Invention Application
- Patent Title: MULTIPATH DOPPLER ADJUSTED FREQUENCY TRACKING LOOP
- Patent Title (中): 多路径调制频率跟踪环路
-
Application No.: PCT/US0102747Application Date: 2001-01-26
-
Publication No.: WO0159937A2Publication Date: 2001-08-16
- Inventor: AGRAWAL AVNEESH , SIH GILBERT , ROH MARK , BUTLER BRIAN , CHALLA RAGHU
- Applicant: QUALCOMM INC
- Assignee: QUALCOMM INC
- Current Assignee: QUALCOMM INC
- Priority: US49134900 2000-01-26
- Main IPC: H04B1/7087
- IPC: H04B1/7087 ; H04B1/7115 ; H04B1/7117 ; H04L27/00 ; H04B1/00
Abstract:
A novel and improved method and apparatus for frequency tracking is described. Two main sources of error that contribute to the frequency difference between locally generated carriers and those used to modulate received signals include frequency offset between the two timing sources and doppler effects due to relative movement between the sources. The present invention provides a tracking mechanism for removing the effects of error due to frequency offset as well as compensation for frequency error due to doppler in a plurality of multipath signals. Each finger (700a..700n) of a RAKE receiver utilizing the present invention will compute a frequency error for that finger. The weighted average of all of these frequency errors is calculated (710) and filtered (720) to provide a control signal for varying the frequency of IF and RF frequency synthesizers, accounting for the common frequency offset seen at each finger. Additionally, each finger is equipped with a rotator (706a...706n) for providing frequency adjustment specific to that finger. The frequency of each finger is adjusted through feedback of the frequency error finger.
Information query