Why is Television Signal from space so degraded?

It seems that all video from space is slightly degraded, ie lower rez
than normal NTSC. Is this a function of lower grade cameras,
compressed signal, or some orbital condition?

I notice that digital images look fine, such as videos returned to
Earth.

The downlinked video is MPEG2 compressed.

There are different settings for the bandwidth of the video signals set by
the CATO (comm officer) depending on how much bandwidth the payloads folks
are asked to give up.

The external cameras (truss and Lab mounted) seem to generate better quality
video than the Canadarm2-mounted cameras. However the arm cameras are
necessarily smaller physical units.

At the highest settable frame rate (I think that's the parameter, but would
have to check) even the arm camera video looks decent, although it's
obviously not quite broadcast quality by the time it makes it downhill.



"Gary Coffman" wrote in message
...
On 16 Aug 2003 10:10:24 -0700, (Explorer8939)
wrote:
It seems that all video from space is slightly degraded, ie lower rez
than normal NTSC. Is this a function of lower grade cameras,
compressed signal, or some orbital condition?

Many of the cameras they use aren't up to current broadcast
practice. They typically run them with auto iris control, which
doesn't work well in high contrast settings. Most importantly,
the lighting isn't up to broadcast standards, nor is the camera
work.

In broadcasting we say that at least 50% of picture quality
is dependent on lighting, and the camera operator. Current
broadcast camera technology is rarely the limiting factor to
good picture quality.

Gary

"Tim Braithwaite" wrote in
:

The downlinked video is MPEG2 compressed.

There are different settings for the bandwidth of the video signals
set by the CATO (comm officer) depending on how much bandwidth the
payloads folks are asked to give up.

I do feel compelled, for the benefit of those who think CATO is Green
Hornet's chauffeur, that your answer applies only to ISS. :-) Shuttle video
is not, as far as I know, MPEG2 compressed.


--
JRF

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Absolutely. Thanks, Jorge

I'm talking about ISS video and the ISS control room. This is, after all,
sci.space.station


"Jorge R. Frank" wrote in message
...
"Tim Braithwaite" wrote in
:

The downlinked video is MPEG2 compressed.

There are different settings for the bandwidth of the video signals
set by the CATO (comm officer) depending on how much bandwidth the
payloads folks are asked to give up.

I do feel compelled, for the benefit of those who think CATO is Green
Hornet's chauffeur, that your answer applies only to ISS. :-) Shuttle
video
is not, as far as I know, MPEG2 compressed.


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
think one step ahead of IBM.

"Tim Braithwaite" wrote in
news
Absolutely. Thanks, Jorge

I'm talking about ISS video and the ISS control room. This is, after
all, sci.space.station

Right. My mistake, I'm browsing through the groups too quickly. Sorry! :-)


--
JRF

Reply-to address spam-proofed - to reply by E-mail,
check "Organization" (I am not assimilated) and
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