GPS car navigation system

• US 6,041,280 A
• Filed: 04/25/1996
• Issued: 03/21/2000
• Est. Priority Date: 03/15/1996
• Status: Expired due to Term

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Kohli, Sanjai, Chen, Steven
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US08/637,537
• Time in Patent Office: 1,426 Days
• Field of Search: 364/449.1, 364/449.2, 364/449.4, 364/449.3, 364/449.7, 364/449.8, 364/450, 364/4, 340/988, 340/990, 340/995, 342/357, 342/457, 701/207, 701/208, 701/209, 701/210, 701/213, 701/214, 701/217
• US Class Current: 701/201
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01C 22/00 Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/47 the supplementary measurement being an inertial measurement, e.g. tightly coupled inertial
• CPC Class Codes: G01S 19/50 whereby the position solution is constrained to lie upon a particular curve or surface, e.g. for locomotives on railway tracks
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/7115 Constructive combining of multi-path signals, i.e. RAKE receivers
• CPC Class Codes: H04B 2201/70715 with application-specific features
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]

Abstract

A GPS car navigation system derives GPS position update information from motion of the car along the actual track. Turns along the track are detected when they actually occur and are compared with the predicted turns so that the time and position at the actual turn can be used to update the then current GPS derived position of the vehicle. Updating position information with actual turn data improves the accuracy of GPS navigation especially during single satellite navigation.

Claims

1. A method of updating GPS position information for a vehicle navigating on roadways, comprising the steps of:

estimating the location of a vehicle along a predetermined track from the signals from a single GPS satellite;

deriving an indication that the vehicle has made a turn at a particular point along a predetermined track;

comparing the turn indication with stored navigation data to select data related to one or more predicted turns at or near the particular point;

comparing the turn indication with the predicted turn data to verify that the indicated turn corresponds to the predicted turn; and

updating the estimated position of the vehicle along the track to indicate that the vehicle was at the predicted turn location at a time corresponding to the turn indication.

2. A GPS system for navigating a vehicle, comprising:

a map data base including a known track;

means for estimating a position of a vehicle along a known track by tracking a single GPS satellite information related to the direction of travel of the with a receiver mounted in the vehicle;

means for detecting changes in the direction of travel of the vehicle; and

means for comparing the detected changes in the direction of travel of the vehicle with known changes in direction of the known track to improve the estimate of the position of the vehicle along the known track.

3. The invention of claim 2, wherein the means for estimating a position of a vehicle further comprises:

means for estimating altitude, clock and cross-track data to provide an estimate of the position of the vehicle along the known track.

4. A method of terrestrial navigation, comprising the steps of:

tracking one GPS satellite to provide an estimate of the position of the vehicle related to the travel of the vehicle along a selected track; and

deriving vehicle navigation data from changes in the direction of travel of the vehicle along the selected track to improve the estimate of the position of the vehicle along the selected track.

5. The invention of claim 4, wherein the step of tracking one GPS satellite to provide an estimate of the position further comprises the step of:

forming altitude, clock and cross-track estimates.