KnowraOptical telegraphLinked fromLinked fromThe 6 pages that link to Optical telegraph, each with the reason it gives.All 6Broader topic 2Related 1Compared with 3TelegraphyBroader topic: It established long-distance coded signaling before practical electrical telegraphy.Morse codeCompared with: Optical systems also encoded messages, but used mechanical or visual codes rather than Morse signals.Electrical telegraphCompared with: It sent coded messages before electrical signals could travel through wires.Flag semaphoreRelated: Flag semaphore carries the same principle of encoded visual signals, but usually without fixed relay towers.History of telecommunicationBroader topic: Its relay towers carried coded messages across distances before electrical telegraphy.Pavel SchillingCompared with: It was an established alternative to electrical signaling when Schilling built his telegraph.