Implementation of a coherent real-time noise radar system

The utilisation of continuous random waveforms for radar, that is, noise radar, has been extensively studied as a candidate for low probability of intercept operation. However, compared with the more traditional pulse-Doppler radar, noise radar systems are significantly more complicated to implement, which is likely why few systems exist. If noise radar systems are to see the light of day, system design, implementation, limitations etc., must be investigated. Therefore, the authors examine and detail the implementation of a real-time noise radar system on a field programmable gate array. The system is capable of operating with 100% duty cycle, 200\ua0MHz bandwidth, and 268\ua0ms integration time while processing a range of about 8.5\ua0km. Additionally, the system can perform real-time moving target compensation to reduce cell migration. System performance is primarily limited by the memory bandwidth of the off-chip dynamic random access memory

Global panopticon

Contemporary panopticon infrastructure and technologies are deployed to secure citizens using video surveillance, biometrics, labelling technologies, satellites and the global fibre network. This is an expanding business sector

Application of LSI to signal detection: The deltic DFPCC

The development of the DELTIC DFPCC serial mode signal processor is discussed. The processor is designed to detect in the presence of background noise a signal coded into the zero crossings of the waveform. The unique features of the DELTIC DFPCC include versatility in handling a variety of signals and relative simplicity in implementation. A theoretical performance model is presented which predicts the expected value of the output signal as a function of the input signal to noise ratio. Experimental results obtained with the prototype system, which was breadboarded with LSI, MSI and SSI components, are given. The device was compared with other LSI schemes for signal processing and it was concluded that the DELTIC DFPCC is simpler and in some cases more versatile than other systems. With established LSI technology, low frequency systems applicable to sonar and similar problems are feasible

Synthetic aperture sonar

Synthetic aperture techniques have been applied very successfully for many years in astronomy and radar to obtain high resolution images, an outstanding example in recent years being the use in remote sensing satellite systems. In underwater acoustics, because of the inherent problems caused by random fluctuations in the signal path, the slow velocity of the acoustic wave and the unknown movements of the transducer as it traverses the aperture, the application of the synthetic aperture technique has mainly been limited to the very useful but rather inferior non-coherent technique known as side-scan sonar. However the rapid advances that are being made in micro-chip technology and fast digital signal processing, and the development in image processing algorithms has created renewed interest in the possible application of the synthetic aperture technique to underwater acoustics. This thesis describes such a study

An electronically focused multiple beam side scan sonar

Phased arrays have been in use since World War II but their commercial application has been constrained by the bulk and cost of the beam forming system. High resolution side scan sonar systems have many operational parameters that may only be extended with the aid of phased arrays, the resolution and the imaging rate being the most important. This thesis describes a microprocessor controlled dynamically focused side scan sonar where high resolution and high image acquisition rates are achieved. Dynamic focusing prevents the depth of field limitations of fixed focus arrays by updating the array phases at regular intervals so as to create a focal point which recedes from the array in synchronism with the returning echoes from the transmitted pulse. A high image acquisition rate is achieved through the simultaneous formation of multiple beams. Using a microprocessor as a low-cost controller demands rapidly executable software and a little specialized hardware. Programmable quadrature phase shifters give phase and amplitude control. A beam forming board combines the phase shifted signals into a beam and samples it. A 'time domain multiplexed' transmitter solves the problem of efficient insonification of swaths. The system timing is complex; while image samples are captured data is formatted and presented for recording on a chart recorder. This occurs in real-time, while the focus of each of the multiple beams is changed almost every two meters. Tank tests of the completed system provide confirmation of the resolution predicted with theory and computer simulation. Sea trials confirm that resolution close to that predicted may be obtained under operational circumstances. The results obtained fully justify the assertion that low cost microprocessor controlled dynamically focused multiple beam phased arrays are both an attainable and an attractive solution to the problems faced by the designer of high resolution side scan sonar systems

Fish tracking technology development. Phase 1 project definition desk study

The document reports on Phase 1 of a definition study to appraise the options to develop fish tracking equipment, in particular tags and data logging systems in order to improve the efficiency of the Environment Agency's tracking studies and to obtain a greater understanding of fish biology. Covered in this report are radio telemetry, audio telemetry, High Resolution Position Fixing, data storage and archival tags and other fish tracking systems such as biosonics