Why is video inverted for transmission?

[Clark Martin]

I've seen those leaded glass blocks used for viewing portals into
radiation treatment rooms. They had a fairly strong yellow tint, as in
everything was in black and yellow.

That was the original use for uranium, yellow coloring. And thorium was
used in dental powder.

Grin.
Now there is a great idea, uranium glass for radiation shielding....
BTW, is there a warning on those lead glass bricks about not eating
them, or letting children play with them? More paranoia.

Guess what. Uranium IS used for radiation shielding. I used to work
for a company that makes linear accelerators. In some models a plate of
depleted uranium is used as there isn't much room. Uranium is something
like 2.5 times as dense as lead.

It can only be used in the low energy machines. The high energy
machines produce neutrons and those you don't want around uranium.

 

[Michael A. Terrell]

You'll probably find that your Sony is limited to WXGA (1366x768).
Check the specs. WXGA is ok, but is nowhere near what can be done
with a "real" 32" LCD computah monitor. For example, an HP LP3065 30"
monitor will do WQXGA (2560x1600) or roughly twice the number of
pixels.

I already have a 22" HP monitor that will do 2048 * 1536. I use it
on the computer that I use for graphic work and web design.

DTV compression levels were established by cranking up the compression
until the complaints rolled in on the support phone numbers. I also
went through that exercise with CATV. Cramming extra channels into
the pipe is worth lots of money. What we have today is "adequate"
picture quality that paying customers can afford. There may be a
market for high quality broadcast video, but the GUM (great unwashed
masses) prefer cheap. So, we get maximally compressed video of
minimal quality. I don't like it, but my DirecTV subscription is
affordable, so I'll tolerate the loss in quality.

All I watch is local news, and a little Sci-Fi Channel. Cable TV
costs me about $15 a month for that. I can't get the Sci Fi channel
without paying for a tier of sports channels that I don't have time to
watch. The cheapest package with the Sci-Fi channel is ?$45 a month on
Direct TV, and Dish network wants $30 a month.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

Jerry Avins wrote:

(snip)


I was thinking about farm houses in the plain states. Far from the
big cities, and fairly flat. There could still be water towers
around, though. It might be too far out for affordable cable.

A lot of steel in modern barns and silos.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

Michael A. Terrell wrote:

...


I was once so far out in the Atlantic that the Coast Guard, who were
looking for us in Long Island Sound, found us only by accident and that
only after five hours of motoring closer to shore. The motor had quit
the afternoon before, then a storm came up. We drifted as far as we did
because of the tide pulling us out with a sea anchor I gas improvised to
keep from getting swamped by waves.

Come first light and a calm sea, I got the flywheel off and figured out
that the condenser was shorted. I made a replacement from four sheets of
foil-lined paper from cigarette packs -- smoking saved our lives -- that
worked well enough to get us under way. There are plenty of reasons to
make capacitors.

I carreied a spare capacitor, pouints and distributor cap with me in
my vehicle's tool box, so i didn't ned to improvise critical parts away
from the shop.

He also apparently operated a _legal_ land based spark gap transmitter.
[I was once challenged on that statement - Checking with rep of Antique
Wireless Association of Holcomb NY showed claim was _feasible_.]

WHEN did he operate it? Spark is not a legal mode, and hasn't been
for a LONG LONG time. Even with a tuned circuit to couple the RF to the
antenna, the broadband noise will wipe out other communications. Spark
was replaced by Alexanderson generators.

Marine spark equipment was grandfathered for a long time after it was
banned on land. You didn't need a BFO to read it precisely because it
wasn't CW. A late friend was a passenger in a two-seater in Alaska that
broke up on making an emergency landing. He improvised a spark-gap
transmitter using the battery and spark coil, as well as other wires
ripped out of the plane. For two hours he alternated between tapping out
his best-guess position and keeping fire going. Then a plane dropped
survival equipment and food. Two hours later yet, a helicopter landed
and picked them up. He asked the crew if his signal had been heard of if
they had been found by accident. "Hear you" came the answer. "You were
all over two bands. Nobody could hear anything else." To quote the Edda,
"Even the black dog will have its day."

A large tesla coil do in a pinch.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Robert Latest]

["Followup-To:" header set to sci.electronics.design.]

