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27-721: APS-4 operated in the X band at 3 cm, compared to the 10 cm S band used by most radars of the era. This allowed the antenna to be greatly reduced in size and the unit as a whole to fit into a single streamlined fairing that could be mounted to many aircraft. In American service it was used on many aircraft, including the Douglas C-47 Skytrain , North American P-82D/F/H Twin Mustang , Vought F4U-2\5N Corsair , Grumman F6F-3/5 Hellcat , Curtiss SB2C-5 Helldiver and Grumman TBF-3 and TBM-3S Avenger , and Curtiss SC Seahawk . In Fleet Air Arm and RAF service it

54-491: A target illuminator or illuminator radar . A typical fire-control radar emits a narrow , intense beam of radio waves to ensure accurate tracking information and to minimize the chance of losing track of the target. This makes them less suitable for initial detection of the target, and FCRs are often partnered with a medium-range search radar to fill this role. In British terminology, these medium-range systems were known as tactical control radars . Most modern radars have

81-445: A track-while-scan capability, enabling them to function simultaneously as both fire-control radar and search radar. This works either by having the radar switch between sweeping the search sector and sending directed pulses at the target to be tracked, or by using a phased-array antenna to generate multiple simultaneous radar beams that both search and track. Fire-control radars operate in three different phases: The performance of

108-401: A fire-control radar is determined primarily by two factors: radar resolution and atmospheric conditions. Radar resolution is the ability of the radar to differentiate between two targets closely located. The first, and most difficult, is range resolution, finding exactly how far is the target. To do this well, in a basic fire-control radar system, it must send very short pulses. Bearing resolution

135-831: A more-or-less experimental basis, such as in the K band .) Notable deep space probe programs that have employed X band communications include the Viking Mars landers ; the Voyager missions to Jupiter , Saturn , and beyond; the Galileo Jupiter orbiter ; the New Horizons mission to Pluto and the Kuiper belt , the Curiosity rover and the Cassini-Huygens Saturn orbiter. An important use of

162-529: A single coaxial cable with a power adapter connecting to an ordinary cable modem. The local oscillator is usually 9750 MHz, the same as for K u band satellite TV LNB. Two way applications such as broadband typically use a 350 MHz TX offset. Small portions of the X band are assigned by the International Telecommunication Union (ITU) exclusively for deep space telecommunications. The primary user of this allocation

189-448: Is a radar that is designed specifically to provide information (mainly target azimuth , elevation , range and range rate ) to a fire-control system in order to direct weapons such that they hit a target. They are sometimes known as narrow beam radars , targeting radars , tracking radars , or in the UK, gun-laying radars . If the radar is used to guide a missile, it is often known as

216-566: Is not authorised to allocate frequency bands for military radio communication . This is also the case pertaining to X band military communications satellites . However, in order to meet military radio spectrum requirements, e.g. for fixed-satellite service and mobile-satellite service , the NATO nations negotiated the NATO Joint Civil/Military Frequency Agreement (NJFA). 2. 7250-7300 MHz

243-475: Is often used in modern radars. The shorter wavelengths of the X ;band provide higher-resolution imagery from high-resolution imaging radars for target identification and discrimination. X-band weather radars offer significant potential for short-range observations, but the loss of signal strength ( attenuation ) under rainy conditions limits their use at longer range. X band 10.15 to 10.7 GHz segment

270-504: Is paired with 7975-8025 MHz for the MOBILE-SATELLlTE allocation. 3. The FIXED and MOBILE services are not to be implemented in the band 7250-7300 MHz in most NATO countries, including ITU Region 2. 4. In the band 7300-7750 MHz the transportable earth stations cannot claim protection from the other services. The Radio Regulations of the International Telecommunication Union allow amateur radio operations in

297-765: Is the American NASA Deep Space Network (DSN). DSN facilities are in Goldstone, California (in the Mojave Desert ), near Canberra, Australia , and near Madrid, Spain , and provide continual communications from the Earth to almost any point in the Solar System independent of Earth rotation. (DSN stations are also capable of using the older and lower S band deep-space radio communications allocations, and some higher frequencies on

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324-886: Is the second harmonic of C-band and fourth harmonic of S-band . The European X-band frequency is used for the Compact Linear Collider (CLIC) . 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 Fire-control radar A fire-control radar ( FCR )

351-405: Is typically ensured by using a narrow (one or two degree) beam width. Atmospheric conditions, such as moisture lapse, temperature inversion , and dust particles affect radar performance as well. Moisture lapse and temperature inversion often cause ducting, in which RF energy is bent as it passes through hot and cold layers. This can either extend or shorten the radar horizon , depending on which way

378-420: Is used for terrestrial broadband in many countries, such as Brazil, Mexico, Saudi Arabia, Denmark, Ukraine, Spain and Ireland. Alvarion , CBNL , CableFree and Ogier make systems for this, though each has a proprietary airlink. DOCSIS (Data Over Cable Service Interface Specification) the standard used for providing cable internet to customers, uses some X band frequencies. The home / Business CPE has

