HD dilemmas

For the last entry I was using a VisionPlus DTV card to check out the new WIN high definition TV transmission. As of today I’m using a high definition (1080i) CRT-based RPTV and a HD set top box, and this reminds me of a problem we’ll have with HDTV for a while yet.

The RPTV runs PAL TV at 100 hertz. But 576p, 720p and 1080i all kick it back to 50 hertz. The problem: it flickers at 50 hertz. This is inevitable in CRTs (unless they get ones that will run much, much faster) because during the design phase of the CRT, you have to choose the persistence of the phosphors. Too long and you don’t get the benefit of 100 hertz. But because they don’t persist for long, when the tube is running at 50 hertz you get flicker.

The answer is obvious: go for a digital display. Plasma or LCD or some form of projector. Except for one problem with these: none of these has the resolution to fully display 1080i HD, so they all have to scale this down to fit their native resolution.

Eventually their resolution will rise to meet the challenge, but for the time being if you want to watch 1080i high resolution TV, you have to choose between the 50 hertz flicker of CRT-based devices, or a loss of resolution from a digital display device.

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