Abstract: A method, system, and apparatus are disclosed for multipath isolation through the combined use of antenna diversity and frequency diversity. In particular, the present disclosure utilizes antenna diversity and frequency diversity to combat the deleterious effects of reflected signals on the positioning accuracy of satellite navigation systems. In at least one embodiment, the present disclosure uses two antennas and two frequencies for operation with a satellite navigation system. The present disclosure segregates the antennas and frequencies into two classes: references and monitors. The reference measurements are used for estimating the state of the vehicle, and the monitor measurements are used to detect faults that might degrade the reference estimation. Thus, the present disclosure enables an improvement in the positioning error experienced by roving users in downtown and indoor environments.

Abstract: A method, system, and apparatus are disclosed for multipath isolation through the combined use of antenna diversity and frequency diversity. In particular, the present disclosure utilizes antenna diversity and frequency diversity to combat the deleterious effects of reflected signals on the positioning accuracy of satellite navigation systems. In at least one embodiment, the present disclosure uses two antennas and two frequencies for operation with a satellite navigation system. The present disclosure segregates the antennas and frequencies into two classes: references and monitors. The reference measurements are used for estimating the state of the vehicle, and the monitor measurements are used to detect faults that might degrade the reference estimation. Thus, the present disclosure enables an improvement in the positioning error experienced by roving users in downtown and indoor environments.

Abstract: A multi-constellation GNSS augmentation and assistance system may include a plurality of reference stations. Each reference station may be adapted to receive navigation data from a plurality of different global navigation satellite systems and to monitor integrity and performance data for each different global navigation satellite system. An operation center may receive the integrity and performance data transmitted from each of the plurality of reference stations. A communication network may transmit a message from the operation center to navcom equipment of a user for augmentation and assistance of the navcom equipment.

Abstract: In a new receiver design, the specific transmitter unit is unchanged from a prior patent application but may also be substantially as described in the prior art. The transmitter is initially activated by the input of the pseudo-random generator code. This code may be any alpha-numeric series, but must be identical to that input to the receiver. When the code is input through the keypad, the transmitter uses internal algorithms to generate a unique shift-register feedback combination. This creates a pseudo-random (PN) code which repeats after a programmable number of bits, depending upon desired maximal signal correlation time. That is the longer the code the longer the correlation time. This PN code sequence is clocked at the desired clock (CHIP) rate inside the transmitter unit. The PN code sequence which is thus generated is then added in phase to the data which is a substantially lower rate than the CHIP rate.

Abstract: Digital information is convolved with a pseudorandom code and then transmitted at radio frequency in a spread spectrum signal to a receiver also containing the same pseudorandom code. Since the transmitted signal is below the noise floor for that bandwidth, it is virtually unjammable and undetectable without possession of the pseudorandom code. Successful extraction of the transmitted information depends upon precise matching of the transmitted frequency and the exact phase matching of the pseudorandom code at the receiver with the convolved pseudorandom code in the transmitted signal.