Engines In System Simultaneously Receiving GPS And GLONASS Signals

Abstract

A receiver for receiving both GPS signals and GLONASS signals is provided. This receiver includes an analog front end (AFE), a GPS digital front end (DFE) and a GLONASS DFE for receiving an output of the AFE, and a dual mode interface (DMI) for receiving outputs of the GPS and GLONASS DFEs. Search engines are provided for receiving outputs of the DMI. Notably, certain front-end components of the AFE are configured to process both the GPS signals and the GLONASS signals.

1 . A receiver for receiving GPS signals and GLONASS signals, the receiver comprising:
 an analog front end (AFE);   a GPS digital front end (DFE) and a GLONASS DFE for receiving an output of the AFE;   a dual mode interface (DMI) for receiving outputs of the GPS and GLONASS DFEs;   search engines for receiving outputs of the DMI;   tracking engines for receiving outputs of the DMI;   a GPS pre-correlation noise estimator configured to receive GPS-specific signals from the dual mode interface; and   a GLONASS pre-correlation noise estimator configured to receive GLONASS-specific signals from the dual mode interface,   wherein the GPS pre-correlation noise estimator and the GLONASS estimator are separate from any training engines.   
     
     
         2 . The receiver of  claim 1 , wherein each of the GPS and GLONASS pre-correlation noise estimators comprises:
 a first integrate and dump block to remove out-of-band noise for both I and Q components of an incoming signal; and   a second integrate and dump block for generating a noise estimate output based on an output of the first integrate and dump block.   
     
     
         3 . The receiver of  claim 2 , wherein each of the GPS and GLONASS pre-correlation noise estimators can further comprise a counter that counts each dump. 
     
     
         4 . The receiver of  claim 1 , wherein results from the GPS pre-correlation noise estimator and the GLONASS pre-correlation noise estimator are configured to determine a presence of interference. 
     
     
         5 . The receiver of  claim 2 , wherein the receiver is configured to use the presence of interference, combined with a signal strength of a GPS/GLONASS signal to exclude a satellite from being used in a navigation solution. 
     
     
         6 . A tap generator for a receiver configured to receive GPS and GLONASS signals, the tap generator comprising:
 a shift register configured to shift when a new chip is generated, each register of the shift register storing a different chip, wherein a middle register provides a prompt code;   a plurality of multiplexers, each multiplexer configured to select one of the chips stored by the shift register, each multiplexer outputting one of: a noise(N) code, a very early (VE) code, an early (E) code, a late (L) code, and a very late (VL) code; and   a control circuit for controlling the plurality of multiplexers.   
     
     
         7 . The tap generator of  claim 6 , wherein the control circuit comprises:
 a plurality of adders, each adder adding a relative tap spacing (RTS) for one of: a tap N, a tap VE, a tap E, a tap L, and a tap VL, and a truncated code phase; and   a plurality of floor blocks, each floor block configured to floor one of five sums generated by the five adders, and generate a control signal for one of the five multiplexers.