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The low-frequency optical-signal phase noise induced by mechanical vibration of the base occurs in field-deployed fibers. Typical telecommunication data transfer is insensitive to this type of noise but the phenomenon may influence links dedicated to precise Time and Frequency (T&F) fiber-optic transfer that exploit the idea of stabilization of phase or propagation delay of the link. To measure effectiveness of suppression of acoustic noise in such a link, a dedicated measurement setup is necessary. The setup should enable to introduce a low-frequency phase corruption to the optical signal in a controllable way. In the paper, a concept of a setup in which the mechanically induced acoustic-band optical signal phase corruption is described and its own features and measured parameters are presented. Next, the experimental measurement results of the T&F transfer TFTS-2 system’s immunity as a function of the fibre-optic length vs. the acoustic-band noise are presented. Then, the dependency of the system immunity on the location of a noise source along the link is also pointed out.

AbstractReactions of 3-formylchromones with benzyl carbamate and triphenyl phosphite in acetic acid lead to the corresponding diphenyl chromone-3-[α(-N-benzyloxycarbonyl)amino]-methanephosphonates 2 in high yields. Deprotection of the Z-substituted diphenyl esters 2 by means of acetic hydrogen bromide solution and the subsequent hydrolysis by means of 20% aq. HCI, lead to the final chromone-3-(α-amino)methanephosphonic acids 4. Attempts of synthesis of the corresponding chromone-2- aminophosphonic derivatives by this way, have failed. On the other hand, chromone-2-(α-amino)methanephosphonic acid (6) was successfully obtained by an addition of tris(trimethylsilyl) phosphite to the aldimine, which was formed from the 2-formylchromone.