Question: For how long did the broadcaster of Song of Summer alternate different broadcasting systems?

full_context: Document 1: BBC Television: After a series of test transmissions and special broadcasts that began in August, regular BBC television broadcasts officially resumed on 1 October 1936, from a converted wing of Alexandra Palace in London, which housed two studios, various scenery stores, make-up areas, dressing rooms, offices, and the transmitter itself, now broadcasting on the VHF band. BBC television initially used two systems, on alternate weeks: the 240-line Baird intermediate film system and the 405-line Marconi-EMI system, each making the BBC the world's first regular high-definition television service, broadcasting Monday to Saturday from 15:00 to 16:00 and 21:00 to 22:00.
Document 2: BBC Television: Baird Television Ltd. made Britain's first television broadcast, on 30 September 1929 from its studio in Long Acre, London, via the BBC's London transmitter, using the electromechanical system pioneered by John Logie Baird. This system used a vertically-scanned image of 30 lines – just enough resolution for a close-up of one person, and with a bandwidth low enough to use existing radio transmitters. Simultaneous transmission of sound and picture was achieved on 30 March 1930, by using the BBC's new twin transmitter at Brookmans Park. By late 1930, 30 minutes of morning programmes were broadcast Monday to Friday, and 30 minutes at midnight on Tuesdays and Fridays, after BBC radio went off the air. Baird broadcasts via the BBC continued until June 1932.
Document 3: Theme from A Summer Place: ``Theme from A Summer Place ''is a song with lyrics by Mack Discant and music by Max Steiner, written for the 1959 film A Summer Place, which starred Sandra Dee and Troy Donahue. It was recorded for the film as an instrumental by Hugo Winterhalter. Originally known as the`` Molly and Johnny Theme'', the piece is not the main title theme of the film, but a secondary love theme for the characters played by Dee and Donahue.
Document 4: Song of Summer: Song of Summer is a 1968 black-and-white television film written, produced, and directed by Ken Russell for the BBC's "Omnibus" series which was first broadcast on 15 September 1968. It portrays the final six years of the life of Frederick Delius, when he was blind and paralysed, and when Eric Fenby lived with the composer and his wife Jelka as Delius's amanuensis. The title is borrowed from the Delius tone poem "A Song of Summer", which is heard along with other Delius works in the film.
Document 5: BBC Television: After a series of test transmissions and special broadcasts that began in August 1936, the BBC Television Service officially launched on 2 November 1936 from a converted wing of Alexandra Palace in London. ``Ally Pally ''housed two studios, various scenery stores, make - up areas, dressing rooms, offices, and the transmitter itself, which then broadcast on the VHF band. BBC television initially used two systems on alternate weeks: the 240 - line Baird intermediate film system and the 405 - line Marconi - EMI system. The use of both formats made the BBC's service the world's first regular high - definition television service; it broadcast from Monday to Saturday between 15: 00 and 16: 00, and 21: 00 and 22: 00. The first programme broadcast -- and thus the first ever, on a dedicated TV channel -- was`` Opening of the BBC Television Service'' at 15: 00. The first major outside broadcast was the coronation of King George VI and Queen Elizabeth in May 1937.
Document 6: BBC Television: The two systems were to run on a trial basis for six months; early television sets supported both resolutions. However, the Baird system, which used a mechanical camera for filmed programming and Farnsworth image dissector cameras for live programming, proved too cumbersome and visually inferior, and ended with closedown (at 22:00) on Saturday 13 February 1937.
Document 7: Song Without End: Song Without End, subtitled The Story of Franz Liszt (1960) is a biographical film romance made by Columbia Pictures. It was directed by Charles Vidor, who died during the shooting of the picture and was replaced by George Cukor. It was produced by William Goetz from a screenplay by Oscar Millard, revised (uncredited) by Walter Bernstein and based on screenwriter Oscar Saul's original 1952 script (uncredited). The music score was by Morris Stoloff and Harry Sukman with music by Franz Liszt, and the cinematography by James Wong Howe and Charles Lang (uncredited). The film also features music of those contemporaries of Liszt whom he unselfishly championed by featuring them in his numerous performances (e.g., Richard Wagner, Hector Berlioz, among others).
Document 8: The Last Rose of Summer: The 2017 film Three Billboards Outside Ebbing, Missouri starts with The Last Rose of Summer, performed by Renée Fleming from the CD The Beautiful Voice by Renée Fleming, the English Chamber Orchestra & Jeffrey Tate 1998) The version performed is part of the opera Martha by Friedrich von Flotow. In this starting scene of Three Billboards Outside Ebbing, Missouri, the profound melancholy at the heart of the film is expressed by this song that depicts the passing of youth, beauty and ultimately life itself; a theme that is also known as Vanitas.
