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50hz 100hz i dont know this means


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Old 13-04-2012, 22:14
suzieque
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Is there a list of terms like the example in my title, there are any number of figures quoted in tv set sales details but i dont know what they mean or the effect on the performance of the tv.
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Old 13-04-2012, 22:43
Gneiss
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Here are a couple of basic ones....

http://www.csgnetwork.com/glossaryh.html
http://www.wilsonselectronics.net/dictionary.htm
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Old 14-04-2012, 07:41
mac2708
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Have a look at this http://www.which.co.uk/technology/tv...res-explained/
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Old 14-04-2012, 15:01
AidanLunn
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"Hz" = Hertz. Names after the German geezer that made it up.

It's a unit of measurement meaning "times per second".

Television set wise it means how many times the beam for displaying the image in an older CRT set would need to make a "sweep" down the image to make up one complete frame

So one complete picture, or "frame" if you like, would use 2 sweeps down the tube face to make it up. This is using interlaced video, where the information for video is transmitted in the order of lines 1 3, 5, etc, then 2, 4, 6 etc. There are 25 frames per second, as as there are 2 sweeps to 1 frame, 50Hz = 25fps.

Progressive video is transmitted in the order of lines 1, 2, 3, 4, 5 etc. Unlike interlaced, each sweep makes up one whole picture within the same timeframe. So there's double the amount of information transmitted - effectively 100Hz instead of 50Hz.
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Old 14-04-2012, 17:00
chrisjr
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It is not the case that SD or HD using progressive necessarily uses twice the bandwidth of interlaced . At the same frame rate both are identical. The only difference between the two is that 1080i for example uses two blocks of 540 lines and 1080p uses one block of 1080 lines.But the actual number of lines per second is the same.

SD TV broadcasts use interlaced at 50Hz, 25fps. Freeview HD can use 1080p at 25fps or 1080i at 50Hz, 25 fps.

In this context 100hz means that the TV is "inventing" additional frames that were not broadcast which it fires at the screen at twice the rate of a "normal" 50Hz display. The intention is to reduce some of the perceived artefacts of 50hz display such as flicker.
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Old 14-04-2012, 17:15
Simon Rodgers
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Basically the faster, the smoother.
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Old 14-04-2012, 18:36
Orbitalzone
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It should be noted that UK TV broadcasts at 50Hz / 25 frames a second and so a 50Hz TV should be perfectly fine for viewing this, however often a higher spec TV might feature 100Hz, 200Hz or even 600Hz (sort of) processing capabilities.... this is to double, quadruple etc the amount of times the image is produced on the TV screen, supposedly to reduce flicker and increase smoothness of pictures.

Does repeating the same frame twice or four times actually improve the viewed image though?

In reality it may improve the image to some degree (or not) but it's more likely due to the overall superior processing that the higher spec TV has rather than it being 100Hz or 200Hz etc....

A good quality 50Hz LCD TV can easily outperform a mediocre quality 100Hz TV despite what the manufacturers might have you believe. It should not be assumed that 100Hz is better than 50Hz or 200Hz is better than 50 or 100Hz TVs.

You'll find comments all over the web where TV owners find they get better pictures by turning off a lot of the "picture enhancement features"

With old fashioned CRT TV's the 100Hz certainly reduced screen flicker but often introduced nasty digital artifacts due to the processing of the image..... LCD and Plasma's generally don't suffer screen flicker to any great degree compared to CRT's
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