Digital Terrestrial TV broadcasting (DTV) began in metropolitan areas of Australian on Jan. 1, 2001 & in regional areas between Jan 1, 2001 & Jan 1, 2004. All existing
analogue (PAL) broadcasting is scheduled to be shut down in 2008. Existing TV broadcasters will be loaned additional channels during the overlap periods, to enable them to simulcast in both formats. After the simulcast period they will return the unused spectrum of the existing analogue channels to the commonwealth. No new commercial television broadcasters will be allowed before December 2006. In
the US the FCC requires all broadcasters be able to transmit HDTV by 2006.
TV broadcasters are being required to broadcast DTV in both High Definition (HDTV) and
Standard Definition (SDTV) formats. They must transmit a standard Definition signal at all times and within
two years of commencement must also provide at least 20 hours a week of High Definition signal although SBS will be allowed to use up-converted material to achieve this quota.
Australia's DTV system is based on the European DVB-1 standard adapted to our conditions and requirements. In addition to Australia, DVB-T has been selected by most European countries (including the U.K.) as well as India.
Video Sound &
Transmission Formats
The Video information will be encoding using MPEG-2 system, with the audio using either the MPEG layer II or Dolby Digital (ac-3) perceptual Sound Compression systems A number of image formats are allowed for both HDTV and SDTV But the most popular are expected to be:
HDTV
720 lines of 1 280 pixels with 25Hz progressive scanning
1080 lines of 1920 pixels with 50HZ interlaced scanning
SDTV
576 lines of 720 pixels, with 50HZ interlaced scanning ('576i')
Note that HDTV is normally transmitted in 16:9 windscreen format, whereas SDTV may be in either 16:9 or standard 4:3 aspect ratio. The 576i SDTV format is almost identical to the video recorded on DVD's with most DVD's using Dolby Digital with up to 5.1 audio channels.
The DVB-T System uses a method of modulation called COFDM, the beauty of this system is that it offers improved multipath distortion compared with the American ATSC system, and also allows multiple transmitters broadcasting the same signal in overlapping service areas to ensure good coverage.
The channels that are being loaned to the various Broadcasters have not been fully assigned by the ABA as yet.
The Broadcasting band will have the channels 9A and 12 added to it with Channels
10 and 11 moved up by 1 MHz. The Channels 0 through to 5A will not be considered
for DTV. while UHF channels 68-69 may be used for non Broadcasting purposes in
the future and will be avoided.
The New Zealand Situation There are no immediate plans to phase out analogue TV in NZ. Digital broadcasting will not commence in January 2001.Only one UHF Channel (Ch 48) is currently transmitting Digital encoded material. The planned national digital system will be basically be the same as Australia and Europe.
The Transistor invented in 1948 by J. Bardeen, W.
Shockley and W. Brattain was invented by accident. They were
experimenting with a diode when they discovered their creation.
