36-458: Eesti Televisioon ( ETV ) (English: Estonian Television ) is an Estonian free-to-air television channel owned and operated by Estonian Public Broadcasting . It made its first broadcast on 19 July 1955. Eesti Televisioon ( Estonian Television ) was launched on 19 July 1955. Before that, television broadcasts in Estonia could only be received from Moscow. The first Estonian-language TV presenter
72-459: A distributor like TNT may start producing its own programming, and shows presented exclusively on pay-TV by one distributor may be syndicated to terrestrial stations. The cost of creating a nationwide channel has been reduced and there has been a huge increase in the number of such channels, with most catering to a small group. From the definitions above, use of the terms network or station in reference to nationwide cable or satellite channels
108-552: A more detailed treatment of this and the above frequency ranges, see Electromagnetic spectrum . Gravitational waves are also described in Hertz. Current observations are conducted in the 30–7000 Hz range by laser interferometers like LIGO , and the nanohertz (1–1000 nHz) range by pulsar timing arrays . Future space-based detectors are planned to fill in the gap, with LISA operating from 0.1–10 mHz (with some sensitivity from 10 μHz to 100 mHz), and DECIGO in
144-427: Is 1/time (T ). Expressed in base SI units, the unit is the reciprocal second (1/s). In English, "hertz" is also used as the plural form. As an SI unit, Hz can be prefixed ; commonly used multiples are kHz (kilohertz, 10 Hz ), MHz (megahertz, 10 Hz ), GHz (gigahertz, 10 Hz ) and THz (terahertz, 10 Hz ). One hertz (i.e. one per second) simply means "one periodic event occurs per second" (where
180-556: Is a terrestrial frequency or virtual number over which a television station or television network is distributed. For example, in North America , channel 2 refers to the terrestrial or cable band of 54 to 60 MHz , with carrier frequencies of 55.25 MHz for NTSC analog video ( VSB ) and 59.75 MHz for analog audio ( FM ), or 55.31 MHz for digital ATSC ( 8VSB ). Channels may be shared by many different television stations or cable-distributed channels depending on
216-494: Is also used to describe the clock speeds at which computers and other electronics are driven. The units are sometimes also used as a representation of the energy of a photon , via the Planck relation E = hν , where E is the photon's energy, ν is its frequency, and h is the Planck constant . The hertz is defined as one per second for periodic events. The International Committee for Weights and Measures defined
252-436: Is nonetheless mapped to the 1 input on most British television sets). On digital platforms, such (location) channels are usually arbitrary and changeable, due to virtual channels . A television station is a type of terrestrial station that broadcasts both audio and video to television receivers in a particular area. Traditionally, TV stations made their broadcasts by sending specially-encoded radio signals over
288-418: Is possible to use adjacent channels only because they are all at the same power, something which could only be done terrestrially if the two stations were transmitted at the same power and height from the same location . For DTT, selectivity is inherently better, therefore channels adjacent (either to analog or digital stations) can be used even in the same area . Commonly, the term television channel
324-481: Is technically inaccurate. However, this is an arbitrary, inconsequential distinction, and varies from company to company. Indeed, the term cable network has entered into common usage in the United States in reference to such channels, even with the existence of direct broadcast satellite . There is even some geographical separation among national pay television channels in the U.S., be it programming (e.g.,
360-493: Is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle ) per second . The hertz is an SI derived unit whose formal expression in terms of SI base units is s , meaning that one hertz is one per second or the reciprocal of one second . It is used only in the case of periodic events. It is named after Heinrich Rudolf Hertz (1857–1894),
396-691: Is used to mean a television station or its pay television counterpart (both outlined below). Sometimes, especially outside the U.S. and in the context of pay television, it is used instead of the term television network , which otherwise (in its technical use above) describes a group of geographically-distributed television stations that share affiliation / ownership and some or all of their programming with one another. This terminology may be muddled somewhat in other jurisdictions , for instance Europe , where terrestrial channels are commonly mapped from physical channels to common numerical positions (i.e. BBC One does not broadcast on any particular channel 1 but
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#1732784029046432-452: Is usually measured in kilohertz (kHz), megahertz (MHz), or gigahertz (GHz). with the latter known as microwaves . Light is electromagnetic radiation that is even higher in frequency, and has frequencies in the range of tens of terahertz (THz, infrared ) to a few petahertz (PHz, ultraviolet ), with the visible spectrum being 400–790 THz. Electromagnetic radiation with frequencies in the low terahertz range (intermediate between those of
