Special filters block Web surfers from seeing sites abroad run by Chinese dissidents, human rights groups and news organizations.

The filter would block all signals of frequencies above, say, 10 kHz.

Given that filters often block sites unintentionally or can easily be circumvented, such companies may be on to something.

But, on the plus side, this filter (which is really only a giant-sized pre-filter with biological properties) never once blocked.

The filters then block the light and the pixel appears dark.

But of course, many filters now block the site.

China's digital filters, in other words, blocked them before the page could get back to me.

Yahoo, which argued that filters would block even legal material, is considering an appeal.

The low-pass filter will block noise without impeding the performance of your fax or phone.

Don't understand why my filter doesn't block them - but really, I didn't expect this on the TT!