The study of the distribution of the terrestrial radionuclides (238U, 232Th e 40K), performed by using airborne gamma-ray spectroscopy techniques, is influenced by the height of the detector with respect to the ground. An uncertainty of 10% at a flight height of 100 m originates an estimation error of the order of 7% in 208Tl gamma signal, a daughter isotope of the 232Th decay chain. The use of a new class of spectrometers mounted on board of UAV (Unmanned Aerial Vehicle), for refined measurements in hostile places and boondocks, necessitates an accurate real-time estimation of the flight height. The Radgyro is an aircraft dedicated to multiparameter surveys and it is able to carry a set of instruments for a maximum payload of 120 kg, among which four NaI(Tl) gamma-ray spectrometers. An inertial station with an integrated GNSS (Global Navigation Satellite System) receiver provides the aircraft trim with a maximum frequency of 400 Hz. The aircraft is equipped with a network of three GNSS receivers positioned on the extremities of the hull of aircraft. A 24 Ghz radar altimeter detects the height with a frequency of 60 Hz. The measurement of pressure and temperature permit to infer the barometric height at 2 Hz. With the aim to study the uncertainties related to the flight height through the measurements acquired by the altimeters in comparison with the GNSS data, three flights were performed on the sea with a flight height range of 31-249 m, for a total time of 4702 seconds of effective flight. At the end of this study, we can affirm that the abundances error of K, U and Th increases of the 7.7%, 0.5% and 2.7% respectively, as a result of uncertainties related to the flight altitude.
Studio della quota di volo mediante GNSS, altimetro radar e barometro per rilievi di spettroscopia gamma da velivolo
ALBERI, Matteo;BALDONCINI, Marica;MANTOVANI, Fabio;STRATI, Virginia
2016
Abstract
The study of the distribution of the terrestrial radionuclides (238U, 232Th e 40K), performed by using airborne gamma-ray spectroscopy techniques, is influenced by the height of the detector with respect to the ground. An uncertainty of 10% at a flight height of 100 m originates an estimation error of the order of 7% in 208Tl gamma signal, a daughter isotope of the 232Th decay chain. The use of a new class of spectrometers mounted on board of UAV (Unmanned Aerial Vehicle), for refined measurements in hostile places and boondocks, necessitates an accurate real-time estimation of the flight height. The Radgyro is an aircraft dedicated to multiparameter surveys and it is able to carry a set of instruments for a maximum payload of 120 kg, among which four NaI(Tl) gamma-ray spectrometers. An inertial station with an integrated GNSS (Global Navigation Satellite System) receiver provides the aircraft trim with a maximum frequency of 400 Hz. The aircraft is equipped with a network of three GNSS receivers positioned on the extremities of the hull of aircraft. A 24 Ghz radar altimeter detects the height with a frequency of 60 Hz. The measurement of pressure and temperature permit to infer the barometric height at 2 Hz. With the aim to study the uncertainties related to the flight height through the measurements acquired by the altimeters in comparison with the GNSS data, three flights were performed on the sea with a flight height range of 31-249 m, for a total time of 4702 seconds of effective flight. At the end of this study, we can affirm that the abundances error of K, U and Th increases of the 7.7%, 0.5% and 2.7% respectively, as a result of uncertainties related to the flight altitude.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
