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- Pridružio: 29 Feb 2008
- Poruke: 1490
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flyby68 ::iz iskustva upotrebe balistickih projektila , od Iracko-Iranskoga rata kada su se gadjali "scud" raketama nemilosrdno , pa do Sadamovih raketiranja Izraela u prvom zalivskom ratu, pa sve do upotrebe tih raketa na bojistima bivse YU (Luna,Orkan ) , takva vrsta oruzja nije donijela prevagu na bojistu , nije zadala bilo kakav odlucujuci udarac protivniku...a precizne rakete nisu jeftine i zahtijevaju i satelitska vodjenja (koja se lako blokiraju , svi znamo ciji su sateliti za navigaciju ;USA(ne znam ime satelita  ), Evropa Galileo, Rusija Glonas)
komplikovana sredstva veze i izvidjanja i pracenja ciljeva na udaljenostima od 150-300 kilometara, kompjuterske sisteme i razna elektronska cuda da bi bile precizne a to nije jeftino !
Davno je bio Iransko-Irački rat i niko sigurno ne priča o tome da se u drugoj deceniji 21. veka prave sredstva koja su na nivou 80-tih godina prošloga veka... 
A, oko navođenja...pa, nije baš tako da se mora navoditi preko satelita, ili da treba izviđati i pratiti ciljeve na par stotina kilometara, itd...itd...
Navođenje preko GPS-a je samo jedna mogućnost...nikako ne i jedina.
- THE GLOBAL POSITIONING SYSTEM (GPS)
Satellite navigation systems provide a highly accurate means of determining the precise position of an object on or over the earth’s surface. Accurate satellite data allows a cruise missile to receive regular mid-course updates which counteract the drift inherent in traditional gyroscope-based inertial navigation systems (‘INS’). Packaged with even a simple INS, satellite navigation systems give a cruise missile accuracies of between 10 and 100 metres.
Two satellite navigation systems are currently being established. The United States has recently completed its Global Positioning System (‘GPS’); its Russian equivalent is the Global Navigation Satellite System (‘GLONASS’).
The US GPS consists of twenty four NAVSTAR satellites in polar orbit (three of which are back-ups), a network of ground stations which constantly check and maintain the accuracy of the satellite data, and the necessary receiver units which translate the satellite data into precise positional information. The system can be used to obtain both horizontal (latitude and longitude) and vertical (altitude) fixes. Signals from three satellites are needed to obtain horizontal fixes, the signal from a fourth to obtain the vertical fix and give a complete three-dimensional position. If the receiver picks up data from more than four satellites, the accuracy of the fix is increased.
Although the GPS was originally intended to be used for purely military applications, the shooting down of an off-course Korean commercial airliner by Soviet fighters in 1983 led President Reagan to direct that it be made available for commercial users.
The commercial Course/Acquisition (‘C/A’) Code is openly available, and was intended to give accuracies of between 30 and 100 metres. However, when it became clear that in practice the C/A code was accurate to nearer 10 metres, the US Department of Defense introduced Selective Availability (‘S/A’), which deliberately reduces the accuracy of the signal (‘degrades’ it) to some 100 metres in the horizontal plane and 140 metres in the vertical. It is claimed that S/A fixes will be accurate 95% of the time, yet in circumstances when an optimal configuration of four or five satellites is not ‘visible’ to the receiver it is possible that this accuracy may fall to around 300 metres.
GPS accuracies are expressed in terms of dRAMS, one dRAM being a 2.5% probability of inaccuracy. The accuracy of the S/A code is defined as 100 metres with a 2 dRAMS confidence. This means that 95% of fixes will be accurate to within 100 metres of the actual position. It does not, however, follow that a missile guided by S/A code would achieve a Circular Area Probable (‘CEP’) of 100 metres: dRAM has a 95% confidence level and CEP a 50% confidence level, therefore the two figures cannot be interchanged. As the 2 dRAM S/A GPS fix equates to a CEP four tenths as large, the CEP of a cruise missile utilising the S/A code would be approximately 40 metres (i.e. 50% of missiles fired would arrive within 40 metres of the target).
Although the full implementation of the Russian GLONASS has slowed since the break up of the Soviet Union, it should offer a very similar service to its US counterpart. Like the GPS, GLONASS consists of twenty four satellites which transmit both military and civilian signals of comparable accuracies to the GPS P and C/A codes. Whilst the two systems operate slightly differently, integrated receivers accessing signals from both networks will reportedly give accuracies of some 20 metres, effectively circumventing US efforts to degrade the S/A code.
- DIFFERENTIAL GPS
The data transmitted by GPS can, however, be significantly upgraded by a process known as Differential GPS (‘DGPS’). This relies on a second receiver, known as the reference receiver, located in a precisely-determined spot, broadcasting a correction signal on a different frequency to the other GPS receiver. This can be effective even if the two receivers are more than 1.000 km apart, and makes it possible for users of the military P-code to attain fixes accurate to between 75 cm and 5 metres. S/A code can be improved by a factor of ten, to between 2 and 5 metres.
