Date: Mon, 17 Apr 2000 22:57:33 PDT
From: "neil barnes" <[EMAIL PROTECTED]>
Subject: Re: TV tuners
Simon,
Please understand this does *not* represent the view of the BBC but is a
personal observation...
UK digital TV uses the same channel allocations as normal terrestrial
television. The difference is (er) that the coding is digital instead of
analogue. This is significant because with an analogue signal, you can
tolerate a *lot* of noise on the signal and still get a recognisable signal
as long as the syncs are recognisable. As the noie increases, the signal
will get gradually worse - hiss on the audio and sparklies on the video (the
coding mechanism means that you can often still get clear audio when the
picture is completely unusable.
On the other hand, there isn't any redundancy in the digital signal. In the
same channel width as an analogue channel, the data contains (IIRC) 6
channels in a multiplex. Data is distributed in both frequency and time to
alleviate the inevitable data loss and let the error correction do its
stuff. However, digital systems are not noted for graceful failure. Once you
get more bit or burst errors than the correction can handle, you have big
errors in the output - you've probably seen picture freezes and 'blocking'
where chunks of picture don't change between successive frames.
So the conclusion is: TV decoders (analog *or* digital as available) are
fine for a desktop where you're likely to have a hard-wired and properly
distributed system, but you're unlikely to get sensible pictures even for
analogue on the move unless you're orbiting Emley Moor, Sutton Coldfield, or
Crystal Palace ;(
Neil (on his way today to set upthe next FutureWorld exhibition in Cardiff)
>From: "Simon Dale" <[EMAIL PROTECTED]>
>Reply-To: Libretto <[EMAIL PROTECTED]>
>To: Libretto <[EMAIL PROTECTED]>
>Subject: TV tuners
>Date: Mon, 17 Apr 2000 20:09:57 -0700
>
>Date: Tue, 18 Apr 2000 04:03:42 +0100
>From: "Simon Dale" <[EMAIL PROTECTED]>
>Subject: TV tuners
>
>Has anyone had any experience with these? I'd be especially interested to
>hear about people in the UK.
>
>I can imagine watching TV on your sub notebook would be cool (and perhaps
>delay my itching to get a PC that can play DVDs) but what are they like in
>use? Can you actually get a picture in the UK without balancing your PC on
>a friends head while standing on a chair or moving to live next to a
>transmitter?
>
>I'd be after a device which allows full screen viewing at full frame rate
>with good quality pictures (and easy signal reception), teletext and stereo
>sound if possible. USB would also be preferable I think, then I can use it
>whilst at home too (ie PC card slot used to connect to the LAN). I've seen
>the Hauppauge USB device but noticed that it was only mono, which seems a
>little odd in this day and age. It seems reasonably priced and Hauppauge
>know what they're doing - don't they?
>
>Could someone tell me if digital TV in the UK will make it easier to get a
>signal or more difficult? I guess that depends on the TV system, but I
>wonder if it will be possible to have _DECENT_ pocket TVs, and similar
>devices, on the digital system.
>
>I guess this way I could play a stand alone DVD player into my VAIO using
>RF? It's a result I suppose...not exactly portable though (come to think
>of
>it I have seen small portable players that have video/ audio out (I guess
>an
>RF modulator would sort that out- or does the Hauppauge allow straight
>signal input?))
>
>Thanks
>
>Simon
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