OVERVIEW:  The SPO-3 aka Sirena-3 airborne radar warning receiver (RWR) is a passive airborne sensor that detects and warns aircrew of hostile radars.

DETAILS: 
  The SPO-3 Sirena used four antenna installed on different quadrants of an aircraft to locate threat radars that were "painting" the aircraft.  The system then provided the aircrew with an audible alert and a visual threat axis.  The system is reportedly unable to detect pulse doppler-type radars. It is capable of automatic chaff dispensing.

Specifications:

	Frequency:	2-10 Ghz
	Accuracy:	± 12 degrees
	
			
NOTES:  IOC 1959 (approx). Replaced by the SPO-10, whose performance was similar.


SOURCES: Burdin, Sergey. Tupolev TU-22. Barnsley: Pen and Sword, 2005. pg. 81; International Electronic Countermeasures Handbook, 2004 "SPQ-10 Siren." pg. 77. ; Friedman, Norman. The Naval Institute Guide to World Naval Weapons Systems, 1997-1998. Annapolis, MD: Naval Inst Press, 1997, pg.pg. 516 


