Abstract: A multi-aperture free-space optical communications receiver comprises a plurality of telescopes each having a clear objective aperture with a diameter between 50 mm and 250 mm and arranged for receiving light collectively from an optical communications light source. A coherent combiner unit is configured for coherently combining the collectively received light to produce a combined optical signal therewith. Each telescope is arranged in association with, respectively, a wavefront detector to determine a wavefront of said received light directed to it by the respective telescope, a steerable reflector unit including a deformable mirror controllable to deform according to said determined wavefront such that said received light is reflected by the deformable mirror with a modified wavefront, and an optical signal receiver comprising a single-mode optical fibre.

Abstract: A multi-aperture free-space optical communications receiver comprises a plurality of telescopes each having a clear objective aperture with a diameter between 50 mm and 250 mm and arranged for receiving light collectively from an optical communications light source. A coherent combiner unit is configured for coherently combining the collectively received light to produce a combined optical signal therewith. Each telescope is arranged in association with, respectively, a wavefront detector to determine a wavefront of said received light directed to it by the respective telescope, a steerable reflector unit including a deformable mirror controllable to deform according to said determined wavefront such that said received light is reflected by the deformable mirror with a modified wavefront, and an optical signal receiver comprising a single-mode optical fibre.

Abstract: Communication apparatus comprises a first transceiver unit (205A) and a signal processing device (106) configured to receive a signal from the first transceiver unit and to produce a signal for transmission by the first transceiver unit. A cable (201A) connects the first transceiver unit to the signal processing device. The first transceiver unit comprises a housing; a first pair of transducers (204T, 204R) located at, or adjacent, a first end of the housing, and a second set of transducers (206T, 206R) located at, or adjacent, an opposite end of the housing.

Abstract: Communication apparatus comprises a first transceiver unit (205A) and a signal processing device (106) configured to receive a signal from the first transceiver unit and to produce a signal for transmission by the first transceiver unit. A cable (201A) connects the first transceiver unit to the signal processing device. The first transceiver unit comprises a housing; a first pair of transducers (204T, 204R) located at, or adjacent, a first end of the housing, and a second set of transducers (206T, 206R) located at, or adjacent, an opposite end of the housing.

Abstract: A method of extracting a radial velocity characteristic of a target from coherent pulse bursts comprising the steps of applying to data a ‘best fit’ model of the echo returns from a target in the presence of clutter to obtain a residue (error) value and minimising the error value by a predetermined method to give the best fit value for the target radial velocity. The method enables more information to be retrieved from coherent bursts than conventional methods and therefore greatly enhances performance of radiation pulse echo detection.