Visual "clipping"?

On 9/04/2007, Michael A. Terrell posted this:
> Martin Heffels wrote:
>> 
>> On Tue, 04 Sep 2007 12:23:52 -0400, "Michael A. Terrell"
>> <mike.terrell@earthlink.net> wrote:
>> 
>>>   Never worked at a TV transmitter site, have you?  If they are
>>> operating under the specified power, they are in violation of their
>>> license, and no one is stupid enough to overbuy on the transmitter
>>> requirements.
>> 
>> Help me here..... Since when would this be a violation? A
>> transmitter-license usually states the _maximum_ amount of power, so what
>> is different here? Stories are plenty of radio and television-stations
>> cutting down their power for power-saving reasons (money, money, money).
>
>
>    In the US a station has to notify the FCC if they are not operating
> at the power they are licensed for.  It has to be logged on a set
> schedule and kept in the station's permanent files for the FCC field
> inspectors.  If a station is operating below the level they are licensed
> for, they are not serving the area they agreed to provide service to.
> VERY few stations were ever allowed to differ from their rated power. 
> The only two I ever saw were on military bases where the transmitter
> power was listed, with "Or as deemed necessary".  These were in remote
> locations and major repairs were consider as 'Depot Level' repairs. 
> Reduced or increased power was allowed, to stay on the air, but none of
> these were high power stations.  The license was deemed a 'Courtesy
> License' by the FCC, which meant that they had little authority over a
> military transmitter, but the 'Courtesy License' was granted to make
> sure the frequency coordinators didn't assign a civilian station an
> allocation that would interfere.
>
>
>    If your power level is too high, you can cause problems for other
> stations, and if it's too low, your advertisers will demand refunds.
>
>    I was a broadcast engineer at one military and two civilian TV
> stations over a 17 year period.  I lost count of the AM radio stations I
> did work for, or located parts and equipment to keep on the air.

However, the original remark was not about the *licensed* power, it was 
about the *rated* power. I.e., the electrical or electronic limits, not 
the legal limits.

-- 
Gene E. Bloch (Gino)
letters617blochg3251
(replace the numbers by "at" and "dotcom")

"Gene E. Bloch" wrote ...
> However, the original remark was not about the *licensed* power, it was 
> about the *rated* power. I.e., the electrical or electronic limits, not 
> the legal limits.

But as Mr. Terrell also observed, profit-making businesses don't
commonly waste money buying an over-powered transmitter.
They are frightfully expensive in any case. 

Radium wrote:
> On Sep 3, 8:27 pm, isw <i...@witzend.com> wrote:
> 
>> In article <1188874984.222039.197...@y42g2000hsy.googlegroups.com>,
> 
>>  Radium <gluceg...@gmail.com> wrote:
> 
>>> Hi:
> 
>>> Clipping in an audio signal results when an audio device receives a
>>> signal that is too loud. The audio signal distorts into square-waves
>>> because the "tops" of the signal are flattened. The device cannot
>>> handle power levels over a certain level. When this level is exceeded,
>>> clipping occurs. Clipping is usually harsher in digital devices than
>>> in analog devices. Analog clipping tends to be fuzzy and soft compared
>>> to digital clipping.
> 
>>> What is the visual-equivalent of "clipping"? Is there a difference
>>> between analog and digital in terms of visual-clipping? If so, what is
>>> the difference?
> 
>> Clipping causes whites lose all texture -- very similar to overexposed
>> film.
> 
> What does this look like on a screen?
> 
>>> Auditory-clipping can damage speakers. Can visual-"clipping" damage
>>> monitors?
> 
>> No. Prolonged blacks can damage television transmitters, however (video
>> is inverted for transmission, so black requires full power from the
>> transmitter).
> 
> Prolonged black can damage a monitor/screen? That's weird. White is
> analogous to the loudest sound a loudspeaker can playback. Black is
> analogous to a loudspeaker not being feed any signal.
> 
I suggest that you go back and read the post you replied to. Do you have 
a TV transmitter?
Allen

