Unstable data compression compounded by a lack of high-definition television (HDTV) digital broadcast spectrum has forced Australia"s national broadcaster to choke the quality of its digital signal to free-to-air digital television viewers.

Australian Broadcasting Corp. (ABC) managing director Russell Balding told a Senate Estimates committee hearing that the ABC"s decision to broaden the amount of digital content over the bandwidth of the HDTV signal had resulted in a sacrifice of digital reception quality.

"Compression technology is continuing to address it. But it comes back to the fact that we have made the decision to not just have high definition television. We have made a decision to have as broad a range of content available as possible. That compromises, to a degree, the quality of the high definition signal," Balding said.

The ABC currently transmits two HDTV channels, the main ABC service - which is actually converted from standard definition digital to HDTV - and ABC2 which is created in HDTV but can also be received on standard definition. ABC2 describes itself as "new and time-shifted ABC programming" which features a mix of children"s programs, repeats and documentary and arts oriented programming.

The quality compromise issue appears to have raised the ire of some country Victorians, with Labor Senator Steven Conroy forcing an admission from Balding that some of Aunty"s customers are complaining "the high definition signal is worse than the standard definition signal."

"It is a finite spectrum that we have to work with. We have to fit it all in," Balding said.

ABC director of technology and distribution Colin Knowles was more direct about what the lack of compression and bandwidth capacity meant, telling the Estimates committee ABC2 would have to be killed off to in order to improve HDTV bandwidth.

"In order to accommodate the second channel and the main channel, we have had to reduce the amount of available bandwidth for the high definition channel," he said.

"Most of the content that people complain about is in fact converted from standard definition up to high definition rather than converted from high definition down, if you like, to squeeze into place. It is a trade off."

Asked whether the ABC"s publicly funded rival SBS was transmitting a superior HDTV signal, Balding was emphatic about where his viewing loyalty lay.

"I do not watch SBS," Balding said adding his "very early model" HDTV box at home provided him with "a good quality picture".