Quote:
Originally Posted by brianc
Hi All
It's interesting to note that the German 441 line system being shown is an intermediate film "Zwischenfilm" system. Was this because the scanning was mechanical ... (Brian°
|
Sorry Brian, but the 441 lines system set up first in Germany by 1938, then in France ("Fernsehsender Paris") and in Italy in 1943, was an all-electronic scanning, exactly like your EMI-Marconi 405 lines and our French pre-war CDC (Compagnie des Compteurs) 455 lines systems.
During WWII, French TV pioneer Henri de France made some 800-1000 lines experiments, in particular 819 lines (that would later be adopted by French Government, with AM sound and positive picture video, in order not to pay royalties to Americans, whose 525 lines system adapted to European AC 50 Hz power results in... 625 lines). He also made experiments in 1029 lines.
While Britain luckily kept quite all its AM radio networks safe during WWII, occupied France lost 90 percent of its own network (only Limoges transmitter escaped to destruction by Germand forces). The 441 lines TV station created by german officer Kurt Hinzmann was itself totally safe and could restart as soon as october 1945, while your 405 lines station had to wait until April 1946 to repeat its "Mickey Mouse" cartoon interrupted on Sept. 1, 1939. French government thus gave total priority to AM radio, having to rebuild the LW 500 kW Allouis station, about 40 kms in the West of Bourges (which would only transmit from 1952) and all MW transmitters and aerials in main cities (Lille, Rennes, Lyons, Nancy, Marseilles, Nancy...).
So did France wait for 4-5 years and finally decide to take profit of WWII research on improved scanning to launch a nationwide high-def. network in the Fifties to come. Paris 441 lines station was serving about 3,000 homes in Greater Paris area, but thanks to its band I frequencies (video 42.00 MHz - audio 46.00 MHz) and to its 30 kW power, one could find some vertical "H" up to 130-150 kms around Eiffel Tower. It could even be received by two entusiasts in Auxerre (Northern Burgundy) and Vichy.
In 1949 Francois Mitterand, then Secretary of State for broadcasting, decided to chose 819 lines scanning, while a 729 lines system, intermediate between 819 and 625 lines had also been submitted by French Thomson Company. Although many people believe that it was based upon a desire to claim for "French TV, the best pictures in the world", the real reason was exclusively economical : through German post-war market, Americans tried (and succeeded) to sell their NTSC 525 lines technology adapted to Europe as previously explained. So did France adopt features that escaped to those used in the NTSC system and its 625 lines version. I found these explanations in a text published by a belgian TV engineer in French "Television Pratique" magazine in 1953-1954.
While Britain would wait until 1955 before using Band III, France used it as soon as 1949 in Paris and for most of its regional stations. Only a few ones used band I 14 MHz wide (!) channels 2 (video 52.40 MHz - audio 41.25 MHz) & 4 (video 65.55 MHZ - audio 54.40 MHz), most of them being severely disturbed by BBC-TV during summer periods, in particular Caen, Boulogne, Troyes, Nantes and Limoges. Programmes on both 441 lines and 819 lines stations were different until the famous 1952 British & French Week, hosted live from Paris on BBC-TV, thanks to the first standards converter in the world (a 405 lines camera scanning a 819 lines specially designed CRT). From that time, both 441 & 819 lines networks relayed the same programme.
On january 3, 1956 the 441 lines transmitter burnt on the top of Eiffel tower after a long night of General Elections covering. Because it was initially intended to maintain 441 lines transmissions until 1958 only, its viewers were indemnified in order to replace (or adapt... yes, some people did it !) their 441 lines receiver with 819 lines service.
In 1959-1960, some "second network" tests were made in 819 lines from Eiffel tower on adjacent channels to chF8a, but this gave so poor results that RTF decided to adopt 625 UHF transmissions. However because of receivers' already rather high price (due to 819 lines technology) it was decided to maintain similar features to 819 VHF system, that is to say positive video and AM sound.
The coming of SECAM colour, on 625 UHF exclusively, put an end to "high def." 819 lines scanning, most of renewed equipment on ORTF1 being 625 lines bw or SECAM, optically converted to 819 to be broadcast on VHF network. Digital conversion only occured in the mid-70s when new TF1 public company began broadcasting in 625 UHF with SECAM system.
Here a pic of Eiffel tower with 441 audio and video separate vertical aerials, and audio-video temporary medium-power aerial for new 819 lines service.
Because research was still on its way for high-power transmissions in band III, only 3kW peak-video power could be used until new feeders and aerials could be designed in order to broadcast with 20 kW power (150 kW ERP). The thin aerial shown on the pic was later replaced by a new "turnstile" one circa 1953-1954. The microwaves link dish to Lille (then installed in the Townhall's clocktower) was introduced in 1951-1952, after one year autonomous broadcasts in this 1st French regional station. All subsequent stations were systematically fed by microwaves links from Paris. The first French 819 lines band I station was launched in Caen (ch. 2h) in 1956.
Louis
http://television.625lignes.free.fr/...fel%201949.jpg