Extending the unambiguous range of CW polyphase radar systems using number theoretic transforms
Pace, Phillip E.
Jenn, David C.
MetadataShow full item record
Polyphase continuous waveform (CW) radar systems often use the popular Frank code and P4 code due to their linear time-frequency characteristics as well as their low periodic ambiguity sidelobes. The phase relationship of the Frank code corresponds to a sawtooth folding waveform. The phase relationship of the P4 code is symmetrical with a parabolic distribution. The radar system's unambiguous target detection range is limited by the number of subcodes within the code period (code length). Increasing the code length to extend the unambiguous range results in a larger range-Doppler correlation matrix processor in the receiver, a longer compression time and an increase in the receiver's bulk memory requirements. In addition, the entire code period may not be returned from the target due to a limited time-on-target resulting in significant correlation loss. To significantly extend the unambiguous range beyond a single code period, this thesis explores the relationship between the polyphase codes (Frank and P4) and the number theoretic transforms (NTT) where the residues exhibit the same distribution as the polyphase values. The unambiguous range is extended from the number of subcodes within a single code period to the dynamic range of the transform without requiring a large increase in correlation processing. The dynamic range of a NTT is defined as the greatest length of combined phase sequences that contain no ambiguities or repeated paired terms. By transmitting N 2 coprime code periods, the unambiguous range can be extended by considering the paired values from each sequence. A new Frank phase code formulation is derived as a function of the residue number system (RNS) where each residue corresponds to a phase value within the code period (modulus) sequence. Based on the symmetrical distribution of the P4 code, a new phase code expression is derived using both the symmetrical number system (SNS) and the robust symmetrical number system (RSNS). Here each phase value within the code period corresponds to a symmetrical residue. MATLAB simulations are used to verify the new expressions for the RNS, SNS and RSNS phase codes. Implementation considerations of the new approach are also addressed.
Approved for public release; distribution is unlimited.
Showing items related by title, author, creator and subject.
Photonic analog-to-digital converters preprocessing using the robust symmetrical number system for direct digitization of antenna signals Tong, Kee Leong (Monterey, California. Naval Postgraduate School, 2010-12);The need to realize pervasive battlespace awareness is placing an increasing demand on the bandwidth and resolution performance of modern sensors, communication receivers and electronic warfare. Fundamental to realizing ...
A Robust Symmetrical Number System with Gray code properties for applications in signal processing Akin, Ilker Aydin (Monterey, California. Naval Postgraduate School, 1997-09);A new symmetrical number system with applications in parallel signal processing is investigated. The Robust Symmetrical Number System (RSNS) is a modular system in which the integer values within each modulus, when considered ...
Hatziathanasiou, Thomas N. (Monterey, California. Naval Postgraduate School, 1998-06-01);A new interferometer direction finding array architecture based on the optimum symmetrical number system (OSNS) is presented. OSNS arrays are capable of unambiguous high-resolution direction finding with as few as three ...