'From Here To There And Back Again'

All the latest developments in broadcast technology are pretty well documented in the trade mags, but no matter how efficient your camera, video and distribution system is, your production goes nowhere without the right cabling to transport and protect it. We take a look at the popular current cable systems with Camden based specialists VDC Trading, suppliers of Van Damme cable, Neutrik and OpticalCon assemblies to the broadcast industry.

Probably the largest consumers of professional cable in the industry are the outside broadcast trucks. Between the need for audio and video connections from sports grounds, concerts and public events to the truck and the transfer of the final mixes to and from commentary studios and out to satellite uploads, an OB truck can require several kilometres of cable. All of which must be one hundred percent reliable or the whole system fails.

"For audio, most of the outside trucks and TV studios we supply use Van Damme Brown Series OB Transmission grade, pre-jacketed 8 way Starquad multicore via 26 pole Mil spec OB CON connectors," explained VDC technician Adam Jafrabati. "Featuring an extremely tough polyurethane outer jacket, better than 90% coverage braided screens for high rejection of EMI and RFI and with overall diameters sized to suit the common outside broadcast multipins, these cables are mechanically and electrically built to excel in the most hostile of environments. I would prefer to see a more robust connector in common use but the OB CON is extremely light which is useful in an outside broadcast truck where weight is a factor."

For the video links, some trucks at sporting events are still using Triax cable but most of the industry now uses HD Video cable with SD having become effectively redundant. HD cable are available in a number of varieties including low smoke for sensitive environments.

There is a range of multicore options for video too. The HD Vision range of 75 Ohm precision multicore coaxial cables comprises 4 and 6 way PVC jacketed dynamic multicores. Great attention has been paid to their electrical characteristics and tolerances to ensure trouble free performance with SMPTE 292M HD-SDI signals as well as SDI and analogue video.

There is also a growing trend towards the use of fibre optic cable thanks to its ability to carry huge amounts of information and channels. VDC Trading has expanded its production facilities to include a Fibre Optic clean room needed to construct and terminate fibre optic assemblies. For broadcast purposes, Van Damme Tourlight fibre optic cables are Tactical Single Mode & Multi-Mode fibre optic OS1 & OM3 deployable fibre cables for outside broadcast and robust studio floor or fibre infrastructure. They are extremely robust, are available in an increasing number of variations and can carry huge amounts of information. Ideally connected by HMA expanding beam connectors, they can withstand the dirt and grime of the outside broadcast environment and the HMA connector is easy to connect as there is no male or female version. They are always compatible. The expanding beam means that the signal at the connector is expanded to such a size that connection is always one hundred percent. Easy to wipe clean and replace if necessary, the HMA connector is becoming a favourite solution to fibre optic connections in the field. One of these cable systems has been supplied to BBC Scotland recently by VDC and interest is growing amongst the OB community.

These days hybrid multicores are commonly adopted. Once only available in one or two formats, the hybrid cable can now be made to a huge range of specifications. A typical combination is 8 channels of audio, two of HD video and two of CAT 6A data. Encased in a rugged outer sleeve, the hybrid can carry all the cabling requirements in one go. Specially built termination panels allow for a faster and simpler set up. These are becoming especially popular for the fast rigging of large video arrays in the live arena for concert broadcasts. They provide provision for network, HDTV distribution via HDMI Cat X converters, control signals and satellite broadcasts.

Reliability is everything in the world of cable. The floss of signal from a single cable can mean the failure of a live broadcast and often a time consuming hunt for the offending cable among many. Each connection and soldered joint is applied according to strict quality controlled standard and checked for faults at every stage of assembly. At VDC a testing station is used to test every cable before it leaves the premises. Designed by the team at VDC, the testing station has a multitude of input and output connectors. Any faulty connection cause the light on the top to flash and, yes, a loud siren to sound. It is a matter of pride amongst the staff to avoid the shame of a failed cable!

VDC Trading CEO Niall Holden summarised: "Despite the fact that it is frightening thought that the success of your show might be down to a single soldered joint to a cable that you keep kicking as you cross the studio, you can take heart that amongst the cable community we have people who cared enough about it to make sure it's up to the task."

Image: The assembly floor at VDC Trading.

www.vdctrading.com

(JP)