Thomson-csf

Thaddeus Hawkes

Jean-Claude Reymond

Jean C Reymond

Leon P Robin

Roger Trocellier

A coupler for interconnecting transmission lines in an optical communication system. In a preferred embodiment it comprises an elongated bi-conically shaped rod of transparent material which continues into two cylindrical mixing rods. The lines are split up into two groups coupled to respective ones of the two plane endfaces of the coupler. The dimensions of each tapered central portion are determined such that the radiation pattern in the common plane of the identical minor bases is substantially hemispherical no matter what the direction of propagation of the light modes along the axis from one end to the other, given the numerical aperture of the associated transmission lines.

Coupler for optical communication system

A reciprocal coupler for connecting anyone of a plurality of optical signal transmission lines to all the other transmission lines in an optical communication system. The coupler comprises an elongated transparent optical mixing rod optically coupled by a first endface to each of the waveguides forming the lines to be interconnected and by its second endface to both ends of return guides provided by a fiber bundle which form a loop.

An arrangement for measuring by correlation the lag produced by the transmission of a coded signal through a delaying medium and which permits a high signal-to-noise ratio and high accuracy. The received coded signal is applied to two correlators followed by a subtractor to form a discriminator circuit utilized to lock the frequency of a generator which provides two reference coded signal utilized respectively for correlation and to form an automatic tracking loop. The lag measurement is obtained by state-decoding of the transmission coded signal and of one of the reference coded signal and by pulse counting at a period sub-multiple of the bit period.

Arrangement for measuring the lag between two timed signals by

A coupler for coupling in the same manner any one of a plurality of optical signal transmission lines to all of the other transmission lines. The coupler comprises at least three elongated frusto-conical shaped arms of transparent material coupled together by their minor bases through a connecting medium and connected by their major bases to end faces of optical transmission lines respectively. The base diameters and the axial length of these arms are determined such that each minor base has a hemispherical radiation pattern given the numerical aperture of the associated transmission line.

A bit stream with a bit rate equaling the frequency of a train of accompanying clock pulses is transcoded into a two-level signal voltage having a reduced rate of changeover compared with the rate of alternation between 0 and 1 bits. Upon any shift from one kind of bit (e.g., 0) to the other kind of bit (e.g., 1), a transition between signal-voltage levels occurs in the middle of a clock-pulse cycle; the first bit of the first-mentioned kind (0) in a succession of a plurality of such bits, after a shift from the other kind of bit (1), is translated into a transition between signal-voltage levels occurring at the end of the corresponding clock-pulse cycle. Transcoding is accomplished with the aid of a three-stage shift register whose stage outputs are logically combined. Upon transmission of the signal voltage via a data channel to a remote receiver, the original bit stream is reconstituted by a decoder comprising a four-stage shift register stepped at twice the clock-pulse frequency, again with logical combination of the stage outputs. A timing-signal extractor at the receiver is locked in step with the transmitter, prior to data transmission, under the control of a synchronizing sequence of alternating 0 and 1 bits transcoded into a square wave of half the clock-pulse frequency.

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Paris, France

Thaddeus Hawkes