468-518: The Bally Sports group of regional sports channels, which share several programs), or simply regionalized advertising inserted by the local cable company. Should a legal distinction be necessary between a (location) channel as defined above and a television channel in this sense, the terms programming service (e.g. ) or programming undertaking (for instance, ) may be used instead of the latter definition. MHz The hertz (symbol: Hz )
504-606: The European Broadcasting Union (EBU). From the restoration of independence in 1991 to 31 December 1992, it was a member of the International Radio and Television Organisation (OIRT). ETV stopped showing commercials in 1998–1999, and has again ceased doing so since 2002: its low-cost advertising rates were damaging the ability of commercial broadcasters to operate. The introduction of a system of broadcast receiver licences , payable by viewers,
540-449: The 0.1–10 Hz range. In computers, most central processing units (CPU) are labeled in terms of their clock rate expressed in megahertz ( MHz ) or gigahertz ( GHz ). This specification refers to the frequency of the CPU's master clock signal . This signal is nominally a square wave , which is an electrical voltage that switches between low and high logic levels at regular intervals. As
576-468: The 1970s. In some usage, the "per second" was omitted, so that "megacycles" (Mc) was used as an abbreviation of "megacycles per second" (that is, megahertz (MHz)). Sound is a traveling longitudinal wave , which is an oscillation of pressure . Humans perceive the frequency of a sound as its pitch . Each musical note corresponds to a particular frequency. An infant's ear is able to perceive frequencies ranging from 20 Hz to 20 000 Hz ;
612-690: The Estonian Parliament on 18 January 2007, Eesti Televisioon merged with Eesti Raadio (Estonian Radio, ER ) on 1 June 2007 to form the Estonian Public Broadcasting service, or Eesti Rahvusringhääling (ERR). During the consolidation, the ETV24 news service was replaced with ERR Uudised (ERR News). On 1 July 2010, Estonia completed its transition to digital terrestrial television , discontinuing all analogue services. An informational on-screen message indicating this
648-813: The air, called terrestrial television . Individual television stations are usually granted licenses by a government agency to use a particular section of the radio spectrum (a channel ) through which they send their signals. Some stations use LPTV broadcast translators to retransmit to further areas. Many television stations are now in the process of converting from analog terrestrial ( NTSC , PAL or SECAM ) broadcast, to digital terrestrial ( ATSC broadcast , DVB or ISDB ). Because some regions have had difficulty picking up terrestrial television signals (particularly in mountainous areas), alternative means of distribution such as direct-to-home satellite and cable television have been introduced. Television channels specifically built to run on cable or satellite blur
684-476: The average adult human can hear sounds between 20 Hz and 16 000 Hz . The range of ultrasound , infrasound and other physical vibrations such as molecular and atomic vibrations extends from a few femtohertz into the terahertz range and beyond. Electromagnetic radiation is often described by its frequency—the number of oscillations of the perpendicular electric and magnetic fields per second—expressed in hertz. Radio frequency radiation
720-406: The competition, and so she was hired. Kalmer Tennosaar (1928–2004) began as a presenter on 1 January 1956, and subsequently worked as an editor and fellow of music programmes (1957–1962, and then after 1968). He became very popular as the host of a children's songs show "Entel-tentel". Tennosaar later continued his career as a singer. On 1 January 1993, ETV was admitted as a full active member of
756-440: The event being counted may be a complete cycle); 100 Hz means "one hundred periodic events occur per second", and so on. The unit may be applied to any periodic event—for example, a clock might be said to tick at 1 Hz , or a human heart might be said to beat at 1.2 Hz . The occurrence rate of aperiodic or stochastic events is expressed in reciprocal second or inverse second (1/s or s ) in general or, in
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#1732784029046792-403: The first person to provide conclusive proof of the existence of electromagnetic waves . For high frequencies, the unit is commonly expressed in multiples : kilohertz (kHz), megahertz (MHz), gigahertz (GHz), terahertz (THz). Some of the unit's most common uses are in the description of periodic waveforms and musical tones , particularly those used in radio - and audio-related applications. It
828-449: The hertz has become the primary unit of measurement accepted by the general populace to determine the performance of a CPU, many experts have criticized this approach, which they claim is an easily manipulable benchmark . Some processors use multiple clock cycles to perform a single operation, while others can perform multiple operations in a single cycle. For personal computers, CPU clock speeds have ranged from approximately 1 MHz in
864-413: The highest normally usable radio frequencies and long-wave infrared light) is often called terahertz radiation . Even higher frequencies exist, such as that of X-rays and gamma rays , which can be measured in exahertz (EHz). For historical reasons, the frequencies of light and higher frequency electromagnetic radiation are more commonly specified in terms of their wavelengths or photon energies : for
