180-line is an early electronic television system. It was used in Germany after March 22, 1935, using telecine transmission of film, intermediate film system, or cameras using the Nipkow disk. Simultaneously, fully electronic transmissions using cameras based on the iconoscope began on January 15, 1936, with definition of 375 lines.
The Berlin Summer Olympic Games were televised,[2] using both closed-circuit 375-line fully electronic iconoscope-based cameras and 180-line intermediate film cameras[3] transmitting to Berlin, Hamburg, Munich, Nuremberg, and Bayreuth via special Reichspost long-distance cables in August 1936. In Berlin, twenty-eight public 180-line television rooms were opened for anybody who did not own a television set.
| System | Field frequency | Active picture | Field blanking | No. of broad pulses | Broad pulse width | Line frequency | Front porch | Line sync | Back porch | Active line time | Video/syncs ratio |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 180-line | 25 Hz | 169 lines | 11 lines | 1 per field | 200 μs | 4500 Hz | 2.2 μs | 20.0 μs | 2.2 μs | 197.8 μs | 75/25 |
Some TV sets for this system were available, including the French Grammont models,[5][6] Telefunken FE II[1] and FE III,[7] and Fernseh Tischmodell[8]
After February 1937, both 180- and 375-line systems were replaced by a superior, 441-line system.