That is not what the masses need. The masses on living room couches need
something that turns their old analog TV into a digital TV. Walmart used
to have a converter for around $250,

They cost about 20-30 Euros over here and will be equally cheap when DVB-T
hits the US.

robert

 

[Robert Latest]

["Followup-To:" header set to sci.electronics.design.]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Now you've got it. I was not talking about distortion. In heavy
multipath your analog picture might look yucky (out here it does) but
it's there. You can still watch the news. When the digital gets hit with
too much multipath the picture ain't there at all. Huge difference.

Not really. I'd call the digital artifacts "distortion" as well. Picture
getting all checkered up, occasional freezes, sound dropouts etc. Still a
lot less pleasant than a "snowy" analog pic.

robert

 

[ChairmanOfTheBored]

I already have a 22" HP monitor that will do 2048 * 1536. I use it
on the computer that I use for graphic work and web design.




All I watch is local news, and a little Sci-Fi Channel. Cable TV
costs me about $15 a month for that. I can't get the Sci Fi channel
without paying for a tier of sports channels that I don't have time to
watch. The cheapest package with the Sci-Fi channel is ?$45 a month on
Direct TV, and Dish network wants $30 a month.

Hi res display, and zero digital or HD channels...

Yeah, you're a real brain, bozo.

 

[Jerry Avins]

Wrong attribution, but no harm done.

When I was fairly young I got a remote control bus for Christmas. it used a
spark gap transmitter. The receiver used a powered carbon detector.
Every time a signal was found, the carbon would start to conduct and fire a
relay setting up action on the preprogrammed mechanics and motor. When
an action ws complete, a arm would come down a hit the carbon detector
to break conduction and get ready for another command. it used to trigger
on lightning. I got my first real shock when i unscrewd the insulated antenna
out, and stuck my finger in the hole and pushed the button. I guess
that was my first electronic project, except my mother used to tell me about
the time when I poured water into a lamp socket. It goes buzzz.

I assume you meant powDered carbon detector. That's a new one on me. I'm
familiar with another form of coherer, one that used powdered nickel and
silver. (Filings from a dime and a nickel worked nicely.) That kind of
coherer is bistable. Once contact is established by RF, it is permanent
until disrupted by shaking. For that reason, we fastened the coherers we
made to the clapper of a bell or buzzer it controlled.

Commercial coherers are evacuated to minimize oxidation. We just
replaced the filings when they got "stale".
http://home.luna.nl/~arjan-muil/radio/coherer.html

Jerry

 

[Don Bowey]

You obviously have zero capacity to make valid assessments.
Particularly in Usenet.

Lay off the beans and your gas may eventually go away.

 

[Don Bowey]

Hi res display, and zero digital or HD channels...

Yeah, you're a real brain, bozo.

You are a mouthy POS. Why not put a cork in it?

Perhaps he likes the quality for watching DVDs, not that it's anyone's
business.

 

[Jerry Avins]

Gene E. Bloch wrote:

...

Oh - Thunderbird. I use it for e-mail. Its spell checker is very
bizarre, IMHO

Luckily I also use the organic spell checker after a pass or three of
Thunderbird's. When I remember to do it, that is...

I use a bunch of spell checkers (not by choice - each program seems to
have a checker of its own), and they *all* are bizarre - it's just that
what one screws up the next does fine, etc

A spell checker ought to be an OS service. That way, any additions such
as frequently encountered names become universal.

Jerry

 

[Jerry Avins]

Jerry Avins wrote:

(snip)


Trying to remember non-electronic ignition systems, I thought they
would work without the capacitor. (or condenser as I remember it.)

The points would ark more and wear out faster, but probably not
so fast that you wouldn't get back to shore.

The capacitor -- even the ones in radios were called condensers then --
forms a resonant circuit with the coil. When the points open, L-C
ringing raises the coil voltage until the plug arcs over. (Because of
the half-cycle delay, leakage in wet wires can drain a lot of the energy
so spark potential would never be reached. Creating a second gap by
pulling the wire out of the coil but leaving it close eliminates that
loss and will often let a wet engine start.) With no capacitor, severe
arcing at the points dissipates much of the coil energy, making for
unreliable ignition at best. Some coils, -- I've seen it in a car --
have enough self capacitance to work reasonably well. In any case, the
original condenser had to come out; it had shorted.

