Low-cost radar systems have been developed for homeland security missions. These detect and track small maneuvering craft in the water. The systems consist of a conventional marine radar, a capture card that digitizes the radar signals, and a computer that processes them. We have an experimental system that can monitor western Lake Ontario. It runs in real time, with operator controls, and can store captured radar video. The achieved detection and tracking is demonstrated with recorded datasets. The combination of lower thresholds plus a sophisticated multi-target tracker gives excellent performance.

Navy Radar operations are being curtailed in a littoral environment. This is due to two factors: The encroachment of the cell phone systems into the Navy radar bands and in-band interference from other radars. The Spectral width of most pulsed radars is significantly wider than necessary with the present modulation schemes. Most radars utilize some form of constant envelope pulse with phase or frequency modulation. This causes the spectrum to broaden several times the information bandwidth. If both the amplitude and phase of the transmitted signal are allowed to change a significantly narrower bandwidth can be achieved. In this paper a method to create waveforms with instantaneous bandwidths of 20 MHz confined within ?100 dB are presented. The theoretical spectral results of three popular phase modulation schemes (phase shift keying, minimum phase shift keying, and derivative phase shift keying) are compared with the spectrally clean results. In addition the Chireix out-phasing method is presented as an alternative to generating amplitude and phase modulated waveforms. The Chireix method provides a way of improving the efficiency compared to the conventional class A power amplifier. Preliminary results are shown for a spectrally clean waveform.

This paper addresses the problem of scheduling radar dwells in multi-function phased array radar systems. The timing constraint of radar tasks are usually modeled by the minimal and maximal temporal distance between any two consecutive dwells of a task. Such a timing constraint makes it difficult for traditional real-time scheduling techniques to provide predicatable timing guarantee, without over-consuming the resources. We propose a novel approach to model the dwells as periodic real-time tasks. The periods of the tasks are synthesized by the minimal and maximal temporal distance constraint of the dwells. The synthetic periods allow the template-based scheduling algorithm to compute efficient dwell schedules with low overhead. We evaluate the algorithms via extensive simulations. Simulation results show that this algorithm can significantly improve the resource utilization.

Analog-to-Digital Converters ADCs used in MTI or Pulse Doppler Radars generate spurious signals from large clutter echoes because of the non-linear ADCs. These spurious signals can appear as real moving targets in the Doppler passband of a radar. This paper mathematically shows how these spurious signals are mitigated and a means of implementing the process is provided.

We detail a delta-sigma based system built to produce high-resolution analog waveforms at UHF. With bandwidths as large as 80 MHz and noise floors as low as -140 dBc/Hz, the generated waveforms show potential for use as LO and RF transmission waveforms in a UHF radar system. Finally, the waveform generator system is described as an ideal technology for use in a digital phased array radar.

This paper presents a modification of a Linear Frequency Modulation-Continuous Waveform shipborne surveillance radar with two antennas to transform it into an Airport Surface Detection Equipment with a single antenna. The most important additional subsystem for this new equipment is a Reflected Power Canceller to overcome the problem of insufficient isolation between the transmitter and receiver due to imperfect matching between the transmitter and the antenna. This system is currently being developed by the Spanish company Indra Sistemas S.A. in co-operation with the Technical University of Madrid.

A multifunction, single platform RF sensor capable of performing target acquisition and tracking, combat identification, high data rate communications, and active protection is of interest to the U.S. Army. The sensor ultimately must be affordable and the size minimized to meet the demands of a rapidly deployable force. To address these needs, the Army Research Laboratory has built and tested a multifunction radar test bed capable of performing multiple tasks simultaneously at Ka-band. The system has integrated high-end RF components together with commercial-off-the-shelf (COTS) signal processing technology. Key elements of the test bed are a commercial direct digital synthesizer (DDS) for adaptable waveform generation, multiple COTS field programmable gate array (FPGA) processors for real-time data acquisition and signal processing, a COTS FPGA based multi-port input/output (I/O) board programmed for radar timing and control, and an electronically scanned antenna (ESA) based upon a Rotman lens beam-former with active elements for multi-beam generation. The radar is capable of transmitting and receiving two simultaneous and independent beams in azimuth with up to 3-GHz of bandwidth and up to 8 watts of average power. The current configuration uses one beam for a radar target acquisition function and the other for a high data rate communication channel. The emphasis of this paper is on the radar?s waveform generation and signal processing capability.

This paper describes the process employed implementing an advanced embedded signal processing subsystem for a legacy search Digital Signal Processor (DSP), with emphasis on cost and Open Architecture (OA). This effort produced a low-cost, reconfigurable search DSP in a 15 month design cycle. A team of international partners was assembled, including Lockheed Martin (LM) Maritime Systems and Sensors (Moorestown, NJ), Indra Sistemas (Indra) (Madrid, Spain) and CSP Inc. (CSPI) (Billerica, MA). LM acted as the system design agent and was responsible for definition of the Commercial Off the Shelf (COTS) architecture, technical requirements and Fire Control System (FCS) integration. Indra?s responsibility was for software development that included the design, implementation and test of radar signal processing functions on general purpose processors. CSPI?s responsibilities included providing development hardware, software, and training, as well as the development of a real-time interface to the legacy radar?s processing cabinet.

This paper deals with the Doppler frequency extraction of foliage penetration radar (FPR). The strong echoes from dense foliage environment and big attenuation of the radar microwave often make it difficult for traditional time-frequency distributions to clearly and locally represent the Doppler frequency. A Hilbert-Huang Transform (HHT) technology is proposed here to extract desired signal from interference and give a new Hilbert spectrum of the Doppler frequency. Higher signal to clutter ratio (SCR) and higher resolution in the time-frequency distribution are obtained.

In this contribution a real time calibration system, capable of handling several different sensors and estimating the "constant" biases of these different sensors, is described. The system can use the most common sensors used for airport surveillance. Theoretical results of the system are provided.