Allen wrote:
> 
> Radium wrote:
> > On Sep 3, 8:27 pm, isw <i...@witzend.com> wrote:
> >
> >> In article <1188874984.222039.197...@y42g2000hsy.googlegroups.com>,
> >
> >>  Radium <gluceg...@gmail.com> wrote:
> >
> >>> Hi:
> >
> >>> Clipping in an audio signal results when an audio device receives a
> >>> signal that is too loud. The audio signal distorts into square-waves
> >>> because the "tops" of the signal are flattened. The device cannot
> >>> handle power levels over a certain level. When this level is exceeded,
> >>> clipping occurs. Clipping is usually harsher in digital devices than
> >>> in analog devices. Analog clipping tends to be fuzzy and soft compared
> >>> to digital clipping.
> >
> >>> What is the visual-equivalent of "clipping"? Is there a difference
> >>> between analog and digital in terms of visual-clipping? If so, what is
> >>> the difference?
> >
> >> Clipping causes whites lose all texture -- very similar to overexposed
> >> film.
> >
> > What does this look like on a screen?
> >
> >>> Auditory-clipping can damage speakers. Can visual-"clipping" damage
> >>> monitors?
> >
> >> No. Prolonged blacks can damage television transmitters, however (video
> >> is inverted for transmission, so black requires full power from the
> >> transmitter).
> >
> > Prolonged black can damage a monitor/screen? That's weird. White is
> > analogous to the loudest sound a loudspeaker can playback. Black is
> > analogous to a loudspeaker not being feed any signal.
> >
> I suggest that you go back and read the post you replied to. Do you have
> a TV transmitter?
> Allen


   Are you kidding?  The radium troll barely has enough neurons to pound
out his drivel.


-- 
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

"Gene E. Bloch" wrote:
> 
> On 9/04/2007, Michael A. Terrell posted this:
> > Martin Heffels wrote:
> >>
> >> On Tue, 04 Sep 2007 12:23:52 -0400, "Michael A. Terrell"
> >> <mike.terrell@earthlink.net> wrote:
> >>
> >>>   Never worked at a TV transmitter site, have you?  If they are
> >>> operating under the specified power, they are in violation of their
> >>> license, and no one is stupid enough to overbuy on the transmitter
> >>> requirements.
> >>
> >> Help me here..... Since when would this be a violation? A
> >> transmitter-license usually states the _maximum_ amount of power, so what
> >> is different here? Stories are plenty of radio and television-stations
> >> cutting down their power for power-saving reasons (money, money, money).
> >
> >
> >    In the US a station has to notify the FCC if they are not operating
> > at the power they are licensed for.  It has to be logged on a set
> > schedule and kept in the station's permanent files for the FCC field
> > inspectors.  If a station is operating below the level they are licensed
> > for, they are not serving the area they agreed to provide service to.
> > VERY few stations were ever allowed to differ from their rated power.
> > The only two I ever saw were on military bases where the transmitter
> > power was listed, with "Or as deemed necessary".  These were in remote
> > locations and major repairs were consider as 'Depot Level' repairs.
> > Reduced or increased power was allowed, to stay on the air, but none of
> > these were high power stations.  The license was deemed a 'Courtesy
> > License' by the FCC, which meant that they had little authority over a
> > military transmitter, but the 'Courtesy License' was granted to make
> > sure the frequency coordinators didn't assign a civilian station an
> > allocation that would interfere.
> >
> >
> >    If your power level is too high, you can cause problems for other
> > stations, and if it's too low, your advertisers will demand refunds.
> >
> >    I was a broadcast engineer at one military and two civilian TV
> > stations over a 17 year period.  I lost count of the AM radio stations I
> > did work for, or located parts and equipment to keep on the air.
> 
> However, the original remark was not about the *licensed* power, it was
> about the *rated* power. I.e., the electrical or electronic limits, not
> the legal limits.


   Its obvious that you've never built a TV station from the ground up. 
Even a spare 10% transmitter power capacity could cost a couple hundred
thousand dollars in capital assets. and its unlikely the governing
agency will allow you to use equipment capable of excess power, any more
than you can build whatever tower height you want.  It costs millions of
dollars to build a full power commercial TV station.


