Editing Signals intelligence (section)

===Monitoring friendly communications===
More a part of [[communications security]] than true intelligence collection, SIGINT units still may have the responsibility of monitoring one's own communications or other electronic emissions, to avoid providing intelligence to the enemy. For example, a security monitor may hear an individual transmitting inappropriate information over an unencrypted radio network, or simply one that is not authorized for the type of information being given. If immediately calling attention to the violation would not create an even greater security risk, the monitor will call out one of the BEADWINDOW codes<ref>{{cite web|last=Combined Communications-Electronics Board (CCEB)|title=ACP 124(D) Communications Instructions: Radio Telegraph Procedure|date=January 1987|url=http://www.nor.com.au/community/sarc/acp124~1.pdf|id=ACP 224(D)|access-date=2 October 2007|archive-url=https://web.archive.org/web/20070901131123/http://www.nor.com.au/community/sarc/acp124~1.pdf|archive-date=1 September 2007}}</ref> used by Australia, Canada, New Zealand, the United Kingdom, the United States, and other nations working under their procedures. Standard BEADWINDOW codes (e.g., "BEADWINDOW 2") include:

# '''Position:''' (e.g., disclosing, in an insecure or inappropriate way), "Friendly or enemy position, movement or intended movement, position, course, speed, altitude or destination or any air, sea or ground element, unit or force."
# '''Capabilities:''' "Friendly or enemy capabilities or limitations. Force compositions or significant casualties to special equipment, weapons systems, sensors, units or personnel. Percentages of fuel or ammunition remaining."
# '''Operations:''' "Friendly or enemy operation – intentions progress, or results. Operational or logistic intentions; mission participants flying programmes; mission situation reports; results of friendly or enemy operations; assault objectives."
# '''Electronic warfare (EW):''' "Friendly or enemy electronic warfare (EW) or emanations control (EMCON) intentions, progress, or results. Intention to employ electronic countermeasures (ECM); results of friendly or enemy ECM; ECM objectives; results of friendly or enemy electronic counter-countermeasures (ECCM); results of electronic support measures/tactical SIGINT (ESM); present or intended EMCON policy; equipment affected by EMCON policy."
# '''Friendly or enemy key personnel:''' "Movement or identity of friendly or enemy officers, visitors, commanders; movement of key maintenance personnel indicating equipment limitations."
# '''[[Communications security]] (COMSEC):''' "Friendly or enemy COMSEC breaches. Linkage of codes or codewords with plain language; compromise of changing frequencies or linkage with line number/circuit designators; linkage of changing call signs with previous call signs or units; compromise of encrypted/classified call signs; incorrect authentication procedure."
# '''Wrong circuit:''' "Inappropriate transmission. Information requested, transmitted or about to be transmitted which should not be passed on the subject circuit because it either requires greater security protection or it is not appropriate to the purpose for which the circuit is provided."
# Other codes as appropriate for the situation may be defined by the commander.

In WWII, for example, the Japanese Navy, by poor practice, identified a key person's movement over a low-security cryptosystem. This made possible [[Operation Vengeance]], the interception and death of the Combined Fleet commander, Admiral [[Isoroku Yamamoto]].

{{anchor|ELINT}}