As the demand for high-definition, broadcasting signal transmissions has increased and the transition to DTV/HDTV has been fully realised, the role of fibre optics as the signal transmission medium continues to grow. Fibre optic infrastructures offer the advantage of higher bandwidth, optical signal clarity and more reliable real-time transmissions. This enables providers to service even more applications for emerging technologies such as 4K and 8K ultra high-definition television (UHDTV), Internet-protocol television (IPTV) and multi-channel audio.
For TV Studio and internal Outside Broadcast Vehicle conditions, various traditional butt-joint fibre optic standardised connection technologies are being increasingly utilised against copper types. This is because they offer improved bandwidth signal handling over larger distances and different signal types can be multiplexed over a single fibre optic cable. In addition, fibre optics allow bi-directional communication whereas copper systems can only transmit in one direction. Fibre optic cables are small and lightweight compared to copper alternatives and this is particularly important inside the OB Vans in order to minimise space and the overall weight of the installed vehicle. Finally, FO cables are inherently immune to EMI/RFI interference and cannot contribute to ground loops.
One of the other key benefits of fibre optic systems is their general immunity to interruption by moisture or immersion in water, as there is no electrical current to “short-out.” All electrical connections, in contrast, need to be fully moisture protected.
However, it is the environmental operational conditions that need to be considered carefully when installing fibre optic cabling systems in the field. Particular attention should be paid to the potential for ingress of dust and dirt, especially for multiple mating situations. So much so that butt-jointed FO connector types are only normally suited for controlled environment conditions, where dirt and dust is minimised and connectors can easily be routinely cleaned.
Nevertheless, it is possible to apply fibre optics in operating conditions with much harsher environment, such as those experienced for outdoor outside broadcast installations like sports venues and music events. This is done by utilising Expanded Beam fibre optic connector design technology.
HARTING expanded beam connectors expand the diameter of the optical beam by approximately 40 times; this expanded beam will be coupled into the opposite connector and is then collimated back down to the original beam size, and re-coupled into the fibre. Since the beam size is expanded by as much as 40 times, the influence of a 0.020 mm piece of dirt between a pair of ceramic ferrule based connectors is reduced by 40 times in a pair of expanded beam connectors.
It is this effect of collimating and greatly increasing the optical beam diameter that results in the connector being less sensitive to small particles of dust or other contamination, which could completely obscure transmission in butt-joint type connectors…
