Analysis of radar coverage overlap over the continental U.S

Currently, beacon interrogator identification numbers within the Continental U.S. (CONUS) are coded using 4 bits, thus allowing to differentiate up to 15 beacons only as 0 is not an assigned value. In areas, such as the northeastern region, where the beacon density is high, coverage overlaps of 15 or more radars may preclude aircraft flying over these zones from unequivocally determining the identity of the beacon they are communicating with. The purpose of this paper is to identify all areas within the CONUS presenting a potential overlap of 15 or more beacons and to assign each of them an identity number allowing a clear distinction from all surrounding overlapping radars. The database used in this study included all continental ASR-7, ASR-8 and ASR-9 beacons (Airport Surveillance Radar-Models 7,8 & 9) as well as ATCBI-6 (Air Traffic Control Beacon Interrogator-Model 6) and En route Mode S radars. Coverage was generated by dividing the CONUS into 3-nmi square cells and calculating the total number of radars reaching each of them. An algorithm was then developed to minimize the number of identity codes necessary for unambiguous differentiation. Solutions affecting radar characteristics such as relinking or range reduction were considered to further decrease this number.