A Theatrical Challenge - slightly O/T

"Dave H" wrote in message
...
Don't use a camcorder it will mosy likely have to go miles away to get
the MD in view.

They all have zooms these days, and will go quite wide.

I'm sure they will,
Why say what you said then?

Bill

"Roderick Stewart" wrote in
message .myzen.co.uk...
If the impedance of the cable is the same as the output impedance of the
camera (75 Ohms is usual for video), it doesn't matter what its length
is,
I suppose you mean 'in the context of a relatively small building'.

An infinite
length of cable would be electrically the same as a 75 Ohm resistor.
What's that got to do with it Dear Roderick?
A resistor would be cheaper of course -- infinitely.

For the stated purpose, i.e. watching a conductor waving a stick, as
long as the cable is the correct impedance, you could safely run several
hundred metres of it without bothering with equalisation.
A cable of infinite length might introduce some propogation delay however.
Maybe someone could work out how many metres of cable would cause a delay of
one semi-quaver.

Bill

(feeling a bit crotchety)

In article ,
Bill Wright wrote:
For the stated purpose, i.e. watching a conductor waving a stick, as
long as the cable is the correct impedance, you could safely run
several hundred metres of it without bothering with equalisation.


A cable of infinite length might introduce some propogation delay
however. Maybe someone could work out how many metres of cable would
cause a delay of one semi-quaver.

TV Centre used to have many miles of co-ax running round under one floor
of the doughnut to 'time' all the studios to the same distance from master
control.
Just thought you'd like some more useless info. ;-)

--
*Elephants are the only mammals that can't jump *

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Bill Wright wrote:
If the impedance of the cable is the same as the output impedance of the
camera (75 Ohms is usual for video), it doesn't matter what its length
is,
I suppose you mean 'in the context of a relatively small building'.

An infinite
length of cable would be electrically the same as a 75 Ohm resistor.
What's that got to do with it Dear Roderick?
A resistor would be cheaper of course -- infinitely.

The previous poster seemed to think that a separate distribution amplifier
would be necessary because of the length of cable to be driven, and I was
simply trying to point out that it shouldn't make any difference. Length isn't
everything you know...

For the stated purpose, i.e. watching a conductor waving a stick, as
long as the cable is the correct impedance, you could safely run several
hundred metres of it without bothering with equalisation.
A cable of infinite length might introduce some propogation delay however.
Maybe someone could work out how many metres of cable would cause a delay of
one semi-quaver.

Long cables carrying baseband video can result in HF loss as you'd expect, but
for some purposes it isn't noticeable or not important. If it's an encoded
colour signal, then typically you'd notice a reduction in colour saturation due
to a reduction in subcarrier long before you'd notice a reduction in fine
detail, but many picture monitors have autochroma circuitry that can conceal
even this. And as somebody has pointed out, colour isn't really needed to relay
an image of a conductor, and a monochrome monitor could be brighter anyway.

I've never bothered to work out how many microseconds there are to the
semiquaver, but it must be a lot.

Bill

(feeling a bit crotchety)

Too many bars?

Perhaps you need a rest.

Rod.
--
Virtual Access V6.3 free usenet/email software from
http://sourceforge.net/projects/virtual-access/

"Roderick Stewart" wrote in
message .myzen.co.uk...
The previous poster seemed to think that a separate distribution amplifier
would be necessary because of the length of cable to be driven, and I was
simply trying to point out that it shouldn't make any difference. Length
isn't
everything you know...
No, the diameter (of the cable I mean) matters as well.

Long cables carrying baseband video can result in HF loss as you'd expect,
but
for some purposes it isn't noticeable or not important.
From the sublime to the rediculous, did you know that many domestic CCTV
cameras are wired with four core alarm cable? The results are pretty rough
on a long run!

(feeling a bit crotchety)

Too many bars?

Perhaps you need a rest.

Ohhh!

Bill

The message
from "Dave Plowman (News)" contains these words:

In article ,
Bill Wright wrote:
For the stated purpose, i.e. watching a conductor waving a stick, as
long as the cable is the correct impedance, you could safely run
several hundred metres of it without bothering with equalisation.


A cable of infinite length might introduce some propogation delay
however. Maybe someone could work out how many metres of cable would
cause a delay of one semi-quaver.

TV Centre used to have many miles of co-ax running round under one floor
of the doughnut to 'time' all the studios to the same distance from master
control.
Just thought you'd like some more useless info. ;-)

*Elephants are the only mammals that can't jump *

No wonder they've got problems with mice, then. ;-)

--
Regards, John.

Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

"Owain" wrote in message
...
Roderick Stewart wrote:
Long cables carrying baseband video can result in HF loss as you'd
expect, but for some purposes it isn't noticeable or not important.

I suppose any loss counts as a form of brevement.

Oh my goodness.

Bill

Don't use a camcorder it will mosy likely have to go miles away to get
the MD in view.

They all have zooms these days, and will go quite wide.

I'm sure they will,
Why say what you said then?

Because I would never use a camcorder over a cctv camera, I'm talking a
mains powered, mountable on a 3/8 thread, BNC terminator, interchangeable
lens not one of these dome camera things or the like.

Dave

"Dave H" wrote in message
...
Don't use a camcorder it will mosy likely have to go miles away to get
the MD in view.

They all have zooms these days, and will go quite wide.

I'm sure they will,
Why say what you said then?

Because I would never use a camcorder over a cctv camera, I'm talking a
mains powered, mountable on a 3/8 thread, BNC terminator, interchangeable
lens not one of these dome camera things or the like.

Of course you wouldn't but these people are trying to ring up something
temporary with a budget of zero, so beggars can't be choosers. Lot's of old
camcorders lurk in cupboards, with mechanical recording-type faults but a
perfect actual camera.

I detect slight technical snobbery here.

I know for a fact that the BBC uses an old knackered camcorder as a webcam
at one particular location. Now you wouldn't say they were wrong would you?

Bill

"Owain" wrote in message
...
Bill Wright wrote:
I suppose any loss counts as a form of brevement.
Oh my goodness.

Would a 50% loss be a semibrevement?

Excuse me gentlemen. I'm just off to put my head in a bucket of cold water.

Bill