Editing Signals intelligence (section)

===Electronic order of battle===
Generating an '''electronic order of battle''' (EOB) requires identifying SIGINT emitters in an area of interest, determining their geographic location or range of mobility, characterizing their signals, and, where possible, determining their role in the broader organizational [[order of battle]]. EOB covers both COMINT and ELINT.<ref>{{cite web|author=743d Military Intelligence (MI) Battalion|title=Warfighter Guide to Intelligence 2000|publisher=Joint Spectrum Center, (US) Defense Information Services Agency|date=August 1999|url=http://www.gordon.army.mil/AC/Fall/Fall%2001/JSCmtrc.htm|archive-url=https://web.archive.org/web/20070814165342/http://www.gordon.army.mil/AC/Fall/Fall%2001/JSCmtrc.htm|url-status=dead|archive-date=2007-08-14|access-date=26 October 2007}}</ref> The [[Defense Intelligence Agency]] maintains an EOB by location. The Joint Spectrum Center (JSC) of the [[Defense Information Systems Agency]] supplements this location database with five more technical databases:
:# FRRS: Frequency Resource Record System
:# BEI: Background Environment Information
:# SCS: Spectrum Certification System
:# EC/S: Equipment Characteristics/Space
:# TACDB: platform lists, sorted by nomenclature, which contain links to the C-E equipment complement of each platform, with links to the parametric data for each piece of equipment, military unit lists and their subordinate units with equipment used by each unit.

[[File:JSC-Databases-and-Flow.GIF|thumb|EOB and related data flow]]
For example, several voice transmitters might be identified as the command net (i.e., top commander and direct reports) in a tank battalion or tank-heavy task force. Another set of transmitters might identify the logistic net for that same unit. An inventory of ELINT sources might identify the [[Radar MASINT#AN/TPQ-36 and −37 counterartillery radars|medium]]- and [[Radar MASINT#AN/TPQ-37|long-range]] counter-artillery radars in a given area.

Signals intelligence units will identify changes in the EOB, which might indicate enemy unit movement, changes in command relationships, and increases or decreases in capability.

Using the COMINT gathering method enables the intelligence officer to produce an electronic order of battle by traffic analysis and content analysis among several enemy units. For example, if the following messages were intercepted:
:# U1 to U2, requesting permission to proceed to checkpoint X.
:# U2 to U1, approved. please report at arrival.
:# (20 minutes later) U1 to U2, all vehicles have arrived to checkpoint X.

This sequence shows that there are two units in the battlefield, unit 1 is mobile, while unit 2 is in a higher hierarchical level, perhaps a command post. One can also understand that unit 1 moved from one point to another which are distant from each 20 minutes with a vehicle. If these are regular reports over a period of time, they might reveal a patrol pattern. Direction-finding and [[Radiofrequency MASINT|radio frequency MASINT]] could help confirm that the traffic is not deception.

The EOB buildup process is divided as following:
:* Signal separation
:* Measurements optimization
:* Data fusion
:* Networks build-up

Separation of the intercepted spectrum and the signals intercepted from each sensor must take place in an extremely small period of time, in order to separate the different signals to different transmitters in the battlefield. The complexity of the separation process depends on the complexity of the transmission methods (e.g., [[Frequency-hopping spread spectrum|hopping]] or [[time-division multiple access]] (TDMA)).

By gathering and clustering data from each sensor, the measurements of the direction of signals can be optimized and get much more accurate than the basic measurements of a standard [[direction finding]] sensor.<ref name=Kessler>{{cite journal|url=http://www.darpa.mil/DARPATech2000/Presentations/tto_pdf/6KesslerDDBB&WRev1.pdf|first=Otto|last=Kessler|publisher=Defense Advanced Research Projects Agency|title=SIGINT Change Detection Approach|journal=Dynamic Database: Efficiently Convert Massive Quantities of Sensor Data into Actionable Information for Tactical Commanders|url-status=dead|archive-url=https://web.archive.org/web/20080227075206/http://www.darpa.mil/DARPATech2000/Presentations/tto_pdf/6KesslerDDBB%26WRev1.pdf|archive-date=27 February 2008}}</ref> By calculating larger samples of the sensor's output data in near real-time, together with historical information of signals, better results are achieved.

Data fusion correlates data samples from different frequencies from the same sensor, "same" being confirmed by direction finding or radiofrequency MASINT. If an emitter is mobile, direction finding, other than discovering a repetitive pattern of movement, is of limited value in determining if a sensor is unique. MASINT then becomes more informative, as individual transmitters and antennas may have unique side lobes, unintentional radiation, pulse timing, etc.

'''Network build-up''', or analysis of emitters (communication transmitters) in a target region over a sufficient period of time, enables creation of the communications flows of a battlefield.<ref>{{cite journal|author=Terry, I.|title=US Naval Research Laboratory – Networked Specific Emitter Identification in Fleet Battle Experiment Juliet|journal=NRL Review|year=2003|url=http://www.nrl.navy.mil/content.php?P=03REVIEW207|access-date=26 October 2007|url-status=dead|archive-url=https://web.archive.org/web/20071126144234/http://www.nrl.navy.mil/content.php?P=03REVIEW207|archive-date=26 November 2007}}</ref>