Technology behind the Trek

The journalist in Evelyn Waugh's famous novel "Scoop" was told to send his stories out of Africa by hiring native runners to carry the notes in cleft sticks. We're using a quicker system: satellite telephones.

Though the Internet and cellular telephones are now available in most African capitals, most of the continent remains unconnected to land-based telephone lines or the electrical grid. We're able to stay in touch with the outside world with the help of laptop computers, miniaturized satellite telephones and long-lasting batteries.

The key to our communications routine is Inmarsat, a satellite communication system developed in 1979 for the marine industry. In recent years, it has become a key method for businesses, aid workers and journalists who work in remote areas to stay in telephone contact with the outside world. Its web address: www.inmarsat.org.

Four Inmarsat satellites are positioned around the earth, each covering about a third of the globe's surface. The satellites orbit the earth 22,223 in space -- a distance that allows the satellite remains to remain in "geosynchronous" orbit so that they are always in the same place in the sky. To connect to the Inmarsat system, we are carrying satellite telephones about the size of a notebook computer. The top of the satellite telephone is an eight-by-eight inch antenna that, when pointed at the satellite, is able to send and receive voice or data transmissions.

Our little telephone communicates with the satellite, which then relays the call to much larger dishes positioned around the Earth. The calls are then connected to conventional land-based telephone systems. When we receive a call, the system works in reverse.

The satellite telephones have their limitations. There is some time delay because the calls must make a round trip of more than 45,000 miles between Africa and Philadelphia. And the sound quality doesn't exactly capture the sound of a drop of a pin. Sometimes it sounds like the call is coming from under water.

When we connect our computers to the satellite telephone, the data transmission is very slow -- about 2,400 bits per second, or 1/24th the speed that most American households connect to the Internet. At that speed, a single photograph takes about a half-hour to transmit. It doesn't allow web-surfing, so we try to limit the transmissions to text messages.

Electrical power is another concern. Outside the major cities, most villages have no reliable power systems. Most people rely on individual diesel or gasoline generators or they learn to get by without power.

Fortunately, we'll be travelling with our own power-station -- the truck. We'll charge our batteries during the day from the truck, and if we have to, we can connect the computers and satellite telephones directly to the truck's battery.

-- Andrew Maykuth