Satellite to Satellite communication ?

[Norris Watkins]

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

[Marc 182]

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

[Ken Taylor]

"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

[Joann Evans]

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....

[Greg D. Moore \(Strider\)]

"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

[Paul F. Dietz]

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

[George William Herbert]

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

[Stewart Smith]

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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[Ken Taylor]

"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.

[Gregory G Rose]

(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

[Ken Taylor]

Echo cancellation reduces echo, it doesn't do anything to delay except
potentially add to it. Delay doesn't show up as an echo - echo is due to
mismatches; delay is due to propagation delays, processing delays, and
similar time-wasters.

Ken

"Stewart Smith" > wrote in message
y.com...
> 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
> >
>
>
> ---
> Outgoing mail is certified Virus Free.
> Checked by AVG anti-virus system (http://www.grisoft.com).
> Version: 6.0.548 / Virus Database: 341 - Release Date: 12/5/03
>

[Marc 182]

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

[Henry Spencer]

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. |

[Jim Kingdon]

> 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.

It has also been talked about for commercial GSO communications
satellites. There's a list under "GEO broadband schemes" at
http://www.ee.surrey.ac.uk/Personal/L.Wood/constellations/overview.html

At least according to that page, the main motivator is to reduce the
delay which would result from a

mobile handset->satellite->ground station->satellite->mobile handset

path. I suppose the question is how many degrees these satellites
would be separated by. I guess for any separation less than about 120
degrees, the

mobile handset->satellite->satellite->mobile handset

path would be a shorter distance (unless I've mis-done the geometry).

[Ken Taylor]

"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

[Stewart Smith]

Thanks for setting me straight Francois, you are correct


"(null)" > wrote in message news:1070919774.530038@smirk...
> 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.
>


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Checked by AVG anti-virus system (http://www.grisoft.com).
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[Joann Evans]

"Greg D. Moore (Strider)" wrote:
>
> "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.

It's been my imprression that there may be some military sat-to-sat
stuff going on at 60 gigahertz. This band is readily absorbed by oxygen,
making ground intercept of these signals impractical.

(Googling for a minute)

Here's a reference:

http://www.ydi.com/deployinfo/wp-benefits-60ghz.php



--

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

[David Lesher]

"Ken Taylor" > writes:

>Echo cancellation reduces echo, it doesn't do anything to delay except
>potentially add to it. Delay doesn't show up as an echo - echo is due to
>mismatches; delay is due to propagation delays, processing delays, and
>similar time-wasters.


You need a thiotimoline injector to solve the delay issue.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

[Hop David]

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

[Kevin Willoughby]

In article <1070919774.530038@smirk>, says...
> Echo cancelling does nothing to reduce time-of-flight issues.
> A half-second delay is still a half-second delay.

A half second is a half second, but canceling the echo does help
intelligibility by removing some noise from the signal. Time-of-flight
isn't the only issue.


> Adding reverb is contraindicated for telephone communications,
> as it tends to reduce intelligibility. Check out speakerphones
> for examples thereof.

Excessive reverb is a bad thing. Done correctly, reverb adds a sense of
presence without interfering with intelligibility.


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

True, but these tools are useful for lots of other real-world problems.
--
Kevin Willoughby

Imagine that, a FROG ON-OFF switch, hardly the work
for test pilots. -- Mike Collins

[Ken Taylor]

"David Lesher" > wrote in message
...
> "Ken Taylor" > writes:
>
> >Echo cancellation reduces echo, it doesn't do anything to delay except
> >potentially add to it. Delay doesn't show up as an echo - echo is due to
> >mismatches; delay is due to propagation delays, processing delays, and
> >similar time-wasters.
>
>
> You need a thiotimoline injector to solve the delay issue.
> --
Was that Heinlen or Asimov? :-)

Ken

[Ken Taylor]

"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

[Pascal Bourguignon]

"Ken Taylor" > writes:

> "David Lesher" > wrote in message
> ...
> > "Ken Taylor" > writes:
> >
> > >Echo cancellation reduces echo, it doesn't do anything to delay except
> > >potentially add to it. Delay doesn't show up as an echo - echo is due to
> > >mismatches; delay is due to propagation delays, processing delays, and
> > >similar time-wasters.
> >
> >
> > You need a thiotimoline injector to solve the delay issue.
> > --
> Was that Heinlen or Asimov? :-)

Asimov.


--
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http://www.informatimago.com/ . * . .*
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a man to pay for what he does not . . / .\ . * .
want merely because you think it .*. / * \ . .
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