Mitigation of Adaptive Antenna Induced Bias Errors in GNSS Receivers

Antenna arrays equipped with adaptive filtering allow global navigation satellite system (GNSS) receivers to operate in environments with harsh, sustained interference. However since these antennas utilize spatial and temporal filters, they have the potential to introduce significant bias errors into the code and carrier phase measurements made by GNSS receivers. For precision navigation applications, these biases must be mitigated. A novel bias estimation and correction technique is described in which additional logic is added to the receiver in order to provide runtime compensation for these antenna-induced biases. The technique is general in the sense that it can be applied to a wide variety of adaptive antenna and receiver implementations. It utilizes a computationally efficient bias estimation equation that incorporates stored antenna data, the adaptive filter weights, and the receiver discriminator function. After estimating the bias, the receiver can compensate for the bias errors either in the navigation processor or in the tracking loop of the GNSS receiver. Simulations demonstrate centimeter-level bias correction accuracy for a variety of signals using an adaptive antenna array in an environment with interference.