JED - April 2011 - (Page 51)

EW 101 ES vs. SIGINT – Part 4 Processing Issues By Dave Adamy ES DATA COLLECTION SIGINT DATA COLLECTION RADAR THREAT his month, we will deal with SIGNALS processing issues that can differentiate ES and SIGINT system requirements. These differences have to do with Collect only externals data Collect externals and internals (frequency, Modulation type & data. the nature of the informalevel, Received signal strength, Externals data similar to ES tion that must be collected from signals emitter location, intercept time) requirement of interest and the time criticality of COMM Parametric range and resolution Internals data adequate to THREAT output reporting. SIGNALS only adequate to support threat recover required military Perhaps the most important issue ID, EOB, and Jamming activity information from demodulated separating ES and SIGINT system missignals sions is the nature and amount of data that must be collected on threat signals encountered. Figure 1: Data collection requirements vary significantly between ES and SIGINT systems. In general, radar ES systems collect only enough data to determine which of the enemy’s weapons data that might be required for a typical pulse-radar threat are being used and to allow selection of the correct countersignal collected by and ELINT system is shown in Table 1. measures. All of this takes place within a single-digit number Communication ES systems deal with the externals of threat of seconds. The collection and use of received data are shown in signals to support electronic order of battle development, emFigure 2. Note that the threat parameters stored in the Threat ployment of countermeasures, and choice of fire and maneuver ID Table are the result of extensive analysis of data previously tactics. In general, this must be done very quickly because of collected by ELINT systems. the dynamic nature of tactical operations. The amount of data Figure 1 summarizes the data requirements for radar and (typically digital) is determined by the number of parameters communications ES and SIGINT systems. that must be collected and the required resolution to support ELINT systems (i.e., SIGINT systems operating against radar tactical analysis. Table 2 shows a typical array of parameters threats) must collect much more complete data over the whole that could be required for communications ES collection on anticipated parametric range. This detailed data, which can each threat. be collected over extended time and/or multiple intercepts, If there are 250 signals present and the environment is collectsupports the detailed analysis necessary to determine that the ed 10 times per second, the required data bandwidth might be: radar ES systems must identify immediately. A summary of the 250 signals x 27 bits/signals x 10 collections per second = 67,500 bits/sec T Collect only enough data to Determine radar type & operating mode Data range of known threats Adequate parametric resolution to resolve identification ambiguities Collect enough data to support detailed analysis Data range limited by practical range of any future threat Adequate parametric resolution to determine capabilities of any future threat The Journal of Electronic Defense | April 2011 51 Table 1: ELINT Data for a Typical Pulse Radar Threat Parameter Pulse Width Pulse Repetition Interval Radio Frequency Scan Type Scan Period BPSK Clock Rate BPSK Bits on Pulse FM on Pulse Range Total Bits / signal 0 to 30 sec 0 to 50Mpps 0 to 1000 0 to 10 MHz .1 sec 100 pps 1 bit 100 kHz Range .1 to 20 μsec 3 to 3000 μsec .5 to 40 GHz Resolution .1 μsec 3 μsec 100 MHz # of bits 9 11 10 6 9 bits 16 bits 10 7 78 bits COMINT (i.e., SIGINT against communications threats) is normally assumed to extract militarily useful information carried by communication signals. However, this information must typically be tied to the location and type of emitter in order to be useful. Therefore, a COMINT system will, in most cases, be required to capture both the external and internal signal data as shown in Figure 3. In addition to the bits required for the externals data, the modulation must be captured. This will require some number

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

JED - April 2011
Table of Contents
The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor
Washington Report
World Report
Latin American EW
The US IR Decoy Industry: Planning for a Viable Future
AOC/Shephard EW 2011 Preview
Book Review
EW 101
AOC News
AOC Industry and Institute/University Members
Index of Advertisers
JED Quick Look

JED - April 2011