Ahassan
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The Kolchuga passive sensor is an ESM system developed in Ukraine. Its detection range is limited by line-of-sight but may be up to 800 km (500 miles) for very high altitude, very powerful emitters. Frequently referred to as Kolchuga Radar, the system is not really a radar, but an ESM system comprising three or four receivers, deployed tens of kilometres apart, which detect and track aircraft by triangulation and multilateration of their RF emissions.
Kolchuga is able to detect and identify many types of radio devices mounted on ground, airborne, or marine objects. Target detection relies only on an emitter having sufficient power and being within Kolchuga's frequency range. Target identification, however, is more complex and is based on the measurement of different parameters of the transmitted signal—such as its frequency, bandwidth, pulse width, pulse repetition interval, etc. Kolchuga has been reported to use around forty different parameters when identifying a target. These parameters are compared to a database in order to identify both the type of emitter and, in some cases, even the specific piece of equipment (by identifying the unique signature or "fingerprint" that most transmitters have, due to the variations and tolerances in individual components). The database within Kolchuga is said to have the capacity to store around three hundred different types of emitter and up to five hundred specific signatures for each type.
Since becoming publicly known following the Cassette Scandal, the capabilities of Kolchuga have been the source of many rumours and uninformed speculation in forums such as [5]. Many observers have a tendency to credit it with magical powers of detection. Many of these do not stand up to detailed engineering analysis, or have not been confirmed, but are recorded in this section for completeness, together with reasons for doubting the claim. Note that the material in this section should not be regarded as accurate. Claims include:
* That Kolchuga has a range of 800 km. It will certainly have the sensitivity to see high power sources at such a range. However, basic line-of-sight arguments outlined in the sections above show that this would require aircraft to be flying at impractically high altitudes and/or for the Kolchuga stations to be deployed on very high mountains. The claim is thus technically possible but operationally very unlikely.
* That Kolchuga can detect US stealth aircraft by their radio and radar emissions. Whilst technically possible, stealth aircraft do not radiate when in battle, so this mode of operation is militarily irrelevant.
* Kolchuga is sufficiently sensitive to detect US stealth aircraft from unconventional sources of RF emissions, including radiation from exhaust trails and electromagnetic interference from the engine. (Technically the power levels of these sources are likely to be so small, if at all, that there would be insufficient energy for Kolchuga to measure these effects at one site, let alone the two or more required for triangulation. They would also be almost impossible to distinguish for normal background RF noise and would not appear like the conventional emissions types Kolchuga is designed to receive and analyse).
* Kolchuga is sufficiently sensitive to operate as a bistatic radar receiver and hence exploit other transmitters in the environment. (This is likely to be true for the specific case of forward scatter in which the radar cross section of even a stealth aircraft can become very large for a few moments. However, achieving forward scatter simultaneously in two or more receivers is geometrically impossible, so triangulation would not work. Secondly, unless Kolchuga has been specifically designed to work as a bistatic radar receiver with a certain radar type—and there's no evidence of Kolchuga being deployed in conjunction with specific radar types—then it will lack the essential matched filter required to reliably detect reflected pulses in the presence of noise. Therefore, if this effect works at all, it is likely to be unreliable and fleeting).
* Ukrainian sources often make claims such as "[Kolchuga] is head and shoulders above all American, Russian, French, Czech, or Brazilian developments in this field"[6]. Such claims are unsubstantiated and pure speculation, as the performance and even existence of many ESM systems are highly classified and not deducible by ELINT. It may or may not be true, but must be regarded with caution, particularly as those making the claims are often either journalists or those with an interest in exporting the system.
It has been exported to Russia where additional development has been performed and the system is marketed in conjunction with the new S-400 surface to air missile (SAM) system.
Kolchuga is able to detect and identify many types of radio devices mounted on ground, airborne, or marine objects. Target detection relies only on an emitter having sufficient power and being within Kolchuga's frequency range. Target identification, however, is more complex and is based on the measurement of different parameters of the transmitted signal—such as its frequency, bandwidth, pulse width, pulse repetition interval, etc. Kolchuga has been reported to use around forty different parameters when identifying a target. These parameters are compared to a database in order to identify both the type of emitter and, in some cases, even the specific piece of equipment (by identifying the unique signature or "fingerprint" that most transmitters have, due to the variations and tolerances in individual components). The database within Kolchuga is said to have the capacity to store around three hundred different types of emitter and up to five hundred specific signatures for each type.
Since becoming publicly known following the Cassette Scandal, the capabilities of Kolchuga have been the source of many rumours and uninformed speculation in forums such as [5]. Many observers have a tendency to credit it with magical powers of detection. Many of these do not stand up to detailed engineering analysis, or have not been confirmed, but are recorded in this section for completeness, together with reasons for doubting the claim. Note that the material in this section should not be regarded as accurate. Claims include:
* That Kolchuga has a range of 800 km. It will certainly have the sensitivity to see high power sources at such a range. However, basic line-of-sight arguments outlined in the sections above show that this would require aircraft to be flying at impractically high altitudes and/or for the Kolchuga stations to be deployed on very high mountains. The claim is thus technically possible but operationally very unlikely.
* That Kolchuga can detect US stealth aircraft by their radio and radar emissions. Whilst technically possible, stealth aircraft do not radiate when in battle, so this mode of operation is militarily irrelevant.
* Kolchuga is sufficiently sensitive to detect US stealth aircraft from unconventional sources of RF emissions, including radiation from exhaust trails and electromagnetic interference from the engine. (Technically the power levels of these sources are likely to be so small, if at all, that there would be insufficient energy for Kolchuga to measure these effects at one site, let alone the two or more required for triangulation. They would also be almost impossible to distinguish for normal background RF noise and would not appear like the conventional emissions types Kolchuga is designed to receive and analyse).
* Kolchuga is sufficiently sensitive to operate as a bistatic radar receiver and hence exploit other transmitters in the environment. (This is likely to be true for the specific case of forward scatter in which the radar cross section of even a stealth aircraft can become very large for a few moments. However, achieving forward scatter simultaneously in two or more receivers is geometrically impossible, so triangulation would not work. Secondly, unless Kolchuga has been specifically designed to work as a bistatic radar receiver with a certain radar type—and there's no evidence of Kolchuga being deployed in conjunction with specific radar types—then it will lack the essential matched filter required to reliably detect reflected pulses in the presence of noise. Therefore, if this effect works at all, it is likely to be unreliable and fleeting).
* Ukrainian sources often make claims such as "[Kolchuga] is head and shoulders above all American, Russian, French, Czech, or Brazilian developments in this field"[6]. Such claims are unsubstantiated and pure speculation, as the performance and even existence of many ESM systems are highly classified and not deducible by ELINT. It may or may not be true, but must be regarded with caution, particularly as those making the claims are often either journalists or those with an interest in exporting the system.
It has been exported to Russia where additional development has been performed and the system is marketed in conjunction with the new S-400 surface to air missile (SAM) system.
