Signalling dissent

``Technologies that transmit data under the noses of repressive authorities in this way are spreading like wildfire among pro-democracy groups, says Mr Moss. For example, after Egypt switched off its internet in January some activists brought laptops to places like Tahrir Square in Cairo to collect, via short-range wireless links, demonstrators’ video recordings and other electronic messages. These activists then broadcast the material to the outside world using range-extending antennae. ''