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Recent Advances in Radar Technology
Using Calibration to Optimize Performance in Crucial Measurements
Matra Marconi Receives Green Light for METOP
Franco-British contractor Matra Marconi Space has been given the green light to develop and produce three new meteorological satellites (designated METOP) for use in the European Meteorological Satellite Organisation’s (EUMETSAT) planned polar system programme. The new METOP vehicles will be placed in polar orbits (at an altitude of 840 km) from April 2003 onwards and will be used to complement EUMETSAT’s existing METEOSAT platforms. METOP is designed for use in operational meteorological applications that are currently performed solely by the US’ National Oceanic and Atmospheric Administration weather satellite constellation.
Using a service module derived from a multimission platform developed by France’s National Center of Space Studies and Matra Marconi Space, METOP’s payload will include a microwave humidity sounder, infrared atmospheric sounding interferometer and advanced scatterometer. A contract for the $780 M METOP programme is scheduled to be signed in the near future.
Rohde & Schwarz Launches New Communications Control Processor
German contractor Rohde & Schwarz has announced the availability of GP2000, a new 10 kHz to 30 MHz (10 kHz to 30 MHz reception, 1.5 to 30 MHz transmission) communications band control processor. Designed for use in complex, split-site applications, GP2000 can be integrated with a range of company and noncompany transceivers, transmitters and receivers and, depending on the equipment connected to it, can handle A1A, B8E, F1B, F3E, H3E, J3A and J7B emission classes. An optional Aeronautical Radio Inc. interface is available for the control of airborne high frequency (3 to 30 MHz) radios.
DE RWR to Equip Polish Helicopters
French contractor Dassault Electronique (DE) has announced that its EWR-99 radar-warning receiver (RWR) has been selected by Poland’s PZL-Swidnik for use on the military variants of its W-3 Sokol multipurpose helicopter. Already mandated for retrofit aboard the French army’s fleet of combat helicopters, EWR-99 is an ultra-compact unit that is user programmable and database oriented. The receiver is able to detect CW, pulsed and pulse Doppler emitters, and incorporates instantaneous frequency measurement.
Elisra Wins Australian and German Electronic Warfare Contracts
Israeli contractor Elisra Electronic Systems Ltd. has been awarded contracts to supply the royal Australian navy (RAN) and German army with examples of its AES-210E electronic support measure (ESM)/electronic intelligence system and SPS-65 threat-warning equipment, respectively. The $30 M RAN contract covers the installation of AES-210E aboard the service’s 11 SH-2G(A) and 16 S-70B-2 helicopters where it will be teamed with the company’s LWS-20 laser warner, Northrop Grumman’s AN/AAR-54 passive missile-approach warner and a variant of Tracor’s AN/ALE-47 countermeasures dispenser system (CMDS). Elisra will be responsible for systems integration on both platforms and Siemens Plessey Australia (now part of British Aerospace Australia) will provide maintenance support.
The German programme covers retrofit of the SPS-65 system aboard German army CH-53G helicopters where it will be partnered with a Rokar CMDS. SPS-65 comprises the SPS-20(V) pulsed RWR, SRS-25 superheterodyne receiver (for the detection of CW, high pulse repetition frequency and low probability-of-intercept radars) and LWS-20 laser warner. Eurocopter Germany will install the equipment. The $10 M programme is scheduled for completion by the end of 2002.
Racal Publicises Noncooperative Bistatic Radar Programme
UK contractor Racal Radar Defence Systems (RRDS) has published the first details of its noncooperative bistatic radar technology validation programme. Conceived to provide a covert passive radar-plotting capability for military applications, the technology utilises donor emitters, an omnidirectional antenna array and a receiver/processing package. Functionally, the system detects donor emitters and processes their direct path outputs and scattered reflection components to produce a plan position indicator plot. Target azimuth is derived by locking on to the donor transmission using the hitchhiking technique (N.J. Willis, Bistatic Radar, Artech House, 1991, pp. 175–190 and 198–218) with true target azimuth from the donor measured by observation/triangulation or by a separate sensor, such as an ESM system.
Target range is calculated using the time-of-arrival difference between the breakthrough donor side lobe (traveling the distance between the donor and receiver) and the donor’s scattered reflection (traveling the distance between the donor and target, and the target and receiver). This calculation assumes donor pulse discrimination throughout the donor’s scan pattern with direct breakthrough from the donor to the receiver, allowing all or a sufficient number of pulses to be detected to permit accurate prediction of the pulses that are obscured.
Because of its reliance on predictable donor waveform and scan behaviour, RRDS believes that the direct breakthrough approach is extremely flexible and that it has proved its viability during the course of the present trial programme. Calculation of true target azimuth from the receiver requires knowledge of the distance and azimuth angle of the donor emitter from the receiver with donor signal angle-of-arrival determination achieved via data derived from a separate ESM capability. Because the technique cannot interrogate the donor radar directly, range and azimuth errors should be expected. RRDS believes that this drawback can be largely overcome by making the processing algorithms more resilient to parameter error.
In terms of donor transmitter parameters, the technique can use simple pulse repetition frequency, and staggered and jittered emitters. RF complex types are deemed to be less-than-desirable donors (unless some predictable pattern exists with which the receiver can be synchronised) as are emitters performing sector scans. RRDS further believes that the approach offers a high degree of resistance to countermeasures with its ability to derive a useable plot even when the donor emitter is subjected to noise jamming. In addition, due to the geometry of bistatic operation, the distortion generated in the positions of any off-axis false targets may allow real targets to be located more easily than with a conventional radar system.
The RRDS noncooperative bistatic radar has been tested both on land and at sea. In the ground-based prototype, a 600 x 500 x 450 mm receiver package was installed in a van-type vehicle that also was equipped with an omnidirectional antenna array, data storage/analysis laptop computer and Litton Marine Systems BridgeMaster navigation radar to generate ground-truth confidence plots for correlation. Trials on the test bed were performed near Gatwick Airport (West Sussex, UK) where the airfield’s air traffic control radars were used to generate a ground plot. During the course of the overall programme, the experimental equipment reportedly achieved ranges of up to 130 km consistently.
In terms of an operational system, key requirements include a receiver with a tuning frequency wide enough to cover the majority of currently used radar bands (to maximise the possibility of obtaining a donor) and a system that can be reconfigured readily so it is compatible with the widest range of emitter characteristics. Such a capability would enable the system to select the best available donor for a particular task. Operational applications include surveillance and navigation operations that are immune to antiradiation missile attack, and passive support for covert operations.
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