B-2 DMS AN/APR-50 (SAFE PASSAGE) / TELS / PAS

flateric

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Publication Title Jane's Avionics
Publication date Apr 30, 2009
Section Airborne electronic warfare (EW) systems
TITLE : AN/APR-50 Defensive Management Suite (DMS)

TEXT : TypeAirborne Electronic Counter Measures (ECM), Electronic Support Measures(ESM) and Radar Warning Receiver (RWR) system.DescriptionAN/APR-50 Defensive Management System (DMS) is installed in USAF B-2aircraft. The system is classified and very few technical details havebeen released. It is believed that the system is designed to presentaircrew with intercepted emitter information overlaid on a pre-programmeddisplay of known emitter locations. The installation features a number ofantennas, distributed all around the airframe, feeding nine radiofrequency front ends, which detect and analyse a wide variety of signals.Each of these front ends may be tuned to a different part of the frequencyspectrum. Five receivers take the outputs of the front ends and pass themto the processor.There is considerable speculation that the AN/APR-50 utilises an ECMtechnique known as ’active cancellation’ - this stealth technique employsan array of antennas to transmit a signal which is out of phase withincoming radar emissions, thus effectively reducing the intensity of thereflected returns through interference. If the emitted interferencesignal, travelling in the same direction, is exactly matched in terms ofamplitude, period and phase, to the reflected radar signal, then thethreat radar would not be able to detect any return signal, thus failingto ’see’ the aircraft. This is called destructive interference. In termsof applying such ECM techniques to an airborne platform, incoming signalswill have many different characteristics of amplitude, period and phase,which, combined with the many different directions of reflection,resulting in phase/amplitude shift, will make true ’cancellation’extremely difficult to achieve in the real world. It is more likely thatthe characteristics of the strongest incident signal would be selected bythe system processor for destructive interference.Operational statusThe Northrop Grumman Company designation of the system is ZSR-63. InJanuary 1993, Northrop Grumman was awarded a US$117 million contract tocontinue development of the AN/APR-50. Northrop Grumman was also awardedUS$53.9 million to carry on with ESM development, including extension ofthe frequency range. It is believed that this was originally for Band 2and the extension was to cover Band 4 from 500 MHz to 1 GHz. While it isbelieved that baseline versions of the system failed to meet operationalexpectations, software changes completed during the second quarter of 1998were incorporated to address these problems. AN/APR-50 systems installedin Block 30 aircraft are described as ’fully capable in Bands 1 to 4’.Additional software upgrades were implemented during 2001-2002.
 
looking for higher-res image of AN/APR-50 program logo and patch...
here's DMS Modernization program challenge coin
 

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http://smaplab.ri.uah.edu/smap-center/conferences/dmsms02/presentations/smith.pdf
 
flateric said:

http://www.businesswire.com/news/home/20120216005939/en/BAE-Systems-Selected-Provide-Electronic-Warfare-Systems

And the gold:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA397957

"2.5.3.7 The AN/APR-50 Electronic Warfare System
The AN/APR-50 electronic warfare system is currently used on the B-2 Spirit. The system is capable of covering the lower frequencies and up to Band 4 from 500 MHz to 1 GHz. Very little information is available on this highly classified system. ("ADF Employment of the Global Hawk Uninhabited Aerial Vehicle.")"


and
http://www.saffm.hq.af.mil/shared/media/document/AFD-070223-227.pdf

As best I have been able to tell, the AN/APR-50 is only the ESM part of the defensive systems package, not the whole thing as some articles have reported.

 
...
 

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Cant resist an amateurish attempt at patch lore...

The left hand image posted by flateric has hands extending from the leading edges of the wings in approximatley the position of the Radar arrays, one of the fists is grasping lightening bolts. Implication that the radar system is actively involved in electronic warfare / active cancellation? :-[
 
start_the_van.png
 
Threat Emitter Locator System (TELS) (ZSR-63)
Defense Management Systems (ZSR-61)
Defense Management Processors (DMP) (ZSR-61)
 
Mat Parry said:
Cant resist an amateurish attempt at patch lore...

The left hand image posted by flateric has hands extending from the leading edges of the wings in approximatley the position of the Radar arrays, one of the fists is grasping lightening bolts. Implication that the radar system is actively involved in electronic warfare / active cancellation? :-[

for me it looks like fist breaks the incoming lightning, shielding a/c from the threat
 
That seems like a better interpretation of the image (and of the more mundane / less sci fi function of this system)...
 
The B-2 DMS (Defensive Management System) includes 3 processors (DMP-1 (ZSR 61), DMP-2 (ZSR 61), ZSR 63). DMP-2 can act as backup to DMP-1 or ZSR-63 processor. DMS includes the TELS (Threat Emitter Locator System), to detect, locate and identify radar transmitters, and PAS (Pilot Alert System), a light detection and ranging (lidar) system designed for detection of contrail formations behind the B-2 Stealth Bomber. It also includes detailed threat location Electronic Order of Battle (EOB) files, Electronic IDentification (EID) libraries and threat detection range display and signature management capabilities. Early Warning radars for example have lines showing detection ranges for "spike" (4 main directional lobes, dotted lines) and "fuzzball" (general return from other angles, solid lines) for each emitter from the 'known emitters" in the EOB file (white) or discovered unexpected emitters (yellow). Flight planning avoids getting to 'fuzzball' ranges, and not straying inside "spike" ranges as much as possible.

The TELS includes a ZSR-63 processor (mentioned above) and a pre-processor. The pre-processor identifies beam report messages from RPs and matches them to known EID (electronic ID) numbers within the EID library file. The processor establishes emitter initial position and attempts to correlate to known emitters in the EOB files or leave as 'pop up' , and sends to DMP for display. The pre-processor has no backup in case of failure, but the processor functions can be run by DMP-2 if the ZSR-63 fails.

The EID Library (One per EID Region) may have up to 200 emitter entries. It can be edited by crew but "nobody touches EID due to its complexity".

TELS has 25 antennas. Spatial and frequency coverage is provided by 17 antennas covering Bands 1-4.

The DMS uses EOB files containing threat emitter locations. 5 EOB sector files are active at one time - 2 behind, 2 in front and current segment. Each segment is 160 NM x 800 NM meaning the total displayed coverage is 800NM x 800NM.

Each EOB sector Core memory stores up to 750 plotted individual emitters in the five EOB segments.

PALS (Ophir Systems) is a LIDAR based contrail detection system. It activates at a certain barometric altitude and warns the crew when a contrail is formed.
 
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