-- 
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

On 9/04/2007, Michael A. Terrell posted this:
> "Gene E. Bloch" wrote:
>> 
>> On 9/04/2007, Michael A. Terrell posted this:
>>> Martin Heffels wrote:
>>>> 
>>>> On Tue, 04 Sep 2007 12:23:52 -0400, "Michael A. Terrell"
>>>> <mike.terrell@earthlink.net> wrote:
>>>> 
>>>>>   Never worked at a TV transmitter site, have you?  If they are
>>>>> operating under the specified power, they are in violation of their
>>>>> license, and no one is stupid enough to overbuy on the transmitter
>>>>> requirements.
>>>> 
>>>> Help me here..... Since when would this be a violation? A
>>>> transmitter-license usually states the _maximum_ amount of power, so what
>>>> is different here? Stories are plenty of radio and television-stations
>>>> cutting down their power for power-saving reasons (money, money, money).
>>> 
>>> 
>>>    In the US a station has to notify the FCC if they are not operating
>>> at the power they are licensed for.  It has to be logged on a set
>>> schedule and kept in the station's permanent files for the FCC field
>>> inspectors.  If a station is operating below the level they are licensed
>>> for, they are not serving the area they agreed to provide service to.
>>> VERY few stations were ever allowed to differ from their rated power.
>>> The only two I ever saw were on military bases where the transmitter
>>> power was listed, with "Or as deemed necessary".  These were in remote
>>> locations and major repairs were consider as 'Depot Level' repairs.
>>> Reduced or increased power was allowed, to stay on the air, but none of
>>> these were high power stations.  The license was deemed a 'Courtesy
>>> License' by the FCC, which meant that they had little authority over a
>>> military transmitter, but the 'Courtesy License' was granted to make
>>> sure the frequency coordinators didn't assign a civilian station an
>>> allocation that would interfere.
>>> 
>>> 
>>>    If your power level is too high, you can cause problems for other
>>> stations, and if it's too low, your advertisers will demand refunds.
>>> 
>>>    I was a broadcast engineer at one military and two civilian TV
>>> stations over a 17 year period.  I lost count of the AM radio stations I
>>> did work for, or located parts and equipment to keep on the air.
>> 
>> However, the original remark was not about the *licensed* power, it was
>> about the *rated* power. I.e., the electrical or electronic limits, not
>> the legal limits.
>
>
>    Its obvious that you've never built a TV station from the ground up. 
> Even a spare 10% transmitter power capacity could cost a couple hundred
> thousand dollars in capital assets. and its unlikely the governing
> agency will allow you to use equipment capable of excess power, any more
> than you can build whatever tower height you want.  It costs millions of
> dollars to build a full power commercial TV station.

Do you *really* think I've never built a TV station form the ground up?

Really?

Well, you're correct. It doesn't keep from speculating, however.

For example, it *might* be true that it's a good idea to spend extra 
money to put in safety factors (although, to be fair, I *do* run my 
100W lightbulbs at 100W). It could be cheaper in the long run than 
fixing the reasult of not doing so.

The above has certinaly been true in civil construction for millennia.

-- 
Gene E. Bloch (Gino)
letters617blochg3251
(replace the numbers by "at" and "dotcom")

Gene E. Bloch wrote:
> On 9/04/2007, Michael A. Terrell posted this:
>> "Gene E. Bloch" wrote:
>>>
>>> On 9/04/2007, Michael A. Terrell posted this:
>>>> Martin Heffels wrote:
>>>>>
>>>>> On Tue, 04 Sep 2007 12:23:52 -0400, "Michael A. Terrell"
>>>>> <mike.terrell@earthlink.net> wrote:
>>>>>
>>>>>>   Never worked at a TV transmitter site, have you?  If they are
>>>>>> operating under the specified power, they are in violation of their
>>>>>> license, and no one is stupid enough to overbuy on the transmitter
>>>>>> requirements.
>>>>>
>>>>> Help me here..... Since when would this be a violation? A
>>>>> transmitter-license usually states the _maximum_ amount of power, 
>>>>> so what
>>>>> is different here? Stories are plenty of radio and television-stations
>>>>> cutting down their power for power-saving reasons (money, money, 
>>>>> money).
>>>>
>>>>
>>>>    In the US a station has to notify the FCC if they are not operating
>>>> at the power they are licensed for.  It has to be logged on a set
>>>> schedule and kept in the station's permanent files for the FCC field
>>>> inspectors.  If a station is operating below the level they are 
>>>> licensed
>>>> for, they are not serving the area they agreed to provide service to.
>>>> VERY few stations were ever allowed to differ from their rated power.
>>>> The only two I ever saw were on military bases where the transmitter
>>>> power was listed, with "Or as deemed necessary".  These were in remote
>>>> locations and major repairs were consider as 'Depot Level' repairs.
>>>> Reduced or increased power was allowed, to stay on the air, but none of
>>>> these were high power stations.  The license was deemed a 'Courtesy
>>>> License' by the FCC, which meant that they had little authority over a
>>>> military transmitter, but the 'Courtesy License' was granted to make
>>>> sure the frequency coordinators didn't assign a civilian station an
>>>> allocation that would interfere.
>>>>
>>>>
>>>>    If your power level is too high, you can cause problems for other
>>>> stations, and if it's too low, your advertisers will demand refunds.
>>>>
>>>>    I was a broadcast engineer at one military and two civilian TV
>>>> stations over a 17 year period.  I lost count of the AM radio 
>>>> stations I
>>>> did work for, or located parts and equipment to keep on the air.
>>>
>>> However, the original remark was not about the *licensed* power, it was
>>> about the *rated* power. I.e., the electrical or electronic limits, not
>>> the legal limits.
>>
>>
>>    Its obvious that you've never built a TV station from the ground 
>> up. Even a spare 10% transmitter power capacity could cost a couple 
>> hundred
>> thousand dollars in capital assets. and its unlikely the governing
>> agency will allow you to use equipment capable of excess power, any more
>> than you can build whatever tower height you want.  It costs millions of
>> dollars to build a full power commercial TV station.
> 
> Do you *really* think I've never built a TV station form the ground up?
> 
> Really?
> 
> Well, you're correct. It doesn't keep from speculating, however.
> 
> For example, it *might* be true that it's a good idea to spend extra 
> money to put in safety factors (although, to be fair, I *do* run my 100W 
> lightbulbs at 100W). It could be cheaper in the long run than fixing the 
> reasult of not doing so.
> 
> The above has certinaly been true in civil construction for millennia.
> 
Oh.  So that's why small rural bridges never have weight limits posted 
on them?

