Abstract: A fiber-optic acoustical sensor system includes a light source, an elongate optical cable conducting light from the light source to an optical acoustical transducer located at a distance from the light source along this cable, and a polarizer at the acoustical transducer. The sensor system includes a polarizer providing orthogonally-polarized light along the optical cable to the polarizer located adjacent to the transducer. Because of the polarizer adjacent to the transducer, disturbances of the optical cable and resulting polarization perturbations of the light transmitted along this cable do not affect the optical acoustical transducer. The acoustic transducer is responsive to sound energy to provide an optical return signal indicative of this sound energy.

Abstract: A digital communication system having a punctured convolutional coding system and method. The digital communication system includes a coder for coding a digital input to be transmitted from a transmitter and a decoder for decoding the coded input received at the receiver. The coder includes a convolutional coding circuit of rate k/n for outputting a convolutional coded output and a puncturing circuit for puncturing the convolutionally coded output to achieve a punctured code rate of z/q, where z=.gamma.k. The puncturing circuit punctures the convolutional coded output according to a deleting pattern chosen to have a bit length of L=p.gamma.n, where p.gtoreq.2. The puncturing circuit outputs a punctured output at punctured code rate of z/q and the punctured output is transmitted to the receiver. The receiver decodes the transmitted punctured output and outputs a decoded output.