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39-521: ST-1 carries 16 high-power K u band transponders and 14 medium-power C-band transponders. Weighing over 3,000 kg (6,600 lb.) at launch, ST-1 generates more than 6,500 watts of electrical power. The satellite's broad C-band coverage beam extends from the Middle East to Japan, including all of Southeast Asia. ST-1 also features two K u -band spot beams: a "K1" beam that stretches from Taiwan to Singapore and from Indonesia to Malaysia and

78-464: A ) because of the presence of the atmospheric water vapor resonance peak at 22.24 GHz, (1.35 cm) which made the center unusable for long range transmission. In radar applications, it ranges from 12 to 18  GHz according to the formal definition of radar frequency band nomenclature in IEEE Standard 521–2002. K u band is primarily used for satellite communications , most notably

117-779: A band transponders. NSS 6 , launched in December 2002 and positioned at 95° East, contains only K u -band transponders with a footprint on Indonesia ( Sumatra , Java , Borneo , Celebes , Bali , Nusa Tenggara , Moluccas ). NSS 6 is intended to be replaced by SES-12 at the same location, which launched in June 2018 and carries 54 K u -band transponders. The IPSTAR 1 satellite, launched in 2004 also uses K u band footprints. Other satellites that provides K u band covers Indonesia are MEASAT-3b , JCSAT-4B , AsiaSat 5 , ST-2 , Chinasat 11, Koreasat 8/ABS-2 , SES-8 , Telkom-3S , and Nusantara Satu . Other ITU allocations have been made within

156-461: A "K2" beam centred over the Indian subcontinent. The ST-1 satellite currently delivers telephony, digital DTH broadcasting, VSAT and other business services throughout the region. Singapore Telecom and Taiwan's Chunghwa Telecom Company are currently operating the replacement satellite ST-2 after ST-1 has reached its mission duration in 2011. This article about one or more communications satellites

195-835: A dish of a given size. Position feedback accuracies are higher and the antenna may require a closed loop control system to maintain position under wind loading of the dish surface. ELF 3 Hz/100 Mm 30 Hz/10 Mm SLF 30 Hz/10 Mm 300 Hz/1 Mm ULF 300 Hz/1 Mm 3 kHz/100 km VLF 3 kHz/100 km 30 kHz/10 km LF 30 kHz/10 km 300 kHz/1 km MF 300 kHz/1 km 3 MHz/100 m HF 3 MHz/100 m 30 MHz/10 m VHF 30 MHz/10 m 300 MHz/1 m UHF 300 MHz/1 m 3 GHz/100 mm SHF 3 GHz/100 mm 30 GHz/10 mm EHF 30 GHz/10 mm 300 GHz/1 mm THF 300 GHz/1 mm 3 THz/0.1 mm Megahertz The hertz (symbol: Hz )

234-523: A heavy rain area usually gives poor results. This problem can be solved by using an appropriate link budget when designing the wireless communication link. Higher power can overcome the loss to rain fade . Measurements of rain attenuation in Indonesia have been done for satellite communication links in Padang, Cibinong, Surabaya and Bandung. The DAH Model for rain attenuation prediction is valid for Indonesia, as

273-584: A higher powered signal from the satellite to compensate. Therefore, the K u band satellites typically require considerably more power to transmit than the C-band satellites. Another weather-caused degradation called "snow fade" is not specific to the K u band. It is due to snow or ice accumulation on a dish significantly altering its focal point. The satellite operator's Earth station antenna requires more accurate position control when operating at K u band due to its much narrower beam focus compared to C band for

312-548: 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

351-427: 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

390-438: Is a stub . You can help Misplaced Pages by expanding it . Ku band The K u band ( / ˌ k eɪ ˈ j uː / ) is the portion of the electromagnetic spectrum in the microwave range of frequencies from 12 to 18  gigahertz (GHz). The symbol is short for "K-under" (originally German : Kurz-unten ), because it is the lower part of the original NATO K band , which was split into three bands (K u , K , and K

429-449: Is also less vulnerable to rain fade than the K a band frequency spectrum. There are, however, some disadvantages of the K u band system. Around 10 GHz is the absorption peak due to orientation relaxation of molecules in liquid water. Above 10 GHz, Mie scattering takes over. The effect is a noticeable degradation, commonly known as rain fade , during heavy rain (100 mm/h). This problem can be mitigated by transmitting

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468-490: 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

507-679: Is split by the International Telecommunication Union (ITU) into multiple segments that vary by geographical region. NBC was the first television network to uplink a majority of its affiliate feeds via K u band in 1983. Some frequencies in this radio band are employed in radar guns used by law enforcement to detect vehicles speeding, especially in Europe. Segments in most of North and South America are represented by ITU Region 2 from 11.7 to 12.2 GHz ( Local Oscillator Frequency (LOF) 10.75 to 11.25 GHz), allocated to

