Television is going digital rapidly. And for good reasons. Reasons like digital signals are more robust. And hog lower bandwidths as compared with analogue TV. And are easy to encrypt. (Ho hum !) What's more important is that digital signals can carry additional services such as data. And that digital signals are perfect for implementing interactivity. Add the fact that digital transmissions consume much lower power than analog makes the equation more favorable !

Background
Digital TV services currently use 3 delivery mechanisms: Cable, Satellite and Terrestrial. Most countries have traditionally implemented analogue TV networks, starting with terrestrial analogue TV and moving on to Cable networks. Satellite TV came next (analogue initially, followed by digital). And this is usually followed by Digital Terrestrial TV implementation.

The standard implementation path for digital terrestrial television is to receive digital signals using the existing "fork" antenna. This is so because analogue & digital must co-exist for a number of years, until the analog system can be switched off. (Since digital signals consume less power, the side effects on the analogue picture is negligible.) A digital convertor set-top-box picks up the digital signal from the existing antenna and converts for display to the television set.
Thus, by using existing reception systems, DTT enables households to benefit from DVD quality image & sound.

Like (digital) Satellite TV, Digital Terrestrial TV can be free-to-air or on subscription or pay-per-view. Also possible is 2 way interaction, smart card based subscriptions, broadband internet access, ... the works. And most importantly, DTT bypasses the cable operator, using existing (analogue) terrestrial antenna along with a set-top-box convertor (which costs around $ 100/-).

The DTT Option
In most countries where DTT has been implemented, it has caught on well. Two countries stand out - UK & U.S.A. In the U.K., where DTT has been implemented by public broadcaster BBC (Freeview), it is a roaring success, overtaking analogue terrestrial television and becoming a real threat to Satellite broadcaster SkyTV. Last reports of purchases of set-top-box convertors was in excess of 50,000 per week ! At the current pace, analogue terrestrial TV signals may well be switched off in the U.K. before the end of 2004 !

DTT has also made rapid progress in the U.S. The U.S. Govt. has decided to switch off analogue TV signals by the year 2007. Towards this end, it has recently made it mandatory for all television manufacturers to supply DTT ready TV sets from 2004. (Japan has tentatively decided 2010 as the cut off date for DTT.)

As TVs with built-in STB become more widespread, the simple arrangement of an "fork" antenna feeding TV set could become the norm. And this will become even more attractive because DTT can also enable digital TV reception at mobile locations, such as by trailers. As well as enable reception of digital programs using an indoor antenna placed on a TV set.