Er, isn't it 'volume' compression? Probably multi-band volume compression, but not bandwidth afaik. There isn't enough bandwidth to spare to allow 500 channels to all de-compress their bandwidth at the same time; they'd rather cram more channels in than let each one have more bandwidth at advert time.

Volume (i.e. level) compression raises the 'low levels' much more; sort of squashes it all upwards so whilst the maximum level does not change, much more of the signal is at or near maximum level so it sounds louder.

Power is the area under the graph of level against time, so the 'fuller' this area is, the more power there is. If this makes sense... :freak3:

I remember Channel Five getting done for this a few years ago. I got the above from a website on the matter.

HI, I'M BARRY SCOTT!!!! :mad:

How about the SafestyleUK bloke, "YOU BUY ONE, YOU GET ONE FREE,I SAID YOU BUY ONE...."
No thanks, I wouldn't anything from a fat, bearded bloke in a green cloak!

No band width......

imagine each channel has a ten kilohertz step...

10

20

30


etc


channel 10 transmits at 15khz with a 2.5 kz safe bleed zone either side, so always stays within the 10hz band width...

channel 20 at 25khz channel 30 at 35khz

when the commercial comes on they still transmit at 15 25 35 etc, but use the whole band width (10Khz) to send the signal... result is more power... you can work out the rest...


Ive seen it done on cb radios back in the 80,s when some friends at marconi's borrowed some rigs for testing;)

boots who needs boots, ;);)


the same principle is used by the broadcasters... they have admitted it.

mart

Most decent AV systems have the option to do the reverse of what the advertisers do, so not to annoy the neighbours :) (i.e make loud scenes quieter and quiet scenes louder )

Surely increasing the bandwidth would only allow them to broadcast a wider frequency band, i.e. more data in the same period of time?

Seeing as the audio bandwidth is tiny when compared to that needed for a video signal, I can't see how it would make the signal louder - not that I never miss the bleeding obvious though! :D

To make an audio signal louder you increase the power (sound pressure level). As tv audio has a decent enough bandwidth to start off with, it's the only way I can see to do it (again, I am not saying that I am right, just I haven't heard about alternatives etc.). And I know they do it. Radio is also very compressed so that it sounds louder; listen to a CD track and then hear the same track on the radio - it will sound different (note there are tracks with special 'radio' edit mixes, so you'd have to be sure it was the same as the CD track).

Funily enough this is also (in part) compression. The 'night' mode reduces the dynamic range (the difference between loud and quiet parts) and then reduces the volume slightly.

In normal mode you need it loud to hear the quiet bits, but then the loud bits are very loud in deed.

Of course 'night' mode also does things like reduce the bass etc. to limit disturbance.

LOL:D
<<Presses "mute">>

Alcazar

:lol: I wouldn't know about that but my work colleague used to be on one of 'those' channels

"barry scott" is on snet! why don;t you ask him not to shout on any future ads ;)