Broadcast Connectors and Cables Bring Viewers Closer to the Action
Audiovisual equipment is integrating with increasingly sophisticated signal equipment to support 8K video and even machine learning.
Things have changed dramatically since the days when long delays and grainy images were common during the broadcast of live events. Today, when broadcasters transmit images from international events like the Olympics, viewers expect minimal latency, or delay in the flow of images. They may also expect to see an inset image of what is happening in the track events while simultaneously watching the swim events on the main screen, which takes broadcast technology to another level.
At Integrated Systems Europe (ISE) 2020, Xilinx, a processing platform company that invented the field programmable gate array (FPGA), introduced new broadcast and pro audiovisual (A/V) computing products with machine learning capabilities that can enhance broadcast quality even further. These technologies enable region-of-interest encoding to detect faces and features; intelligent digital signage to identify gender, age, and gesture detection; automatic object tracking and window cropping to output multiple high-definition windows from a single 4K camera to switch content at live events; and speech recognition for automated transcripts.
“Machine learning is a rapidly developing technology that is stimulating new usage models in pro A/V and broadcast,” said Ramesh Iyer, director of pro A/V and broadcast at Xilinx. Machine learning is expected to bring new capabilities, such as the ability to monetize analytics, improve workflow efficiency, as well as enhance the viewers’ experience, he added.
The Rise of Fiber
Fiber optic cabling supports a wide bandwidth and has the capacity to handle high volumes of data. It is also characterized by low signal loss and electromagnetic interference (EMI) immunity. These characteristics have made it popular for broadcasting major sporting events, where the wide bandwidth can serve multiple channels with high-quality images and minimal latency over longer distances. The signal attenuation is virtually flat until very high frequencies are reached. With copper, the attenuation constantly increases with the signal frequency.
“For fiber, the most important feature is the cleanliness of the fiber interface; small dust particles at the connection point will decrease the signal quality,” said Serge Buechli, business development manager at LEMO SA. He advocates using proper cleaning tools to rapidly clean the fiber optic ferrules, particularly if the connectors are unmated often.
Fiber optic cables are also fragile and can be damaged during the setup at venues. In busy event environments, common mishandling includes heavy trucks driving over cables, which can crush or bend the fiber and result in signal loss. The cables have to be robust and resistant to crush or impact, said Buechli.
LEMO produces hybrid connectors for the broadcast industry that meet technical standards set by the Society of Motion Picture and Television Engineers (SMPTE). “The SMPTE connector is an industry standard used for national TV, theaters, and sport arenas,” said Buechli. “The contact configuration has both copper and fiber optic signal contacts. Two of the copper contacts are used to power the equipment, for instance the camera at a remote location, while two other copper contacts are used as a signal interface, to make sure the connector is correctly mated before sending the fiber optic signals.”
The SMPTE created the SMPTE 311 EU standard (known as SMPTE 304 in North America) relatively soon after high-definition (HD) cameras were in use. Copper cables were not able to carry the uncompressed HD signals as far as triax and coax cable could, yet even the largest coax cable was limited to around 300 meters (1,000 feet) for HD and serial digital interface (SDI) video. The SMPTE 311 standard introduced composite cables — two single-mode fibers, two low-voltage control signal wires, and two to eight copper power cables — that can multiplex audio and video signals and deliver power.
These push-pull, self-latching 3K.93.C hybrid connectors have two fiber optic contacts, two signal contacts, and two power contacts and operate over a wide temperature range of -55°C to 90°C. Housed in a stainless-steel shell, they are shielded, sealed to IP68, and suitable for use with cables spanning 8.6mm to 16mm in diameter. They also comply with SMPTE 304, SMPTE 311, Japan’s Association of Radio Industries and Business (ARIB), and the European Broadcasting Union (EBU) standards for signal and cable and have been tested to handle 4K and 8K signals in addition to temperature and humidity cycles. Test results showed no data rate errors, said Buechli.
The latest SDI standard for uncompressed, unencrypted digital video signals is the 12G SDI. It is used for ultra HD video at a bit rate of 12Gb/s. This version was introduced in 2015 to support standard dynamic range (SDR) and high dynamic range (HDR) image formats into single or multiplex 12G SDI 10-bit interfaces. It is designed for uncompressed, latency-free distribution of 4K over long lengths of a single coax cable.
COAX Connectors offers 12G broadcast-quality connectors designed to provide advantages in set-up and operation. “Our 12G broadcast quality connectors, which exceed the requirements of SMPTE standard ST2082-1, are based on coax technology and have found numerous applications in broadcasting, including use in outside broadcast trucks,” said Emma Ashton, marketing manager at COAX Connectors. “While fiber brings the benefit of bandwidth and transmission distance, for certain applications, fiber is not rugged enough to withstand the amount of handling it is subjected to on a daily basis,” she said.
For applications that require high densities of 12G connectors, COAX Connectors’ range of Micro (HD) BNC connector have a 7.8mm diameter capable of achieving mounting densities more than four times greater than those of standard BNCs. They also have a BNC locking mechanism with a patented coupling nut that allows for the use of a special tool to disconnect the connectors when they are closely mounted. Their design helps free up space for additional channels and reduces weight, which are important factors for equipment that has to be transported and assembled regularly.
“BNC connectors are already in widespread use in broadcast applications and many companies favor them when upgrading to 12G,” said Ashton.
“The design of the [KORUS Series’] internal dimensions and connector construction have been optimized to make these connectors suitable for the demands of HD. For instance, on a right-angle Korus BNC, the right-angle portion of the contact is swept to provide a smooth transition.” (A swept contact is sometimes referred to as a swept radius contact, as it is a single piece with a smooth swept radius rather than two straight contacts joined to form a right angle. This improves performance and increases frequency range.)
COAX Connectors also offers connectors that minimize discontinuities in the signal path, mitigate impedance mismatches, and reduce coupling effects to meet the impending BS EN 61169-63 standard. This stipulates performance requirements for SDI connectors for 75Ω BNC.
Ashton is also confident that BNCs will have a place in 8K broadcasting, the next jump in television resolution. “Currently the SMPTE spec for 8K is for delivery over multiple channels. With proven excellent return loss at 12G our, 12G BNCs and 12G Micro (HD) BNCs are already able to deliver 8K over multiple channels.”
Most forecasts predict that we will see 8K hit the consumer market in the next two years. High-performance broadcast connectors and cables are already standing by.