Question: For how long did the radio match broadcaster alternate different broadcasting systems?

full_context: Document 1: Premier League: Television has played a major role in the history of the Premier League. The League's decision to assign broadcasting rights to BSkyB in 1992 was at the time a radical decision, but one that has paid off. At the time pay television was an almost untested proposition in the UK market, as was charging fans to watch live televised football. However, a combination of Sky's strategy, the quality of Premier League football and the public's appetite for the game has seen the value of the Premier League's TV rights soar.
Document 2: Arsenal F.C.: Arsenal have appeared in a number of media "firsts". On 22 January 1927, their match at Highbury against Sheffield United was the first English League match to be broadcast live on radio. A decade later, on 16 September 1937, an exhibition match between Arsenal's first team and the reserves was the first football match in the world to be televised live. Arsenal also featured in the first edition of the BBC's Match of the Day, which screened highlights of their match against Liverpool at Anfield on 22 August 1964. BSkyB's coverage of Arsenal's January 2010 match against Manchester United was the first live public broadcast of a sports event on 3D television.
Document 3: FA Cup: In the early years of coverage the BBC had exclusive radio coverage with a picture of the pitch marked in the Radio Times with numbered squares to help the listener follow the match on the radio. The first FA Cup Final on Radio was in 1926 between Bolton Wanderers and Manchester City but this was only broadcast in Manchester, the first national final on BBC Radio was between Arsenal and Cardiff in 1927. The first final on BBC Television was in 1937 in a match which featured Sunderland and Preston North End but this was not televised in full. The following season's final between Preston and Huddersfield was covered in full by the BBC. When ITV was formed in 1955 they shared final coverage with the BBC in one of the only club matches shown live on television, during the 1970s and 1980s coverage became more elaborate with BBC and ITV trying to steal viewers from the others by starting coverage earlier and earlier some starting as early as 9 a.m. which was six hours before kick off. Nowadays, this continues with Setanta and ESPN having all-day broadcasts from Wembley, but terrestrial TV coverage usually begins two hours before kick off. The sharing of rights between BBC and ITV continued from 1955 to 1988, when ITV lost coverage to the new Sports Channel which later became Sky Sports.
Document 4: 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 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: 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 7: 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 8: England national football team: All England matches are broadcast with full commentary on BBC Radio 5 Live. From the 2008–09 season until the 2017–18 season, England's home and away qualifiers, and friendlies both home and away are broadcast live on ITV (often with the exception of STV, the ITV affiliate in central and northern Scotland). England's away qualifiers for the 2010 World Cup were shown on Setanta Sports until that company's collapse. As a result of Setanta Sports's demise, England's World Cup qualifier in Ukraine on 10 October 2009 was shown in the United Kingdom on a pay-per-view basis via the internet only. This one-off event was the first time an England game had been screened in such a way. The number of subscribers, paying between £4.99 and £11.99 each, was estimated at between 250,000 and 300,000 and the total number of viewers at around 500,000.
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: Timeline of the BBC: 1930 9 March -- The majority of the BBC's existing radio stations are regrouped to form the BBC National Programme and the BBC Regional Programme. 14 July -- Transmission of the first experimental television play, The Man With the Flower in His Mouth. 30 September -- Number of radio licences reaches 12 million ``or roughly every second home in the country ''.
Document 11: 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 12: List of FA Cup broadcasters: FA Cup Broadcasters Country Flag Broadcaster (s) United Kingdom BT Sport BBC Sport Argentina Etv Armenia Armenina Second TV Channel Australia Nine Network Austria ORF (Final only) Azerbaijan AzTV Belgium Eleven Sports Bolivia ESPN Bosnia and Herzegovina Sport Klub Brazil ESPN Bulgaria Nova Sport Chile ESPN China GDTV Tencent (online) Sohu (online) PPTV (online) Sina (online) Colombia ESPN Croatia Sport Klub Czech Republic Nova Sport Denmark SBS Media Ecuador ESPN France TF1 Georgia Setanta Sports Germany Eurosport Greece Nova Sports Hong Kong Now TV Viu TV Hungary TV2 Group Iceland 365 Media India (Sub-continent) Sony network (STAR) Indonesia beIN Sports (all matches) SCTV (Semi-Final + Final) Israel Charlton Italy Fox Sports Japan STAR Sports Korea (South) Bein sports tv Macedonia Sport Klub Malaysia Astro Mexico Sky Mexico Middle East & North Africa beIN Sports Montenegro Sport Klub Myanmar Shwe Lan Thin Sky Net Netherlands Fox Sports Eredivisie Norway Viasat 4 (MTG) Paraguay ESPN Peru ESPN Philippines beIN Sports Portugal Sport TV Republic of Ireland Eir Sport TV3 (Final only) Romania Pro TV Russia RTR Serbia Sport Klub Singapore SingTel Slovenia Sport Klub Spain Teledeporte Sub-Saharan Africa Supersport Sweden Viasat Turkey TRT TT Net United States FOX Sports Uruguay ESPN Vietnam SCTV
Document 13: FA Cup: Many[who?] expected BSkyB to make a bid to show some of the remaining FA Cup games for the remainder of the 2009–10 season which would include a semi-final and shared rights to the final. ESPN took over the package Setanta held for the FA Cup from the 2010–11 season. The 2011 final was also shown live on Sky 3D in addition to ESPN (who provided the 3D coverage for Sky 3D) and ITV. Following the sale of ESPN's UK and Ireland channels to BT, ESPN's rights package transferred to BT Sport from the 2013–14 season.
Document 14: 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 15: BBC Television: Postwar broadcast coverage was extended to Birmingham in 1949 with the opening of the Sutton Coldfield transmitting station, and by the mid-1950s most of the country was covered, transmitting a 405-line interlaced image on VHF.[original research?]
ground_truth: six months
sub_queries: Who used to brodcast the matches on the radio? Answer: the BBC
For how long did the the BBC alternate different broadcasting systems? Answer: six months