Jerry

 

[Jerry Avins]

Ron Hunter wrote:

(snip)


There are plenty of things in physics labs that do radiation
work that don't have warnings on them. I would expect lead glass
bricks to be less of a problem than solid lead bricks.

The usual problem with lead crystal goblets is acidic liquids
that can dissolve some of the lead out. Usually lead glass bricks
are not stored in acidic liquids.

Nor are they steeped in potable liquids.

Jerry

 

[Joerg]

Then it ain't digital.

Sure it ain't. But what happens if that station goes digital?

Oh well, we bought an "All in the Family" DVD at Long's so if the teevee
goes dark in 2009 we'll have that ;-)

 

[Jerry Avins]

Michael A. Terrell wrote:

...

I carreied a spare capacitor, pouints and distributor cap with me in
my vehicle's tool box, so i didn't ned to improvise critical parts away
from the shop.

This was a friend's boat and I trusted him. It turned out not to be
equipped with RDF (not unusual in the late 40s), compass, bailing pump
or even bucket, to say nothing of ship-to-shore radio. I nearly lost my
life, and I actually lost my naiveté. Since then, I check a boat's
equipment before I accept a joyride.

A large tesla coil do in a pinch.

The pilot had a broken leg. My friend improvised a windbreak from the
broken-off wing, and made fire by soaking clothes from his suitcase in
fuel. I don't know how he made his interrupter. His 300 or so pounds --
mostly blubber -- probably insulated him. It may also have contributed
to the plane's breakup on touching down.

Jerry

 

[G]

Wrong attribution, but no harm done.


I assume you meant powDered carbon detector. That's a new one on me. I'm
familiar with another form of coherer, one that used powdered nickel and
silver. (Filings from a dime and a nickel worked nicely.) That kind of
coherer is bistable. Once contact is established by RF, it is permanent
until disrupted by shaking. For that reason, we fastened the coherers we
made to the clapper of a bell or buzzer it controlled.

Commercial coherers are evacuated to minimize oxidation. We just
replaced the filings when they got "stale".
http://home.luna.nl/~arjan-muil/radio/coherer.html

I said carbon because I was not sure what was in it. I really thought it was a
diode of some sort. I must have been in third or fourth grade when I first
opened up the bus and looked inside. The coherer looked like a fuse
with stuff inside.

greg

 

[Jeff Liebermann]

I already have a 22" HP monitor that will do 2048 * 1536. I use it
on the computer that I use for graphic work and web design.

My comments were in reference to your proposed use of a 32" Sony HDTV
as a computer monitor. Most (not all) have limited dot resolution.
I've had a few bad experiences with customers attempting to use such
large HDTV displays for computer monitors. Most of the time, they
find that the 1366x768 screen appears as a relatively small picture,
surrounded by a large black border. In order to make the display
useful, I've had to install VGA to video converters.

All I watch is local news, and a little Sci-Fi Channel. Cable TV
costs me about $15 a month for that. I can't get the Sci Fi channel
without paying for a tier of sports channels that I don't have time to
watch. The cheapest package with the Sci-Fi channel is ?$45 a month on
Direct TV, and Dish network wants $30 a month.

Kevin Martin, FCC Chair has been issuing anual press releases
indicating his support for ala carte cable programming. Here's the
lastest:
<http://www.pcmag.com/article2/0,1759,2174261,00.asp>
Even AT&T has at time expressed their "support":
<http://www.usatoday.com/tech/news/2005-11-30-at&t-ala-carte_x.htm>
Of course, nothing ever really happens. The big problem is that the
FCC has also forced the cable companies to carry local broadcast
channels. In addition, the highest cost channels to the CATV carrier
are the sports channels, which are only affordable because literally
everyone pays for them. If users were allowed to select their own
channel lineup, local advertisers will lose their free ride, and the
sports channels will become very expensive.

