TECHNOLOGY AREAS: Sensors, Electronics, Battlespace

ACQUISITION PROGRAM: SPAWAR PMW-180 SSEE shipboard crytographic systems

OBJECTIVE: The objective of this work is to increase the amplitude sensitivity within a receiver for improved digital representations of minimum signal(s) across a desired frequency bandwidth.

DESCRIPTION: Many naval RF receivers and commercial wireless systems have their coverage range determined by the minimum amplitude signal they can receive. Advanced space time adaptive processing (STAP) can sometimes be used to lift the signals out of the environmental noise, but quantification of the complete signal spectrum including the noise is often needed. However, many analog to digital converters set the least significant bit to be half a bit above the receiver noise temperature and do not address techniques to lower receiver noise temperature below the environmental noise temperature. This topic requests efforts to do those things to achieve sensitivities in excess of 90 dBm over at least the HF band, 0.1-30 MHz.

PHASE I: Proposal should include a design concept for a data converter and numerical techniques that would enhance minimum signal sensitivity. A numerical simulation of the entire approach should be developed and demonstrated by the close of the first phase. In addition to the modeling of the noise floor characteristics, the ADC dynamic range and spur free dynamic range should be calculated

PHASE II: Convert the design into an appropriate circuit layout for fabrication and test. Iterations to improve the size, weight, power, and especially performance of the design are expected.

PHASE III: Incorporate ADC into a high sensitivity receiver such as the Navy�s SSEE.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: In sparse signal environments such as rural areas, wireless tower coverage is limited by the attenuation of the distance and maximum handset battery draw. If the towers could extend their range or hear via the diminished signals associated with multipath, there would be fewer coverage dead zones and improved service. In addition, in urban areas, all handsets could turn down their transmitter power for longer battery life.

REFERENCES:
1. http://www.freepatentsonline.com/5272479.html
2. http://lecroy.com/lrs/dsheets/2249.htm
3. http://books.google.com/books?id=exI4EsUoP7sC&dq=analog+to+digital+converters+high+sensitivity&psp=1
4. http://www.freepatentsonline.com/4672359.html
5. Cerny, C. L., et. al., "Data Converters Parameter Relationships for RF Receivers and Exciters", The 5th IEE International Conference on ADDA 2005, University of Limerick, Ireland, 25-27 July, 2005.

KEYWORDS: analog to digital converters; sparse signal environments; noise floor; non-linear amplification; thermal fluctuations; environmental noise; STAP