Aerospace and Electronic Systems Magazine August 2016 - 42

News & Information and with posters from: Dai, Wei, Imperial College, UK Gordon Oswald, Aveillant, UK Albert Huizing, TNO, Netherlands Tony Gillespie, UCL, UK Karl Woodbridge, UCL, UK Feng Li, Beijing Institute of Technology, China Carmine Clemente, Strathclyde University, UK David Stupples, City University, UK Andy Stove, University of Birmingham, UK Pietro Stinco, University of Pisa, Italy Francesco Fioranelli, Matt Ritchie, UCL, UK Mike Inggs, Daniel O'Hagan, University of Cape Town, South Africa RADAR TECHNOLOGY The development of technology is not the only driver in the acquisition of new radar systems. If we consider that a piece of military equipment should have an in-service lifetime of at least twenty years, it is likely that the requirements will change significantly over this time, so there will be both 'technology push' and 'requirements pull'. In addition, there will be the inevitable constraints of cost, and of Size, Weight And Power (SWAP), and - of increasing importance - of spectral purity. As an example to set the scene, it was pointed out that 2015 marked the fiftieth anniversary of Gordon Moore's famous publication [1], in which he observed that computing power (as measured by the number of transistors on a processing chip) essentially doubles every eighteen months. This relationship has been found to hold for many decades. His paper considered the implications of this result, and includes a cartoon of people standing in line to buy a 'personal computer'. To have predicted that more than fifty years ago is surely remarkable! Perhaps less well known is that the final paragraph of the paper considered the implications for radar, and in particular phased array radar. In this way it showed an extraordi- Hugh Griffiths and Alfonso Farina. 42 nary ability to predict the future, and should serve as an inspiration for the meeting. DISCUSSION The following paragraphs summarise the presentation and discussion under each of the eight topics. However, a first comment is that radar may be regarded in some quarters as a 'mature' technology, which tends to imply that all the important work has already been completed and that future advances will be incremental. That is far from the case, of course, but it suggests that we should instead use the term 'RF sensing', which encapsulates networked, cognitive and passive techniques which represent so much more than conventional approaches, and also acknowledges the common ground with electronic warfare. Waveform Diversity: Modern digital signal processing now allows us to generate precise, wide bandwidth radar waveforms and to vary them, potentially on a pulse-by-pulse basis - and this is the foundation of waveform diversity. In the future it will be possible to generate radar signals with precisely-controlled spectral characteristics, and this will be critical as the problem of spectrum congestion becomes ever more severe. Indeed, the classical tool for evaluating the performance of radar waveforms - the ambiguity function - says nothing about the spectral properties of the signal. As well as this, we can generate waveforms with ultra-low range sidelobes, but it is important to appreciate and to take into account the distinction between the code, which is the sequence of phase values, the waveform, when it is modulated onto a carrier with real phase transitions between each code element, and the emission, which is subject to the distortions introduced by transmitter and receiver. Electronic warfare is a key driver for waveform diversity, both to prevent detection/identification and then to mitigate the effects of hostile electronic attack. A significant amount of work has been accomplished on waveform design and associated adaptive receive processing based on optimization according to a wide range of different mathematical structures and metrics; however, it has been only relatively recently that mechanisms for subsequent physical implementation/application of these waveforms and processing schemes have emerged. There was discussion of the requirements for physical implementation of advanced waveforms and waveform-domain receive processing, providing various examples, and then discussed possible avenues for research moving forward including bio-mimetic approaches, waveform/transmitter co-design, and the coupling of different waveform domains. Bistatic radar techniques have been around since the very earliest days of radar, but it is only recently that they have properly come of age. This is partly because there are now applications where bistatic operation offers a genuine advantage, and partly because technology now permits things which were previously very difficult. Passive radar techniques have now attained a level of maturity that means that they are now seriously considered for mainstream applications such as Air Traffic Management, especially with ever-increasing pressure on spectrum [2]. A defense business website estimates that the civil and defense market for passive radar will be worth more than US$10 billion over the next ten years [3]. Key advances will need to IEEE A&E SYSTEMS MAGAZINE AUGUST 2016

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine August 2016