The transmitter's part is built near the town Die Berechnung der Entfernung ist deswegen schwierig und erhält Ungenauigkeiten. UWB  You can hear a high and a low tone, corresponding to the sweep rates of 870 and 307 sweeps/sec. For this role, the delay line was not usable, and the magnetic drum, recently introduced, provided a convenient and easily controlled variable-delay system. Another problem is that the refraction process is highly dependent on the angle between the signal and the ionosphere, and is generally limited to about 2–4 degrees off the local horizon. Let us understand how it works. Er muss mehr Energie enthalten, als die Summe aller möglichen Dämpfungen auf dem Hin- und Rückweg das Echosignal abschwächen könnte, so dass es im Empfänger nicht mehr registriert werden könnte. As the names imply, both of the NRL systems relied on the comparison of returned signals stored on magnetic drums. For example, near the town of Kovylkino, 144 antenna-feeder masts with a height of 34 m each were deployed on a site measuring 1300 x 200 m. Antenna fields work in conjunction with the hardware complex, the elements of which are mounted in standard containers. 802.11ad  FMCW RADAR   It is used as early warning radar applications. Another early shortwave OTH system was built in Australia in the early 1960s. Six one-million-watt OTH radars see far beyond the range of conventional microwave radars by bouncing their 5-28-MHz waves off the ionosphere, an ionized layer about 200 km above the earth. (56°41'35.0" N   43°29'11.0" E). Creative Commons Attribution-Share Alike 3.0 Unported license, Development of such systems became practical in the late 1980s due to the rapidly increasing processing power available. It is known that no further research was carried out by Soviet teams until the 1960s and 70s. Diese Mehrfachreflexionen werden im Unterschied zur einfachen Reflexion, dem single-hop, nach der Anzahl der Reflexionen an der Ionosphäre zum Beispiel two-hop für eine Zweifachreflexion benannt. Die Genauigkeit der Positionsbestimmung beträgt etwa 100 Meter (entspricht der genutzten Wellenlänge). The OTH radar can detect objects as far as 1000 to 3000 Km. Cobra Mist used an enormous 10 MW transmitter and could detect aircraft over the western Soviet Union from its location in Suffolk. The “Container” radar station will allow constant monitoring of the activity of the air forces of foreign countries and timely pre-emptive knowledge of any activity. One of the ways to detect and detect surface targets far from the use of over-the-horizon [OTH] radars, which are also referred to as super horizons, horizons and cosmic systems. A newer system has recently been used for coastal surveillance in Canada, and is now offered for sales by Maerospace[25] , Australia has also deployed a High Frequency Surface Wave Radar. In the Russian Aerospace Forces, the Container-type over-the-horizon detection surveillance radar combat crews entered the combat duty (Kovylkino settlement in the Republic of Mordovia). There are two separate antennas used in OTH radar one for transmission and the other for reception. Die Radarsignalverarbeitung muss dann die Schwellwerte für die Signalerkennung an die ebenfalls registrierten Reflexionen an der Erdoberfläche (Clutter) entsprechend dem Auftreten dieser Störungen durch eine dynamische zeitabhängige Verstärkungsregelung anpassen. As it detects the objects beyond the radar horizon range with the help of ionosphere, it is known as Over-the-horizon or OTH radar. Die Ausbreitung der elektromagnetischen Wellen muss sich entweder durch Beugung an die Erdoberfläche anpassen, oder gezielt an der Appleton-Schicht der Ionosphäre reflektiert werden. A radar can simultaneously lock on to more than 5 thousand airborne objects of various types, including small ones. Analogs of such stations worked at Chernobyl and Nikolaev in Ukraine, as well as in Komsomolsk-in-Amur. GSM  [9] By 2002, the west coast facilities were downgraded to "cold storage" status, meaning that only minimal maintenance was performed by a caretaker. Deshalb und wegen der außergewöhnlich kleinen Sendeleistung 30 Watt[8] sind bei Wera gegenseitige Störungen gering. Durch die mögliche Impulsintegration kann das Signal-Rausch-Verhältnis im Radarempfänger wesentlich verbessert werden und damit die energetischen Bedingungen für das Überhorizontradar verbessern. Um die genaue Höhe der Appleton-Schicht der Ionosphäre zu bestimmen, werden spezielle Ionosonden (sogenannte chirpsounder) genutzt. Alle anderen Radarkonzepte eignen sich nicht dafür, Reichweiten von mehreren 1000 km zu erzielen. Doing so required the use of computers, another reason OTH systems did not become truly practical until the 1960s, with the introduction of solid-state high-performance systems.