441 lines is the number of scan lines in some early electronic monochrome analog television systems. Systems with this number of lines were used with 25 interlaced frames per second in France and Germany from 1939 to 1943, as well as by RCA in the United States with 30 interlaced frames per second from 1938 to 1941.
|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|
|441 lines||50 Hz||383 lines||29 lines||8 per field||36.3 μs||11.025 kHz||1.0 μs||9.0 μs||6.3 μs||74.3 μs||70/30|
After trials in 375 lines during the Berlin Olympic Games of 1936, by 1937 Germany had introduced a 441 lines with 50 interlaced fields per second television system that replaced the previous 180 lines network relayed by a special Reichspost (National Post Office) cable network in the country's main cities (Berlin, Hamburg, Munich, Bayreuth, Nuremberg). The system's line frequency was 11.025 kHz and the broadcast frequencies were 46.0 MHz for vision and 43.2 MHz for sound. Its image aspect ratio was close to 1.15:1.
|System||Lines||Frame rate||Channel bandwidth (in MHz)||Visual bandwidth (in MHz)||Sound offset||Vestigial sideband||Vision mod.||Sound mod.||Aspect ratio|
A project began in 1938 involving the National Post and several companies including Bosch, Blaupunkt, Loewe, Lorenz, TeKaDeand Telefunken that aimed to produce 10,000 units of the television system. However, due to the onset of the Second World War only about 50 devices were installed in military hospitals and various government departments. The transmitter's aerials in Berlin were destroyed during an Allied Forces' bombing in November 1943, but the station was also relayed by a special coaxial cables network to "wide screen" public "TV-rooms" (Fernsehstuben) so it carried on this way until 1944.
The Einheitsempfänger is a German TV receiver created in 1939. It could only receive one channel, since its receiving frequency was preset at the factory. This allowed for lower prices and would have made difficult the reception of foreign channels (broadcasting in the same system), were any of them available.
The dimensions of the 1939 receiver were:
By 1941 the "Fernsehsender Paris" station transmitted from the Eiffel Tower in Paris using the German 441 lines system and its main technical characteristics, while however keeping the previous French 455 lines frequencies 42 MHz - 46 MHz in use from 1938 to 1940, thus with a [ clarification needed ] on a stick spectrum space than the station operating in Berlin. Television programs were mainly for wounded soldiers of the Wehrmacht occupation troops who recovered in the Greater Paris Area hospitals, but they also included French-language shows. Broadcasts were monitored in the United Kingdom during the Second World War to gather intelligence information from occupied France. Because the 819 lines standard had been adopted in 1948 for the national network, it was due to cease on January 1, 1958. However, after a long elections coverage night, most of the equipment was destroyed by fire on January 3, 1956. It was decided to indemnify the 3,000 owners of remaining 441 lines sets and to entitle them to reduced rates for their new 819 lines receivers. Since July 1952 the 441 lines transmitter was no longer broadcasting separate programs, but simply picked up the national network's picture through an 819-441 lines "optical converter" (a 441 lines camera, slightly out of focus, pointed at an 819 lines monitor equipped with an oval spotlight cathode ray tube).
The line frequency was 11,025 Hz with vision broadcast at 46.0 MHz and sound at 42.0 MHz. Aerials were independent for audio and vision at the top of the Eiffel tower, both vertically polarized. No gain being obtained from these pre-war basic aerials, the effective radiated power was only the transmitter's peak one, i.e. 30 kW which enabled a good reception in a radius of 100 km (62 miles) around Paris. As displayed in J.M. Frost's WRTH (World Radio TV Handbook) editions at that time, the transmitter's frequencies (42-46 MHz) were listed as channel "F1" or channel "S" (or "Special" channel) in the European Broadcasting Union's official documents.
|System||Lines||Frame rate||Channel bandwidth (in MHz)||Visual bandwidth (in MHz)||Sound offset||Vestigial sideband||Vision mod.||Sound mod.|
Replacing pre-war tests in 343 lines, broadcasts using the 441 lines system began in Italy in 1939 with regular services from Rome using 2 kW power and Milan using 400 watts of power in the frequency band of 40-45 MHz. Broadcasts were discontinued on May 31, 1940.
As in France, all technical data – VHF frequencies excepted – were identical to those in use in Germany.
Field tests in Los Angeles on various line systems began in 1936, and the United States had adopted RCA's 441-line system by 1938. The following year the first pre-built TV receivers were sold on a very limited basis, mostly in New York City, the new system being publicly launched by NBC during the New York World's Fair in April 1939. Its manufacturers included RCA, General Electric, DuMont, and Andrea. Following a decision of the NTSC (National Television System Committee), the 525-line standard replaced the 441-line standard on July 1, 1941.
|System||Lines||Frame rate||Channel bandwidth (in MHz)||Visual bandwidth (in MHz)||Sound offset||Vestigial sideband||Vision mod.||Sound mod.|
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal.
NTSC, named after the National Television System Committee, is the analog television color system that was introduced in North America in 1954 and stayed in use until digital conversion. It was one of three major analog color television standards, the others being PAL and SECAM.
Phase Alternating Line (PAL) is a colour encoding system for analogue television used in broadcast television systems in most countries broadcasting at 625-line / 50 field per second (576i). It was one of three major analogue colour television standards, the others being NTSC and SECAM.
SECAM, also written SÉCAM, is an analog color television system first used in France. It was one of three major color television standards, the others being PAL and NTSC.
