TECHNOLOGY AREAS: Sensors, Electronics, Battlespace

ACQUISITION PROGRAM: PEO IWS 1.0, PEO IWS 2.0

OBJECTIVE: Research and develop improved processing technology that will allow for the processing of signals of interest in the simultaneous presences of high powered, in band emissions from onboard radiators. These techniques may require specific new hardware configurations, but the hardware itself must be within current receiver capabilities. The addition of a resource manager that can direct the tuning of narrow and wideband filters in the EW receiver is one of the approaches that may be considered. Current technology will allow up to

20ms prior knowledge of radar transmission parameters.

DESCRIPTION: Navy ships employ a number of high powered, high duty cycle RF emitters in order to fulfill their missions. They also employ high sensitivity receivers to detect, identify, and track other platforms. This function is also necessary in order to fulfill their mission. A serious problem arises when these functions are required to operate simultaneously. The receivers can not process both the week signal they are required to detect at the same time these high powered emitters are transmitting. The reason being that the signal of interest may have a received power on the order of -80 dBm but the received power from the on board emitter may be +40 dBm or more. To fully function in this environment the instantaneous dynamic range of the receiver must be at least 120dB. This is beyond current receiver technology. Various methods are currently used to mitigate this problem. In the case where the interfering signal is at a frequency other than the signal of interest filters or channelized receivers can be used to eliminate the interference. When both signals are in the same band of the receiver, then blanking may be used. The problem with these methods is that the bands of frequencies that are blanked or filtered are no longer available to detect signals of interest that may be within these bands.

PHASE I: The awardee shall research and identify technologies and processing algorithms that effectively increase the effective dynamic range of a receiver and/or mitigate the blinding effects of simultaneous in band high power emitters. The awardee shall research and identify their approach, document all requirements, both hardware and software, and provide an outline of the model and code for any processing algorithms. These techniques may require specific hardware configurations, e.g., setting adjacent channels of a channelized receive to the same frequency but different detection thresholds; addition of dynamic filters to the front end of the receiving antenna; or the addition of processing hardware to characterize the known signal (on board emitter) so as to identify it and separate it from the signal of interest. On going work in the development of miniature fast tuning, adjustable bandwidth and adjustable attenuation filters may also be applicable to this task. Past efforts in detecting signals with very low S/N may be applicable to this problem. In particular, techniques based on, correlation, HOSP (Higher-Order Spectral Processing), and ICA (Independent Component Analysis),and cepstral separation in the time domain.

PHASE II: The awardee shall develop, document, and code the algorithm(s) as described above. All products shall be tested and validated. Documentation shall be of a level of detail for eventual incorporation into SEWIP Block 2 specifications.

PHASE III: The awardee shall refine the algorithm(s) as required and participate in the efforts to field these capabilities to the fleet.

PRIVATE SECTOR COMMERCIAL POTENTIAL: Reduction of interference for commercial RF communications.

References:
1. "Adaptive Blind Signal and Imagine Processing", A. Cichocki. Amari, 2002.

2. "Advanced Signal Processing Applied to Electronic Warfare", SBIR Phase II Contract #N00178-99-C-3035; by MultiSpec Corp., December 1999.

3. "Signal Processing with Alpha-Stable Distributions and Applications", C. L. Nikias/M. Shao, 1995.

4. "Zero-Order Statistics: A Signal Processing Framework for Very Impulsive Processes", J. G. Gonzalez/ D.W. Griffith/ G. R. Arce. NSF Grant MIP-9530923 ATIRP CA No. DAAL01-96-2-0002, 1996.

5. "Higher-Order Spectra Analysis", C. L. Nikias/A. P. Petropulu , 1993.

6. "Microwave Frequency Selective Limiters", Padisan Phudpong and Ian C. Hunter, Institute of Microwaves and Photonics, School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK.

7. "Perfectly-Matched Bandstop Filters using Lossy Resonators", Andrew C. Guyette, Ian C. Hunter, Roger D. Pollard and Douglas R. Jachowski, Institute of Microwaves and Photonics, School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK, Microwave Technology Branch, Electronics Science and Technology Division, Naval Research Laboratory, Washington, DC 20375.

8. "Compact, Frequency-Agile, Absorptive Bandstop Filters", Douglas R. Jachowski, Microwave Technology Branch, Electronics Science and Technology Division, Naval Research Laboratory, Washington, DC 20375.

9. "Spontaneous and Explicit Estimation of Time Delays in the Absence/Presence of Multipath Propagation", Hing Cheung So, The Chinese University of Hong Kong, 1995.

There are no SEWIP Block 2 references available at this time.

KEYWORDS: electronic warfare; open architecture; softkill; combat system; algorithm; EMI; EMC

** TOPIC AUTHOR (TPOC) **

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