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Guest
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 Posted: Fri Oct 10, 2008 6:59 pm Post subject: Why there is static noise in the astronaut communications ? |
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Hi,
I wonder why there is static noise in the astronaut communications
with earth?
Since we can send TV signals to satellite and beam it down with crispy
voice, I thought today>s technology is able to eliminate/prevent those
static noise getting into communications.
Thanks.
Michelle |
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Graham.
Guest
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| Posted: Sat Oct 11, 2008 3:01 am Post subject: Re: Why there is static noise in the astronaut communication |
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<michelle.long09@gmail.com> wrote in message
news:2373ccb8-e18c-4177-ba46-afd760b54e18@p59g2000hsd.googlegroups.com...
[quote]
Hi,
I wonder why there is static noise in the astronaut communications
with earth?
Since we can send TV signals to satellite and beam it down with crispy
voice, I thought today>s technology is able to eliminate/prevent those
static noise getting into communications.
[/quote]
I think spacecraft and pressure-suits can be noisy environments.
--
Graham.
%Profound_observation% |
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BMJ
Guest
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| Posted: Sat Oct 11, 2008 8:09 am Post subject: Re: Why there is static noise in the astronaut communication |
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michelle.long09@gmail.com wrote:
[quote]
Hi,
I wonder why there is static noise in the astronaut communications
with earth?
Since we can send TV signals to satellite and beam it down with crispy
voice, I thought today>s technology is able to eliminate/prevent those
static noise getting into communications.
Thanks.
Michelle
[/quote]
I>m an amateur radio operator and I recently became interested in amateur
satellites. Whenever I listen to one, I have to set the squelch on my
radio wide open in order to hear the downlink signal because it>s often
weak (sometimes just a few watts). Along with that signal, I hear
background static, though I can eliminate some of it as the radio has some
built-in filtering. The satellites themselves might not, though, as launch
weight would have been a consideration in their designs and filters might
have been eliminated in order to make them lighter. (Final designs are
often a result of such tradeoffs.)
I suspect that the radios used in the spacesuits don>t transmit a strong
signal, as they only have to work over short distances, with the air-ground
circuit relaying it. Those same signals might also be subject to
interference from sources on board the shuttle or ISS. The signal strength
might also be affected if their antennas aren>t properly aligned or there>s
something blocking them because the astronauts are moving about.
By comparison, the signals to commercial birds in geostationary orbit have
to be stronger and more precisely directed in order to reach them.
Somewhere in the path, those signals will likely be processed to remove as
much noise as possible and amplified for the end users due to how those
signals will be used.
Maybe someone working in the business could correct me on this. |
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Brian Gaff
Guest
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| Posted: Sat Oct 11, 2008 2:29 pm Post subject: Re: Why there is static noise in the astronaut communication |
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Several reasons.
Firstly, the iss in particular is a noisy environment, and as has been said
so are the inside of suits. There is not a complete digital path either,
for example the Russian Vhf and Uhf system is, as I understand it, an FM
system. Indeed many Shuttle systems still use this technology, but of course
the helmet cams and the newer comms are digitally coded, as are the Ku band
stuff of course. However a lot of the lines it runs through to and from
various places may well be analogue, You can actually hear the changes in
quality sometimes as the feed moves from one route to another.
To me what they tend to use is a mish mash of old and new technology,
addingand mixing and matching as is convenient at the time.
Brian
--
Brian Gaff - briang1@blueyonder.co.uk
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"Graham." <me@privacy.net> wrote in message
news:gcojbp$sjj$1@registered.motzarella.org...
[quote]
michelle.long09@gmail.com> wrote in message
news:2373ccb8-e18c-4177-ba46-afd760b54e18@p59g2000hsd.googlegroups.com...
Hi,
I wonder why there is static noise in the astronaut communications
with earth?
Since we can send TV signals to satellite and beam it down with crispy
voice, I thought today>s technology is able to eliminate/prevent those
static noise getting into communications.
I think spacecraft and pressure-suits can be noisy environments.
--
Graham.
%Profound_observation%
[/quote] |
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John Doe
Guest
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| Posted: Sat Oct 11, 2008 9:24 pm Post subject: Re: Why there is static noise in the astronaut communication |
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During the last Shuttle flight, they held a press conference in HD. This
would have likely been an all digital link and the sound was incredibly
clear.
However, if I am not mistaken, the default voice channels are
essentially analogue radio. No error correction to remove static. This
is how the shuttle does it too, and I think it has to do with having at
least one way to have the simplest possible communication path if all
else breaks.
In terms of EVAs, the suits appears to be noisy (flow of air into
helmet) I suspect that sound properties change when you are in 5% pure
oxygen environment so some of the sounds may be exagerated. And their
voices would be different too since the air is different and different
pressure.
On the ISS itself, there are areas that are quite noisy (fans etc) so
there is a fair amount of background noise. |
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OM
Guest
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| Posted: Sun Oct 12, 2008 2:40 am Post subject: Re: Why there is static noise in the astronaut communication |
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On Sat, 11 Oct 2008 04:55:27 +0000, BMJ <owlstretchingtime@yahoo.com>
wrote:
[quote]I suspect that the radios used in the spacesuits don>t transmit a strong
signal, as they only have to work over short distances, with the air-ground
circuit relaying it.
[/quote]
....I can see it now:
"EV1, Houston; how do you read, over?"
"Houston, EV1; we re>>BZZZT! AH...BREAKER ONE-NINE, THIS HERE>S THE
RAGIN' CAJUN! HOWABOUTCHA BEERGUZZLER? YOU GOT YOUR EARS ON? COME
BACK?<<ver."
OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let>s face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[ |
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OM
Guest
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| Posted: Sun Oct 12, 2008 2:41 am Post subject: Re: Why there is static noise in the astronaut communication |
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On Sat, 11 Oct 2008 09:29:06 GMT, "Brian Gaff"
<briang1@blueyonder.co.uk> wrote:
[quote]for example the Russian Vhf and Uhf system is, as I understand it, an FM
system.
[/quote]
....Which just goes to show you Steely Dan lied. "FM - no static at
all."
OM
--
]=====================================[
] OMBlog - http://www.io.com/~o_m/omworld [
] Let>s face it: Sometimes you *need* [
] an obnoxious opinion in your day! [
]=====================================[ |
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Graham.
Guest
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| Posted: Sun Oct 12, 2008 6:46 pm Post subject: Re: Why there is static noise in the astronaut communication |
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[quote]
for example the Russian Vhf and Uhf system is, as I understand it, an FM
system.
...Which just goes to show you Steely Dan lied. "FM - no static at
all."
OM
[/quote]
That>s what you get if you ask a rock band instead of an enginner.
This guy would have given you the correct answer!
http://en.wikipedia.org/wiki/Stuart_William_Seeley
--
Graham.
%Profound_observation% |
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