Whether based around copper or fibre, broadcasters need to ensure that their cable infrastructure can support multiple applications, including IP transport and 4K/Ultra HD transmission. Shawn Liew writes more.
The move towards IP connectivity, and the more general trend to use fibre even for SDI, has led the broadcast industry to adopt another trend from the telecoms and IT industries.
Identifying this as the use of structured cabling, Chris Smeeton, managing director, Argosy, tells APB: “Essentially, this is the use of standardised, high-capacity data bearers around a building or campus, with the use of subsystems to provide specific capabilities.
Linked to this is the emergence of HDBaseT, a new standard that has applications across a broad range of applications.”
HDBaseT is a global standard for the transmission of 4K/Ultra HD (UHD) video and audio, Ethernet, controls, USB and up to 100W of power over a single, long-distance cable.
HDBaseT is managed and promoted by the HDBastT Alliance, a not-for-profit organisation established in 2010 by LG Electronics, Samsung Electronics, Sony Pictures Entertainment and Valens.
Smeeton continues: “For broadcast and audio-visual use, HDBaseT is capable of carrying high-resolution video — 8K is in the roadmap — and audio, along with control and power over a single cable.
“Using copper, each link can be up to 100m long or even more. Our experience is that 70m is perfectly practical for 4K/UHD. Without it, cable lengths would be limited to around 10m.”
To obtain that level of performance, however, Cat6 or Cat6a cabling is required, Smeeton advises, adding: “Like all Ethernet cables, this uses a twisted pair of copper strands, but it is subject to much tighter constraints on crosstalk and needs to provide consistent performance up to 500MHz.”
While acknowledging that Cat6a is compatible with Cat5e and even Cat3 Ethernet cabling, he suggests that it “makes sense” to use the highest specification cable when installing or replacing copper.
With HDBaseT, its versatility allows large numbers of streams to be carried down a common network, for instance, to feed very large monitor walls, says Smeeton, who also sees an accelerated move to fibre, which offers resolution independence and long cable runs. He elaborates: “For outside broadcast work, SMPTE hybrid is taking over, because it offers simple rigging, is pretty tough and runs as far as 5km without needing repeaters.
“Inside the broadcast or production base, the trend seems to be towards single-mode fibres for video circuits, with multi-mode fibre gaining ground where there is a need to carry a lot of audio circuits.”
All of these developments, Smeeton emphasises, means that broadcast systems designers need to think about requirements for today and tomorrow, and ensure that their cable infrastructure — copper and fibre — is adequate for all future needs. “Suitable cables are readily available, but ensure you talk to a cable specialist to make the right choices for your project,” he concludes.
One company that is focusing heavily on fibre is US-headquartered MultiDyne, particularly with the launch of a specialised Fibre Lab in April this year. Located at the company headquarters in Hauppauge, New York, the Fibre Lab represents a natural progression for MultiDyne, according to Frank Jachetta, president of MultiDyne. “We are able to reduce costs, increase quality control, develop custom applications for less common terminations, and offer more complete fibre solutions for customers worldwide that cover the entire broadcast and production chain.”
He is also quick to point out that MultiDyne is one of the few Certified opticalCON Assembler (COCA) for Neutrik opticalCON fibre cables. With all assembly happening in the MultiDyne Fibre Lab, customers now have the option of purchasing all components of a complete fibre transport solution directly from MultiDyne, through its global dealer network, or simply purchasing new opticalCON cables to upgrade existing fibre systems.
In addition to joining the Neutrik COCA network, MultiDyne has also received training and approval to assemble Lemo tactical fibre cables in-house. “As we already have many Lemo connectors integrated into our fibre transport and conversion products, offering Lemo cables is another attractive accessory for our customers,” explains Jachetta, who is keen to highlight that while the company’s slogan is ‘Fibre First’, MultiDyne, at its core, is a transport company.
Predicting that IP will almost exclusively travel on fibre to support higher data rates, he says: “As the industry transitions to IP, we are in a strong position to help customers making that transition as 10G IP will move over fibre.”
However, MultiDyne does expect different applications to make the transition to IP at different times. For example, news acquisition will be among the last applications to fully migrate to IP, suggests Jachetta. “However, we are prepared to make IP solutions integrate into the base of our Silverback CameraBack systems,” he adds. “This becomes almost a conversion point in a hybrid baseband/IP world.”
MultiDyne also offers rugged field fibre transport systems such as BullDog or LightBox, which can serve as network appliances for multi-point IP transport, in addition to its curent point-to-point missions for fibre transport.
“[IP] is an evolution that we are well prepared to adapt to moving forward, and an opportunity for broadcasters for whom we can offer guidance and support as they make the decision,” says Jachetta.
And while the transition to IP is ongoing, there is still support for SDI, including as a transmission platform for 4K/UHD. 12G-SDI, says Canare, a manufacturer of cables and connectors, has the ability to transmit eight times the amount of bandwidth in HD-SDI (2K, 1080i) and four times the bandwidth in 3G-SDI (2K, 1080p).
The standard, Canare adds, also specifies cables, connectors and return losses of cables used for transmission — that is, coaxial cables with characteristic impedance of 75Ω, connectors of 75Ω BNC (Bayonet Neill-Concelman), and return loss of 4dB or more in the entire transmission path.
The company also sees strong market demand for conventional coaxial cables and BNC connectors able to transmit over distances up to 100m even in bandwidth for 12G-SDI signals. Previously, Canare offered the L-5CFB coaxial cable, which is capable of transmitting HD-SDI and 3G-SDI signals over 100m. However, the distance over which the L-5CFB can transmit 12G-SDI signals is limited to around 68m, prompting Canare to develop the L-5.5CUHD.
The new coaxial cable is capable of transmitting 12G-SDI signals over distances of 100m or more, while having the same 7.7mm diameter as the L-5CFB. According to Canare, many users have the misconception that the obvious solution to increase transmission distance, while reducing attenuation, is to make the cable thicker. Dispelling this notion, Canare says, other paramaters are more important. These include characteristic impedance, cut-off frequency and mechanical strength, among others, which the L-5.5CUHD is built to address.
The company claims that the L-5.5CUHD has the lowest attenuation among coaxial cables of the same size available in the market, while two other coaxial cables of different thickness will also be available in the same series as the L-5.5CUHD.
Canare cites research which shows that there is a high demand for cables that are thin and easier to use in short-distance transmission mainly on racks and can be connected to DIN1.0/2.3 connectors; and for cables that allow transmission over long distances of more than 100m.
This led to the development of the L.3.3CUHD and L-8CUHD cables. The L-3.3CUHD is a thin, short-distance transmission cable with a small external diameter of only 5.5mm, which is intended to transmit 12G-SDI signals over distances of 60m. The L-8CUHD, on the other hand, is a long-distance transmission cable with an external diameter of 11.1mm, which is designed to transmit 12G-SDI signals over distances of 140m.
However, Canare cautions that even if the performance of coaxial cables is improved, degradation will still occur at the entrance and exit of signals if the connectors on their edges do not match each other. To ensure this does not happen, Canare has developed dedicated BNC plugs and receptacle connectors that allow 12GHz signals to be transmitted.
For instance, Canare’s BCN plug offers a return loss of 15dB @12GHz, 26dB@3GHz and 20dB@6GHz. It offers the same features as Canare’s BNC connectors, such as a long sleeve shape and an insulator lock mechanism. The BNC plug’s structure, Canare explains, was designed to minimise changes in the inner diameter that may occur due to deflection of the outer contact.