546-447: Is the ITU model. The DAH model has become an ITU recommendation since 2001 (Recommendation No. ITU-R P.618-7). This model can create a 99.7% available link so that K u -band can be applied in Indonesia. Use of the K u -band for satellite communications in tropical regions like Indonesia is becoming more frequent. Several satellites above Indonesia have K u -band transponders , and even K

585-484: 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),

624-452: 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

663-724: The Astra satellites. The 11.7 to 12.5 GHz segment is allocated to the BSS ( broadcasting satellite service ). Australia is part of ITU Region 3 and the Australian regulatory environment provides a class license that covers downlinking from 11.70 GHz to 12.75 GHz and uplinking from 14.0 GHz to 14.5 GHz. The ITU has categorized Indonesia as Region P, countries with very high rain precipitation. This statement has made many people unsure about using K u -band (11 – 18 GHz) in Indonesia. Using frequencies higher than 10 GHz in

702-579: The Rayleigh criterion , the diameter of a parabolic dish required to create a radiation pattern with a given angular beamwidth ( gain ) is proportional to the wavelength , and thus inversely proportional to the frequency. At 12 GHz a 1-meter dish is capable of focusing on one satellite while sufficiently rejecting the signal from another satellite only 2 degrees away. This is important because satellites in FSS (Fixed Satellite Service) service (11.7-12.2 GHz in

741-446: 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

780-468: 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 ;

819-563: The FSS ( fixed satellite service ), uplink from 14.0 to 14.5 GHz. There are more than 22 FSS K u band satellites orbiting over North America, each carrying 12 to 48 transponders , 20 to 120 watts per transponder, and requiring a 0.8-m to 1.5-m antenna for clear reception. The 12.2 to 12.7 GHz (LOF 11.25 to 11.75 GHz) segment is allocated to the BSS ( broadcasting satellite service ). BSS (DBS direct broadcast satellites ) normally carry 16 to 32 transponders of 27  MHz bandwidth running at 100 to 240 watts of power, allowing

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858-466: The K u band to the fixed service (microwave towers), radio astronomy service, space research service, mobile service, mobile satellite service, radiolocation service (radar), amateur radio service , and radionavigation. However, not all of these services are actually operating in this band and others are only minor users. Compared with C-band , K u band is not similarly restricted in power to avoid interference with terrestrial microwave systems, and

897-517: The U.S.) are only 2 degrees apart. At 4 GHz (C-band) a 3-meter dish is required to achieve this narrow angular resolution. Note the inverse linear correlation between dish size and frequency. For K u satellites in DBS (Direct Broadcast Satellite) service (12.2-12.7 GHz in the U.S.) dishes much smaller than 1-meter can be used because those satellites are spaced 9 degrees apart. As power levels on both C and K u band satellites have increased over

936-496: The antenna's actual receiving element, mounted in front of the dish (and pointed back towards its face); if the waves are more intense, fewer of them need to be collected to achieve the same intensity at the receiving element. A major attraction of the band over lower frequency microwave bands is that the shorter wavelengths allow sufficient angular resolution to separate the signals of different communication satellites to be achieved with smaller terrestrial parabolic antennas . From

975-476: 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

1014-451: The downlink used by direct broadcast satellites to broadcast satellite television , and for specific applications such as NASA 's Tracking Data Relay Satellite used for International Space Station (ISS) communications and SpaceX Starlink satellites. K u band satellites are also used for backhauls and particularly for satellite from remote locations back to a television network's studio for editing and broadcasting . The band

1053-440: 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

1092-403: 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

1131-449: 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

1170-413: 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

1209-454: 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

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1248-412: The power of its uplinks and downlinks can be increased. This higher power also translates into smaller receiving dishes and points out a generalization between a satellite's transmission and a dish's size. As the power increases, the size of an antenna's dish will decrease. This is because the purpose of the dish element of the antenna is to collect the incident waves over an area and focus them all onto

1287-544: 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

1326-409: 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

1365-413: 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

1404-480: 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

1443-454: The use of receiver antennas as small as 18 inches (450 mm). Segments in those regions are represented by ITU Region 1, and they are the 11.45 to 11.7 and 12.5 to 12.75 GHz bands are allocated to the FSS ( fixed satellite service , uplink 14.0 to 14.5 GHz). In Europe K u band is used from 10.7 to 12.75 GHz (LOF Low 9.75 GHz, LOF High 10.6 GHz) for direct broadcast satellite services such as those carried by

1482-403: The years, dish beam-width has become much more critical than gain. The K u band also offers a user more flexibility. A smaller dish size and a K u band system's freedom from terrestrial operations simplifies finding a suitable dish site. For the end users K u band is generally cheaper and enables smaller antennas (both because of the higher frequency and a more focused beam). K u band

1521-482: 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

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