The name "Fryktoria" means a communication network which was used in antiquity to transfer optical messages using the light of fires or torches. The great poet Aeschylus who lived in the 5th century BC, describes in detail in his tragedy 'Agamemnon' (verses 283-316) an implementation of such a network, built to signal the fall of Troy to the Myceneans. This network, which was designed by Palamedes according to the much older and mostly lost epic poem Cypria, employed eight stations and covered an aggregate line-of-sight distance of 550 kilometers, having the longest span at approximately 130Km (81 miles) over sea (see Note 1). Watching 'Agamemnon' with the eyes of a telecom engineer, we identify the same protocol timing issues of the modern optical communications in the words of the "fryktoria" operator, a soldier who was afraid that he might fall asleep in the dark, cold night and miss the signals from afar.

Later optical networks had a more elaborate handshaking scheme. In the "Pyrseia" system of the 3rd century BC, the transmitter made visible two torches, the receiver acknowledged with two torches, all parties went dark for a few moments and finally, the transmitter started to send the message payload. This system encoded each letter of the alphabet with two words of five bits each.

Note 1. I have received comments about the feasibility of establishing such a long span of 130Km because of the limitation imposed by the curvature of the Earth. Although we do not know the exact locations of the fryktoria towers, we can assume that they were built in selected locations, at a resonable height. The heighest peak of Mount Athos stands at 2033 meters (1.26 miles). The heighest peak of Evoia island is on Dirfys mountain. The Delphi peak stands at 1743 meters (1.08 miles). Please note that the points on the adjacent map have been pinned down exactly at the peaks of the mountains, as described in the Agamenon tragedy. Thus, the line-of-sight distance is measured on map making this assumption. Therefore, the maximum line-of-sight distance can be calculated as d = sqrt(2*R*(h1+h2)), where R is the radius of the Earth at 6371Km (3959 miles) and h1, h2 are the heights of the tower locations. This calculation results to d = 219Km (136 miles). Although it is doubtful that a tower can withstand the harsh environmental conditions at the top of the mountain peak, an alternative location at a lower peak could provide the required line-of-sight distance. Therefore, the feasibility of such a span is plausible.

Map created by Fryktoria GIS. Background tiles provided by OpenStreetMap.