Optical Signal Transport on Aerospace Platforms: Analog Versus Digital Links

As aerospace and defense platforms face the continuing demand to capture and process expanding volumes of the electromagnetic spectrum, platforms are confronted with the challenge of internally transporting this large information throughput between sensing and processing locations with high efficiency and low latency. Owing to unfavorable frequency-dependent characteristics, as well as cumbersome size and weight, coaxial cabling is increasingly becoming an infeasible solution, mandating the use of optical links. However, while analog photonic signal transport via radio-over-fiber has long been an alternative to electrical transport, the progress in analog-to-digital converters (ADCs) now affords the system architect the option of implementing a digital optical link, following an ADC located immediately at the antenna site. This work undertakes an analysis of the trade-space associated with this architectural choice, correlating available and projected device performance with fundamental link theory. Resultant from this analysis, a simplified decision framework is proposed, which may be used to suggest the preferable approach given the application requirements.