GPS receiver and method for processing GPS signals

• US 6,272,430 B1
• Filed: 08/17/1998
• Issued: 08/07/2001
• Est. Priority Date: 09/06/1996
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Inventors: Krasner, Norman F.
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/136,011
• Time in Patent Office: 1,086 Days
• Field of Search: 342/357.06, 342/357.1, 342/357.12, 342/357.08, 342/357.01, 342/357.09, 342/358, 701/213, 701/215, 701/207
• US Class Current: 701/207
• CPC Class Codes: G01C 21/206 specially adapted for indoor navigation
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0045 : Transmission from base station to mobile station G01S5/009 takes precedence
• CPC Class Codes: G01S 5/0054 : of actual mobile position, i.e. position calculation on base station
• CPC Class Codes: G01S 5/009 : Transmission of differential positioning data to mobile
• CPC Class Codes: G06F 2221/2111 : Location-sensitive, e.g. geographical location, GPS
• CPC Class Codes: H01Q 1/273 : Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 21/28 : Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H03D 7/163 : the local oscillations of at least two of the frequency changers being derived from a single oscillator
• CPC Class Codes: H03J 2200/11 : Cellular receiver, e.g. GSM, combined with a GPS receiver
• CPC Class Codes: H03J 7/06 : using counters or frequency dividers
• CPC Class Codes: H04B 1/3805 : with built-in auxiliary receivers

Abstract

A global positioning system (GPS) receiver has first circuitry for receiving and processing pseudorandom sequences transmitted by a number of GPS satellites. The first circuitry is configured to perform conventional correlation operations on the received pseudorandom sequences to determine pseudoranges from the GPS receiver to the GPS satellites. The GPS receiver also includes second circuitry coupled to the first circuitry. The second circuitry is configured to receive and process the pseudorandom sequences during blockage conditions. The second circuitry processes the pseudorandom sequences by digitizing and storing a predetermined record length of the received sequences and then performing fast convolution operations on the stored data to determine the pseudoranges. The GPS receiver may have a common circuitry for receiving GPS signals from in view satellites and downconverting the RF frequency of the received GPS signals to an intermediate frequency (IF). The IF signals are split into two signal paths; a first of which provides the conventional correlation processing to calculate the pseudoranges. During blockage conditions, the IF signal is passed to the second signal path wherein the IF signals are digitized and stored in memory and later processed using the fast convolution operations to provide the pseudoranges. Alterative arrangements for the two signal paths include separate downconverting or shared digitizers. One embodiment provides both signal paths on a single integrated circuit with shared circuitry executing computer readable instructions to perform GPS signal processing appropriate to the reception conditions.

Claims

1. A method for using a GPS receiver, said method comprising:

activating said GPS receiver in a first mode of operation which comprises;

receiving first GPS signals from in view satellites;

demodulating said first GPS signals to extract satellite information regarding in view satellites and computing pseudorange information for said in view satellites;

activating said GPS receiver in a second mode of operation which comprises;

receiving second GPS signals from in view satellites;

processing said second GPS signals to determine pseudoranges to in view satellites;

receiving through said communication system a signal;

locking to said signal to generate a GPS local oscillator.

2. A method as in claim 1 wherein during said first mode, said satellite information is extracted from said first GPS signals and stored in a memory and wherein in said second mode, said satellite information stored in said memory and pseudoranges from said second GPS signals are used to calculate a position of said GPS receiver.

3. A method for using a GPS receiver, said method comprising:

activating said GPS receiver in a first mode of operation which comprises;

receiving first GPS signals from in view satellites;

demodulating said first GPS signals to extract satellite information regarding in view satellites and computing pseudorange information for said in view satellites;

activating said GPS receiver in a second mode of operation which comprises;

receiving second GPS signals from in view satellites;

processing said second GPS signals to determine pseudoranges to in view satellites;

receiving through said communication system a signal;

locking to said signal to generate a GPS local oscillator wherein said signal comprises a carrier and wherein said locking comprises frequency locking to said carrier.

4. A method as in claim 3 wherein said GPS receiver in said first mode determines a position of said GPS receiver from said pseudorange information and from said satellite information, and wherein said GPS receiver in said second mode determines said pseudoranges and transmits said pseudoranges for determination of said position of said GPS receiver.

5. A method for using a GPS receiver, said method comprising:

activating said GPS receiver in a first mode of operation which comprises;

receiving first GPS signals from in view satellites;

demodulating said first GPS signals to extract satellite information regarding in view satellites and computing pseudorange information for said in view satellites;

activating said GPS receiver in a second mode of operation which comprises;

receiving second GPS signals from in view satellites;

processing said second GPS signals to determine pseudoranges to in view satellites;

receiving through said communication system a signal;

locking to said signal to generate a GPS local oscillator;

further comprising in said second mode;

receiving non-differential GPS satellite assistance data from said communication system.

6. A method as in claim 5 wherein said non-differential GPS satellite assistance data comprises at least one of (a) Doppler information for in view satellites;

(b) identification information for in view satellites;

or (c) satellite ephemeris information for in view satellites.