900-459: The late 1970s ( Atari , Commodore , Apple computers ) to up to 6 GHz in IBM Power microprocessors . Various computer buses , such as the front-side bus connecting the CPU and northbridge , also operate at various frequencies in the megahertz range. Higher frequencies than the International System of Units provides prefixes for are believed to occur naturally in the frequencies of
936-460: The line between TV station and TV network. That fact led some early cable channels to call themselves superstations . Satellite and cable have created changes. Local programming TV stations in an area can sign-up or even be required to be carried on cable, but content providers like TLC cannot. They are not licensed to run broadcast equipment like a station, and they do not regularly provide content to licensed broadcasters either. Furthermore,
972-677: The location and service provider Depending on the multinational bandplan for a given region, analog television channels are typically 6, 7, or 8 MHz in bandwidth , and therefore television channel frequencies vary as well. Channel numbering is also different. Digital terrestrial television channels are the same as their analog predecessors for legacy reasons, however through multiplexing , each physical radio frequency (RF) channel can carry several digital subchannels . On satellites , each transponder normally carries one channel, however multiple small, independent channels can be on one transponder, with some loss of bandwidth due to
1008-536: The need for guard bands between unrelated transmissions . ISDB , used in Japan and Brazil , has a similar segmented mode. Preventing interference between terrestrial channels in the same area is accomplished by skipping at least one channel between two analog stations' frequency allocations . Where channel numbers are sequential, frequencies are not contiguous , such as channel 6 to 7 skip from VHF low to high band, and channel 13 to 14 jump to UHF . On cable TV, it
1044-564: The rules for capitalisation of a common noun ; i.e., hertz becomes capitalised at the beginning of a sentence and in titles but is otherwise in lower case. The hertz is named after the German physicist Heinrich Hertz (1857–1894), who made important scientific contributions to the study of electromagnetism . The name was established by the International Electrotechnical Commission (IEC) in 1935. It
1080-409: The second as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium -133 atom" and then adds: "It follows that the hyperfine splitting in the ground state of the caesium 133 atom is exactly 9 192 631 770 hertz , ν hfs Cs = 9 192 631 770 Hz ." The dimension of the unit hertz
1116-413: The specific case of radioactivity , in becquerels . Whereas 1 Hz (one per second) specifically refers to one cycle (or periodic event) per second, 1 Bq (also one per second) specifically refers to one radionuclide event per second on average. Even though frequency, angular velocity , angular frequency and radioactivity all have the dimension T , of these only frequency is expressed using
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1152-480: The unit hertz. Thus a disc rotating at 60 revolutions per minute (rpm) is said to have an angular velocity of 2 π rad/s and a frequency of rotation of 1 Hz . The correspondence between a frequency f with the unit hertz and an angular velocity ω with the unit radians per second is The hertz is named after Heinrich Hertz . As with every SI unit named for a person, its symbol starts with an upper case letter (Hz), but when written in full, it follows
1188-403: Was Ofelia Mikk, whose debut was in the 19 July 1955 test broadcast. Her tenure in television was cut short, because she misspoke out of nervousness. The first tenured presenter for the nascent ETV was Ruth Peramets-Püss (1927–2005). To find a presenter, a casting competition was held in 1955, but no suitable person was found. By chance, a film in which she starred, was aired on ETV on the day of
1224-490: Was adopted by the General Conference on Weights and Measures (CGPM) ( Conférence générale des poids et mesures ) in 1960, replacing the previous name for the unit, "cycles per second" (cps), along with its related multiples, primarily "kilocycles per second" (kc/s) and "megacycles per second" (Mc/s), and occasionally "kilomegacycles per second" (kMc/s). The term "cycles per second" was largely replaced by "hertz" by
1260-499: Was considered, but ultimately rejected in the face of public opposition. In 2002, ETV hosted the Eurovision Song Contest 2002 . On 9 January 2006, ETV launched an Internet news service called ETV24. Broadcasting news on Internet, teletext, and on ETV at night. Until 2007 ETV was operated by Eesti Televisioon, the eponymous broadcasting organisation. Pursuant to the new Estonian National Broadcasting Act passed by
1296-743: Was visible on the old ETV frequencies until 5 July 2010. The bulk of ETV's funding comes from government grant-in-aid , around 15% of which is in turn funded by the fees paid by Estonian commercial broadcasters in return for their exclusive right to screen television advertising . ETV itself is editorially fully independent. The more well known journalists of ETV include Tõnu Aav , Maire Aunaste , Grete Lõbu, Anu Välba , Katrin Viirpalu , Reet Linna , Monika Tamla , Kadri Hinrikus , Astrid Kannel , Margus Saar , Peeter Kaldre, Mati Talvik , Marko Reikop , Urmas Vaino , Jim Ashilevi , etc. Television channel A television channel , or TV channel ,
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