Today marks both a revolution and an evolution in the way we do television. Users of equipment are more empowered with less direct help from traditional television engineers. Today we "fix" our gear through menus, if possible. Pick-up tubes are gone, and CCDs are commonplace. And while the user of all types of digital gear is now at least a technician himself, the traditional television and broadcast engineer has become somewhat of a digital engineer as we move forward from today to tomorrow, while taking a brief look back...
From Yesterday To Today: A Perspective on the Digital Revolution
Renville H. McMann, Jr.
I was born a little too late to see mechanical television over the air, but my family was lucky enough to have a 441 line RCA-built Westinghouse 12-inch mirror-viewed receiver in time for the opening of the 1939 World's Fair. This switch from mechanical disks to all electronic vacuum tube pickup and display was probably the first revolution in television history. Since then, revolutions have happened so fast and so often in TV broadcasting that there is a widespread belief, especially among non-engineering management, that the upcoming digital ATV transition is just another ho-hum change in the way of doing things. Those holding this belief are very, very wrong as a little history will show.
The first real revolution in broadcasting was the change from radio to television in 1939. Engineers, used to thinking of base bandwidths measured in kilohertz not TV's megahertz, generally had no knowledge of phase linearity, transient response, cathode ray tubes, gray scale, gamma, photo cathodes, etc. In fact, for the most part, they did not even have high frequency oscilloscopes to look at the TV waveforms they were trying to generate. Luckily for the industry, World War II trained thousands of engineers and technicians in the art of radar, the first cousin of television. Also, the total number of television stations was very small in 1945, building slowly over the next 10 years so there was time to learn the new art of television. Even so, lots of mistakes were made, and on some occasions some pretty terrible pictures were transmitted, but every year, little by little, the pictures got better. The Iconoscope gave way to the Image Orthicon, the Image Orthicon to the Vidicon, and the Vidicon to the Plumbicon, these improvements occurring roughly over two decades. Although each of these improvements was a revolution in its own way, each could easily be understood by engineers and technicians trained on the previous generation of technology. Ham radio was a good background and many a chief engineer got his start that way. For the most part, a few days training by the manufacturer of the equipment was all that was necessary, along with a basic understanding of a circuit design, a little mathematics, and Ohm's law. We tend to forget that in those days equipment broke frequently, and the broadcast engineer was expected to quickly fix it himself and know how to work with a soldering iron and how to climb a tower to check out the antenna. Only in major breakdowns could he (there were very few shes in those days) get help from the manufacturer. At some stations, the chief engineer could not only fix the equipment, but he had actually built it in the first place.
The next two revolutions took place more or less simultaneously in the late '50s, color and video tape recording. Color cameras could be considered as three black and white cameras operating in parallel and hence easily understood; the encoder and decoder did require going back to the books for a refresher on modulation theory, but the same skills honed over the previous 10 years were easily up to the task, and once again the engineers could easily fix it themselves. Video tape recording did require some new skills, mostly mechanical, and another refresher in modulation theory to understand the FM video. Tape recording, itself a revolution, spawned the TV production house, a new facet of our industry, and perhaps a revolution in its own right. However, for the first time the TV production house could not go it alone and build their own cameras and tape recorders, even if they wanted to, although some of the big networks did develop both on a limited basis. It was starting to be the age of specialists. You will note that I haven't mentioned transistors as a revolution because, for the most part, transistors were just a new component, a small, low-voltage version of a valve, subject to the same design equations as the vacuum tubes before them. Transistors, while not a revolution themselves, did cause one: the advent of small, portable equipment which revolutionized station operations, especially ENG. Although small, this new equipment is very complex, and it caused a large scale start of servicing by replacing boards, not individual components. TV engineers began to rely more and more on the manufacturer to fix things at the board level, and, as a result, had less understanding of the subtle intricacies of the equipment's design. Collections of transistors and integrated circuits came on the scene in the 1970s, and made possible high-speed analog to digital conversion, introducing the industry to digital picture manipulation, time based correction, digital tape recording, electronic editing, etc. Note that over 20 years later, this digital conversion of our plants is still not finished, and the equipment has grown so complex that sometimes the manufacturers themselves cannot understand or fix the designs they delivered only a few years previously. Just try and get a 1980 vintage frame synchronizer or noise reducer repaired if anything more involved than a power supply has failed. Thus in 20 years, we have passed from a completely analog plant to a partially digital one. The myriad problems encountered along the way were solved one by one as new pieces of equipment were introduced without jeopardizing the picture quality or interrupting the program flow. There was time for the manufacturers and users to experiment with the new gear in a non-crisis atmosphere, because the older versions were still around and could always be used as a backup.
Now comes digital television and ATV with its subsets of HDTV, SDTV, data transmission, program guides, etc. Not to mention video compression of 50:1 or more.
The FCC wants a complete conversion in nine years. This time, there is no time for an evolutionary approach. The job can be done, but it will require a massive effort on the part of manufacturers and users, both stations and production houses. Much of the needed equipment hasn't been designed, and in some critical areas, it hasn't even been invented. The old-time engineer is going to need lots of help from the new breed of software maven. Circuit design, while still important, needs to be supplemented by strong logic design and de-bugging skills. A mathematical background will be very handy when trying to decipher the discrete cosine transform or Trellis Coding. At first there will be problems, but none that can't be solved by the same type of person that can keep an Ethernet LAN up and running.
Renville H. McMann, Jr. began his career while still in his teens, serving on FM broadcasting pioneer Edwin H. Armstrong's staff during the 1930s. After finishing his education and serving in World War II he joined the NBC Research Laboratory, where he served as liaison engineer with RCA Laboratories on the first successful color VTR. He joined CBS Laboratories in 1955, where he co-invented the first home videocassette system with Dr. Peter Goldmark, who he succeeded as President of CBS Laboratories in 1971. When TV viewers in the 1970s saw live NASA video of Apollo astronauts exploring the moon, it was the color camera system and magnetic scan-conversion techniques invented by McMann at CBS Laboratories that made it possible.
While at CBS, McMann also served as the principal inventor and major participant in the development of the Starlight TV camera for transmitting color pictures from inside the human body, an encoded signal color-correction device, the digital noise reducer, and the CBS Minicam Mark VI, the first hand-held color TV camera system. The holder of 36 patents, McMann served as President of Thomson-CSF Laboratories from 1975 until his appointment in 1982 as VP of Advanced Television, CBS Technology Center. He has chaired the HDTV committee of the Advanced Television Systems Committee, and has been involved in other ATV organizations.
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