26 April 1999 Analog lasercom for bent-pipe satellite crosslinks
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Abstract
Although much of today's space lasercom development is concentrated in digital communications, there still remain applications where the analog lasercom link is preferred. An analog lasercom link transmits RF or IF carriers instead of decoded bits. The most important application is in commercial bent pipe satellite constellations, where modulated carriers are to be relayed between satellites, avoiding the use of costly and risky onboard demod - remod digital processors. In this paper some basic tradeoffs are reported which aid in scoping the performance, limitations, and shortfalls of an analog crosslink. The analysis assumes fiber based technology at either 1.55 or 1.3 microns for the crosslink hardware, using optical intensity modulation (IM) and direct photodetection. When multiple carriers are used to IM the laser, the inherent nonlinearity of the modulation causes power suppression that limits the available bandwidth (number of carriers) that can be relayed using as single optical wavelength. With single wavelength bandwidth limited, the crosslink capacity can only be improved by the use of multiple wavelengths. This tradeoff of suppression and wavelengths is considered here.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert M. Gagliardi, Antonio J. Mendez, "Analog lasercom for bent-pipe satellite crosslinks", Proc. SPIE 3615, Free-Space Laser Communication Technologies XI, (26 April 1999); doi: 10.1117/12.346169; https://doi.org/10.1117/12.346169
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