Although this technology is only just beginning to emerge, it is already utilised for surveying, maritime safety and civilian aviation applications. The integration of DGPS into cruise missile guidance systems is certainly feasible, although this would require that reference updates be transmitted through a data link to the missile in flight via a mother plane or ground station. However, given that DGPS reference stations are being constructed along the coast of the United States and their signals broadcast by way of other satellites, it appears likely that its accessibility will grow.
Integrated into a cruise missile, these navigation systems will enable developing nations to perform a technological leap-frog. Israel already claims that its GPS-equipped Delilah RPV can reportedly attain accuracies of less than 100 metres, and India is working to adapt GPS for both its cruise and ballistic missile programmes. Pakistan, China and Iran are also reported to be seeking means of integrating GPS into RPVs and missiles. Although the degrading of codes from GPS and GLONASS should, in theory, prevent developing nations from developing cruise missiles with accuracies better than 100 metres, this is likely to be circumvented by further advances in technology. Likewise, whilst GPS signals can be jammed using electronic countermeasures, this may not prove practical in all circumstances. However, the GPS S/A code can, if necessary, be switched off, as was the case during operation Desert Storm and during the US invasion of Haiti.
- INERTIAL GUIDANCE
Inertial Guidance or Inertial Navigation Systems (‘INS’) use gyroscopes and accelerometers (which detect motion) to calculate changes in relative positions. Wholly independent of any external signals or support, they cannot be jammed or affected by electronic countermeasures.
The disadvantage of INS is its inherent inaccuracy, making it unsuitable for use as the sole guidance system in a cruise missile. Gyro-scopes are subject to errors which accumulate over time - the longer the flight time, the greater the error. The INS fitted to the US Tomahawk drifts by 900 metres per hour. At its cruising speed of 800 km/hr and a distance of 1,600 km, this inertial drift equates to an error of 1,800 metres, necessitating the use of supplementary guidance systems such as Terrain Contour Matching (TERCOM) or GPS.
Whilst gyroscopes used to be sensitive mechanical devices, Ring Laser and Fibre Optic Gyroscopes are becoming increasingly common; the US company Northrop has developed a micro-optic gyro which places an entire INS on a computer chip. Nonetheless, the 10 degree per hour drift claimed for this system is still too high for cruise missile guidance, and any system so equipped would require regular positional updates from external sources such as GPS in order to achieve the accuracy necessary for a precision strike.
- TERCOM GUIDANCE
Terrain Contour Matching (‘TERCOM’) was first patented in 1958, but it was not until the development of micro-electronics in the 1970s that practical TERCOM systems first appeared.
A pre-requisite for TERCOM is the ability to generate electronic maps from high-resolution satellite images. These are digitised and stored in the system’s memory across a matrix of cells. Each cell covers a set area of ground and is allotted an average elevation. A radar-altimeter is used to compare the elevation of the terrain over which the missile is flying with the elevation data in the on-board maps. This establishes the position of the missile and makes any necessary corrections to its inertial navigation system. Using this technique, TERCOM can achieve accuracies of 30-100 metres.
During the missile’s flight, TERCOM readings are not taken constantly. Rather the INS flies it from one area of distinctive topography to another, where more readings are taken and the missile's heading is corrected if necessary. These are known as ‘waypoint fixes,’ and can also be used to introduce unpredictable changes in the missile’s flight path, allowing it to avoid enemy radar and air defences. But because TERCOM relies on elevation data for its waypoint fixes, over largely flat terrain the missile may have to fly a circuitous route from feature to feature, reducing its overall mission range.
Each waypoint fix utilises a different map, and whilst each contains the same number of cells, the first maps used cover a larger overall area - and thus contain less detail in each cell - than each subsequent map, giving an 'accuracy funnelling' effect as the target is approached.
The real technical difficulty with TERCOM lies not with the guidance system itself, but in the technical infrastructure needed to create the digitised maps. For TERCOM-guided cruise missiles to be effective, databases must be built up of every part of the world in which they might potentially be used. The cost of this exercise to the US is estimated to approach the total investment made in TERCOM-equipped cruise missile hardware. Even so, it is reported that following the Iraqi invasion of Kuwait in 1990, the US military had to embark upon a crash programme to prepare data for the TERCOM guidance systems of its Tomahawk TLAMs.
This reliance on space technology to support TERCOM has hitherto ensured that only the US and Russia have deployed TERCOM-guided cruise missiles. However, the increasing availability of commercial satellite imagery from SPOT and Landsat, together with the growing sophistication of computer aided design (CAD) software means that the ability to produce digitised maps may no longer be beyond the reach of potential proliferators.
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), možeš je predstaviti kao "drone"(mamac, metu, izviđačku BPL), lansira se sa mnogo manje platforme, može da se lansira sa aviona.
