Why Ham radio, radios, and antennas rock!
http://www.economist.com/node/18386151
The Economist
Tuesday March 22nd 2011
Unorthodox links to the internet
Signalling dissent
Savvy techies are finding ways to circumvent politically motivated
shutdowns of the internet
Mar 17th 2011 | from the print edition
WITH a tin can, some copper wire and a few dollars’ worth of nuts, bolts
and other hardware, a do-it-yourselfer can build a makeshift directional
antenna. A mobile phone, souped-up with such an antenna, can talk to a
network tower that is dozens of kilometres beyond its normal range
(about 5km, or 3 miles). As Gregory Rehm, the author of an online
assembly guide for such things, puts it, homemade antennae are “as cool
as the other side of the pillow on a hot night”. Of late, however, such
antennae have proved much more than simply cool.
According to Jeff Moss, a communications adviser to America’s Department
of Homeland Security, their existence has recently been valuable to the
operation of several groups of revolutionaries in Egypt, Libya and
elsewhere. To get round government shutdowns of internet and
mobile-phone networks, resourceful dissidents have used such makeshift
antennae to link their computers and handsets to more orthodox
transmission equipment in neighbouring countries.
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.
According to Bobby Soriano, an instructor at the Philippine branch of
Tactical Tech, a British organisation that teaches communication
techniques to dissidents in five countries, such antennae can even foil
government eavesdropping and jamming efforts. Directional antennae,
unlike the omnidirectional sort, transmit on a narrow beam. This makes
it hard for eavesdroppers to notice a signal is there.
Citizens banned?
Another way of confounding the authorities is to build portable FM radio
stations. One broadcasting expert, who prefers not to be named but is
currently based in Europe, is helping to develop a dozen such “backpack”
radio stations for anti-government protesters in his native land in the
Arabian peninsula. Though these stations have a range of only a few
kilometres, that is enough for the leaders of a protest to use them to
co-ordinate their followers. The stations’ operators act as clearing
houses for text messages, reading important ones over the air for
everyone to hear.
Conventional radio of this sort cannot, unfortunately, transmit video or
web pages. But a group called Access, based in New York, is trying to
overcome that. To help democracy movements in the Middle East and North
Africa get online, it is equipping a network of ham-radio operators with
special modems that convert digital computer data into analogue radio
signals that their equipment can cope with. These signals are then
broadcast from operator to operator until they reach a network member in
an area where the internet functions. This operator reconverts the
signal into computer-readable data and then e-mails or posts the
information online.
Satellites provide yet another way of getting online, though they are
expensive to connect to. It is, however, beyond the authorities in most
places to shut down a satellite operated by a foreign company or
country. The best they can do is try to locate live satellite links
using radiation-detection kit similar to that supposedly employed in
Britain to seek out unlicensed televisions. The result is a game of cat
and mouse between the authorities and satellite-using dissidents.
Tactical Tech, for example, has trained dissidents in five countries to
rig satellite dishes to computers in order to get online. It advises
some users to log on only for short sessions, and to do so from a moving
vehicle.
Such dishes can also be repurposed for long-range internet connections
that do not involve satellites. Yahel Ben-David, an electrical engineer
at the University of California, Berkeley, who has designed secret
cross-border links to the internet for people in several countries, does
so by adding standard USB dongles designed for home Wi-Fi networks. Thus
equipped, two properly aligned dishes as much as 100km apart can
transmit enough data to carry high quality video. Moreover, the beam is
so tightly focused that equipment a mere dozen metres away from its line
would struggle to detect it.
Creative ideas for circumventing cyber-attacks even extend to the
redesign of apparently innocent domestic equipment. Kenneth Geers, an
American naval-intelligence analyst at a NATO cyberwar unit in Tallinn,
Estonia, describes a curious microwave oven. Though still able to cook
food, its microwaves (essentially, short radiowaves) are modulated to
encode information as though it were a normal radio transmitter. Thus,
things turn full circle, for the original microwave oven was based on
the magnetron from a military radar. From conflict to domesticity to
conflict, then, in a mere six decades.
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