HIGH SENSITIVITY GLONASS/GPS AUTOMATIC FREQUENCY CONTROL

摘要

Updates to an AFC loop can be performed to provide high-sensitivity tracking. A 20 ms update interval and PDI=10ms is used for every other update. A setting is used for each update between the 20 ms updates. Notably, the setting uses PDI=5ms. The setting can include first, second, and third cross-dot pairs associated with a first bit, a second bit, and a cross-bit boundary between the first and second bits, respectively. A sum of these pairs can be scaled down when the signal strength is below a predetermined threshold. In another embodiment, the setting can include a first cross-dot pair associated with a first bit and a second cross-dot pair associated with a second bit. A sum of these pairs can also be scaled down when signal strength is below a predetermined threshold.