Sensors Electronic Warfare

To provide you with an understanding of electromagnetic propagation, antennas and devices relevant to military sensor, communications and electronic warfare systems.

• Course introduction: course structure, aims and objectives,
• Information resources: computer centre, library, information retrieval,
• Propagation: radio propagation, reflection, refraction, multipath, fading, attenuation, ionosphere propagation, troposcatter, anomalous propagation,
• Antennas: fundamental antenna concepts and definitions; impedance match, radiation patterns, directivity, gain, polarization, axial ratio, EIRP, effective aperture, noise temperature, etc.
• Overview of antenna types for communications and radar applications including wire antennas, aperture antennas, reflector antennas, low profile and microstrip antennas,
• Antenna arrays: introduction to phased array theory, types of antenna array, feed network design, beam steering and radiation pattern shaping,
• Electromagnetic devices: high power tubes including magnetron, coaxial magnetron, Klystron, Extended Interaction Klystron and Travelling Wave Tube Amplifier,
• Guided waves: waveguides, coaxial lines, microstrip and other RF planar transmission line structures,
• RF and microwave power dividers, combiners and couplers active solid-state devices: RF diodes and transistors and their application in amplifiers and oscillators, ferrite non-reciprocal devices (circulators and isolators),
• PIN diode switches, modulators and phase shifters.

On successful completion of this module you will be able to:

• Describe the principles of operation and characteristics of antenna sensors and electromagnetic system components and recognise how they may be used in a modern military communication or EW system,
• Identify and explain the various models of propagation of electromagnetic waves in free space and transmission lines,
• Analyse and evaluate the performance of electronic warfare system components,
• Assess the propagation of electromagnetic signals in physical environments,
• Design antenna elements and develop phased arrays performance models.

To provide you with an understanding of the subjects supporting the specialist modules and to provide you with the essential signal analysis and statistical tools used in the course.

• Statistics and Noise: Probability, random variables, probability distributions, covariance, correlation. Noise sources, noise bandwidth, noise figure, noise temperature. Cascaded networks. Mathematical representation of noise,
• Analogue and Digital Signal Processing 1: Analogue methods used to describe, analyse and process signals and the behaviour of systems: Fourier and Laplace transforms, correlation and convolution, impulse response and transfer function,
• Analogue and Digital Signal Processing 2: Matched filters, the z-transform. Advantages/ disadvantages of DSP, sampling and quantisation, digital filters, DFT and FFT, DSP applications in communications and radar,
• Decision Theory: Hypothesis testing, probabilities of false alarm and detection, Bayesian systems, error probability and bit error rate, receiver operating characteristics. Bit-error rate lab demo.

• Describe the signal processing methods commonly encountered in sensor, communications and EW systems,
• Evaluate the effect of randomly varying signals on the decision processing in sensor and communication systems,
• Identify and analyse signal and noise waveforms commonly encountered in communications, sensor and electronic warfare systems in the time and frequency domains,
• Analyse the detection performance of such systems.

To provide you with an understanding of the fundamental principles of radar, allowing you to relate this to the design and analysis of radar systems.

• Introduction: comparison with other sensors, frequency bands, relationship between size, wavelength and range, target data, historical notes,
• Radar detection theory: radar range equation, Pd, Pfa and SNR relationships, FAR, No. hits, Integration (quadrature detection),
• Pulsed Radar Parameters: PRF, pulse width, duty ratio, peak and average powers, min range, eclipsing, max unambiguous range, low PRF, spectrum of pulsed radar, signal bandwidth, matched reception, range resolution. Search radar application,
• Losses: effect of clear air, precipitation, multipath; Losses associated with radar system, including the antenna (beam-shape loss),
• CW and FM ranging: The Doppler effect, Doppler sensing, clutter rejection, Doppler filtering/velocity gating. Two phase linear saw-tooth modulation, ranging, effect of Doppler, velocity and range measurement. Missile seeker,
• Radar cross-section: principal factors; surface reflection effects; forms of scattering; echo mechanisms; variation of RCS with angle; typical values; Swerling models,
• Pulse compression: frequency coding (FMOP); Phase coding (PMOP); matched filtering; range and velocity resolution; Compressed pulse width; Range-velocity coupling,
• Clutter: surface and volume backscatter coefficient; spatial and temporal variation; estimation of clutter return and signal-to-clutter ratio for volume and surface clutter; statistical description for clutter; clutter spectrum and de-correlation time,
• CFAR: Constant false alarm rate systems; Clutter statistics and CFAR
• performance · Pulse-doppler radar: principle of operation; clutter spectrum; characteristics of HPRF and MPRF systems; FMICW in range measurement; multiple PRFs in range measurement. Airborne early-warning radar: requirements; design drivers and solution; typical parameters. Battlefield surveillance radar: requirements; system design; unambiguous range and velocity measurement · MTI radar: System diagram; clutter rejection by single and double delay line cancellers; blind speed · GMTI: MTI from an airborne platform, target measurement accuracy in range and in angle; clutter Doppler spread Tracking Radar. Monopulse and conical scan angle- trackers; range and velocity gates for range and Doppler tracking; angle-tracking errors; track-while-scan systems; continuity tracking synthetic-aperture radar: Cross range resolution, unfocussed SAR, focussed SAR, array length, array processing, resolution, Doppler Beam

