of the radar in km, and ht(km) is the height of the target in kilometres, and assuming standard atmospheric radio refraction. Thus, for a Kolchuga at 100 m altitude (above local terrain) and a target at 10 km (30 kft), the range of the system would be approximately 450 km. For targets at altitudes of 20 km (60 kft) the line of sight limitation would be 620 km—but few targets fly at such altitudes. Being line-of-sight limited, the system is an effective early warning air defense system against high power emitters. System parameters According to the manufacturer's brochure (from AIDEX 1997), the upgraded Kolchuga-M is equipped: With four antennas in the VHF, UHF and SHF radio bands with narrow and wide beams With parallel receivers allowing the instant discovery and analysis of signals of radio technical equipment (RTE) in the range 100 MHz -18 GHz and continual tracking across the entire band. [Other sources claim from 130MHz to 18GHz, and a 36 channel preset receiver]. With sensitivity of approximately -145 dBW With equipment for the analysis, processing and continual calculation and tracking of coordinates by triangulation and chronometrical-hyperbolic method. With equipment for the identification, operative displaying of information, long term memory and recording of the results of processing. The brochure also claims that the system provides: The detection, analysis of signals with pulsed and continuous waves and resolution of practically all known radio technical equipment (RTE) deployed on ground, sea and air platforms, including radar units of all classes, identification systems, air traffic control system and navigation systems The composition, character of operation and flight paths of RTE in a zone 600 km deep with complete exception of blind zones and continual high accuracy The detection of take-off of aerial targets and their formation in groups at a distance exceeding that of modern radars. The direction of arrival of solitary and group targets and target indication to active facilities of anti-aircraft systems Special inhibitory sorters omit up to 24 interfering signals, and tracking sorters make it possible to synchronously sort out and track signals from 32 targets; Target identification 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