Noise Radar Technology as an Interference Prevention Method

In some applications, such as automotive and marine/navigation, hundreds of radars may operate in a small environment (e.g., a road complex or a strait) and in an allocated frequency band with limited width. Therefore, a compatibility problem between different radars arises that is not easily solved by time, frequency, space, or polarization diversity. The advent of fast digital signal processing and signal generation techniques makes it possible to use waveform diversity to solve this problem that will be exacerbated in the next future. Ideal waveforms for the diversity are supplied by Noise Radar Technology (NRT), whose application is promising in some military applications as well as in the civilian applications considered in this paper. In addition to being orthogonal as much as possible, the random signals to be transmitted have to satisfy requirements concerning side lobe level and crest factor, calling for novel, original design and generation processes. 1. Introduction In spite of its military origin, dated back to the 1930s, radar technology is being more and more applied in the civilian domain for the safety of air, sea, and land traffic. In sea and road applications, this technology is entering the mass market with a significant yearly reduction of costs, mainly due to the larger and larger integration of the hardware and to the scale economy. For example in the automotive radar the factory cost has fallen by one order of magnitude (from hundreds to tens of dollars) in a few years. A similar situation is to be expected in the field of marine radar [1, 2], present in most vessels, as they (X-band radar) are mandatory for all passenger vessels and for all vessels above 500 tons GT (Gross Tonnage), with a double-band requirement (X-band radar + S-band radar) above 3000？tons GT. The allocated bands are 9.3 to 9.5？GHz (X) and 2.9 to 3.1？GHz. Most marine radars use the simple and cheap magnetron transmitter, a 1940s technology, generating short pulses (from 50–80？ns in the short-range mode to 800–1000？ns in the long-range mode, up to 96？NM) and peak power from a very few kW to 12.5–25？kW (and 50？kW in coastal applications for Vessel Traffic Systems). The large number of marine radars in a given area, simultaneously present above the horizon, makes the mutual interference a very likely event. For a general overview of potential solution to this problem, see [3, 4]. In marine radars the most used solution is based on their relatively short pulses that can be suppressed (video blanking or thresholding) because they are received asynchronously with