ADS-B and Onboard GPS Technologies in Spatial Monitoring of Overflights

Comparing the aircraft surveillance data (air tour data) recorded by ADS-B data logger and Onboard navigation (GPS) technologies

Aviation Authorities have been employing different technologies for aircraft monitoring or surveillance. The three main types of aircraft surveillance technologies are: 1. Radar-based aircraft surveillance 2. Automatic Dependent Surveillance-Broadcast (ADS-B) 3. Other Satellite Communication Devices

Radio detection and ranging (RADAR) is a type of passive remote sensing. In a radar system, radio equipment emits radio waves into the air or to the target and the waves are received after reflection from the target or object in the path of the beam. The time taken by the radio signals to return to the antenna is used to measure the range and the position of the rotating antenna determines the direction of the target (Federal Aviation Administration, 2023). There are two types of radar surveillance namely, primary surveillance radar (PSR) and secondary surveillance radar (SSR) (Giladi, 2020) and they have been the primary means of tracking aircraft in the National Airspace System since the late 1940s.

Beginning early 2000s, Federal Aviation Administration (FAA)'s started the Next Generation (NextGen) initiative or upgrade of air transportation system to meet the demands of 21st century (US DoT, 2007). ADS-B was identified as a cornerstone technology in the implementation of this initiative. FAA required all aircraft flying in designated or controlled airspace or into any airport requiring transponder to be equipped with ADS-B Out avionics from January 1, 2020. A data link transmitter receives its position from Global Navigation Satellite System (GNSS) and periodically broadcast its positional signals along with other information such as tail number, altitude, and velocity to the ground-based receiver, space-based receiver, and other aircraft. The update rate of ADS-B signal is two pings per second whereas radar's rate is one ping per 4s (Zhang et al., 2011).

Aircraft also use lightweight flight data recorders that are supported by Iridium (or similar) satellite constellation or network. The third party vendors catering this service include Spidertracks, Web Sentinel, Garmin, GSat, ForeFlight, inReach, etc. Iridium satellites are a constellation of 66 low-earth orbiting satellites with a global coverage. Iridium satellites are low orbit satellites at an altitude of 781 kilometers from the earth's surface and inclination of 86.4 degree. The devices (Onboard GPS) are smaller in size and cost-effective for obtaining surveillance data. They are connected to the central computer via satellite and the data are displayed and disseminated to the clients.