Terrestrial television is a type of television broadcasting in which the television signal is transmitted by radio waves from the terrestrial (Earth-based) transmitter of a television station to a TV receiver having an antenna. The term terrestrial is more common in Europe and Latin America, while in the United States it is called broadcast or over-the-air television (OTA). The term "terrestrial" is used to distinguish this type from the newer technologies of satellite television, in which the television signal is transmitted to the receiver from an overhead satellite; cable television, in which the signal is carried to the receiver through a cable; and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television channels with frequencies between about 52 and 600 MHz in the VHF and UHF bands. Since radio waves in these bands travel by line of sight, reception is generally limited by the visual horizon to distances of 64–97 kilometres (40–60 mi), although under better conditions and with tropospheric ducting, signals can sometimes be received hundreds of kilometers distant.
Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that standard, is used mostly in the United States, Mexico, Canada, and South Korea. Several former NTSC users, in particular Japan, have not used ATSC during their digital television transition, because they adopted their own system called ISDB.
Multichannel Television Sound, better known as MTS, is the method of encoding three additional audio channels into an analog NTSC-format audio carrier. It was developed by the Broadcast Television Systems Committee, an industry group, and sometimes known as BTSC as a result.
Broadcast television systems are the encoding or formatting standards for the transmission and reception of terrestrial television signals. There were three main analog television systems in use around the world until the late 2010s (expected): NTSC, PAL, and SECAM. Now in digital terrestrial television (DTT), there are four main systems in use around the world: ATSC, DVB, ISDB and DTMB.
Amateur television (ATV) is the transmission of broadcast quality video and audio over the wide range of frequencies of radio waves allocated for radio amateur (Ham) use. ATV is used for non-commercial experimentation, pleasure, and public service events. Ham TV stations were on the air in many cities before commercial television stations came on the air. Various transmission standards are used, these include the broadcast transmission standards of NTSC in North America and Japan, and PAL or SECAM elsewhere, utilizing the full refresh rates of those standards. ATV includes the study of building of such transmitters and receivers, and the study of radio propagation of signals travelling between transmitting and receiving stations.
The following tables show the frequencies assigned to broadcast television channels in various regions of the world, along with the ITU letter designator for the system used. The frequencies shown are for the analogue video and audio carriers. The channel itself occupies several megahertz of bandwidth. For example, North American channel 2 occupies the spectrum from 54 to 60 MHz. See Broadcast television systems for a table of signal characteristics, including bandwidth, by ITU letter designator.
FM broadcasting is a method of radio broadcasting using frequency modulation (FM). Invented in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to provide high fidelity sound over broadcast radio. FM broadcasting is capable of higher fidelity—that is, more accurate reproduction of the original program sound—than other broadcasting technologies, such as AM broadcasting. Therefore, FM is used for most broadcasts of music or general audio. FM radio stations use the very high frequency range of radio frequencies.
The 405-line monochrome analogue television broadcasting system was the first fully electronic television system to be used in regular broadcasting.
The concept of television was the work of many individuals in the late 19th and early 20th centuries, with its roots initially starting from back even in the 18th century. The first practical transmissions of moving images over a radio system used mechanical rotating perforated disks to scan a scene into a time-varying signal that could be reconstructed at a receiver back into an approximation of the original image. Development of television was interrupted by the Second World War. After the end of the war, all-electronic methods of scanning and displaying images became standard. Several different standards for addition of color to transmitted images were developed with different regions using technically incompatible signal standards. Television broadcasting expanded rapidly after World War II, becoming an important mass medium for advertising, propaganda, and entertainment.
Analog high-definition television was an analog video broadcast television system developed in the 1930s to replace early experimental systems with as few as 12-lines. On 2 November 1936 the BBC began transmitting the world's first public regular analog high-definition television service from the Victorian Alexandra Palace in north London. It therefore claims to be the birthplace of television broadcasting as we know it today. John Logie Baird, Philo T. Farnsworth, and Vladimir Zworykin had each developed competing TV systems, but resolution was not the issue that separated their substantially different technologies, it was patent interference lawsuits and deployment issues given the tumultuous financial climate of the late 1920s and 1930s.
MUSE, was an analog high-definition television system, using dot-interlacing and digital video compression to deliver 1125-line high definition video signals to the home. Japan had the earliest working HDTV system, which was named Hi-Vision with design efforts going back to 1979. The country began broadcasting wideband analog HDTV signals in 1989 using 1035 active lines interlaced in the standard 2:1 ratio (1035i) with 1125 lines total. By the time of its commercial launch in 1991, digital HDTV was already under development in the United States. Hi-Vision continued broadcasting in analog until 2007.
A number of experimental and broadcast pre World War II television systems were tested. The first ones were mechanical based and of very low resolution, sometimes with no sound. Later TV systems were electronic.
Band I is a range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum. The first time there was defined "for simplicity" in Annex 1 of "Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961". Band I ranges from 47 to 68 MHz for the European Broadcasting Area, and from 54 to 88 MHz for the Americas and it is primarily used for television broadcasting in compliance with ITU Radio Regulations. With the transition to digital TV, most Band I transmitters in Europe, Africa, Asia and Australia have already been switched off.
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by a radio receiver connected to another antenna. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing and other applications.
In August 1939, Nazi Germany introduced the Einheits-Fernseh-Empfänger E1, also called Volksfernseher, a 441-line, 50 interlaced frames per second television system. The TV was presented to the public in the 16th International radio exhibition Berlin.
W2XMN was an experimental FM radio station located in Alpine, New Jersey. It was constructed beginning in 1936 by Edwin Howard Armstrong in order to promote his invention of wide-band FM broadcasting. W2XMN was the first FM station to begin regular operations, and was used to introduce FM broadcasting to the general public in the New York City area. The station, in addition to being a testing site for transmitter and receiver development, was used for propagation studies and as an over-the-air relay station for distributing network programming to other FM stations in the region.