Multi-stage GLONASS/GPS automatic frequency control

• Main Authors: SUN QINFANG, ZHOU HAO
• Format: Patent
• Language: English
• Published: 18.02.2014
• Subjects: ANALOGOUS ARRANGEMENTS USING OTHER WAVES; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION ORRERADIATION OF RADIO WAVES; MEASURING; PHYSICS; RADIO DIRECTION-FINDING; RADIO NAVIGATION; TESTING

A method of providing automatic frequency control pull-in for efficient receipt of GLONASS bits is described. This method can include first determining whether a channel noise (CNo) is greater than or equal to a predetermined value. When the CNo is greater than or equal to the predetermined value, the pull-in can be performed using a first series of predetection integration periods (PDIs) with activated decision-directed flips (DDFs) until a 20 ms boundary of a GLONASS data bit is found. When the CNo is less than the predetermined value, the pull-in can be performed using a second series of PDIs with always deactivated DDFs. A similar method of providing automatic frequency control pull-in for efficient receipt of GPS bits is also described.