Science Fair Project Encyclopedia
Office de Radiodiffusion Télévision Française
In France, the public monopoly on broadcasting was established in 1945 when the Radiodiffusion française (RDF) was formed.
From the beginning, the public broadcaster experienced fierce competition from the "peripheral stations": French-speaking stations aimed at the French public but transmitting on long wave from neighbouring countries, such as Radio Monte Carlo (RMC) from Monaco, Radio Luxembourg / RTL from Luxembourg, and Europe 1 from Germany (exceptionally, in 1974, RMC was allowed to set up a transmitter on French territory).
RDF was renamed Radiodiffusion Télévision Française (RTF) in 1949 and ORTF in 1964.
On August 8 1974, the ORTF was split into 7 institutions:
- TF1 (later to be privatized - in 1987)
- Antenne 2
- SFP - Société Française de Production (programme production)
- INA - Institut National de l'Audiovisuel (archives)
- TDF - Télédiffusion de France (transmission)
- Radio France - French national and international radio
ORTF stereo microphone system
Around the year 1960 sound engineers of the French broadcast (ORTF) found by a number of practical attempts a stereo main microphone system, which results in a quite even distribution of the phantom sources (hearing event direction) on the stereo loudspeaker base, with two small cardiod characteristic microphones, recording angle of the microphone system of ± 48° = 96°.
This system got empirical an axle angle of α = ± 55° = 110° and a microphone distance (microphone basis) of a = 17 cm.
Here are frequency-independent level differences effective and time of arrival differences working together in the same direction as interchannel signals (loudspeaker signals). The engineers did not want to think of a human ear distance, because a useful microphone system for a set of stereo loudspeakers should be developed. This recording technology is called mixed stereo or equivalence stereo. Usually this special microphone system must be built up from two single small diaphragm microphones. One should not use double diaphragm microphones because of the produced unbalanced directional characteristics and the larger phase responses. Even if it appears advisable to experiment with the two parameters axle angle and microphone basis to which there are practical microphone mounting devices, a firmly installed ORTF microphone set is available.
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