초록 ▼

An airborne surveillance method and system allows an observer aircraft to determine the position and change of position of a multiplicity of target aircraft and thus allows analysis of collision threats from these aircraft. The system uses a phase comparison direction finding antenna to determine di

An airborne surveillance method and system allows an observer aircraft to determine the position and change of position of a multiplicity of target aircraft and thus allows analysis of collision threats from these aircraft. The system uses a phase comparison direction finding antenna to determine direction of nearby ground based SSRs and all target aircraft of interest. The system further makes use of all other available data including Mode C transponder generated altitude information of the target aircraft, the altitude of the observer aircraft, the received signal strength of both the SSR beam and the received transponder signal, the time difference of arrival between the SSR interrogation signal and the response from the target aircraft, and a variety of other factors to determine the position of the target aircraft. The system compensates for the attitude of the observer aircraft and performs optimal Kalman filtering on the input data set to produce an estimate on target position based upon prior estimates and upon information contained in the data set while making estimates of the error magnitude of each measurement and compensating for these errors. The covariance matrix Q of the Kalman filter is adaptively vaired so as to optimize the estimate of the degree of correlation between various input values.

대표청구항 ▼

In an environment having at least one rotating interrogation signal source, a method of locating the position of at least one target object carrying an interrogation signal responsive transponder from an observer object located remotely from said interrogation signal source, the positions of the obs

In an environment having at least one rotating interrogation signal source, a method of locating the position of at least one target object carrying an interrogation signal responsive transponder from an observer object located remotely from said interrogation signal source, the positions of the observer object, target object and interrogation signal source forming a geometrical arrangement, comprising: (a) determining the direction of said interrogation signal source by direction finding on said interrogation signal to develop source direction data; (b) determining the direction to a said target object by direction finding on a transponder signal produced by said transponder to develop target direction data; (c) assembling additional available data relevant to relative positions of said objects and/or said interrogation signal source, said additional data being selected to form a data set best suited to develop a present position estimate of said target object in the present geometrical arrangement; (d) developing a present position estimate of said target object based on said direction data and said data set of additional data; and (e) developing a present position value of said target object by using a past position value to modify the present position estimate including varying the degree of modification based on a value associated with said present position value: said steps (d) and (e) performing the continuous tracking of target object position through geometrical arrangements where the target object position is not readily observable from a single interrogation signal source to allow full time tracking of said target object even when transmitting responses to interrogation signals from only a single interrogation signal source independent of said geometrical arrangement.