Television broadcasting industry marks time with fiber

Television broadcasting industry marks time with fiber


Based on observations, interviews and seminars at the National Association of Broadcasters `95 trade show in April, sales of fiber-optic components, systems and networks into the television production and broadcasting industry are not expected to grow substantially in the short term.

The television industry still views optical fiber transmission as a technology with possible future benefits. But at NAB `95, several television postproduction house executives declared they had no current applications for fiber. They view the telecommunications industry`s networks of fiber cables only as means of transporting analog National Television Standards Committee video/stereo audio signals on digital signal, level-3 transmission lines.

Of course, the television industry is accelerating toward all-digital high-definition broadcasting. A few years ago, this move portended a mandatory need for fiber for uncompressed transmission of high-bit-rate serial digital signals from 150 megabits per second to 1.5 gigabits per second. The need is still valid for full-service postproduction houses in perhaps a dozen major markets. However, compression of digitized, serialized video and audio signals has become the main technology trend and interest in the postproduction industry and the television broadcasting industry.

Fiber focus

Several exhibitors focused on fiber products, however. Force Inc. in Christiansburg, VA, displayed a family of high-speed digital data-link transmitters and receivers that provided digital bit rates to 2.5 Gbits/sec. The units couple to singlemode and multimode fibers, operate at 780, 1300 or 1550 nm, and terminate to several connector types.

They handle uncompressed Society of Motion Picture and Television Engineers 259M serial digital (143- to 360-Mbit/sec and 1.3- to 1.5-Gbit/sec) rates proposed for high-definition television and for Motion Picture Experts Group-2 compressed signal bit rates down to 1.5 Mbits/sec. They also handle several standard data transfer rates for Ethernet, fiber distributed data interface, synchronous optical network/synchronous digital hierarchy, Fibre Channel, asynchronous transfer mode and serial high-performance parallel interface. The units are available as circuit boards and as stand alone packages.

Force is positioning itself to become the supplier of choice for all television production and broadcasting industry digital signal transmission applications, according to Wendell Hensley, vice president for broadcast products marketing.

Another fiber supplier, Telecast Fiber Systems Inc. in Worcester, MA, added to its family of fiber-based field production systems, according to Rich Cerny, founder and president. He cited some notable 1994 events and applications that implemented the company`s products--Woodstock `94, the June 6th D-Day remembrance ceremony in Normandy, eight of nine World Cup USA soccer venues, the Three Tenors` Encore performance in Dodger Stadium at Los Angeles and the first live broadcast from the South Pole.

The company focuses on military specification fiber-optic cables and tank-proof connectors that can interconnect weather-resistant field terminals with base stations. The products can transport a mix of NTSC and phase alternating line video, audio signals, intercommunications, Electronic Industries Association-422/232 data and general-purpose interface circuit closures.

Permanent installations that use Telecast products include the restored Texas State Capitol Building in Austin, equipped with a multi-fiber backbone to facilitate distribution of legislative coverage to a Texas station network. Ron Clark, engineering executive at Station KDFW in Dallas/Fort Worth, says, "Not having to equalize is nice, and the video is excellent."

Cerny emphasizes that although all the current standard systems use analog input/output signals that link to thousands of NTSC/PAL television cameras, analog output microphones and line amplifiers in worldwide use, Telecast is ready for the coming digital changeover. He states, "We have modules that can be plugged into our multichannel system slots on a mix and match basis. They digitize and multiplex all the analog inputs into a high-bit-rate digital stream. So far, however, nobody has asked us for an analog/digital output system."

Lighthouse Digital Systems and Lightwave Systems, subsidiaries of Sundance Resources Inc., presented video and audio fiber-based transmission links. Lighthouse Digital Systems` President Bob Grant demonstrated the versatility of a 4-by-4 optical switch module that provides customer-specified mixes of fiber and coaxial-cable inputs and outputs.

Lightwave Systems` National Sales Manager Rich Creamer accentuated the flexibility of the Fibox multiple-audio-channel digital transmission system, which can pick up either analog or digital sound sources and deliver either analog or digital signals to destination equipment. A new module multiplexes SMPTE 259M digital video into transmission systems.

ADC Telecommunications Inc. accented the range of its FL2000 components for assembling fiber-based premises cabling systems. Product Manager Larry Johnson stated that the system is adaptable to configure customized fiber interconnection systems for large or small main distribution frame, intermediate distribution frame and telephone closet applications.

At the show, The Grass Valley Group was the only manufacturer to use inter-booth fiber-optic components to demonstrate a digital fiber transmission link product. A 2-fiber singlemode cable transported an uncompressed 270-Mbit/sec digital component video signal on an M9125Q transmitter to an M9521Q receiver 500 meters away in another exhibitor`s booth. There, the signal was turned around at baseband and sent back to the Grass Valley booth display on a second 500-meter link.

Grass Valley Group Product Manager Keith Reynolds says that attendee requests for field tests were high. He attributes the reason to the $2000-per-link (transmitter and receiver pair) price point made possible by the four-circuit capacity of the Max 9000 rack frame. Furthermore, the transmitter`s loop-through input design permits redundant feeds from one coaxial cable. At the receiver, a signal status monitor executes a fast switchover to the second channel on loss of signal.

Belden Wire and Cable Co. showed fiber and coaxial cable products to accommodate broadcasters` serial digital signal transportation needs. Marty Van Der Burgt, senior product development engineer, says, "Our 1694A coaxial cable can transmit a 270-Mbit/sec digital signal over 400 meters without errors." He explains that the point at which the bit-error rate becomes noticeable is known as the cliff-effect distance. At a slightly longer distance, bit errors dramatically increase, and the signal`s technical quality falls off rapidly. He observes that singlemode fiber is going to become the medium of choice in television plants working with high-definition television multiplexed video/audio signals moved at an uncompressed 1.5-Gbit/sec bit rate.

Set up in Avid Technology`s booth, open media framework developers used fiber to demonstrate an all-digital postproduction process. Marketing Engineer Franklyn Davis emphasizes that fiber is the medium of choice for designing adaptable building-wide or campus-distributed television postproduction networks.

Davis remarks that open media framework initiative, a standard file format for exchanging digital media information across platforms and between applications, promises to overcome existing limitations. "Our virtual studios involve real-time online participation by Alias Research, Avid Technology, Illustra Information Systems and Studer Editech." The companies were located in different booths and interconnected via a singlemode-fiber Ethernet network engineered by Steve Olynyk, Avid Systems analyst, and installed by Sprint Communications. q

Bob Paulson is owner/principal at Omnimedia Communications in Westborough, MA.

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