FEATURE INTERCONNECTION LIGHT SPEED FOR NETWORK TRAFFIC
Carlos Pardo, CEO and Co-founder of KDPOF says, if you find you’re spoiled for choice when choosing the appropriate physical layer for future data networks, then here’s what to look out for
autonomous vehicles. As self-driving cars need redundancy in the communication network, POF minimises the extra weight. Installation of POF is just easy plug and
E
lectronic devices make the difference when it comes to modern cars,
demanding high speed networks climbing up to one gigabit and beyond. Becoming an integral part of the vehicle, new devices interface with many different clusters of electric/electronic systems. The choice of physical layers is essential
since it has implications for cost and weight, key factors in today’s car models. Selecting the best technology requires a delicate balance between preconditions such as speed, cost, and robustness against electromagnetic noise. Optical and copper-based have traditionally been the two main alternatives for physical layers in automotive applications, with copper coming as UTP (Unshielded Twisted Pair), STP (Shielded Twisted Pair), JTP (Jacketed Twisted Pair), or coaxial cables. The default choice for current architectures are traditional copper-based networks because of the risks and challenges of adopting new physical media. Old views hold that optical transmission media such as Plastic Optical Fibre (POF) are expensive; specific and customised; complex in installation, handling and maintenance; fragile and unstable; only available from a single source as with MOST; lack ecosystem; etc. Let's have a closer look and see if new optical solutions aren't a serious alternative and beat copper in many respects. It is true that POF is more expensive than unshielded twisted pair copper cables. But these only transmit data with up to approximately 100Mbps. IEEE has
18 MAY 2018 | ELECTRONICS Figure 1:
Cost comparison POF versus copper in a reference scenario
just acknowledged this fact by requesting a new project under the umbrella of its TC9 Technical committee with the objective of defining the components of a shielded cable for the 1000BASE-T1 IEEE Ethernet protocol. Now, if we compare the cost of POF with shielded or jacketed twisted pair, or even with coaxial, POF wins. In a reference scenario, the complete system cost has been calculated and compared; (see image 1). In the results, POF saves approx. 23 percent to STP in total cost. So, when it comes to bandwidths of one gigabit and beyond, POF beats copper in cost. Moreover, focusing on the medium cost, plastic price is much more stable over the long term than copper is. In contrast to copper, POF is inherently
Figure 2:
POF beats copper regarding cost, weight, and EMC
immune to electromagnetic noise. POF provides problem-free integration and no EMC adoption R&D costs per derivative or similar occur. POF is made of plastic, so its weight is much lower than the other alternatives. This feature is relevant in sports cars and in
play. Winding and clamping is similar to copper cables. Their good bending performance starts at a radius of 10mm, and gigabit transmission distances of up to 40 meters are possible without in-line connectors, or 15 meters with up to four in-liners. POF even shows robustness against air gap separation: a maximum air gap of 33 millimeters can be tolerated. Further, POF allows fast dynamic bending, tight bending, and dark liquid immersion. It can withstand harsh environments and tolerate conditions such as routing across the engine compartment with temperatures as high as 105°C and down to –40°C. POF cables are very reliable compared
to glass optical fibre (GOF), coax, and STP. As an optical fibre with a large core, it is able to withstand vibrations and misalignments much better than other optical or copper alternatives.
ECOSYSTEM AND STANDARDISATION As a plastic, wide diameter fibre, POF is cheap to manufacture and install. It doesn´t require any sophisticated equipment or professional qualification, and harness manufacturing processes don´t need to be changed. Well- established engineering collaboration between key leading optoelectronic and connector vendors worldwide ensures a well-supplied and competitive market for all the components required in the system: Physical Layer (PHY), Fibre Optic Transceiver (FOT), Fibre cable, and connectors. POF gigabit technology has been standardised through the German VDE- DKE and ETSI. IEEE has published the IEEE Std 802.3bv-2017 standard amendment for Gigabit Ethernet over POF, which defines 1000BASE-RH, physical layer specifications and management parameters for automotive, industrial, and home networking applications. IEEE Std 802.3bv provides a robust and reliable media option for Ethernet automotive networks.
KDPOF
www.kdpof.com e:
info@kdpof.com
/ ELECTRONICS
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