|
|
[return to 1950-1959 Main Section] 1957 French "Teleavia" One of the most unusual designs to hit the television marketplace in 1957 was the "Teleavia", from France, with a large 17" or 21" swivel picture tube. The black & white picture tube also had a tilt adjustment. Contact for Teleavia Schematics
Explanation of Channel "8A" and "R", courtesy of Hervé Benoit, of Paris France: Channel 8A was the channel used by the 819 line TV transmitter in Paris-Tour Eiffel. This was the first 819 lines TV transmitter, started in 1949 before the VHF channeling system was defined. The channels were defined only one or two years later, and of course the Paris transmitter was not exactly on the position of one of these new channels: it had an offset of around 1 MHz to channel 8, therefore it was named "8A". The channels of the 819 lines system (known as CCIR system E) were 14 MHz wide, with a difference of 11.15 MHz between sound and vision carriers. Video modulation was positive and sound was AM. In order to have 12 channels in the VHF range (band I from 41 to 68 MHz + band III from 162 to 220 MHz) despite this very big channel width, odd channels had the sound carrier above the picture carriers and even channels below the picture carrier. So there was always an odd channel within the same spectrum of an even channel, but with an offset of around 1MHz. This, combined with the use of horizontal and vertical polarisation, allowed the placement of more transmitters. Regarding the explanation for "R", it probably meant "reserve". This would have been a provision in view of adding an UHF tuner, which in the early days of UHF was done by means of a special "barette" (bar) inside the tuner (when the second national TV program was started).
To be noted that there is no channel 1 nor channel 3, which originally were defined (reversed channels 2 and 4 respectively).
The reason why they were not used
is that the local oscillator frequency would have fallen inside the IF
spectrum of the IF values then used (vision IF = 28,05 MHz, sound IF = 39,20
MHz). If the IF values had been chosen the other way around, then the
same thing would have happened to channels 2 and 4
[return to 1950-1959 Main Section]
|