February 23, 2012

The rise of digital TV

Digital Television (DTV) uses digital signals to transmit audio and video information, unlike the older technology of analog signals used by analog television. The UK, like many other countries are supplanting their analog television systems by digital over a period of time. This is so that the extensive radio bandwidth used by the analog system can be re-used for other transmissions.

A number of technologies have developed to deliver digital television. There are x different services available for consumers. Firstly, Digital terrestrial television includes around 100 television and radio services, some of them interactive, able to be accessed by a standard TV aerial.  Most of them are free-to-air. They are often referred to as Freeview, the brand name of the broadcasters of these services. The programmes are received through a Freeview box. Then there are digital television services delivered via a satellite signal into a satellite box, and those delivered by underground cables into the home with a cable TV management box.

Growing more popular is the fourth alternative method of receiving digital TV services – Internet Protocol television. This is a system using specialised electronic components and software connected to the internet via a computer.

Latest developments of digital television services include not only live television viewing and interactive TV, but also time-shifted storing of programmes to view them later and high definition services.

Blu-ray technology explained

Blu-ray is a format for high definition DVD. More and more people are upgrading to – or have already upgraded their TV to a LCD or plasma TV which will most probably be capable of displaying the latest high definition (HD) pictures. High Definition TVs playing HD content display brighter colours, far crisper images and a sharper picture. Mostly the HD content will be HD digital content sent through an HD box such as a HD Sky box or a Blu-ray DVD Player or another type of device with a Blu-Ray disc inside.

Like a standard DVD or CD player and recorders the Blu-ray Player reads the data from the spinning reflective disc using a laser. How much such information can be stored on the disc depends on the wavelength of the laser light used to record or read the data. Ordinary DVD devices use a red laser which has a wavelength of 650 nanometres and a double-sided disc can store up to 8.5GB of data enough for a standard film. A HD film needs much more storage space than this and a Blu-ray disc with a much larger capacity is needed. Blu-ray devices use blue-violet lasers – a shorter wavelength of 405 nanometres where the shorter wavelength of the laser gives more precision to cut narrower tracks and store much more data. A single layer disc can hold 25GB of data and a double-sided disc 50GB. Future technology will be multi-layered discs increasing storage up to 200GB. Blu-ray players are also able to play ordinary DVDs though not with High Definition.

Audio visual equipment – Hi Fi Surround sound

At one time it was amazing just to hear scratchy wheezy sounds played from a wax disk, then even more amazing to hear much clearer sounds from a vinyl record played on your record deck. Then came the marvel of stereo speakers and a whole new range of audio sources and equipment to play them on. Speakers and equipment became much more sophisticated and listener’s ears with them. These stereo speakers meant, for the purist, being sat in a particular chair in the “sweet spot” to appreciate the stereo effect. Other folks sat around in other places missed out on the finer points of the music production which may not have been noticed with some types of music but with some -say jazz and classical, this could really diminish pleasure. Now there is surround sound, which involves improving the sound reproduction of an AV source by providing further multi audio channels by adding additional discrete speakers. So multi channel surround sound is perceived by the human ear as coming from all round the room – e.g. 3Dsound!

To achieve this surround sound in your home you need an A/V receiver – a special amplifier, and a number of speakers which are positioned around your room – usually 5 speakers (left, right, centre, left surround, right surround) and then ,for the bass frequencies, a sub woofer. It’s probably better to buy all these different elements as one package. Many systems include iPod docks and will also play audio CDs. A wireless surround sound system will look good and be easier to set up. Surround sound systems still rely on sitting in the “sweet spot” for maximum appreciation.