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

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.

Marc

"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

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....

"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

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.

Paul

Paul F. Dietz wrote:
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.

Yeah. In general, it's always been true that what could be
put on a landline was put on a landline, telecommunications-wise.
The old transoceanic cables didn't have the performance to do
high bandwidth multichannel voice. Comsats took off as the
first good option for transmitting multiple voice channels
across oceans. They then caught on doing TV broadcast,
though that had been a feature on the first experimental
comsat that flew.

Both wire cable and fiber optic cables undersea started
to compete with comsats and are taking increasing quantities
of the market there. They're a lot cheaper now than
satellites are, for major concentrations of traffic.
And as soon as the fiber optic cables were proved out,
the satellite market for transoceanic voice started to
die out slowly. But not entirely. There aren't enough
cables in a lot of places, and both the cables and the
satellites break sometimes, so they end up backing each
other up to a large degree.

Orbital relay works better for broadcast purposes and
for hitting lots of little islands out in an ocean.
And always will.


-george william herbert

Has anybody ever heard of Echo-Cancelling devices? These can mitigate the
effect of the "bounce" to a great degree. Also, to compensate further,
"Reverb" can be added to flesh out tone and timbre.

just some info

S Smith


"Paul F. Dietz" wrote in message
...
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.

Paul



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"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

Stewart Smith wrote:
"Paul F. Dietz" wrote in message
...
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.

Has anybody ever heard of Echo-Cancelling devices? These can mitigate the
effect of the "bounce" to a great degree. Also, to compensate further,
"Reverb" can be added to flesh out tone and timbre.

Echo cancelling does nothing to reduce time-of-flight issues.
A half-second delay is still a half-second delay.

Adding reverb is contraindicated for telephone communications,
as it tends to reduce intelligibility. Check out speakerphones
for examples thereof. As a matter of fact, there is a fair bit
of research for _reducing_ reverberation in speakerphones.

Signal processing techniques are not useful for fixing problems
due to speed of light causing delays.

300,000 km/second: not just a good idea, it's the law.


Francois.