System to Combat Pulse-Doppler Radar Threats Demonstrated
Pulse-Doppler radar systems are extremely effective in long-range search, detection and tracking operations. While physically no larger than many pulsed-radar systems, the pulsed-Doppler (PD) radar provides vast improvements in performance. In addition to greatly increased reliability and improved jamming resistance, PD radar can detect smaller targets at longer ranges in the presence of intense clutter and track either single or multiple targets while searching for more targets. It is no wonder then, that radar-system designers have incorporated PD techniques in ground, shipboard and airborne systems since the 1980s. Three key features making pulsed Doppler system so effective are coherence, which enables detection of Doppler frequencies; digital processing with adjunct advances in accuracy and repeatability; and digital control, enabling extreme flexibility.
Operations undertaken in Desert Storm in the early 1990s and more recent action in Kosovo have demonstrated to NATO air forces the urgent need for techniques to counter PD radar. Fortunately, this need had been anticipated. In a series of developments, ManTech Real-Time Systems Laboratory (Sarasota, FL) laid the groundwork for an advanced PD-radar countermeasure. A series of emitter-identification techniques based upon application of time-frequency algorithms and heuristic decision-making approaches was initiated by ManTech in 1992. By 1996, an embodiment, code-named Vision Pointer, was implemented in a 3/4 ATR enclosure on an RC-135 aircraft at the All Services Combat Identification Exercise and Training ‘96 at Eglin AFB, FL. Vision Pointer scored an impressive success rate of over 95-percent correct signal identification at ranges of up to 174 nmi (See “New ESM Technique Shows Promise Against Doppler Radar Threats,” JED, April 1997). In 1998 Vision Pointer evolved into the Vivid PointerTM VP2010(U) system. Vivid Pointer was implemented in two-card COTS hardware. By 1999 system capability had been expanded to handle multiple Doppler emitters.
In 1998 Condor Systems, Inc. (San Jose, CA), teamed with ManTech to incorporate the advanced PD-identification technology into existing receiver/signal processors and to demonstrate the effectiveness of the technology. A new configuration, now called the Pulse Doppler Identification (PDID) module, was used to augment a standard US radar warning receiver (RWR). Demonstrations and testing under a $690,000 contract awarded to Condor by the USAF Information Warfare Battlelab (Kelly AFB, San Antonio, TX) were conducted initially in August 1999 at the Dynamic Electromagnetic Environment Simulator (Wright-Patterson AFB, OH). Here, the PDID module was exposed to signals typical of present and future combat scenarios. Following the simulator tests, the module was operated against actual pulse Doppler radars of US fabrication in ground-based operations. The prototype unit met or exceeded all goals established by the Battlelab, which has the mission of identifying and rapidly introducing information-warfare innovations into the Air Force.
Ground-based testing has been followed by flight tests of the PDID module interfaced with an AN/ALR-69 RWR, produced by Litton Advanced Systems (College Park, MD). The unit was flown, onboard a C-130 Hercules, against a variety of Doppler radars. As a result of these successful tests, company officials are hopeful for USAF and NATO endorsement of PDID add-ons for use in a variety of currently fielded RWRs. — D. Herskovitz