405-490: The X-band with a wavelength of 3 cm. Peak broadcast power varied from 40 to 70 kW according to radar version. Pulse repetition frequency was adjustable by the operator to either 600 or 1000 pulses per second. The APS-4 emitted a radio beam in the form of a 6° cone. The beam could be directed in three modes, manual, search and intercept. In manual mode the beam was aimed by operator control from 10° above, to 30° below

432-414: The longitudinal axis of the aircraft. In search mode, the radar beam scans through 150° in azimuth, and while doing so would run two lines scans, each separated by 4°. This caused the beam to cover 10° in a vertical plane. In intercept mode, the beam executes a four-line scan, with 6° between lines, to cover a vertical plane of 24°. Results were displayed on one or two 3-inch displays. An improved version

459-557: The APS-4 consists of a control box, one or two indicators, the same number of indicator-amplifiers, an antenna, a transmitter-receiver, and a cable junction box. The antenna and transmitter-receiver were typically housed externally below one wing, in a fiberglass shape that was similar to a Mk 17 500-pound (230 kg) bomb. These displays could be set for ranges of 4, 20, 50, and 100 nautical miles (6, 30, 80, and 160 km). The radar weighed 180 pounds (82 kg). The APS-4 broadcast in

486-450: The RF is bent. Dust particles, as well as water droplets, cause attenuation of the RF energy, resulting in a loss of effective range. In both cases, a lower pulse repetition frequency makes the radar less susceptible to atmospheric conditions. Most fire-control radars have unique characteristics, such as radio frequency, pulse duration, pulse frequency and power. These can assist in identifying

513-466: The X band communications came with the two Viking program landers. When the planet Mars was passing near or behind the Sun, as seen from the Earth, a Viking lander would transmit two simultaneous continuous-wave carriers, one in the S band and one in the X band in the direction of the Earth, where they were picked up by DSN ground stations. By making simultaneous measurements at the two different frequencies,

540-826: The first successful fire-control radars, the SCR-584 , was used effectively and extensively by the Allies during World War II for anti-aircraft gun laying. Since World War II, the U.S. Army has used radar for directing anti-aircraft missiles including the MIM-23 Hawk , the Nike series and currently the MIM-104 Patriot . Examples of fire-control radars currently in use by the United States Navy : After World War II, airborne fire control radars have evolved from

567-769: The frequency range 10.000 to 10.500 GHz, and amateur satellite operations are allowed in the range 10.450 to 10.500 GHz. This is known as the 3-centimeter band by amateurs and the X-band by AMSAT . Motion detectors often use 10.525 GHz. 10.4 GHz is proposed for traffic light crossing detectors. Comreg in Ireland has allocated 10.450 GHz for Traffic Sensors as SRD. Many electron paramagnetic resonance (EPR) spectrometers operate near 9.8 GHz. Particle accelerators may be powered by X-band RF sources. The frequencies are then standardized at 11.9942 GHz (Europe) or 11.424 GHz (US), which

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594-699: The frequency range is specified by the Institute of Electrical and Electronics Engineers (IEEE) as 8.0–12.0 GHz. The X band is used for radar , satellite communication , and wireless computer networks . X band is used in radar applications, including continuous-wave , pulsed, single- polarization , dual-polarization, synthetic aperture radar , and phased arrays . X-band radar frequency sub-bands are used in civil , military , and government institutions for weather monitoring , air traffic control , maritime vessel traffic control , defense tracking , and vehicle speed detection for law enforcement. X band

621-470: The radar, and therefore the weapon system it is controlling. This can provide valuable tactical information, like the maximum range of the weapon, or flaws that can be exploited, to combatants that are listening for these signs. During the Cold War Soviet fire control radars were often named and NATO pilots would be able to identify the threats present by the radar signals they received. One of

648-480: The resulting data enabled theoretical physicists to verify the mathematical predictions of Albert Einstein 's General Theory of Relativity . These results are some of the best confirmations of the General Theory of Relativity. The new European double Mars Mission ExoMars will also use X band communication, on the instrument LaRa, to study the internal structure of Mars, and to make precise measurements of

675-408: The rotation and orientation of Mars by monitoring two-way Doppler frequency shifts between the surface platform and Earth. It will also detect variations in angular momentum due to the redistribution of masses, such as the migration of ice from the polar caps to the atmosphere. The International Telecommunication Union (ITU), the international body which allocates radio frequencies for civilian use,

702-529: Was called the AN/APS-5. A simplified version for single-seat fighters was called the APS-6. X band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum . In some cases, such as in communication engineering , the frequency range of the X band is rather indefinitely set at approximately 7.0–11.2  GHz . In radar engineering,

729-519: Was known as ASV Mark IX and equipped a number of aircraft including the Fairey Firefly , Fairey Barracuda , de Havilland Mosquito and a small number of Grumman Avengers . The APS-4 radar is a lightweight air-to-air and air-to-surface radar with a detection range for large ships of about 15 miles (24 km), and about 5 miles (8.0 km) against aircraft. It could also detect coastline at approximately 75 miles (121 km). Physically,

#996003