Mark Robinson wrote: > Asuming they are using some time domain reflectometry technique, I would > assume that it could be done on a live comms cable. Apparently a special reflector has to be placed at one end of the line. It is a time-of-flight measurement that they are using. > Fibre gyroscopes are popular on high end projects ... they measure > rotation in accuracies of the order of the number of wavelengths around > their circumference. they split the input light, the two signals going > in opposite direction around a circle. the recombination of the light > gives pulses with rotation ... I can't remember how they achieve > quadrature. For some reason that I am not aware of these guys have abandoned any kind of interferometric technique. Perhaps it is too expensive? I understand the math and physics behind this stuff, but as far as the engineering end goes I have no clue... John Hernlund Department of Earth and Space Sciences University of California, Los Angeles hernlund@............ __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>