[1]. Es werden zwei verschiedene Gerätekonzeptionen verfolgt, die sich in der Antennenkonstruktion niederschlagen: OTH-B nutzt die Reflexionseigenschaften der Ionosphäre, um mit Hilfe der Raumwelle Reichweiten von mehr als 2000 km zu erzielen. Heute werden bessere Technologien für das Überhorizontradar eingesetzt. Since the signal refracted from the ground, or sea, will be very large compared to the signal refracted from a "target", some system needs to be used to distinguish the targets from the background noise. Additionally, the range was extended to 3,000 miles (4,800 km), crossing the equator. Over-The-Horizon Ein bekanntes System ist das australische Jindalee Operational Radar Network (JORN); die NATO betreibt eine entsprechende Anlage in Zypern (PLUTO System der Royal Air Force). The second production ROTHR was later set up in Texas, covering many of the same areas in the Caribbean, but also providing coverage over the Pacific as far south as Colombia. On December 1st, the first over-the-horizon 29B6 “Container” radar station in Russia was commissioned, Ministry of Defense outlet Zvezda reported. This basic concept would work for a long-range radar as well, but had the problem that a delay line has to be mechanically sized to the pulse repetition frequency of the radar, or PRF. In the same year, the first tests started. The U.S. Air Force's over-the-horizon-backscatter (OTH-B) air defense radar system is by several criteria the largest radar system in the world. Two techniques are most commonly used; shortwave systems that refract their signals off the ionosphere for very long-range detection,[1] and surface wave systems, which use low frequency radio waves[2] that, due to diffraction, follow the curvature of the Earth to reach beyond the horizon. The detection range of air targets is more than 3000 km at altitudes of up to 100 kilometers, and the sector of view is 240 degrees. In cooperation with the commission, they conducted all inspections and tests for the station. Für die Beugung muss das Radar im unteren Kurzwellenbereich, für die Reflexion muss das Radar im mittleren bis oberen Kurzwellenbereich arbeiten. If the target is above the surface, this range will be increased accordingly, so a target 10 m (33 ft) high can be detected by the same radar at 26 km (16 mi). Modernere Gerätekonzepte können jedoch eine Intrapulsmodulation verwenden, so dass die Sendeenergie über eine längere Impulsdauer verteilt werden kann. Aimed eastward, Duga first ran on 7 November 1971, and was successfully used to track missile launches from the far east and Pacific Ocean to the testing ground on Novaya Zemlya. The first production systems were installed in the test site in Virginia for acceptance testing, but were then transitioned to counter the illegal drug trade, covering Central America and the Caribbean. In an attempt to remove clutter from radar displays, many late-war and post-war radar systems added an acoustic delay line that stored the received signal for exactly the amount of time needed for the next signal pulse to arrive. Most systems used a second transmitter broadcasting directly up at the ionosphere to measure its movement and adjust the returns of the main radar in real-time. [14] In a scenario of a hypothetical escalation, this will also make it possible to quickly identify preparations for an air attack or for various missile strikes. Die Effektivität dieser riesigen Antennen ist jedoch aufgrund der Relation zur Wellenlänge recht gering, so dass sie, um die gewünschte Diagrammbreite (Winkelauflösungsvermögen) zu erreichen, geometrische Ausmaße von mehreren Kilometern erreichen können. The receiving antenna and the main part of the radar are built near For long-range use, the PRF was very long to start, and deliberately changed in order to make different ranges come into view. An over-the-horizon radar under construction in the Far East in the mid-1980s would provide long-range detection of aircraft from the Pacific Ocean. Three operational over-the-horizon radars for ballistic missile detection could provide additional long-range warning of the approach of high-flying aircraft. Das Antennenfeld kann Ziele innerhalb der 200 Meilenzone in einem Sektor von 120° beobachten. Das Überhorizontradar (auch OTH für Over The Horizon genannt) stellt eine Möglichkeit dar, Radarechos ohne quasi-optischen Sichtkontakt weit über die Erdkrümmung hinaus zu erhalten. After a period of public input and environmental studies, in July 2005 the U.S. Air Force Air Combat Command published a "Final Environmental Assessment for Equipment Removal at Over-the-Horizon Backscatter Radar - West Coast Facilities". The hardware equipment and antennas are connected to each other via multiple cable lines. [3] Das sind spezielle Radargeräte, die in ungefährer Entfernung der ersten Reflexion disloziert werden und im Frequenzbereich bis zu 30 MHz die Höhe der reflektierenden Schicht als Funktion der Sendefrequenz in einem sogenannten Ionogramm darstellen können. Das entspricht der halben Wellenlänge in dem genutzten Radarband von etwa 3 MHz. Auch hier bietet die Intrapulsmodulation Vorteile, da jeder einzelne Sendeimpuls ein anderes Modulationsmuster erhalten kann. Es werden oft elektronische Schwenkverfahren mit Phased-Array-Antennen genutzt. On December 1st, the first over-the-horizon 29B6 “Container” radar station in Russia was commissioned, Ministry of Defense outlet Zvezda reported. The figure depicts OTH radar used for long range detection of aeroplanes and ships. Due to the physics of the refraction process, actual accuracy is even lower, with range resolution on the order of 20 to 40 kilometres (12–25 mi) and bearing accuracy of 2 to 4 kilometres (1.2–2.5 mi) being suggested. However, little information on this system is available in western sources, and no details of its operation are known.