The Electronics Revolution Inventing the Future

30 Seeing by Electricity: Development of Television
By 1931 they also appreciated that, apart from the camera, there were two further problems.
The implications of Campbell Swinton’s calculation of the number of picture elements,
in what they called a high-definition system, was that it required at least a 100,000
points. 25 This meant that the radio system needed a wider bandwidth to be able to handle this
rather than the few kHz of the normal radio broadcasts. This required a very high frequency
(VHF) transmission of a wavelength around 50 m (60 MHz). This was new territory for
broadcasters, and a considerable concern as the coverage area of the transmitter was reduced
to ‘line of sight’, which would mean many more transmitters to cover the country. 26
They foresaw a further difficulty: the speed requirements at the receiver. It was quickly
realized that only the cathode ray tube had any real chance of achieving this, though a lot
of development work would be needed to produce a product that was in any way comparable
with a home cine film. By around 1932, virtually all those interested in developing
television systems had come to the same conclusions.
In 1931, HMV merged with the Columbia Record company. Crucially this brought two
men to the joint research team, Isaac Shoenberg, yet another Russian, and his brilliant
electronics engineer, Alan Blumlein. Shoenberg, originally from the Ukraine, had studied
in Kiev before being involved in setting up radio systems in Russia for what later became
the Russian Marconi company. 27 He was to head the joint team. It was an inspired choice.
Shoenberg and Blumlein faced a series of problems. First, Shoenberg had to persuade
his management to invest a considerable sum of money in the development of a television
system. At the time, it was far from clear that a system of adequate quality was achievable,
and it was his confidence in this that persuaded them. His next task was to recruit scientists
and engineers to build up the teams to tackle the various parts of the problem. Part of his
skill was in choosing the right people.
Shoenberg sidestepped the transmitter problem by using his contacts with Marconi to
hire a VHF one. They had quite enough other problems to solve. One team was set to work
to produce improved cathode ray tubes for the receiver. Another dealt with the electronic
circuit problems, particularly dealing with the wide range of frequencies or the ‘bandwidth’
of the signals. Last, and probably the most important, was a team headed by a new
recruit, Dr. J. D. McGee, to tackle an electronic camera, as he was convinced that mechanical
systems would never be satisfactory. 28
Work started in 1932 with a cleverly constructed photosensitive disk mounted inside an
evacuated glass sphere. To one side was a window to bring in the light from the subject
being viewed. On the same side, at an angle, was an electron gun arranged with deflecting
coils to produce the scan in both horizontal and vertical directions. The disk took up an
image of electrical charge corresponding to the light falling on it. The scanned electron
beam would discharge it spot by spot and this signal could be read off electronically. 29
This led to the development of the Emitron tube, which would be the basis of
Shoenberg’s camera. The tube was only around 5% efficient compared with the theoretical
maximum, but this was an enormous improvement over previous systems, and it could
work outdoors in all normal light levels and indoors without excessive lighting.
There has been some controversy as to whether this was really an American design from
RCA, particularly as the early Iconoscope and Emitron tubes look remarkably similar. Also,
HMV had a patent exchange arrangement with RCA and this was carried over to EMI.
While Shoenberg and his team undoubtedly had access to RCA patents, (and RCA to theirs)