Not.

Any system has to be designed with some sort of limits in mind.  If the 
broadcasters want to make decisions about how much of a screen can be 
black and for how long, it's their decision to make.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Matt Ion wrote:
> Richard Crowley wrote:
>> "isw" wrote ...
>>> Radium  wrote:
>>>> Auditory-clipping can damage speakers. Can visual-"clipping" damage
>>>> monitors?
>>> No. Prolonged blacks can damage television transmitters, however (video
>>> is inverted for transmission, so black requires full power from the
>>> transmitter).
>>
>> Prolonged bright areas (whether clipped or not) will damage CRT
>> monitors. I have two on the bench right now to have their CRTs
>> replaced because the image is burned-in.  They came from a
>> security/survelience application and you can somewhat see the
>> hallway and the doors they were monitoring. 
> 
> ANY static image for a prolonged time will cause burn-in on a CRT or 
> plasma display.  The brighter it is, the less time it takes, but it 
> doesn't have to be pure white for burn to occur.  Simply displaying 100% 
> white won't cause instant death of a monitor, however, the way a clipped 
> signal can damage a speaker.

Speaker damage occurs when the *speaker* clips. It's a result of the 
voice coil hammering against the stops. Woofers and midranges are 
protected from the high frequencies that clipping in the amplifier 
generates by their crossover networks. If a tweeter isn't underrared as 
tweeters often are, they won't be damaged by the acceleration forces. 
When an amplifier clips, there's no longer feedback to lower its output 
impedance, and the high output impedance also protects the speaker from 
amplifier overload.

There are few speakers that can withstand the full output of a 500 W 
amplifier even when the amplifier doesn't clip. Speaker ratings apply to 
short bursts of power, not continuous abuse. A 10%-efficient speaker 
driven at 500 watts is having 450 W of heat pumped into it. A two-slice 
toaster runs about 800 W. How long before the voice coil smokes?

Transmitter and amplifier tubes have two ratings: CCS and ICAS*. There 
is significant difference. Speakers are rated what I call MDFR**. What 
will the salespeople tell you, that the rating is bogus or that clipping 
burned it out?

Jerry
________________________________________
* "Continuous commercial service" and "intermittent commercial and 
amateur service".
** "Market-driven fictitious rating"
-- 
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

"Gene E. Bloch" wrote:
> 
> > On 9/04/2007, Michael A. Terrell posted this:
> >
> >    Its obvious that you've never built a TV station from the ground up.
> > Even a spare 10% transmitter power capacity could cost a couple hundred
> > thousand dollars in capital assets. and its unlikely the governing
> > agency will allow you to use equipment capable of excess power, any more
> > than you can build whatever tower height you want.  It costs millions of
> > dollars to build a full power commercial TV station.
> 
> Do you *really* think I've never built a TV station from the ground up?
> 
> Really?
> 
> Well, you're correct.


  I HAVE built a complete TV station, starting with an empty building
and no tower.


> It doesn't keep from speculating, however.


   Speculate all you want, and let everyone see that you have absolutely
no grasp of the subject.


> For example, it *might* be true that it's a good idea to spend extra
> money to put in safety factors (although, to be fair, I *do* run my
> 100W lightbulbs at 100W). It could be cheaper in the long run than
> fixing the reasult of not doing so.


   Do you know that a TV station's EIRP is transmitter power output,
multiplied by antenna gain?


> The above has certinaly been true in civil construction for millennia.


   The only 'Civil' Engineering of a TV station is the buildings, and
the towers.  The rest is Electronics, which is a different discipline,
with different rules.


-- 
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 wrote:
>[snip]
> 
>    Never worked at a TV transmitter site, have you?  If they are
> operating under the specified power, they are in violation of their
> license, ...

*WHAT?*
Please quote a specific regulation that _prohibits_ operating at *LESS* 
than authorized power. My commercial license  (2nd class phone) may have 
expired 40 years ago, but I never heard of such. We even had a backup 
1Kw transmitter for when our 50Kw transmitter went down. There were 
occasions (ice storms) when we switched to backup BEFORE primary went 
down as it was more tolerant of bad SWR. [now this was an FM rather than 
TV but don not see difference for this case]