On successful completion of this module you will be able to:

• Analyse radar detection performance in noise and clutter, relating these principles to conventional radar system design,
• Assess the performance and identify particular operational advantages of modern multi-function radar and SAR systems Skills and Other Attributes,
• Critically assess the detection performance of a radar system, given its design parameters,
• Produce a viable radar system design, given a suitable specification of the required radar performance,
• Generate and analyse radar waveforms and target echoes with MATLAB.

• Ioannis Vagias

To provide you with an understanding of the principles, design and analysis of the electronic threats to radar systems and how radar systems may be protected.

• Radar ES: Operational use; Calculation of ES sensitivity; The radar/ES detection battle; The requirements for a quiet radar; The ES process; Observable parameters; Antenna configurations for AOA measurement; Probability of intercept; Intercept analysis; Signal Sorting,
• Radar EA: Jamming techniques and strategies; SJNR calculations; range-gate and velocity-gate pull-off; angle deception against monopulse trackers; deception and decoy techniques; DRFM,
• Radar ED: Frequency and PRF agility; polarisation diversity; power management; sidelobe suppression; dual-band technique,
• Low probability of intercept radar waveforms: Power management, wideband FM, PSK: pseudo-random phase coding (maximal length sequences), poly-phase. Coding (Frank, P1, 2, 3, 4 codes), FSK: frequency hopping (Costas sequences), hybrid approaches,
• Jamming of SAR systems: Principles of SAR Jamming,
• Anti-Radiation Missile Seekers: ARM operational modes and impact on seeker, monopulse seeker design, detection ranges, example designs. 

On successful completion of this module you will be able to:

• Use concepts of sensitivity, resolution and discrimination to establish the capabilities and applications of receivers used in ES,
• Outline the various electronic attack and associated defence measures applicable to modern radar systems,
• Identify the role and quantify the performance of a modern radar system, given suitable data regarding its transmissions,
• Select and assess appropriate electronic defence measures against specified threats, given an operational specification.

• Dr David James

To introduce the you to the field of EO/IR technology and give an understanding the underlying principles. To give an appreciation of the likely future advances in the technology and the importance of EO/IR technology in the wider defence system.

Simple radiometry and power calculations, signature generation (solid and gaseous), contrast, atmospheric effects, optical systems, detector type (thermal, photon, one and two dimensional arrays, fibre sensors), cooling requirements, detector performance characteristics, simple electronic processing, display options, EO/IR seeker systems, countermeasures (including stealth) and counter-countermeasures, digital image processing.
 



 

On successful completion of this module you will be able to:

• Describe EO/IR systems and the underlying principles and technology,
• Analyse the significance of the EO/IR system in the defence context,
• Assess the performance of EO/IR systems.

Increase the depth of knowledge in the field of EO/IR technology and give an understanding of the underlying principles. Give an appreciation of the likely future advances in the technology and the importance of this technology in the wider defence system.

Advanced radiometry and power calculations, modulation transfer function, minimum resolvable temperature difference, advanced digital image processing, laser systems (principles and applications), laser directed energy weapons, laser countermeasures and electro-optic protection measures.

On successful completion of this module you will be able to:

• Describe EO/IR systems and the underlying principles and technology,
• Analyse the significance of the EO/IR system in the defence context,
• Assess the performance of EO/IR systems.