The presence/absence of an object, movement of the object, the direction of movement, the speed of movement, the shape of the object, the quantity of objects and time information related to these factors are detected without installing a means for transmission. An antenna device (1) has a function of receiving radio waves (EW1 to EW24) transmitted by GPS satellites and outputs a detection signal when the reception of the radio waves (EW1 to EW24) transmitted by the GPS satellites is blocked by an object (A). A signal processing device (2) detects the object (A) based upon the detection signal provided by the antenna device (1).

The method and apparatus for high level testing are disclosed. The high level testing is used to test and recover the damaged differential corrections. The high level test measures the Correction Quality Indicator (CQI) and is based on the information included in the current pseudorange correction (PRC), in the previous range rate correction (RRC), and in the previous PRC projected to a time tag of a current PRC. The method computes CQI and compares the computed CQI value with the threshold value T(FAR), wherein the T(FAR) is the threshold value based on a false alarm rate and confidence interval. If the CQI does not exceed the threshold value T(FAR) the corrections for the tested satellite or a combination of tested satellites are marked as valid for further use in the user receiver differential solution.

A portable three-dimensional position and velocity data archiving system for use with an aircraft during flight testing and evaluations. The system includes a ground based system and an airborne system. Each system includes a GPS receiver electrically connected with a GPS antenna for receiving and interpreting GPS signals transmitted from a GPS satellite constellation. Each system also includes a radio communication device for transferring position and velocity data as well as error correction data and guidance cues between the ground and airborne systems. The portable system acquires, processes, archives, and provides precise three-dimensional position and velocity data for the aircraft in real time. Information regarding aircraft position, direction, velocity, acceleration and any correction needs referenced to a selected coordinate system is immediately presented to a vehicle piloting crew on analog as well as digital indicators.

A differential carrier phase GPS navigational device comprises an integer estimator [32] adapted to estimate an integer that resolves an integer cycle ambiguity, a reference phase predictor [30] adapted to predict a present reference phase value from reference phase information received by a data link receiver [22], and a position calculator [28] for computing a present vehicle position from the estimated integer, the predicted present reference phase value, and GPS signals received at a vehicle GPS receiver [20]. The reference phase predictor [30] comprises electronic circuitry adapted to determine a polynomial function which fits the reference phase information, and to evaluate the polynomial function to determine the predicted reference phase value. Because the position calculator uses a reference phase value that is not delayed, the navigational device is able to provide a vehicle position that corresponds to the present time.

A high integrity navigation system is created using a low integrity navigation computer monitored by a high integrity system. A navigation sensor (e.g. DGPS, GPS, ILS, MLS, and the like) is programmed with a desired trajectory. The navigation sensor calculates the vehicle position and generates a deviation signal indicative of the deviation of the vehicle from the desired trajectory. The navigation computer uses the deviation signal in the control law computations to generate steering commands for controlling the vehicle. The navigation sensor monitors the deviation of the vehicle from the desired trajectory. If the deviation exceeds a predetermined threshold, an integrity alarm signal is communicated to a display or other alarm to alert the operator.