摘要：What is adaptive nulling vs. adaptive beamforming? What are the advantages and disadvantages?
A: Adaptive arrays are perhaps the single most powerful antijamming tool in the GNSS systems engineer’s toolkit. They can provide anywhere from 15 to 90 dB of jamming rejection depending on the specific architecture used. Their main disadvantage is that they require an array of antenna elements, each spaced about four inches apart (center to center), and thus are physically large.
Two general types of adaptive array antenna are used with GNSS receivers: single-output nulling antennas and multiple-output beamsteering antennas. Most deployed systems are single-output adaptive nulling antennas that operate as an antijamming appliqué. In this way, a GPS receiver need not know to what type of antenna it is connected, be it a fixed or controlled reception pattern antenna (FRPA or CRPA). New development systems tend to emphasize multiple-output beamsteering antennas because of their better performance. However, in order to handle the multiple output channels, a new receiver is required, too. The trend is to integrate the array processing with the GNSS receiver in a single unit.
