PRIMARY RADAR The radar (acronym of “radio detection and ranging) is a system that exploits the propagation and the diffraction of electromagnetic waves at very high frequency (GHz) to obtain the detection and the measurement of different characteristics of objects in flight over considerable distances in the space surrounding the transmitting station. It’s not necessary that the target is cooperating, it is totally passive in the detection process. The system exploits a simple and intuitive principle: it transmits an electomagnetic signal of adequate power and appropriately modulated by highly directive antenna for a certain period of time, to listen to the echo that the signal produces when it is reflected by a metallic surface (a nacelle o fan aircraft) or other surfaces that don’t permit the passing of the radiofrequency wave (like mountains, various obstacles, rain, etc…). Since the returning signal is much weaker than the transmitted one (it’s only a little part reflected by the surface of the aircraft) it needs to be amplified during the reception phase, trying to keep down the noise level in order to discriminate useful targets from background noise and interferences (clutter). SECONDARY RADAR Born during the Second World War to help the recognition and the discrimination between friendly aircraft from the enemy ones (referred to as IFF: Identification Friend or Foe), the Secondary radar has assumed function of surveillance during peacetime (SSR Secondary Surveillance Radar), usually together with the primary radar. It needs less power than the primary radar but it requires the cooperation of the target. Also in this case the principle of functioning is quite intuitive: a train of coded pulses that constitute the interrogation of the system is transmitted on a precise frequency. The plane, this time with a special on-board system called "transponders" (auto responder) in particular conditions responds automatically, providing also a coded response (12-bit) on another frequency on a standardized international level (1090 MHz). The received signal is then decoded and interpreted to be associated with a primary echo and presented with the corresponding alphanumeric information. PHOTONIC RADAR IN PISA The testing of the first photonic radar that can handle even the most intense air traffic has started in Pisa. The prototype, the first in the world, uses light to generate and detect radio frequency signals with a great efficiency, even better than the current radars. It was made in Italy with the help of the European Research Council ( ERC ) and thanks to the collaboration between the Inter-University Consortium for Telecommunications of Pisa ( CNIT ) and the Institute of Communication Technologies , Information and perception ( Tecip ) of the Scuola Superiore Sant'Anna of Pisa. At the end of the study, the researchers, led by Antonella Bogoni , will determine the level of precision achieved by the device designed. '' Tests - said Antonella

Bogoni - constitute the first steps towards improved intensive air traffic management and for this reason we placed our radar on the roof Istitut Tecip, to take advantage of the proximity to the airport of Pisa. But our device uses technologies that can be applied both in the port area, for military use or for environmental monitoring, and have already received interest ENAV and Italian and foreign companies . " The radar will monitor the air traffic of the airport ' Galileo Galilei ' for a few weeks. Consequently, the data collected and processed by the radar will be compared with those obtained directly from the aircraft during the flight, thus verifying the accuracy of the device. The radar can detect objects with a higher resolution by using smaller antennas, the technology behind the photonic radar can be used to develop portable devices for people's safety. Among the possible applications the researchers suggest environmental monitoring, traffic control, in air and land, and the integration of communication functions for the authorities to control the airport. http://ansa.it/scienza/notizie/rubriche/tecnologie/2013/07/11/primo-radar-fotonico_9008500.html http://it.wikipedia.org/wiki/Radar http://www.enav.it/portal/page/portal/PortaleENAV/Home/ChiSiamo? CurrentPath=/enav/it/chisiamo/organizzazione_territoriale/funzionamento_radar