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Free space communication links for remote tele-operation of robots have important applications in hazardous environments. They have a distinct advantage over conventional umbilical control in that they allow potentially greater freedom when manoeuvering around obstacles, and obviate any unnecessary cable payload. Omnidirectional, short-wave radio links are widely used for such purposes. Very little consideration has yet been given to the use of microwave frequencies (10 GHz and above), whose fixed line-of-sight operating mode and high bandwidth have made them ideal for external local area networks. In this paper, we examine the broadcast characteristics of a commercial 23 GHz microwave link using a 25 cm diameter horn. Investigations were carried out in a representative environment over a wide range of distances, alignment criteria, and pathways. We describe the investigations in received signal quality for the communication of analogue video and digital data. Received signal tests using image processing equipment show the signal to noise ratio obtained under test conditions, compared to that required for adequate quality. We conclude by assessing the relative merits and disadvantages of using a microwave link for telemetry applications, compared with conventional radio and laser free space systems.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only. |
