JED - March 2011 - (Page 48)

TECHNOLOGY SURVEY RWR AND RADAR ESM SYSTEMS By Ollie Holt 48 The Journal of Electronic Defense | March 2011 his month’s technology survey examines radar warning receivers (RWRs) and radar electronic support measures (ESM) systems. Before we get into the survey details, let’s expand some more on the similarities and differences of radar ESM systems and RWRs (both of which constitute electronic warfare support, or ES, systems) on the one hand and electronic intelligence (ELINT) systems on the other. In his “EW 101” column, Dave Adamy has been conducting an interesting discussion about what distinguishes an ES system from a SIGINT (COMINT or ELINT) system. The major difference between an RWR/ESM receiver and ELINT receiver is that a RWR/ESM receiver needs to quickly scan the frequency range and spatial environment to detect threats and protect the platform it is located on, while an ELINT receiver can slowly scan or stare at a frequency or spatial region and collect information for further analysis. An RWR typically scans a frequency range looking for tracking radars so it can quickly warn the operator of imminent danger or immediately employ countermeasures if needed. An ESM system expands on RWR functionality by not only looking for tracking radars, but also looking for the complete defensive network to develop a situational awareness (SA) picture for the operator along with providing support for countermeasures employment. The ESM receiver is typically an RWR “on steroids.” It not only quickly scans the frequency range and spatial area, but looks for all radar emissions and performs enough data collection and real-time analysis of the detected signals to support signal ID determination, some determination of signal intent and usually provide better direction finding/location than a typical RWR. This data is then used to provide a detailed picture of the Integrated Air Defense System (IADS) or radar systems the platform is about to encounter. T Because an RWR is mostly used for pilot warning of tracking radars and countermeasure employment support, it can be smaller and provide less performance than an ESM receiver. A RWR typically only looks in the frequency ranges where tracking radar emissions may exist and typically only provides system sensitivity performance levels to detect the tracking radar emissions at something more than the lethal missile range. An ESM system typically scans a wider frequency range to not only detect tracking radars, but also early warning radars. ESM systems also typically provide greater detection range (more sensitivity) and more precise DF and location information in support of SA. Because of the higher performance desired in ESM systems, they are usually larger and more complex than an RWR. Also, depending on platform size (helicopter vs. tactical fighter vs. a bomber vs. a surface warfare ship), it defines the size, weight and power budgets for the receiver system. A larger platform also requires better detection range performance because the larger the platform, the greater the range at which threat radar systems can detect the platform. Therefore the RWR or ESM system needs to see further. A larger platform can support more and larger antennas, while also providing more prime power, cooling, space and weight without impacting platform capability. As you review the survey data you will see a rather large variation of systems and technologies. You will notice the wide bandwidth receivers with lower weight and lower installed sensitivity, representing the typical RWR systems. And heavier systems that typically feature narrower instantaneous bandwidth, possibly more channels and higher sensitivity, representing the ESM systems. Wider instantaneous bandwidth systems typically mean quicker response times but less installed sensitivity (i.e., they can’t see as far). The smaller the in-

Table of Contents for the Digital Edition of JED - March 2011

JED - March 2011
The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor
Washington Report
World Report
Airborne Maritime Patrol
What Electronic Warriors Should Know About Physics, Language and Concepts
Technology Survey: RWR/ESM Systems
EW 101
AOC News
AOC Membership Page
AOC Industry/Institute/University Member Guide
Index of Advertisers
JED Quick Look

JED - March 2011