Question of the Month: Difficulty Transmitting a Digital Optical Signal

Question of the Month: Difficulty Transmitting a Digital Optical Signal

Q. I'm having difficulty transmitting a digital optical signal about 75 ft. from a remote Dish satellite receiver to an A/V Home Theater receiver. I've added a Toslink repeater/amp device, but to no avail. Do you have any suggestions? –– George.

Audio Optical Cable

A. Thanks for your e-mail and interesting question.

I suspect the optical pulses are much too weak, even with the Toslink repeater/amp device. I quizzed Axiom's chief engineer, Tom Cumberland, who stated that a normal plastic fiber-optic link is only good for about 6 to 10 feet. Over longer distances, the plastic fiber-optic link causes the pulses to “blur,” so the optical receiver in the AV receiver can’t distinguish between the “on” and “off” optical pulses that relay the digital code.

Tom says that for a run of 75 feet, you'd need at least five repeater/amps to ensure a robust signal at the Home Theater receiver end. Big telecom companies that do long runs of fiber optic cable in new subdivisions and under city streets normally use the glass (not plastic) fiber optic links, which are much less susceptible to the losses you are experiencing.

Perhaps you should reconsider your installation and move the Dish satellite receiver much closer to the Home Theater receiver so you can get a robust optical connection using inexpensive plastic fiber-optic cable.



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