Document 9: BBC Television: Mechanically scanned, 30-line television broadcasts by John Logie Baird began in 1929, using the BBC transmitter in London, and by 1930 a regular schedule of programmes was transmitted from the BBC antenna in Brookmans Park. Television production was switched from Baird's company to what is now known as BBC One on 2 August 1932, and continued until September 1935. Regularly scheduled electronically scanned television began from Alexandra Palace in London on 2 November 1936, to just a few hundred viewers in the immediate area. The first programme broadcast – and thus the first ever, on a dedicated TV channel – was "Opening of the BBC Television Service" at 15:00. The first major outside broadcast was the coronation of King George VI and Queen Elizabeth in May 1937. The service was reaching an estimated 25,000–40,000 homes before the outbreak of World War II which caused the service to be suspended in September 1939. The VHF broadcasts would have provided an ideal radio beacon for German bombers homing in on London, and the engineers and technicians of the service would be needed for the war effort, in particular the radar programme.
Document 10: The Song of the Rivers: The Song of the Rivers () is a 1954 documentary film production by the East Germany film studio DEFA. Dutch filmmaker Joris Ivens was the leading director. The sprawling film celebrates international workers movements along six major rivers: the Volga, Mississippi, Ganges, Nile, Amazon and the Yangtze. Shot in many countries by different film crews, and later edited by Ivens, Song of the Rivers begins with a lyrical montage of landscapes and laborers and proceeds to glorify labor and modern industrial machinery. The musical score is by Dmitri Shostakovich, with lyrics written by Berthold Brecht, and songs performed by German communism's star Ernst Busch and famous American actor, singer and activist Paul Robeson who also narrates. "Song of the Rivers" is an ode to "international solidarity".
Document 11: Summertime Blues: ``Summertime Blues ''is a song co-written and recorded by American rockabilly artist Eddie Cochran. It was written by Cochran and his manager Jerry Capehart. Originally a single B - side, it was released in August 1958 and peaked at number 8 on the Billboard Hot 100 on September 29, 1958 and number 18 on the UK Singles Chart. It has been covered by many artists, including being a number - one hit for country music artist Alan Jackson, and scoring notable hits in versions by The Who, Blue Cheer and Brian Setzer, the latter of whom recorded his version for the 1987 film La Bamba, where he portrayed Cochran. Jimi Hendrix performed it in concert.
Document 12: Richard Blackford: Richard Blackford PhD studied composition with John Lambert at the Royal College of Music and conducting with Norman Del Mar. He was awarded the Mendelssohn Scholarship and the Tagore Gold Medal. He spent a number of years as Hans Werner Henze's assistant in Italy on a Leverhulme scholarship, where he received his first commissions while immersed in the European avant-garde. He returned to London in 1977 to turn his sights to the dramatic potential of music, combining teaching at LAMDA with commissions for theatre scores along with concert commissions. After becoming first Composer in Residence at Balliol College, Oxford, he was commissioned to write the opera "Metamorphoses" for the Centenary of the Royal College of Music. Further collaborations with Ted Hughes and Tony Harrison led to international film and theatre projects, including "The Prince's Play" and "Fram" at the Royal National Theatre. In all he has composed four operas, two musicals, much concert music and the scores to over two hundred films, being nominated for an Emmy Award in 2001 for Outstanding Achievement In Music. The mid-1990s saw a renewed focus on lyrical and dramatic works for the concert hall, notably "Mirror of Perfection" and "Voices of Exile", both subjects of television documentaries. 2011 saw the premiere of Not In Our Time, a 55-minute choral and orchestral work commissioned to mark the Centenary of the Bournemouth Symphony Chorus and for performance on the tenth anniversary of 9/11. It was subsequently performed in Chicago and Bremen to standing ovations.
Document 13: High-definition television: Since the formal adoption of digital video broadcasting's (DVB) widescreen HDTV transmission modes in the early 2000s; the 525-line NTSC (and PAL-M) systems, as well as the European 625-line PAL and SECAM systems, are now regarded as standard definition television systems.
Document 14: Color television: After a series of hearings beginning in September 1949, the FCC found the RCA and CTI systems fraught with technical problems, inaccurate color reproduction, and expensive equipment, and so formally approved the CBS system as the U.S. color broadcasting standard on October 11, 1950. An unsuccessful lawsuit by RCA delayed the first commercial network broadcast in color until June 25, 1951, when a musical variety special titled simply Premiere was shown over a network of five East Coast CBS affiliates. Viewing was again restricted: the program could not be seen on black - and - white sets, and Variety estimated that only thirty prototype color receivers were available in the New York area. Regular color broadcasts began that same week with the daytime series The World Is Yours and Modern Homemakers.
Document 15: Brian Song: ``Brian Song ''is the title song from the 1979 film Monty Python's Life of Brian. It was released as a single in the UK on 16 November 1979 as a Double A side with`` Always Look on the Bright Side of Life''. The song, which charts the growth of the Brian character to manhood, was composed by Andre Jacquemin and Dave Howman with lyrics by Michael Palin. It was performed by sixteen - year - old Sonia Jones with a string and brass accompaniment in the style of a John Barry film theme (the entire brass section was performed via extensive multitracking by John Du Prez). It is included on the Monty Python's Life of Brian album and on the CD Monty Python Sings. Martin Chilton, the Culture Editor for The Telegraph website, listed it as one of the five best Monty Python songs in 2013.
ground_truth: six months
sub_queries: Who was Song of Summer released by? Answer: BBC
For how long did the BBC alternate different broadcasting systems? Answer: six months