Television, line by line
Since the CBCs first black and white images flickered their way through the air to a
relatively small number of Canadian homes in 1952, the technology of television has become
increasingly sophisticated. Here we can only touch on some of the developments that have
improved televisions range, quality, accessibility and convenience, beginning with the basics
of how it works.
Eye am a camera
In a TV camera, the scene picked up through the lens is focused on a photoelectric screen
in the tube. The varying light levels from each bit of the scene release varying amounts of
electrons that are stored on the screen as an electrical image. An electron gun scans the
image line by line from left to right and top to bottom (in 1/30th of a second) causing a current
to flow in the signal plate on the back of the screen and creating an electrical analogue of the
original scene. This picture signal, amplified about 1000 times, is combined with a synchronizing
signal that tells the electron gun when it should begin its next scan. The synchronizing and
picture signals make up the video signal. It is then combined with the audio signal and transmitted.
I think of those cameras as octopuses with little green eyes blinking on and off, their silvery
forms moving ponderously, wrote an early TV performer. The Museums collection contains many
examples that show the evolution of cameras from the huge 130-kilogram octopuses of the 1950s
to the hand-held consumer models of recent years. A large number of manufacturers are represented
in the collection, including Marconi, RCA, EMI, General Electric, Sylvania, Dage, Dumont, Pye,
Philips, and Sony.
|Marconi Mark II monochrome mobile camera (800467), ca 1952 (CSTM/Peter Lindell)|
Before the development of the zoom lens, lenses were mounted on turrets that the operator
had to change for close-ups, medium or long shots. In a studio at least two cameras had to be
used to allow for switching lenses. The collection contains a variety of lenses and turrets.
|Marconi Mark IV monochrome studio camera (840049), ca 1962, with later CBC logo (CSTM/Peter Lindell)||
|Philips colour studio camera with zoom lens (850548), 1970s (CSTM/Peter Lindell)|
While the camera is the eye, more is required to get the full picture. The broadcast camera
chain consists of the camera, control unit, master picture and waveform monitor, and power
supply. The collection contains both studio and mobile examples of these components as well
as other amplifiers and monitors.
You get the picture
The Museums collection reflects the technological and stylistic development of monochrome
(black and white) and colour receivers and represents sets of domestic and foreign manufacture.
Some examples are: a 1949 Westinghouse with an adjustable frame around the screen (700046);
Northern Electrics first model, from around 1950 (690720); one of the first hundred sets made
by Canadian General Electric when it began production in 1949 (951438); a circa 1958 Philco
Predicta with a very sleek space age design (920044); and an early remote control model,
the 1961 Zenith Space Command (850627).
|Northern Electric NT-101 (690720), ca 1950 (CSTM/Peter Lindell)|
|Canadian General Electrics C2505 (951438) featured a moulded plastic cabinet, ca 1949. (CSTM/Peter Lindell)||
|Philco Predicta (920044), ca 1958. Television meets Sputnik. (CSTM/Peter Lindell)|
The collection shows the dual approaches to TV—hide it or flaunt it (a TV set for every
decorating scheme, furniture styled cabinets from peasant to Swedish modern).
The size and shape of the television picture depends on the tube, the end of which is the
screen. In the early days the tubes faces were small and not very bright. Viewers had
to be close to the set in a darkened room. Because early tubes were long and narrow, big
screen TV cabinets were large and tended to dominate the room. Over time, the brightness
of the picture was improved and shallower tubes with wide deflection angles increased the
size of the image and reduced the depth of the TV set. The screen sizes in the collection
range from Sonys 1986 Watchman (870071), virtually pocket-sized, to a projection set (850931)
with a 1.2-metre by 0.9-metre screen.
||Moving pictures (left to right): Sony Watchman (870071), 1986; Hotpoint portable (970362), ca 1955; Philco Safari (860148), ca 1959 (CSTM/Peter Lindell)|
Red, green, blue colour!
You will bring whole art museums into your homes. You will bring musical shows with
rainbows of lovely ladies, handsome men and gorgeous costumes, declares a General Electric
brochure from the 1950s.
||General Electric promotional booklet (L27864), ca 1955 (CSTM)|
On September 1, 1966, colour broadcasting began in Canada. The first
North American colour standard, developed by the Columbia Broadcasting System (CBS),
was set in 1950. But it was not compatible with monochrome sets and was short-lived. In 1953
the U.S. adopted the National Television Standards Committee (NTSC) system as the American
standard. Developed by CBS rival RCA, it was compatible with monochrome sets and remains the
North American standard today. The Museums collection has CBS standard sets (710660, 710662)
and a camera head (710661) as well as an RCA CT-100, the first NTSC receiver available to the
American public (720305).
|Receiver employing the short-lived CBS colour system (710660), ca 1950. (CSTM/Peter Lindell)||
|RCA Victor CT-100 (720305), the first receiver using the new NTSC colour standard, ca 1954. (CSTM/Peter Lindell)|
Colour TV simplified
All colours can be reproduced from varying combinations of three primary colours: red, blue and green.
The colour TV camera employs filters to split incoming light into these elements and generates an
electrical signal for each. In the receivers picture tube these colour signals activate three
electron beams, that vary with the intensity of each colour. The viewing screen at the end of
the picture tube is made of tiny phosphorescent dots arranged in groups of three. As each electron
beam strikes the dot corresponding to its primary colour, the dots form a blend that varies with
the strength of each colour element.
The systems used to combine and encode the three colour signals vary from country to country.
Much of the world, including North and South America uses the NTSC system. Britain, Australia
and most of Europe use the PAL system (Phase Alternating). France, Eastern Europe and Russia use
the SECAM system (système électronique couleur avec mémoire).