by Truls Gjestland
High Definition Television, HDTV, can be broadcasted over the existing transmission infrastructure by the use of novel coding and modulation schemes. SINTEF DELAB has developed and implemented a hardware prototype of a COFDM (Coded Orthogonal Frequency Division Multiplexing) modem which allows HDTV signals to be transmitted over a regular 8 MHz channel. SINTEF DELAB was especially invited to demonstrate the system at the world's largest radio and TV conference in Las Vegas, US, in May.
This modem is presently competing favorably in the European standardization process, and consequently SINTEF DELAB has been commissioned to develop a similar modem for 6 MHz channels for the North American digital TV standardization process.
However, consumer television sets for HDTV are not yet on the market, and it is therefore likely that this novel modulation technique will be used to distribute standard definition digital television signals. The capacity of the existing distribution network can thus be increased by a factor of four with even better performance than todays analog methods.
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