You can still get ala carte programming via 4DTV, but as the feeds
switch to digital, it will probably be dead in a few years. However,
the picture quality if noticeably better than DBS or cable with
excessive compression:
<http://www.skyvision.com/pages/information_center/4dtvguide.html>
<http://www.motorola.com/content.jsp?globalObjectId=5050-8100>
<http://www.faqs.org/faqs/Satellite-TV/4dtv/>
<http://www.4dtvforum.com>

Programming is mostly ala carte:
<http://skyvision.com/programming/alacarte.html>>
If all you want is the Science Channel, you can get that for $42year.
The catch is that you have to subscribe to a minimum of 10 channels to
get that price. Assuming you go for a mix of cheapo channels, that's
about $500/year, which isn't much of a bargain. However, it is ala
carte and is probably a good predictor of what will happen when ala
carte arrives on DBS or CATV.

 

[Jerry Avins]

G wrote:

...

I said carbon because I was not sure what was in it.

!

I really thought it was a
diode of some sort. I must have been in third or fourth grade when I first
opened up the bus and looked inside. The coherer looked like a fuse
with stuff inside.

We used glass tubing plugged with bits of cork and sealing wax. A small
cartridge fuse would have worked, but it was a hassle to get the end
caps off.

Jerry

 

[Michael A. Terrell]

My comments were in reference to your proposed use of a 32" Sony HDTV
as a computer monitor. Most (not all) have limited dot resolution.

Sorry, I forgot the smiley.

I've had a few bad experiences with customers attempting to use such
large HDTV displays for computer monitors. Most of the time, they
find that the 1366x768 screen appears as a relatively small picture,
surrounded by a large black border. In order to make the display
useful, I've had to install VGA to video converters.


Kevin Martin, FCC Chair has been issuing anual press releases
indicating his support for ala carte cable programming. Here's the
lastest:

They have been beating this dead horse since the early '80s, when I
designed and built CATV headends.

<http://www.pcmag.com/article2/0,1759,2174261,00.asp>
Even AT&T has at time expressed their "support":
<http://www.usatoday.com/tech/news/2005-11-30-at&t-ala-carte_x.htm>
Of course, nothing ever really happens. The big problem is that the
FCC has also forced the cable companies to carry local broadcast
channels.

Yes. The old "Must carry" regulations. They were a pain in the '80s
when the switching equipment wasn't versatile enough, and reliable
enough to block some programming, so some channels that people wanted
added to a system required someone to manually switch when something
actually started or stopped. Local ball games that weren't sold out had
be blocked, along with a lot of other crap.

In addition, the highest cost channels to the CATV carrier
are the sports channels, which are only affordable because literally
everyone pays for them. If users were allowed to select their own
channel lineup, local advertisers will lose their free ride, and the
sports channels will become very expensive.

the same local advertisers who try to sell me overpriced furniture
and vehicles, I neither need, nor want. As far as the sports channels,
I wouldn't care if they ALL went bankrupt.

You can still get ala carte programming via 4DTV, but as the feeds
switch to digital, it will probably be dead in a few years. However,
the picture quality if noticeably better than DBS or cable with
excessive compression:
<http://www.skyvision.com/pages/information_center/4dtvguide.html>
<http://www.motorola.com/content.jsp?globalObjectId=5050-8100>
<http://www.faqs.org/faqs/Satellite-TV/4dtv/>
<http://www.4dtvforum.com>

Programming is mostly ala carte:
<http://skyvision.com/programming/alacarte.html>>
If all you want is the Science Channel, you can get that for $42year.
The catch is that you have to subscribe to a minimum of 10 channels to
get that price. Assuming you go for a mix of cheapo channels, that's
about $500/year, which isn't much of a bargain. However, it is ala
carte and is probably a good predictor of what will happen when ala
carte arrives on DBS or CATV.

I know better than to hold my breath. I have dealt with Skyvision
quite a few times, when C-band was the preferred sat service. When word
got out that I had worked with commercial receive only earth stations, I
suddenly had lots of friends I'd never met.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Michael A. Terrell]

Hi res display, and zero digital or HD channels...

Yeah, you're a real brain, bozo.

No, you're the clown. I got the thing for free, and delivered to my
door. I took it, because it was offered by a family member. I have a
life outside of watching TV, you should try it.

They had it for two years, and have never watched any HD programming
on it. They simply wanted a big TV because of failing eyesight. Then,
they just had to have an LCD TV and replaced an almost new TV.

Last year they gave away a fairly new motor home, when they accepted
that they weren't in good enough health to take long trips.

Go play with your troll buddies so they can 'bore' you some more.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida